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. 2023 Aug 8;21(8):e08145. doi: 10.2903/j.efsa.2023.8145
Reference Study Country Duration Funding Design Subject characteristics at baseline (a) Intervention (a) Endpoint assessed Results RoB Tier
Children and adolescents

Asghari et al. (2021)

Iran

Latitude 35.7° N

1 yr

Unclear [No external funding]

RCT (parallel)

Inclusion criteria:

Age 6–13 y; age‐ and sex‐specific BMI Z‐score ≥1.

Exclusion criteria:

Serious illness, vitamin D supplement use.

N participants, randomised/completed/analysed:

G1: 120/100 at 6mo, 92 at 12mo/120

G2: 127/106 at 6mo, 101 at 12mo/127

G3: 131/112 at 6mo, 108 at 12mo/131

Sex (% girls)

G1: 50

G2: 48

G3: 45

Age (y)

G1: 9.2 ± 1.8

G2: 9.4 ± 1.6

G3: 9.4 ± 1.8

Serum 25(OH)D (ng/mL):

G1: 11.5 (8.9) ng/mL [28.8 (22.3) nmol/L]

G2: 11.7 (10.5) ng/mL [29.3 (26.3) nmol/L]

G3: 12.3 (10.2) ng/mL [30.8 (25.3)]

Assay: ECLIA (electrochemiluminescence immunoassay (Roche Diagnostics)

BMI (kg/m2)

G1: 23.2 ± 3.0

G2: 23.5 ± 3.5

G3: 23.3 ± 3.5

Ethnicity [assumed]: Persian

Smoking status: NR

Alcohol use: NR

Health status: Overweight and obese

Season at recruitment (%)

Spring and summer:

G1: 50.8

G2: 50.4

G3: 49.6

Autumn and winter:

G1: 49.2

G2: 49.6

G3: 50.4

Vitamin D3

Doses (labeled)

G1: vitamin D3 4 × 1000 IU/wk => 600 IU/d / 15 μg/d

G2: vitamin D3 1000 IU/d / 25 μg/d

G3: vitamin D3 2000 IU/d / 50 μg/d

Analysed vitamin D3 doses

G2: 25.1 μg/d

G3: 51.1 μg/d

Background vitamin D intake (IU/d):

G1: 30.8 (71.6) IU/d [0.8 (1.8) μg/d]

G2: 43.2 (94.4) [1.1 (2.4) μg/d]

G3: 32.8 (86.0) [0.8 (2.2) μg/d]

Background calcium intake (mg/d):

G1: 574 (353)

G2: 605 (432)

G3: 610 (454)

Compliance

Pill count method – ≥80% of pills consumed (%):

G1: 84.3 (76.9–91.8)

G2: 87.5 (78.5–96.0)

G3: 84.0 (76.3–92.6)

Serum 25(OH)D (ng/mL) at 12 mo:

G1: 23.11 (18.55–26.52) ng/mL [57.78 (46.38–66.3) nmol/L]

G2: 25.56 (21.27–29.58) ng/mL [63.9 (53.18–73.95) nmol/L]

G3: 28.63 (24.55–34.97) ng/mL [71.58 (61.38–87.43) nmol/L]

Serum calcium:

‐ secondary outcome

‐ measured at baseline and at 6 and 12 mo

‐ no cut‐off for elevated levels provided.

Stated that no side effect was reported in any intervention groups, no increase in concentration of calcium was observed and intervention did not have any effect on serum calcium.

Serum calcium at baseline (mg/dl), median (IQR)

G1: 9.9 (9.5–10.4)

G2: 10.1 (9.7–10.6)

G3: 9.9 (9.5–10.4)

Serum calcium at 6 mo (mg/dl), median (IQR)

G1: 10.4 (10.1–10.7)

G2: 10.3 (10–10.6)

G3: 10.5 (10–10.7)

Serum calcium at 12 mo (mg/dl), median (IQR)

G1: 10.4 (10.1–10.7)

G2: 10.3 (10.1–10.7)

G3: 10.3 (10.1–10.7)

 2

Belenchia  et al. (2013)

USA

Latitude [assumed] 38.9° N

6 mo

Private funding

RCT (parallel)

Inclusion criteria:

Aged 9 to 19 y; being at least at the 85th percentile

for BMI.

Exclusion criteria:

1) use of vitamin D

supplements other than a general multivitamin; 2) the use of medication affecting vitamin D metabolism; 3) the use of a tanning bed or undergoing UV light therapy; 4) use of oral hypoglycemic agents; 5) previously diagnosed hepatic or renal disorders; 6) pregnancy; 7) or the use of tobacco or alcohol.

N participants, randomised/completed/analysed:

G1: 23/15/17

G2: 21/14/18

Sex (% Females)

G1: 52

G2: 48

Age (y)

G1: 13.9 ± 2.4

G2: 14.6 ± 2.3

Serum 25(OH)D (ng/mL)

G1: 19.6 ± 7.9 [49 ± 19.75 nmol/L]

G2: 19.2 ± 6.3 [48 ± 15.75 nmol/L]

Assay: ELISA (Immunodiagnostik AG)

BMI (kg/m2)

G1: 38.9 ± 6.7

G2: 39.5 ± 5.1

Ethnicity (%)

African American:

G1: 26

G2: 33

Other ethnicities: NR

Smoking status: NR

Alcohol use: NR

Health status: Obese

Season: Recruitment occurred from Nov 2009 until Jan 2011.

Vitamin D3

Doses

G1: placebo

G2: vitamin D3 4000 IU/d [100 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method (%)

G1: 82

G2: 81

Serum 25(OH)D at 6 mo

G1: no significant change from baseline

G2: significant increase from baseline.

Changes independent of season.

Serum calcium:

‐ secondary outcome

‐ measured at baseline and at 3 and 6 mo

‐ no cut‐off for elevated levels provided.

Serum calcium concentrations remained

unchanged in both groups throughout the study and were well within the normal range at each time point.

 2

Lewis et al. (2013)

USA

Latitude 34° N and 40° N

12 wk

Private funding

(RCT parallel)

Inclusion criteria:

Children at sexual maturity stages 2 and 3. Both parents and grandparents were the same race as the child and considered themselves non‐Hispanic. Children taking nutritional supplements were enrolled after a 4‐week washout. Children agreed to not alter dietary or physical activity pat

Exclusion criteria:

Included menarche, growth disorders, diseases (eg, cerebral palsy), and medications (eg, corticosteroids) known to influence bone metabolism.

N participants,

randomised/completed/analysed:

G1: 66/63/63

G2: 64/59/59

G3: 65/63/63

G4: 64/61/61

G5: 64/58/58

Sex (% Females)

All: 49.8

Age (y)

G1: 11.5 ± 1.2

G2: 11.3 ± 1.2

G3: 11.1 ± 1.1

G4: 11.4 ± 1.4

G5: 11.5 ± 1.2

Serum 25(OH)D (nmol/L)

G1: 71.5 ± 18.6

G2: 71.4 ± 19.5

G3: 71.1 ± 19.7

G4: 65.8 ± 7.3

G5: 70.0 ± 17.5

Assay: 2‐step RIA (Diasorin) and further monitored through DEQAS

BMI‐for‐age percentiles

G1: 63.3 (29.5)

G2: 67.6 (27.8)

G3: 70.4 (28.4)

G4: 71.5 (30.4)

G5: 67.4 (30.1)

Ethnicity (%)

White: 48.9

Black: 51.1

Smoking status: NR

Alcohol use: NR

Health status: Healthy children

Season:

Enrolment in 2009 to 2010 and 2010 to 2011 during the winter (Oct through Dec) when serum 25(OH)D is at its nadir.

Vitamin D3

Doses (labeled)

G1: placebo

G2: vitamin D3 400 IU/d [10 μg/d]

G3: vitamin D3 1000 IU/d [25 μg/d]

G4: vitamin D3 2000 IU/d [50 μg/d]

G5: vitamin D3 4000 IU/d [100 μg/d]

Analysed doses

G1: 0.184 IU

[0.0046 μg]

G2: 486 IU [12.15 μg]

G3: 1140 IU

[28.5 μg]

G4: 1880 IU

[47 μg]

G5: 4710 IU [117.75 μg]

Background vitamin D intake (IU/d)

G1: 151 ± 96 IU/d [3.8 ± 2.4 μg/d]

G2: 198 ± 140 IU/d [5.0 ± 3.5 μg/d]

G3: 143 ± 111 IU/d [3.6 ± 2.8 μg/d]

G4: 184 ± 160 IU/d [4.6 ± 4.0 μg/d]

G5: 175 ± 101 IU/d [4.4 ± 2.5 μg/d]

Background calcium intake (mg/d)

G1: 837 ± 321

G2: 1000 ± 467

G3: 822 ± 375

G4: 914 ± 411

G5: 945 ± 378

Compliance

Pill count method – vitamin D3/placebo (%)

All: 52.3

Serum 25(OH)D, change over 12 wk (nmol/L), mean ± SE

G1: −10.12 ± 2.86

G2: 5.54 ± 2.59

G3: 20.29 ± 2.61

G4: 37.57 ± 2.66

G5: 76.07 ± 2.95

Hypercalcaemia:

‐ safety measure

‐ blood samples were collected at baseline and at 3, 6, 9, and 12 wk, and calcium was apparently analysed

‐ defined serum calcium >10.6 mg/dL[2.625 mmol/L].

Hypercalciuria:

‐ safety measure

‐ second‐void urine samples were collected

at each visit

‐ defined as urine

calcium corrected for creatinine >0.22 mg [0.055 mmol].

Hypercalcaemia

Over 12 wk, 3 children met the criteria defining hypercalcaemia, and none of these children were assigned to 100 μg/d.

Hypercalciuria

Over 12 wk, 3 children met the criteria defining hypercalciuria, and none of these children were assigned to 100 μg/d.

 2

Maalouf et al. (2008)

Lebanon

Latitude [assumed] 33.9° N

1 year

Private funding

RCT (parallel)

Inclusion criteria:

Age 10–17 y.

Exclusion criteria:

Disorders or medications known to affect bone metabolism

N participants, randomised/completed/analysed

Females:

G1: NR/NR/55

G2: NR/NR/58

G3: NR/NR/55

Males:

G1: NR/NR/56

G2: NR/NR/56

G3: NR/NR/60

Sex (%)

Females: 49.4

Boys: 50.6

Age (y)

All: 13.1 ± 2

Serum 25(OH)D (ng/mL):

Females:

G1: 14 ± 7 [35 ± 17.5 nmol/L]

G2: 14 ± 9 [35 ± 22.5 nmol/L]

G3: 13 ± 8 [32.5 ± 20 nmol/L]

Males:

G1: 16 ± 6 [40 ± 15 nmol/L]

G2: 16 ± 7 [40 ± 17.5 nmol/L]

G3: 16 ± 7 [40 ± 17.5 nmol/L]

Assay: RIA (Diasorin)

BMI: NR

Ethnicity [assumed]: Arab

Smoking status: NR

Alcohol use: NR

Health status: Apparently healthy

Season: Summer to early fall

Vitamin D3

Doses (labeled)

G1: placebo

G2: vitamin D3 200 IU/d [5 μg/d]

G3: vitamin D3 2000 IU/d [50 μg/d]

Analysed doses:

Stated that the vitamin D concentration in the three

solutions was within 10% of that anticipated based on the label on the bottles and the dilution protocol.

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – intake of the total dose of vitamin D (%)

G1: 98 ± 3

G2: 98 ± 3

G1: 97 ± 3

Serum 25(OH)D at 1 year (ng/mL)

Females:

G1: 16 ± 8 [40 ± 20 nmol/L]

G2: 17 ± 6 [42.5 ± 15 nmol/L]

G3: 38 ± 31 [95 ± 77.5 nmol/L]

Males:

G1: 17 ± 6 [42.5 ± 15 nmol/L]

G2: 20 ± 7 [50 ± 17.5 nmol/L]

G2: 35 ± 9 [87.5 ± 22.5 nmol/L]

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 6 and 12 mo

‐ defined as >10.7 mg/dl [2.675 mmol/L].

Elevated serum calcium, n of participants

G1: 2 girls (10.8 and 11.1 mg/dl [2.7 and 2.78 mmol/L]) and

3 boys (10.8 mg/dl [2.7 mmol/L])

G2: 1 boy (10.9 mg/dl [2.72 mmol/L])

G3: 1 boy (11.0 mg/dl [2.75 mmol/L])

Stated that the 7 children had serum calcium levels above the upper limit of normal at 1 yr.

 2

Rajakumar et al. (2020)

USA

Latitude [assumed] 40.4° N

6 mo

Mixed funding

RCT (parallel)

Inclusion/exclusion criteria:

Overweight or obese children

(BMI ≥85th percentile) who were free of conditions or treatments that could affect glucose homeostasis, BP, cholesterol concentrations, or vitamin D and calcium metabolism.

Eligible participants were vitamin D–deficient (serum 25‐hydroxyvitamin

D [25(OH)D] <20 ng/mL) and had normal serum calcium (10–14 y: 8.8–10.8 mg/d [2.2–2.7 mmol/L]; ≥15 y, 8.4–10.2 [2.1–2.55 mmol/L] mg/dL) during a screening assessment and who had fasting glucose concentrations of <125

mg/dL and, in the case of postmenarchial girls, had a negative urine pregnancy test at the time of randomization.

N participants,

randomised/completed/analysed:

G1: 76/50/50

G2: 74/48/47

G3: 75/58/58

Sex (% Females)

G1: 71.1

G2: 60.8

G3: 64.0

Age (y)

G1: 13.5 ± 2.3

G2: 13.5 ± 2.2

G3: 13.9 ± 2.4

Serum 25(OH)D (ng/mL)

G1: 14.3 ± 4.3

[35.8 ± 10.8 nmol/L]

G2: 14.4 ± 3.4

[36.0 ± 8.5 nmol/L]

G3: 14.2 ± 3.5

[35.5 ± 8.8 nmol/L]

Assay: LC–MS/MS

BMI (kg/m2)

G1: 30.7 ± 6.9

G2: 30.0 ± 6.1

G3: 30.3 ± 5.8

Ethnicity (%)

Black:

G1: 93.4

G2: 94.6

G3: 93.3

Hispanic:

G1: 2.6

G2: 1.4

G3: 9.3

Smoking status: NR

Alcohol use: NR

Health status: Overweight or obese vitamin D–deficient children

Season: NR

Vitamin D3

Doses (labeled)

G1: vitamin D3 600 IU/d [15 μg/d]

G2: vitamin D3 1000 IU/d [25 μg/d]

G3: vitamin D3 2000 IU/d [50 μg/d]

Analysed doses

G1: 754 IU

[18.85 μg]

G2: 1086 IU

[27.15 μg]

G3: 2142 IU

[53.55 μg]

Background vitamin D intake (IU/d)

G1: 192 (124–288)

[4.8 (3.1–7.2) μg/d]

G2: 197 (121–285)

[4.9 (3.0–7.1) μg/d]

G3: 189 (122–331)

[4.7 (3.1–8.3) μg/d]

Background calcium intake (mg/d)

G1: 905 (701–1287)

G2: 987 (647–1374)

G3: 913 (599–1391)

Compliance

Pill count method and validated by an electronic medication event monitoring system – vitamin D3 (%)

All: 73 (at 3 and 6 mo)

At 3 mo

G1: 73

G2: 68

G3: 77

At 6 mo

G1: 73

G2: 73

G3: 73

Hypercalcaemia:

‐ safety measure

‐ laboratory data were obtained at enrolment and at 3 and 6 mo, and calcium was apparently analysed (see table 1)

‐ normal serum calcium defined as 8.8–10.8 mg/dL [2.2–2.7 mmol/L] (10–14 y) and 8.4–10.2 mg/dL [2.1–2.55 mmol/L] (15 y)

The vitamin D doses were tolerated without development of hypercalcaemia.

 2

Samaranayake et al. (2020)

Sri Lanka

Latitude [assumed] 6.9° N

24 wk

Public funding

(RCT parallel)

Inclusion criteria:

Obese children, who are identified to be having vitamin D deficiency (defined as 25(OH)D < 20 ng/ml or < 50 nmol/L) at a previously conducted cross‐sectional study

Exclusion criteria:

Children who were suffering from any other chronic condition or were on long‐term medication were excluded.

N participants,

randomised/completed/analysed:

G1: 31/27/31

G2: 33/25/33

G3: 32/27/32

Sex (% Females)

G1: 19.4

G2: 33.3

G3: 32.3

Age (y)

G1: 10.61 ± 1.83

G2: 9.75 ± 2.26

G3: 9.95 ± 2.02

Serum 25(OH)D (ng/mL):

G1: 15.47 ± 2.78 ng/mL

[38.68 ± 6.95 nmol/L]

G2: 14.92 ± 3.92 ng/mL

[37.30 ± 9.80 nmol/L]

G3: 14.92 ± 3.04 ng/mL

[37.30 ± 7.60 nmol/L]

Assay: NR

BMI Z‐score

G1: 2.66 ± 0.55

G2: 2.83 ± 0.86

G3: 2.72 ± 0.65

Ethnicity (%)

Sinhala:

G1: 74.2

G2: 69.7

G3: 64.5

Tamil:

G1: 10.5

G2: 9.1

G3: 12.9

Muslim

G1: 16.1

G2: 21.2

G3: 19.4

Smoking status: NR

Alcohol use: NR

Health status: Obese

children

Season: NR

Vitamin D2

Doses

G1: placebo

G2: vitamin D2 2500 IU/wk [62.5 μg/wk = 8.9 μg/d]

G3: vitamin D2 50 000 IU/wk [1250 μg/wk = 178.6 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Participants kept a written record of

their compliance with the treatment.

During the follow up visits the subjects were assessed for compliance to treatment

Stated: Compliance was found to be

satisfactory in all the subjects who completed the trial.

Serum 25(OH)D at 24 wk (ng/mL):

G1: 15.77 ± 3.43 ng/mL [39.43 ± 8.58 nmol/L]

G2: 15.26 ± 3.675 ng/mL [38.15 ± 9.19 nmol/L]

G3: 18.24 ± 5.77 ng/mL [45.60 ± 14.43 nmol/L]

Hypercalcaemia

‐ safety measure

‐ serum calcium measured at baseline, at 12 wk, and 6 mo

‐ no cut‐off provided

No adverse events were reported in the study population.

Mean serum calcium decreased significantly in each group.

 2

Pregnant and lactating women

Enkhmaa et al. (2019)

Mongolia

Latitude 50° N

From 12–16 weeks' gestation to 36–40 weeks' gestation

Mixed funding

RCT (parallel)

Inclusion criteria:

Pregnant women; ≥18 y;

12–16 weeks pregnant; planning to deliver at Mandal Soum Hospital; willing to forego vitamin D supplements other than the study capsules.

Exclusion criteria:

Current known seizure disorder, renal failure, parathyroid disease, thyroid disease, sarcoidosis, cancer, or tuberculosis; history of kidney stones; known sensitivity to multivitamin preparations;

already taking vitamin D supplements containing >600 IU/day [15 μg/d].

N participants, randomised/completed/analysed:

G1: 119/109/119

G2: 121/111/121

G3: 120/113/120

Sex: Females

Age (y)

G1: 28.3 ± 5.6

G2: 28.5 ± 5.7

G3: 28.5 ± 5.4

Serum 25(OH)D (nmol/L)

G1: 18 ± 21

G2: 20 ± 24

G3: 20 ± 22

Assay: VIDAS® enzyme linked fluorescent assay (ELFA, Biomérieux)

Weight status (%)

Underweight (<18.5 kg/m2): G1: 0

G2: 1

G3: 0

Normal weight (18.5–24.9 kg/m2)

G1: 40

G2: 42

G3: 54

Overweight (25–29.9 kg/m2):

G1: 40

G2: 42

G3: 29

Obese (≥30 kg/m2):

G1: 20

G2: 15

G3: 17

Ethnicity [assumed]: Mongol

Smoking status (%)

Never:

G1: 94

G2: 93

G3: 97

Past:

G1: 6

G2: 5

G3: 3

Current:

G1: 0

G2: 2

G3: 0

Alcohol use: NR

Health status: NR

Season at baseline (%)

Winter:

G1: 24

G2: 22

G3: 23

Spring:

G1: 35

G2: 36

G3: 37

Summer:

G1: 19

G2: 22

G3: 21

Fall:

G1: 21

G2: 21

G3: 20

Vitamin D3

Doses

G1: vitamin D3 600 IU/d [15 μg/d] + calcium 300 mg/d

G2: vitamin D3 2000 IU/d [50 μg/d] + calcium 300 mg/d

G3: vitamin D3 4000 IU/d [100 μg/d] + calcium 300 mg/d

Vitamin D3 content was validated by Covance Laboratories (Madison, WI) using LC–MS to ensure the capsules met label claims at the outset of the study.

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – taking at least 80% of their assigned vitamin D supplements (%)

G1: 88

G2: 89

G3: 87

Serum 25(OH)D at 36–40 weeks' gestation (nmol/L)

G1: 46 ± 21

G2: 70 ± 23

G3: 81 ± 29

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at 2 mo and at 36–40 weeks of gestation

‐ defined as >2.6 mmol/L / 10.4 mg/dl

In any instances of hypercalcaemia, the Data Safety and Monitoring Board was to be immediately informed and the participant was to discontinue the supplement until the calcium concentrations could be retested. Any woman with confirmed hypercalcaemia was to be withdrawn from the study.

There were no instances of hypercalcaemia in any study arm at any timepoint.

 2

Hollis and Wagner (2004)

USA

Latitude [assumed] 32° N

3 mo

Unclear funding

(RCT parallel)

Inclusion criteria:

Fully lactating mothers within 1 month after birth were eligible for inclusion in the study if they planned to continue full breastfeeding for the next 3 mo.

Exclusion criteria:

Preexisting type 1 or type 2 diabetes mellitus, hypertension, parathyroid disease, and uncontrolled thyroid disease.

N participants,

randomised/completed/analysed:

All: 64 (enrolled)/18/18

G1: NR/9/9

G2: NR/9/9

Sex: Females

Age (y)

G1: 29.0 ± 6.0

G2: 30.8 ± 5.2

Serum 25(OH)D (ng/mL), mean ± SEM

G1: 27.6 ± 3.3 ng/mL [69.0 ± 8.3 nmol/L]

G2: 32.9 ± 2.4 ng/mL [82.3 ± 6.0 nmol/L]

Assay: HPLC and RIA techniques

BMI (kg/m2): NR

Ethnicity (%)

African American:

G1: 33.3

G2: 22.2

White

G1: 66.6

G2: 77.8

Smoking status: NR

Alcohol use: NR

Health status: Healthy adults

Season: NR

Vitamin D2 + D3

Doses

G1: vitamin D2 1600 IU/d [40 μg/d] + vitamin D3 400 IU/d [10 μg/d]

G2: vitamin D2 3600 IU/d [90 μg/d] + vitamin D3 400 IU/d [10 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – vitamin D3 (%)

Month 1

G1: 89.7

G2: 91.6

Month 2

G1: 87.9

G2: 89.6

Month 3

G1: 89.8

G2: 92.4

Serum 25(OH)D at 3 mo (ng/mL)

G1: 36.1 ± 2.3 ng/mL

[90.3 ± 5.8 nmol/L]

G2: 44.5 ± 3.9 ng/mL [111.3 ± 9.8 nmol/L]

Serum calcium and urinary Ca/Cr ratio:

‐ measured at months 1, 2, 3, and 4 of lactation

‐ no cut‐off for elevated levels provided

Serum calcium concentrations all remained in the normal range.

No observation of hypercalciuria was noted.

 2

Hollis et al. (2011)

USA

Latitude [assumed] 32° N

12–16 weeks of gestation until delivery

Public funding

(RCT parallel)

Inclusion criteria:

(1) maternal age of 16 years or greater at the time of consent, (2) confirmed singleton pregnancy of fewer than 16 completed

weeks of gestation at the time of consent, (3) planned to receive ongoing prenatal care in the Charleston, SC, area, and (4) the ability to provide written informed consent at the first visit.

Exclusion criteria:

Women with a pregnancy at greater than 16 weeks of gestation as calculated by their last menstrual period; pregnant women with preexisting calcium or parathyroid conditions or who required chronic diuretic or cardiac medication therapy, including calcium channel blockers, or who suffered chronic hypertension; pregnant women with active thyroid disease (eg, Graves disease, Hashimoto disease, or thyroiditis) also were excluded, but mothers on thyroid supplement with normal serologic parameters could participate in the study if they were without any other endocrine dysfunction.

N participants,

randomised*/completed/analysed:

G1: 164/111/111

G2: 166/122/122G3: 167/117/117

*received allocated intervention

Sex: Females

Age (y)

G1: 27.0 ± 5.6

G2: 27.4 ± 5.7

G3: 26.6 ± 5.4

Gestational age at enrolment (wk), range

G1: 7.1–18.4

G2: 8.4–17.6

G3: 6.4–21.4

Serum 25(OH)D (nmol/L), mean:

G1: 61.6 ± 27.1

G2: 58.3 ± 22.3

G3: 58.2 ± 21.8

Assay: HPLC and RIA

Weight status (%)

BMI ≤30 kg/m2:

G1: 70.3

G2: 71.3

G3: 76.1

BMI >30 kg/m2:

G1: 29.7

G2: 28.7

G3: 23.9

Ethnicity (%):

Black:

G1: 25.2

G2: 30.3

G3: 28.2

Hispanic:

G1: 40.5

G2: 39.3

G3: 37.6

White:

G1: 34.2

G2: 30.3

G3: 34.2

Smoking status: NR

Alcohol use: NR

Health status: Healthy adults

Season at study entry (%)

April–September

G1: 48.7

G2: 49.2

G3: 47.9

October–March

G1: 51.4

G2: 50.8

G3: 52.1

Vitamin D3

Doses

G1: placebo + vitamin D3 400 IU/d [10 μg/d]

G2: vitamin D3 1600 IU/d [40 μg/d] + vitamin D3 400 IU/d [10 μg/d]

G3: vitamin D3 3600 IU/d [90 μg/d] + vitamin D3 400 IU/d [10 μg/d]

Background vitamin D intake (IU/d):

G1: 181.6 ± 108.4 IU/d [4.5 ± 2.7 μg/d] G2: 195.8 ± 135.0 IU/d [4.9 ± 3.4 μg/d]

G3: 204.2 ± 148.2 IU/d [5.1 ± 3.7 μg/d]

Background calcium intake (mg/d):

G1: 1063.6 ± 539.6 G2: 993.9 ± 514.0

G3: 1073.6 ± 491.9

Compliance

Pill count method – vitamin D3 (%)

G1: 69

G2: 68

G3: 69

Serum 25(OH)D at 1 mo before delivery (nmol/L)

G1: 79.4 ± 34.3

G2: 105.4 ± 35.7

G3: 118.5 ± 34.9

Serum 25(OH)D at delivery (nmol/L)

G1: 78.9 ± 36.5

G2: 98.3 ± 34.2

G3: 111.0 ± 40.4

Serum calcium

‐ collected at each visit (monthly study visits, which

continued until delivery)

‐ no cut‐off for elevated levels provided

Urinary Ca/Cr ratio:

‐ safety measure

‐ collected at each visit (monthly study visits, which

continued until delivery)

‐ defined as Ca/Cr ratio of ≥0.8 mg/mg or ≥2.27 mmol/mmol

‐ vitamin D3 supplementation stopped if the U‐Ca/Cr >1.0 mg/mg (>2.8 mol/mmol)

It was stated that throughout the study, there were no statistically significant differences between groups on any safety measure, including serumcalcium and urinary Ca/Cr. Moreover, review of adverse events by the Data safety and Monitoring Committee showed that not a single adverse event in this trial was attributed to vitamin D supplementation or circulating 25(OH)D levels.

[It was reported that regarding the effect of S‐25(OH)D concentrations on either blood calcium or urinary calcium level, no significant effects were observed, except for the relationship between low circulating 25(OH)D and U‐Ca/Cr]

 2

Roth et al. (2018)

MDIG

Bangladesh

Latitude [assumed] 23.8° N

from 17–24 wk

of gestation to 26 wk postpartum

Private funding

(RCT parallel)

Inclusion criteria:

Age 18 years and above; 17 to 24 completed weeks of gestation based on recalled last menstrual period and/or ultrasound; intends to reside in the trial catchment area for at least 18 months; provides written informed consent.

Exclusion criteria:

1) History of any medical condition or medications that may predispose to vitamin D sensitivity, altered vitamin D metabolism, and/or hypercalcaemia, including active tuberculosis or current therapy for tuberculosis, sarcoidosis, history of renal/ureteral stones, parathyroid disease, renal or liver failure, or current use of anti‐convulsant; 2) High‐risk pregnancy based on one or more of the following findings by point‐of‐care testing:

Severe anemia (hemoglobin <70 g/L assessed by Hemocue); Moderate–severe proteinuria (≥300 mg/dl (3+ or 4+) based on urine dipstick; Hypertension (≥1 systolic blood pressure reading ≥140 mmHg and/or ≥1 diastolic blood pressure reading ≥ 90 mmHg, in repeat measurements taken at least one minute apart); 3) High‐risk pregnancy based on one or more of the following findings by maternal history and/or ultrasound (Multiple gestation; Major congenital anomaly; Severe oligohydramnios); 4) Unwillingness to stop taking non‐study vitamin D or calcium supplements or a multivitamin containing calcium and/or vitamin D; 5) Currently prescribed vitamin D supplements as part of a physician's treatment plan for vitamin D deficiency; 6) Previous enrolment in the trial during a previous pregnancy.

N participants,

randomised/completed/analysed:

G1: 259/229/229

G2: 260/237/237

G3: 259/237/237

G4: 260/230/230

G5: 260/231/231

(Information on complete case analysis available in Table S6 in the Supplementary Appendix)

Sex: Females

Age (y); median, range

G1: 23, 18–38

G2: 22.5, 18–40

G3: 22, 18–35

G4: 22, 18–38

G5: 23, 18–38

Serum 25(OH)D (nmol/L)

G1: 27.7 ± 13.8

G2: 27.4 ± 14.3

G3: 28.7 ± 14.0

G4: 27.0 ± 14.7

G5: 26.6 ± 13.2

Assay: HPLC–MS/MS

(Information from the Supplementary Appendix)

BMI: NR

Ethnicity [assumed]: Bangladeshi

Smoking status: NR

Alcohol use: NR

Health status: Healthy pregnant women

Season: Between March 2014 and Sept 2015

Vitamin D3

Doses

G1: prenatal placebo + postpartum placebo + calcium 500 mg/d

G2: prenatal vitamin D3 4200 IU/wk [105 μg/wk = 15 μg/d] + postpartum placebo + calcium 500 mg/d

G3: prenatal vitamin D3 16 800 IU/wk [420 μg/wk = 60 μg/d] + postpartum placebo + calcium 500 mg/d

G4: prenatal vitamin D3 28 000 IU/wk [700 μg/wk = 100 μg/d] + calcium 500 mg/d

G5: prenatal vitamin D3 28 000 IU/wk [700 μg/wk = 100 μg/d] + postpartum vitamin D3 28 000 IU/wk [700 μg/wk = 100 μg/d] + calcium 500 mg/d

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method (%)

Prenatal; 100% of scheduled doses:

G1: 87.8

G2: 88.2

G3: 86.9

G4: 84.3

G5: 90.9

Postpartum; 100% of scheduled doses:

G1: 76.9

G2: 70.9

G3: 74.7

G4: 67.8

G5: 74.5

Maternal serum 25(OH)D at delivery (nmol/L)

G1: 24.30 ± 15.96

G2: 69.34 ± 19.44

G3: 100.37 ± 23.80

G4: 111.20 ± 27.83

G5: 113.49 ± 25.49

Maternal serum 25(OH)D at 3 mo postpartum (nmol/L)

G1: 27.38 ± 12.70

G2: 31.72 ± 10.57

G3: 51.47 ± 11.69

G4: 59.97 ± 13.60

G5: 99.60 ± 20.60

Maternal serum 25(OH)D at 6 mo postpartum (nmol/L)

G1: 29.87 ± 12.84

G2: 30.53 ± 11.26

G3: 45.01 ± 12.02

G4: 51.97 ± 12.83

G5: 103.83 ± 23.27

Hypercalcaemia:

‐ for primary safety measure

‐ maternal total serum calcium was measured at enrolment, 30 wk of gestation, delivery, 3 mo, and 6 mo postpartum, or during hospitalization (if feasible)

‐ possible hypercalcaemia defined as any serum calcium >2.60 mmol/L (>10.4 mg/d)

‐ confirmed hypercalcaemia defined as a serum calcium >2.60 mmol/L on a repeat specimen or a single serum calcium >2.80 mmol/L (>11.2 mg/dL).

Prenatal period:

No episodes of confirmed hypercalcaemia.

Possible hypercalcaemia, n of participants

G1: 1

G2: 1

G3: 4

G4: 3

G5: 2

Postpartum period:

Confirmed hypercalcaemia (asymptomatic), n of participants

G1: 1

G2: 0

G3: 1

G4: 1

G5: 5

Possible hypercalcaemia, n of participants

G1: 7

G2: 10

G3: 13

G4: 17

G5: 16

 2

Wagner et al. (2006)

USA

Latitude [assumed] 32.7° N

6 mo

Public funding

(RCT parallel)

Inclusion criteria:

Fully lactating mothers within 1 month postpartum planning to continue full breastfeeding for the next 6 mo.

Exclusion criteria:

Included pre‐existing type I or II diabetes, hypertension, parathyroid disease, and uncontrolled thyroid disease.

N participants,

randomised/completed/analysed:

All: 19/10/NR

G1: 10/NR/NR

G2: 9/NR/NR

Sex: Females

Age (y)

G1: 30.3 ± 3.3

G2: 28.3 ± 5.9

Serum 25(OH)D (nmol/L)

G1: 80.5

G2: 85

Assay: HPLC and RIA techniques

BMI (kg/m2): NR

Ethnicity (%)

African American:

G1: 11.1

G2: 11.1

White

G1: 66.7

G2: 88.9

Hispanic:

G1: 22.2

G2: 0

Smoking status: NR

Alcohol use: NR

Health status: Healthy adults

Season: NR

Vitamin D3

Doses

G1: vitamin D3 400 IU/d [10 μg/d]

G2: vitamin D3 6400 IU/d [160 μg/d]

Background vitamin D intake (IU/d)

G1: 273.6 ± 274.5 IU/d [6.8 ± 6.9 μg/d]

G2: 272.6 ± 114.5

[6.8 ± 2.9 μg/d]

Background calcium intake (mg/d):

G1: 1116.8 ± 587.3

G2: 1133.2 ± 286.7

Compliance

Pill count method – vitamin D3 (%)

G1: ≥80

G2: ≥80

Serum 25(OH)D at 7 mo (nmol/L), mean

G1: 38.4 ng/mL

[96.0 nmol/L]

G2: 58.8 ng/mL

[147.0 nmol/L]

Serum calcium and urinary Ca/Cr ratios:

‐ safety measure

‐ measured at baseline and then monthly

‐ no cut‐off for elevated levels provided

Maternal serum calcium and urinary Ca/Cr ratios remained in the normal range for both groups.

 1

General adult population

Aloia et al. (2013)

USA

Latitude [assumed] 40.7° N

6 mo

Private funding

RCT (parallel)

Inclusion criteria:

White, healthy, postmenopausal women.

Exclusion criteria:

Any chronic medical illness; osteoporosis; pregnancy; use of medications that influence bone metabolism or interfere with vitamin D metabolism; unexplained weight loss during the previous year.

N participants, randomised/completed/analysed:

G1: 31/24/31

G2: 35/26/35

G3: 47/36/47

G4: 46/34/46

Sex: Females

Age (y)

G1: 58.6 ± 6.7

G2: 60.0 ± 8.5

G3: 59.7 ± 7.1

G4: 57.6 ± 7.1

Serum 25(OH)D (nmol/L)

G1: 67 ± 17

G2: 66 ± 19

G3: 64 ± 16

G4: 69 ± 17

Assay: RIA (Diasorin)

BMI (kg/m2)

G1: 26.8 ± 3.9

G2: 26.7 ± 3.3

G3: 26.9 ± 3.6

G4: 27.4 ± 3.9

Ethnicity: White

Smoking status: NR

Alcohol use: NR

Health status:

Healthy population

Season: winter

Vitamin D3

Doses

G1: double placebo

G2: placebo + calcium 1200 mg/d

G3: vitamin D3 100 μg/d + placebo

G4: vitamin D3 100 μg/d + calcium 1200 mg/d

Background vitamin D intake (IU/d)

G1: 215 ± 205 IU/d [5.4 ± 5.1 μg/d]

G2: 185 ± 140 IU/d [4.6 ± 3.5 μg/d]

G3: 180 ± 163 IU/d [4.5 ± 4.1 μg/d]

G4: 158 ± 105 IU/d [4.0 ± 2.6 μg/d]

Background calcium intake (mg/d)

G1: 890 ± 259

G2: 906 ± 320

G3: 876 ± 310

G4: 907 ± 288

Compliance

Pill count method – vitamin D (%)

All: 78%

Pill count method – calcium (%)

All: 78%

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 15 and 28 weeks.

‐ no cut‐off provided

Hypercalciuria:

‐ safety measure

‐ spot urine sample collected at baseline and at 15 and 28 weeks

‐ defined as Ca/Cr ratio >0.23 and >0.37

Hypercalcaemia

One incident of transient hypercalcaemia was noted in G4.

Hypercalciuria

Ca/Cr ratio >0.23:

The frequency of values exceeding this concentration was highest in G4: 10 instances vs 1–2 in the other groups.

Ca/Cr ratio >0.37:

There was 1 episode of hypercalciuria in each group.

No adverse events were believed to be related to supplementation other than hypercalciuria.

 2

Aloia et al. (2018)

USA

Latitude [assumed] 40.7° N

1 yr

Unclear funding

RCT (parallel)

Inclusion criteria:

Serum 25(OH)D level < 32 ng/mL [80 nmol/L]; willingness to discontinue self‐administration of vitamin D and calcium supplements; last menstrual period greater than five years

ago; if present, hypertension and diabetes stable for the last

three months.

Exclusion criteria:

T‐score of the total hip

below −2.5 standard deviations; history of osteoporotic fracture, hypercalciuria, hypercalcaemia or nephrolithiasis; hypercalciuria or hypercalcaemia at screening visit; use of medication that influences calcium or vitamin D metabolism; significant deviation from normal in medical history, physical examination or laboratory tests as evaluated by the primary investigator.

N participants, randomised/completed/analysed:

G1: 66/45/66

G2: 66/47/66

Sex: Females

Age (y)

G1: 62.2 (58.2–68.2)

G2: 61.0 (57.5–67.9)

Serum 25(OH)D (ng/mL)

G1: 27.9 ± 5.7 ng/mL [69.8 ± 14.3 nmol/L]

G2: 27.5 ± 7.3 ng/mL [68.8 ± 18.3 nmol/L] Assay: CLIA (DiaSorin)

BMI (kg/m2)

G1: 27.0 (23.6–30.8)

G2: 28.0 (24.9–31.2)

Ethnicity: White

Smoking status: NR

Alcohol use: NR

Health status:

Healthy population

Season: NR

Vitamin D3

Doses [labeled] 1)

G1: vitamin D 600 IU/d [15 μg/d] + calcium 1200 mg/d

G2: vitamin D3 10 000 IU/d [250 μg/d] + calcium 1200 mg/d

1) Assuming a dietary intake of 200 IU/d [5 μg/d] vitamin D and 800 mg/d calcium in G1; assuming dietary intake of 800 mg/d calcium in G2.

Analysed doses by corporation (Tischcon):

G1: 710 IU [17.75 μg/d]

G2: 12 069 IU [301.73 μg/d]

Analysed doses by independent laboratory (Covance Laboratories)

G1: 755 IU [18.88 μg/d]

G2: 12 700 IU [317.5 μg/d]

Background vitamin D intake: NR

Background calcium intake (mg/d)

G1: 900 (675–1214)

G2: 878 (628–1114)

Compliance

Pill count method – vitamin D (%)

G1: 87

G2: 85

Pill count method – calcium (%)

G1: 84

G2: 81

Serum 25(OH)D (ng/mL) at 1 year:

G1: 33.7 ± 6.1 ng/mL [84.3 ± 15.3 nmol/L]

G2: 86.6 ± 26.4 ng/mL [215.5 ± 66.0 nmol/L]

Calcium intake at 1 year (mg/d):

G1: 1843 (1728–1986)

G2: 1986 (1779–2136)

Hypercalcaemia:

‐ primary outcome

‐ serum calcium measured at baseline and at 3, 6, 9, and 12 mo; non‐corrected and albumin‐corrected serum calcium

‐ defined as serum calcium >10.2 mg/dL

Hypercalciuria:

‐ primary outcome

‐ 24‐h urine calcium collected at baseline and at 3, 6, 9, and 12 mo.

‐ defined as 24‐h urine calcium excretion >250 mg.

Participants with hypercalcaemia or hypercalciuria first had their laboratories repeated. If repeated levels confirmed results, the calcium supplement was decreased to 600 mg/d. If laboratory values were still high at the next follow‐up visit, the calcium supplement was discontinued. If the levels on the subsequent follow‐up visit still showed hypercalciuria or hypercalcaemia, the vitamin D supplement was discontinued.

Hypercalcaemia over 1 yr, n of ≥1 event

Serum calcium not corrected for albumin:

G1: 11

G2: 15

Serum calcium corrected for albumin:

G1: 11

G2: 14

In G2, 23% of patients had hypercalcaemia at least once during the study period (15 patients had 23 events)

vs 17% (11 patients had 17 events) in G1.

After correcting serum calcium for albumin, 21% of patients in G2 had hypercalcaemia at least once during the study duration (14 patients had 20 events) vs 17% (11 patients had 17 events) in G1.

Hypercalcaemia over 1 yr, OR (95% CI)

Serum calcium not corrected for albumin:

G2 vs G1: 0.84 (0.25, 2.79)

Serum calcium corrected for albumin:

G2 vs G1: 0.74 (0.22, 2.4)

Hypercalciuria over 1 yr, n of ≥1 event

G1: 19

G2: 34

In G2, of the 34 subjects with an instance of hypercalciuria, 14 developed hypercalciuria once, 15 developed hypercalciuria 2–3 times, and 5 subjects developed hypercalciuria 4 times during the study.

In G1, of the 19 subjects with an instance of hypercalciuria, 10 were hypercalciuric once, 7 were hypercalciuric 2–3 times and 2 were hypercalciuric 4 times during the study.

Hypercalciuria over 1 yr, OR (95% CI)

G2 vs G1: 3.6 (1.39, 9.30)

[the OR does not refer to recurrent cases alone]

 2

Billington et al. (2020)

Canada

Latitude [assumed] 51.0° N

3 y

Private funding

RCT (parallel)

Inclusion criteria:

Healthy men and postmenopausal women; 55–70 years; lumbar spine and total hip bone mineral density T scores

greater than −2.5, assessed using dual–x‐ray absorptiometry.

Exclusion criteria:

Serum 25(OH)D < 30 or > 125 nmol/L; serum calcium >2.5 or <2.10 mmol/L; consumption of vitamin D supplements of more than 2000 IU/day within the previous 6 mo; use of bone‐active medication within the past 2 y; disorders known to affect vitamin D metabolism.

N participants, randomised/completed/analysed:

G1: 124/113/124

G2: 125/115/125

G3: 124/109/124

Sex (% Females)

G1: 48.4

G2: 53.6

G3: 50.8

Age (y)

G1: 62.0 ± 4.2

G2: 62.7 ± 4.3

G3: 62.0 ± 4.1

Serum 25(OH)D (nmol/L)

G1: 76 ± 21

G2: 80 ± 20

G3: 78 ± 18

Assay: CLIA (Diasorin Liaison XL system)

BMI (kg/m2)

G1: 27.7 ± 4.4

G2: 27.8 ± 5.0

G3: 27.2 ± 4.4

Ethnicity [assumed]: Caucasian

Current smokers (%)

G1: 2.4

G2: 1.6

G3: 4.0

Alcohol use: NR

Health status:

Healthy population

Season: NR

Vitamin D3

Doses

G1: vitamin D3 400 IU/d [10 μg/d]

G2: vitamin D3 4000 IU/d [100 μg/d]

G3: vitamin D3 10 000 IU/d [250 μg/d]

If dietary calcium intake was <1200 mg/day, a daily supplement containing either 300 mg or 600 mg elemental calcium was provided to approximate a total daily intake of 1200 mg.

Participants starting calcium supplementation at baseline (%)

G1: 75

G2: 63.2

G3: 73.4

During the study, 32.7% of supplement takers discontinued taking the supplement and 18.2% of those not taking supplement initiated the supplementation.

Background vitamin D intake

G1: 166 ± 88 IU/d [4.2 ± 2.2 μg/d]

G2: 178 ± 92 IU/d [4.5 ± 2.3 μg/d]

G3: 188 ± 120 IU/d [4.7 ± 3.0 μg/d]

Background calcium intake (mg/d)

G1: 600 ± 303

G2: 624 ± 279

G3: 639 ± 344

Compliance

Adherence rate of vitamin D doses (%)

G1: 99.6

G2: 99.7

G3: 99.1

Serum 25(OH)D at 3 mo (nmol/L)

G1: 76 ± 17

G2: 114 ± 22

G3: 187 ± 38

Hypercalcaemia:

‐ secondary outcome

‐ serum calcium measured at baseline and at 3, 6, 12, 18, 24, 30, and 36 mo

‐ defined as total serum calcium >2.55 mmol/L,

‐ participants were asked to discontinue the

study intervention if repeat testing demonstrated persistent hypercalcaemia.

Hypercalciuria:

‐ secondary outcome

‐ 24‐h urine collected at baseline and at 12, 24, and 36 mo

‐ spot urine collected for Ca/Cr ratio at 6, 18, and 30 mo, and at other time points in cases for which the participant could not provide a 24‐h urine sample or required

follow‐up testing after hypercalciuria was detected

‐ defined as 24‐h urine calcium excretion >7.5 mmol/day for participants of <75 kg body weight; a weight‐based cutoff <0.1 mmol/kg/day was used for those >75 kg

‐ Ca/Cr ratio was served as a safety flag for the identification of significant hypercalciuria; a ratio of ≥1.0 mmol/mmol at 6, 18, or 30 mo and at a follow‐up review of the participant's next

24‐h urine calcium excretion resulted in discontinuation of the study treatment.

Participants were asked to discontinue the study intervention if repeat testing demonstrated persistent

hypercalcaemia.

Hypercalcaemia

Hypercalcaemia, n of events

G1: 0

G2: 4

G3: 12

P = 0.02 for trend.

Hypercalcaemia, n of ≥1 event

G1: 0

G2: 4

G3: 11

16 episodes of mild hypercalcaemia (serum calcium 2.56–2.64 mmol/L) occurred in 15 participants. Hypercalcaemia resolved on follow‐up testing in all cases. Calcium intake was reduced prior to follow‐up testing in 10 of these cases (discontinued in 8 and decreased in 2).

2 participants in G3 withdrew from the study due to hypercalcaemia; a diagnosis of primary hyperparathyroidism was suspected in 1.

12 events occurred within the first 12 mo and the remaining 4 events occurred at month 30.

1 participant in G3 experienced 2 episodes of transient hypercalcaemia, at mo 6 and mo 30.

Hypercalciuria

Hypercalciuria, n of events

G1: 27

G2: 40

G3: 56

Hypercalciuria, n of ≥1 event

G1: 21

G2: 28

G3: 38

Recurrent episodes of elevated 24‐h urine calcium excretion were common, occurring in 5 (4.0%), 8 (6.4%),

and 14 (11.3%) participants in G1, G2, and G3, respectively.

No participants discontinued the study treatment because of hypercalciuria.

 2

Brohult et al. (1973)

Sweden

Latitude[assumed] 60.1° N

1 yr

Private funding

CT

Inclusion criteria:

Out‐patients with definite rheumatoid arthritis.

Exclusion criteria:

Treatment with steroid, gold, or antimalaria therapy (the institution of such therapy was

avoided as far as possible).

N participants, randomised/completed/analysed:

G1: 25/21/NR

G2: 24/18/NR

Sex (% Females)

68

Age (y); mean, range

All: 52, 18–69

G1: 53, NR

G2: 51, NR

Serum 25(OH)D: NR

BMI: NR

Ethnicity [assumed]: Caucasian

Smoking status: NR

Alcohol use: NR

Health status:

Rheumatoid arthritis

Season: NR

Vitamin D2

Doses

G1: placebo

G2: vitamin D2 100 000 IU/d [2500 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance: NR

Serum calcium

‐ secondary outcome

‐ serum calcium checked every other month

‐ no cut‐off for elevated levels provided

Serum calcium did not change significantly in either of the groups.

One of the patients G2 had a serum calcium value of 7.0 mg/l [3.5 mmol/L] after 10 months' treatment; this was the only serum calcium value to exceed the normal upper limit.

 3

Burnett‐Bowie et al. (2012)

USA

Latitude [assumed] 42.3° N

12 wk

Mixed funding

RCT (parallel)

Inclusion criteria:

Healthy people aged 18–45 y; serum 25OHD level ≤ 20 ng/ml [50 nmol/L]; normal kidney, liver, and thyroid function; males had normal testosterone levels; females had regular menses (oral contraceptive use was allowed).

Exclusion criteria:

disorders or use of medications known to affect phosphate or vitamin D metabolism;

histories of nephrolithiasis, diabetes mellitus, malabsorption, recent ethanol abuse, or clinically significant disease

N participants, randomised/completed/analysed:

All: 92/90/90

G1: NR/50/50

G2: NR/40/40

Sex (% Females)

G1: 60

G2: 62

Age (y)

G1: 27 (22–39)

G2: 26 (23–32)

Serum 25(OH)D (ng/mL)

G1: 18 ± 7 ng/mL [45 ± 17.5 nmol/L]

G2: 18 ± 7 ng/mL [45 ± 17.5 nmol/L]

Assay: LC–MS/MS

BMI (kg/m2)

G1: 26 ± 7

G2: 25 ± 4

Ethnicity (%)

White/Caucasian:

G1: 40

G2: 45

Black/African American:

G1: 36

G2: 20

Asian:

G1: 12

G2: 7.5

Multiple races/other:

G1: 12

G2: 7.5

Smoking status: NR

Alcohol use: NR

Health status:

Healthy population, vitamin D‐deficient

Season at baseline (%)

Fall:

G1: 28

G2: 37.5

Spring:

G1: 24

G2: 20

Summer:

G1: 30

G2: 25

Winter:

G1: 14

G2: 22.5

Vitamin D2

Doses

G1: placebo

G2: vitamin D2 50 000 IU/wk [1250 μg/wk = 178.6 μg/d]

Daily calcium intake was maintained at

1000–1500 mg/d in both groups through diet and/or supplements.

Background vitamin D intake (IU/d)

G1: 65 (31–130) IU/d [1.6 (0.8–3.3) μg/d]

G2: 150 (75–231) IU/d [3.8 (1.9–5.8) μg/d]

Background calcium intake (mg/d)

G1: 939 ± 523

G2: 1162 ± 651

Compliance

Taking 85% of the study pills (n)

G1: 3

G2: 2

The remaining participants were 100% compliant.

Serum 25(OH)D at wk 12 (ng/mL):

G1: No significant change from baseline)

G2: 43 ± 12 ng/mL [107.5 ± 30 nmol/L]

Hypercalcaemia:

‐ secondary outcome

‐ serum calcium measured at baseline and at 4, 8, and 12 wk

‐ no cut‐off provided

‐ participants were monitored for hypercalcaemia at each visit and withdrawn if necessary.

No subject developed hypercalcaemia.

 2

Ceglia et al. (2013)

USA

Latitude [assumed] 42.4° N

4 mo

Private funding

RCT (parallel)

Inclusion criteria:

Ambulatory; community‐dwelling; postmenopausal women; ≥65 y; maintaining usual level of physical activity and habitual diet during the study to limit the impact of physical activity and dietary variation on skeletal muscle; moderate risk for disability based on a short physical performance battery score of ≤9 (out of a possible 12 points)

Exclusion criteria:

Active parathyroid

disease; chronic kidney disease; nephrolithiasis; malignancy; liver disease; malabsorption; diabetes; unstable heart disease;

severe osteoarthritis; neurodegenerative disease; vitamin D intake >400 IU/d or a 25OHD level < 22.5 or > 60 nmol/L; a calcium intake >1000 mg/d; abnormal serum calcium or 24‐h urinary calcium >275 mg; medications such as hormone replacement therapy in the last 6 months, oral glucocorticoids in the last month, diuretics, antiseizure medications, drugs to treat osteoporosis in the last year, and prescribed antiplatelet and anticoagulant medications; travel to latitudes below 35° N; use of tanning beds, wheelchair, walker, and nasal oxygen

N participants, randomised/completed/analysed:

G1: 13/12/12

G2: 11/9/9

Sex: Females

Age (y)

G1: 80 ± 5

G2: 76 ± 4

Serum 25(OH)D (nmol/L)

G1: 48.3 ± 8.8

G2: 43.6 ± 10.3

Assay: RIA (Diasorin)

BMI (kg/m2)

G1: 25 ± 3

G2: 29 ± 7

Ethnicity (%)

Caucasian

G1: 92

G2: 78

Smoking status: NR

Alcohol use: NR

Health status: Older mobility‐limited women

Season: NR

Vitamin D3

Doses

G1: placebo

G2: vitamin D3 4000 IU/d [100 μg/d]

Background vitamin D intake: NR

Background calcium intake (mg/d)

G1: 1316 ± 1257

G2: 963 ± 663

Compliance

Pill count method:

Was performed but results NR; stated that adherence to the intervention was high.

Serum 25(OH)D at 4 mo (nmol/L)

G1: 52.5 ± 17.1

G2: 80.0 ± 11.5

Elevated urine Ca/Cr ratio:

‐ safety measure

‐ spot urine sample for Ca/Cr ratio collected at baseline, on day 30, and at 4 mo

‐ cut‐off defined as >0.325 (corresponding to a 24‐h urine calcium of 350 mg)

‐ if elevated Ca/Cr ratio occurred, the study pills were discontinued, and a repeat spot urine and serum calcium level were drawn within the following 7 days; if the ratio normalised and serum calcium was normal, pills could be resumed, but repeat testing on pills was performed during the following 2 and 4 weeks.

One subject in G2 had a transient high spot urine Ca/Cr ratio, which resolved on follow‐up testing on study pills.

 2

Diamond et al. (2013)

Australia

Latitude [assumed] 33.9° S

3 mo

Unclear funding

RCT (parallel)

Inclusion criteria:

serum 25(OH)D ≤ 50 nmol/L; no evidence of hypocalcaemia (serum calcium <2.15 mmol/L), significant renal impairment (serum creatinine >0.15 mmol/L), malignancy or were receiving treatment with vitamin D3, calcitriol or high‐dose oral calcium supplements (>1,200 mg/day of elemental calcium) for at least 6 mo prior to the study.

Exclusion criteria: NR

N participants, randomised/completed/analysed:

All: 30/26/26

G1: NR/11/11

G2: NR/15/15

Sex (% Females)

G1: 72.7

G2: 40.0

Age (y)

G1: 45.5 ± 16.9

G2: 47.4 ± 14.4

Serum 25(OH)D (nmol/L)

G1: 41.2 ± 11.9 nmol/L

G2: 35.8 ± 10 nmol/L

Assay: CLIA (DiaSorin LIAISON)

BMI: NR

Ethnicity [assumed]: Caucasian

Smoking status: NR

Alcohol use: NR

Health status: Vitamin D deficient patients

Season: Recruitment in Feb to Apr (autumn)

Vitamin D3

Doses

G1: vitamin D3 2000 IU/d [50 μg/d]

G2: vitamin D3 5000 IU/d [125 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method: NR

Serum 25(OH)D at 3 mo (nmol/L):

G1: 75.3 ± 15.9

G2: 114.4 ± 22.2

Hypercalcaemia:

‐ secondary outcome

‐ serum calcium measured at baseline and at 1, 2 and 3 mo

‐ no cut‐off provided

No patient demonstrated hypercalcaemia.

 3

Drincic et al. (2013)

USA

Latitude 41.2° N

21 wk

Private funding

RCT (parallel)

Inclusion criteria:

BMI ≥30 kg/m2

Exclusion criteria:

Past or current hepatic or kidney disease; taking medications that

affect vitamin D metabolism; any malabsorptive conditions from medical or surgical causes; history of hypercalcaemia, sarcoidosis or active kidney stones; history of fractures; current use of bisphosphonates;

no more than 800 IU [20 μg] daily of vitamin D from food and supplements; outdoor job during the previous summer; plans to visit a sunny region during the

study.

N participants, randomised/completed/analysed:

All: 67/58/62

G1: NR/NR/22

G2: NR/NR/20

G3: NR/NR/20

Sex (% Females)

G1: 59

G2: 55

G3: 65

Age (y)

G1: 47.1 ± 12.5

G2: 45.7 ± 12.6

G3: 44.5 ± 12.9

Serum 25(OH)D (ng/mL)

G1: 20.3 ± 6.4 [50.8 ± 16 nmol/L]

G2: 26.5 ± 6.7 [66.3 ± 16.8 nmol/L]

G3: 23.2 ± 15.2 [58 ± 38 nmol/L]

Assay: RIA (DiaSorin)

BMI (kg/m2)

G1: 36.7 ± 4.6

G2: 36.1 ± 5.1

G3: 37.9 ± 7.2

Ethnicity: Caucasian

Smoking status: NR

Alcohol use: NR

Health status: Healthy women and men with BMI ≥30.0 kg/m2

Season: Winter

Vitamin D3

Doses (labeled)

G1: vitamin D3 1000 IU/d [25 μg/d]

G2: vitamin D3 5000 IU/d [125 μg/d]

G3: vitamin D3 10 000 IU/d [250 μg/d]

Analysed vitamin D3 doses

G1: 911 IU [22.8 μg/d]

G2: 5747 IU [143.7 μg/d]

G3: 11 495 IU [287.4 μg/d]

Background vitamin D intake (IU/d)

G1: 207 ± 277 [5.2 ± 6.9 μg/d]

G2: 203 ± 230 [5.1 ± 5.8 μg/d]

G3: 279 ± 313 [7.0 ± 7.8 μg/d]

Background calcium intake: NR

Compliance

Pill count method – vitamin D (%)

All: 95 on average,

range 94–97.

Serum 25(OH)D change at 21 weeks (ng/mL)

G1: 12.4 ± 9.7 [31 ± 24.3 nmol/L]

G2: 27.8 ± 10.2 [69.5 ± 25.5 nmol/L]

G3: 50.7 ± 16.4 [126.8 ± 41 nmol/L]

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 1, 3, 6, 10 and 21 wk

‐ no cut‐off provided

There was no increase in serum calcium levels during the study in any treatment group; there were no hypercalcaemia events during the study.

 2

Gallagher et al. (2012); Gallagher et al. (2014a)

ViDOS

USA

Latitude [assumed] 41.2° N

1 yr

Mixed funding

2012 for baseline info,

2014 for the outcomes

RCT (parallel)

Inclusion criteria:

Healthy, white, postmenopausal women aged 57 to 90 years who were at least 7 years postmenopausal (determined from the history of their last menstrual period) with vitamin D insufficiency

Exclusion criteria:

Significant health problems,active nephrolithiasis or history of more than two kidney stones in their lifetime, chronic renal failure (serum creatinine > 1.4 mg/dL), chronic liver disease, medical conditions severe enough to prevent reasonable physical activity, serum 25(OH)D levels < 5 ng/mL (12.5 nmol/L), serum calcium levels of 10.3 mg/dL (2.575 mmol/L) or more or serum calcium levels more than 0.3 mg/dL higher than the upper normal limit on two baseline tests, and 24‐h urine calcium levels > 300 mg/dL (7.5 mmol) on two baseline tests; taking currently bisphosphonates or had taken them for > 3 months in the past were excluded; use of fluoride, parathyroid hormone (PTH) or its derivatives, calcitonin, estrogen (in the last 6 mo), corticosteroids (> 10 mg/d), phenytoin or phenobarbital, or high‐dose thiazide (> 37.5 mg/d); multivitamins containing vitamin D were not allowed in the study.

N participants, randomised/completed/analysed:

G1: 21/18/19

G2: 20/16/18

G3: 21/17/18

G4: 20/19/19

G5: 21/20/20

G6: 20/18/18

G7: 20/16/17

G7: 20/18/18

Sex: Females

Age (y)

G1: 66 ± 6.5

G2: 68 ± 8.6

G3: 68 ± 8.1

G4: 66 ± 7.4

G5: 66 ± 6.3

G6: 69 ± 7.7

G7: 66 ± 7.1

G8: 65 ± 6.1

Serum 25(OH)D (nmol/L)

G1: 37.7 ± 9.1

G2: 37.8 ± 10.8

G3: 39.0 ± 9.5

G4: 37.4 ± 10.2

G5: 38.2 ± 10.1

G6: 39.8 ± 8.2

G7: 37.2 ± 9.2

G8: 38.6 ± 9.1

Assay: RIA (Diasorin)

BMI (kg/m2)

G1: 31.1 ± 5.3

G2: 30.3 ± 5.4

G3: 28.2 ± 6.1

G4: 30.0 ± 5.4

G5: 30.4 ± 5.4

G6: 30.2 ± 5.7

G7: 29.7 ± 6.4

G8: 32.1 ± 6.2

Ethnicity: White

Smoking status (%)

Current:

G1: 19

G2: 10

G3: 5

G4: 20

G5: 5

G6: 15

G7: 0

G8: 10

Former:

G1: 33

G2: 35

G3: 33

G4: 40

G5: 38

G6: 20

G7: 50

G8: 45

Never:

G1: 48

G2: 55

G3: 62

G4: 40

G5: 57

G6: 65

G7: 50

G8: 45

Alcohol users (%)

G1: 33

G2: 35

G3: 57

G4: 50

G5: 52

G6: 70

G7: 70

G8: 80

Health status: Healthy.

Season: NR

Vitamin D3

Doses (labeled)

G1: placebo + calcium2)

G2: vitamin D3 400 IU/d [10 μg/d] + calcium2)

G3: vitamin D3 800 IU/d [20 μg/d] + calcium2)

G4: vitamin D3 1600 IU/d [40 μg/d] + calcium2)

G5: vitamin D3 2400 IU/d [60 μg/d] + calcium2)

G6: vitamin D3 3200 IU/d [80 μg/d] + calcium2)

G7: vitamin D3 4000 IU/d [100 μg/d] + calcium2)

G8: vitamin D3 4800 IU/d [120 μg/d] + calcium2)

2) Calcium to maintain total intake between 1200 to 1400 mg/d (was based on a baseline 7‐day food diary)

Analysed vitamin D3 doses (mean of the capsules measured every 6 mo over 3 y)

G2: 503 IU [12.6 μg]

G3: 910 IU [22.8 μg]

G4: 1532 IU [38.3 μg]

G5: 2592 IU [64.8 μg]

G6: 2947 IU [73.8 μg]

G7: 4209 IU [105.2 μg]

G8: 4937 IU [123.4 μg]

Background vitamin D intake (IU/d)

G1: 105 ± 61 IU/d [2.6 ± 1.5 μg/d]

G2: 98 ± 58 IU/d

[2.5 ± 1.5 μg/d]

G3: 135 ± 70 IU/d [3.4 ± 1.8 μg/d]

G4: 125 ± 71 IU/d [3.1 ± 1.8 μg/d]

G5: 98 ± 55 IU/d

[2.5 ± 1.4 μg/d]

G6: 109 ± 62 IU/d [2.7 ± 1.6 μg/d]

G7: 106 ± 83 IU/d [2.7 ± 2.1 μg/d]

G8: 137 ± 86 IU/d [3.4 ± 2.2 μg/d]

Background calcium intake (mg/d)

G1: 593 ± 182

G2: 606 ± 212

G3: 741 ± 247

G4: 754 ± 244

G5: 612 ± 190

G6: 725 ± 263

G7: 673 ± 324

G8: 768 ± 348

Compliance

Pill count method – vitamin D3 capsules (%)

All: 94 on average

Pill count method – calcium tablets (%)

All: 91 on average

Serum 25(OH)D at 1 yr:

G1 vs. the other groups: levels were significantly lower (visual presentation)

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 3, 6, 9, and 12 mo

‐ during the study, defined as serum calcium >0.3 mg/dL [0.075 mmol/L] above the upper limit of reference; i.e. >10.5 mg/dL [2.625 mmol/L]

‐ for poststudy analysis, defined as serum calcium level ≥ 10.3 mg/dL [2.75 mmol/L]; i.e. exceeding the upper reference limit

Hypercalciuria:

‐ safety measure

‐ 24‐h urine calcium measured at baseline and at 3, 6, 9, and 12 months.

‐ during the study, defined as a 24‐h urine calcium >400 mg [10 mmol/d] at any study visit

‐ for poststudy analysis, defined as a 24‐h urine calcium >300 mg [7.5 mmol]

‐ for poststudy analysis, severe hypercalciuria defined as a 24‐h urine calcium >400 mg [10 mmol]

If hypercalcaemia or hypercalciuria developed during the treatment period, calcium measurements were repeated within 2 weeks; if hypercalcaemia or hypercalciuria persisted, calcium supplements were withdrawn, dietary calcium was rechecked, and a repeat calcium measurement was performed within 2 weeks; if elevation persisted, vitamin D was withdrawn.

Overcollection of 24‐h urine was considered based on an individual's mean 24‐h urine creatinine level being 20% higher than the mean for all tests.

Hypercalcaemia

Serum calcium ≥2.75 mmol/L, n of events

G1: 3

G2: 2

G3: 1

G4: 5

G5: 6

G6: 1

G7: 1

G8: 1

Serum calcium ≥2.75 mmol/L, n of ≥1 event

G1: 1

G2: 1

G3: 1

G4: 4

G5: 4

G6: 1

G7: 1

G8: 1

Hypercalcaemias were transient and did not lead to reduction of calcium or vitamin D doses.

Hypercalciuria

24‐h urine calcium >7.5 mmol/d, n of events

G1: 8

G2: 13

G3: 11

G4: 8

G5: 15

G6: 10

G7: 10

G8: 6

24‐h urine calcium >7.5 mmol/d, n of ≥1 event

G1: 4

G2: 8

G3: 7

G4: 5

G5: 6

G6: 6

G7: 6

G8: 5

24‐h urine calcium >10 mmol/d, n of ≥1 event

G1: 3

G2: 2

G3: 3

G4: 2

G5: 4

G6: 1

G7: 2

G8: 2

24‐h urine calcium levels >10 mmol/d were normalised at repeated testing in all but 5 participants. Calcium supplements were withdrawn in 2 of these participants and their follow‐up urine calcium was <7.5 mmol/L. Hypercalciuria still continued in 2 participants, and both calcium and vitamin D3 were discontinued permanently. One participant refused follow‐up testing. The respective groups were not reported.

One participant with 24‐h urine calcium >7.5 mmol/d was not included in the results above due to overcollection of 24‐h urine.

[additional data on recurrent hypercalciuria cases were received from the authors upon request]

 1

Gallagher et al. (2013)

ViDOS

USA

Latitude [assumed] 41.2° N and 39.7° N

1 year

Public funding

RCT (parallel)

Inclusion criteria:

Postmenopausal African American women aged 57–90 years; vitamin D insufficiency with serum 25(OH)D of <20 ng/mL [50 nmol/L].

Exclusion criteria:

Significant comorbidities; history of cancer except skin cancer

within last 10 years; terminal illness; previous hip fracture; hemiplegia; uncontrolled type 1 diabetes ± significant proteinuria or fasting blood glucose greater than 140 mg in type 2 diabetes; active kidney stone disease or kidney stones >2 times in lifetime; chronic renal failure (serum creatinine >1.4 mg/dL); evidence of chronic liver disease including alcoholism; physical conditions like rheumatoid arthritis, osteoarthritis, and

heart failure severe enough to prevent reasonable physical activity; having severe vitamin D deficiency; serum 25OHD <5

ng/mL (<12.5 nmol/L) or > 20 ng/mL (>50 nmol/L); BMI > 45 kg/m2; serum calcium <10.3 mg/dL (>2.57 mmol/L) or 0.3 mg/dL (>0.075 mmol/L) more than the upper limit of normal on 2 baseline tests; 24‐h urine calcium >290 mg/dL (7.25 mmol) on 2 baseline tests; bone mineral density T‐score less than −3 on spine or hip specific

to race; on bisphosphonates for >3 months in the past; had been taking fluoride, PTH, or derivatives, eg, teriparatide in the last 6 months; had previous treatment within the last 6 months with calcitonin or estrogen, chronic high‐dose corticosteroid therapy

(>10 mg/d) for more than 6 months; were currently on anticonvulsants (phenytoin, phenobarbital), high‐dose thiazide therapy (>37.5 mg/d), and any drugs interfering with vitamin D metabolism; or the subjects were not able to give informed consent.

N participants, randomised/completed/analysed:

G1: 17/14/14

G2: 2/2/0

G3: 24/20/20

G4: 23/18/18

G5: 23/20/20

G6: 3/3/0

G7: 4/4/0

G8: 14/10/10

Sex: Females

Age (y)

G1: 66.6 ± 6.9

G2: NR

G3: 69.3 ± 8.9

G4: 67.1 ± 6.2

G5: 64.0 ± 6.5

G6: NR

G7: NR

G8: 65.6 ± 6.5

Serum 25(OH)D (ng/mL)

G1: 13.6 ± 3.8 [34 ± 9.5 nmol/L]

G2: NR

G3: 13.5 ± 4.6 [33.8 ± 11.5 nmol/L]

G4: 12.5 ± 4.7 [31.3 ± 11.8 nmol/L]

G5: 13.8 ± 4.0 [34.5 ± 10 nmol/L]

G6: NR

G7: NR

G8: 13.6 ± 4.7 [34 ± 11.8 nmol/L]

Assay: RIA (DiaSorin)

BMI (kg/m2):

G1: 31.4 ± 6.1

G2: NR

G3: 32.1 ± 5.4

G4: 32.3 ± 9.6

G5: 35.0 ± 7.4

G6: NR

G7: NR

G8: 33.3 ± 5.5

Ethnicity: African American

Smoking status: NR

Alcohol use: NR

Health status: Healthy

Season: NR

Vitamin D3

Doses (labeled)

G1: placebo

G2: vitamin D3 400 IU/d [10 μg/d] + calcium3,4)

G3: vitamin D3 800 IU/d [20 μg/d] + calcium3)

G4: vitamin D3 1600 IU/d [40 μg/d] + calcium3)

G5: vitamin D3 2400 IU/d [60 μg/d] + calcium3)

G6: vitamin D3 3200 IU/d [80 μg/d] + calcium3)

G7: vitamin D3 4000 IU/d [100 μg/d] + calcium3,4)

G8: vitamin D3 4800 IU/d [120 μg/d] + calcium3,4)

3) Calcium to maintain a total intake of 1200–1400 mg/d.

4) The group was excluded from the analyses due to the small number of participants.

Analysed vitamin D3 doses (mean of the capsules measured every 6 mo over 3 y)

G2: 503 IU [12.6 μg]

G3: 910 IU [22.8 μg]

G4: 1532 IU [38.3 μg]

G5: 2592 IU [64.8 μg]

G6: 2947 IU [73.8 μg]

G7: 4209 IU [105.2 μg]

G8: 4937 IU [123.4 μg]

Background vitamin D intake: NR

Background calcium intake (mg/d)

G1: 540 ± 190

G2: NR

G3: 604 ± 282

G4: 523 ± 197

G5: 529 ± 231

G6: NR

G7: NR

G8: 584 ± 210

Compliance

Pill count method – vitamin D (%)

in Omaha: 91

in Indiana: 81

Pill count method – calcium (%)

in Omaha: 79

in Indiana: 70

Serum 25(OH)D at 1 yr

G1 vs other groups: significantly lower

(visual presentation)

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 12 mo

‐ defined as >0.3 mg/dl above the upper

limit of the normal range, which was >10.5 mg/dL in Omaha and > 10.8 mg/dL in Indiana at any visit.

”Fasting blood samples

were collected at all visits (baseline, 3, 6, 9, and 12 mo… …comprehensive

panel including serum calcium, creatinine, complete blood count, and lipid profile was performed at baseline and 12 mo”…” A basic metabolic panel was done at 3, 6, and 9 mo”

Hypercalciuria:

‐ safety measure

‐ 24‐h urine calcium measured at baseline and at 3, 6, 9, and 12 mo

‐ during the study defined as 24‐h urine calcium >400 mg (10 mmol) at any of the follow‐up visits (based on the limit established for Caucasians).

‐ in a post hoc analysis, a upper limit of 270 mg was defined for African Americans

If hypercalcaemia or hypercalciuria developed during the treatment period, calcium measurements were repeated within 2 weeks; if hypercalcaemia or hypercalciuria persisted, calcium supplements were withdrawn, dietary calcium was rechecked, and a repeat calcium measurement was performed within 2 weeks; if elevation persisted, vitamin D was withdrawn.

Hypercalcaemia

Hypercalcaemia occurred in 7% of women. Stated there was no correlation between vitamin D dose and hypercalcaemia.

One participant in G1 discontinued intervention due to hypercalcaemia. (Figure 1)

Hypercalciuria

24‐h urine calcium >270 mg:

Incidence was 15%

24‐h urine calcium >300 mg:

Incidence was 9% based on the limit of 300 mg.

Stated there was no correlation between the vitamin D dose and hypercalciuria.

 1

Grimnes et al. (2012)

Norway

Latitude 69° N

1 yr

Private funding

RCT (parallel)

Inclusion criteria:

Postmenopausal women; aged 50–80 y; a T‐score in total hip or lumbar spine (L2–4) ≤ −2.0

Exclusion criteria:

Hormone replacement therapy or other therapy affecting bone remodeling during the last 12 months before enrolment; use of steroids; renal stone disease; systolic blood

pressure > 175 mmHg or diastolic blood pressure > 105 mmHg; serum creatinine >110 μmol/l, suspected primary hyperparathyroidism (serum calcium >2.55 mmol/L; serum calcium >2.50 mmol/L combined with plasma PTH >5.0 pmol/l; serum calcium >2.45 mmol/L combined with plasma PTH >7.0 pmol/l); chronic disease like ischemic heart disease, diabetes, granulomatous disease, and cancer

N participants, randomised/completed/analysed:

G1: 149/135/135

G2: 148/140/140

Sex: Females

Age (y)

G1: 63.5 ± 6.8

G2: 62.9 ± 7.6

Serum 25(OH)D (nmol/L)

G1: 71.2 ± 22.3

G2: 70.7 ± 23.0

Assay: LC–MS/MS

BMI (kg/m2)

G1: 24.6 ± 3.2

G2: 25.0 ± 3.4

Ethnicity [assumed]: Caucasian

Smoking status (%)

Never smoked:

G1: 24

G2: 23

Former smoker:

G1: 39

G2: 40

Current smoker:

G1: 38

G2: 37

Alcohol use: NR

Health status (%)

Asthma/COPD:

G1: 10

G2: 6

Thyroid disease:

G1: 9

G2: 13

Arthrosis:

G1: 9

G2: 11

Other musculoskeletal disease:

G1: 11

G2: 15

Hypertension:

G1: 19

G2: 17

Hypercholesterolemia:

G1: 11

G2: 12

Previous osteoporotic fracture:

G1: 36

G2: 36

Season: NR

Vitamin D3

Doses

G1: vitamin D3 800 IU/d [20 μg/d] + calcium 500 mg

G2: vitamin D3 6500 IU/d [162.5 μg/d] + calcium 500 mg

Background vitamin D intake (μg/d)

G1: 8.1 ± 6.0

G2: 9.1 ± 6.2

Background calcium intake (mg/d)

G1: 1044 ± 552

G2: 1062 ± 524

Compliance

Pill count method – vitamin D (%)

All: 97

Pill count method – calcium (%)

All: 92

Serum 25(OH)D change at 1 year (nmol/L)

G1: 18.0 ± 18.9

G2: 114.7 ± 34.6

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and 3, 6, 9 and 12 mo

‐ defined as serum calcium ≥2.56 mmol/L

‐ modest hypercalcaemia defined as 2.60–2.80 mmol/L

‐ severe hypercalcaemia defined as >2.80 mmol/L

‐ according to the study protocol, participants experiencing severe hypercalcaemia should be excluded.

Serum calcium 2.56–2.59 mmol/L during the study, n of participants

G1: 8

G2: 9

Serum calcium ≥2.60 mmol/L during the study, n of participants

G1: 4

G2: 9

No severe hypercalcaemias occurred.

The modest hypercalcaemias (serum calcium 2.60–2.80 mmol/L) occurred at serum 25(OH)D levels across a range of 64–256 nmol/L. These participants continued in the study, and all the hypercalcaemias had resolved at

retesting without stopping the treatment.

One participant with serum calcium 2.77 mmol/L was erroneously excluded and did not complete the study (the respective group was not reported). A control value after one week was 2.39 mmol/L.

 1

Heaney et al. (2003)

USA

Latitude 41.2° N

≈20 wk

Private funding

RCT (parallel)

Inclusion criteria:

Men in good general health, who habitually consumed no more than one serving of milk/d and who did not take a vitamin supplement.

Exclusion criteria:

Men who, over the 5‐mo course of the study were planning a winter vacation to a location at which either the altitude or the latitude would be predicted to result in significant cutaneous vitamin D synthesis from solar radiation (e.g., a mountain ski resort or a Gulf Coast locale).

N participants,

randomised/completed/analysed:

All: 67/NR/NR

Sex: Men

Age (y)

All: 38.7 ± 11.2

Serum 25(OH)D (nmol/L) based on analysed doses

G1: 70.2 ± 23.4

G2: 72.1 ± 16.0

G3: 69.3 ± 16.7

G4: 65.6 ± 24.2

Assay: RIA

BMI (kg/m2)

All: 26.2 ± 2.4

Ethnicity [assumed]: Caucasian

Smoking status: NR

Alcohol use: NR

Health status: Healthy men

Season: Winter months of 2 successive years (late Oct to late Feb or early Mar of each year)

Vitamin D3

Doses (labeled)

G1: placebo

G2: vitamin D3 1000 IU/d /25 μg/d

G3: vitamin D3 5000 IU/d /125 μg/d

G4: vitamin D3 10 000 IU/d / 250 μg/d

Analysed vitamin D3 doses

G2: 836 IU / 20.9 μg/d

G3: 5500 IU / 137.5 μg/d

G4: 11 000 IU/d / 275 μg/d

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – vitamin D3/placebo: NR

Serum 25(OH)D, change at equilibrium (nmol/L) based on analysed doses:

G1: −11.4 ± 17.7

G2: 12.0 ± 16.2

G3: 91.9 ± 37.6

G4: 159.4 ± 62.4

Elevated serum calcium above the upper limits of

normal:

‐ safety measure

‐ total serum calcium measured at each visit

‐ defined as >2.6 mmol/L

Elevated serum calcium, n of events

Stated: Serum calcium in G1 and G2 did not change significantly from baseline (mean 9.6 mg/dL [2.65 mmol/L]) at any time point at either dose.

No value rose above the upper limit of normal.

 3

Hin et al. (2016)

BEST‐D

United Kingdom

Latitude [assumed] 51° N to 58° N

1 yr

Mixed funding

RCT (parallel)

Inclusion/exclusion criteria:

Individuals who were ambulatory, living in the community and not currently taking more than 400 IU (10 μg) vitamin D3 daily were eligible to participate.

N participants,

randomised/completed/analysed:

G1: 101/95/101

G2: 102/98/102

G3: 102/97/102

Sex (% Females)

G1: 49.0

G2: 50.0

G3: 49.0

Age (y)

G1: 72 ± 6

G2: 72 ± 6

G3: 71 ± 6

Serum 25(OH)D (nmol/L)

G1: 47 ± 1.5

G2: 55 ± 2.2

G3: 49 ± 1.5

Assay: CLIA

(Beckman Coulter Ltd., High Wycombe, England)

BMI (kg/m2)

G1: 28 ± 5

G2: 27 ± 4

G3: 27 ± 5

Ethnicity [assumed]: Caucasian

Smoking status (%)

Current smokers:

G1: 7

G2: 7

G3: 7

Alcohol use: NR

Health status: Included a substantial number of healthy older people who are the group most at risk of osteoporotic fractures

Season: NR

Vitamin D3

Doses

G1: placebo

G2: vitamin D3 2000 IU/d / 50 μg/d

G3: vitamin D3 4000 IU/d / 100 μg/d

Background vitamin D intake: NR

Background calcium intake (mg/d)

G1: 713 ± 302

G2: 695 ± 292

G3: 724 ± 287

Compliance

Pill count method – vitamin D3/placebo (%)

At 6 mo

G1: 87

G2: 93

G3: 93

At 12 mo

G1: 85

G2: 92

G3: 90

Serum 25(OH)D at 12 mo (nmol/L)

G1: 53 ± 16

G2: 102 ± 25

G3: 137 ± 39

Elevated plasma levels of albumin‐corrected calcium:

‐ safety measure

‐ percentage of participants with calcium above the reference interval at 1, 6 and 12 months ‐ defined as >2.55 mmol/L

Elevated plasma levels of albumin‐corrected calcium above the normal range, n of events

Stated: At randomization, albumin‐corrected calcium was mildly elevated (>2.55 mmol/L) in 8 participants (6 who were subsequently allocated vitamin D3 and two who were subsequently allocated placebo). By 12 mo, there were no new cases with elevated plasma levels of albumin‐corrected calcium.

Among the 8 participants who had marginally elevated plasma levels of

albumin‐corrected calcium at baseline, 6 (5 allocated vitamin D3 and 1 allocated placebo) still had elevated levels at 12 mo, but none was considered clinically significant.

 2

Johnson et al. (2022)

D2d study

USA

Latitude [assumed] 42.3° N

3 yr

Mixed funding

RCT(parallel)

Inclusion criteria:

Eligible participants met at least two of three glycemic criteria for prediabetes as defined by the 2010 American Diabetes Association (ADA) guidelines. Other inclusion criteria were age greater than or equal to 30 years (25 years for American Indians, Alaska Natives, Native Hawaiians, or other Pacific Islanders) and body mass index (BMI) of 24–42 kg/m2 (22.5–42 kg/m2 for Asian Americans)

Exclusion criteria:

A low serum 25 hydroxyvitamin D (25[OH]D) concentration was not an inclusion criterion. Key exclusion criteria included use of diabetes or weight‐loss medications or a history of hyperparathyroidism, nephrolithiasis, hypercalcaemia, chronic kidney disease (defined as estimated glomerular filtration rate [eGFR] <50 mL/min/1.73 m2), calcium‐to‐creatinine ratio greater than 0.275 at baseline, or bariatric surgery. Persons were also excluded for use of supplements containing total doses of vitamin D higher than 1000 IU/day or total calcium higher than 600 mg/day.

N participants,

randomised/completed/analysed:

G1: 1212/1119/1212

G2: 1211/1123/1211

Sex (% Females)

G1: 45.0

G2: 44.7

Age (y)

G1: 60.4 ± 10.0

G2: 59.6 ± 9.9

Serum 25(OH)D (ng/mL)

G1: 28.2 ± 10.1 ng/mL [70.5 ± 25.3 nmol/L]

G2: 27.7 ± 10.2 ng/mL [69.3 ± 25.5 nmol/L]

Assay: LC–MS/MS with

calibrators that are traceable to the National Bureau of Standards and

Technology and validated by quarterly proficiency testing program administered by the Vitamin D External Quality Assessment scheme (DEQAS, United Kingdom)

BMI (kg/m2)

G1: 32.1 ± 4.4

G2: 32.0 ± 4.5

Ethnicity (%)

Asian:

G1: 5.3

G2: 5.5

Black or African American G1: 26.0

G2: 24.9

White:

G1: 66.5

G2: 66.9

Other

G1: 2.3

G2: 2.8

Hispanic or Latino

G1: 8.7

G2: 9.9

Smoking status: NR

Alcohol use: NR

Health status: Overweight/obese persons with prediabetes

Season: NR

Vitamin D3

Doses (labeled)

G1: placebo

G2: vitamin D3 4000 IU [100 μg/d]

Analysed doses: Doses were analysed but the results were not provided

Stated: To optimize safety, participants were asked to limit calcium supplements to 600 mg/d

Background vitamin D intake IU/d

G1: 316 ± 397 IU/d

[7.9 ± 9.9 μg/d]

G2: 310 ± 401 IU/d [7.8 ± 10.0 μg/d]

Background calcium intake (mg/d)

G1: 107 ± 176

G2: 100 ± 175

Compliance

Pill count method – vitamin D3/placebo (%)

All: 84.1

Hypercalcaemia:

‐ secondary outcome

‐ serum calcium was measured at month 3, and annually thereafter

‐ defined as serum calcium value (uncorrected for albumin concentration) was > the site's clinical laboratory upper level of normal and ≥ the upper level of normal plus 1 mg/dL

If serum calcium (uncorrected for albumin concentration) was > the site's clinical laboratory upper level of normal and ≥ the upper level of normal plus 1 mg/dL, testing was repeated within 6 weeks. If the repeat serum calcium value was > the site's clinical laboratory upper level of normal, the participant was confirmed to have met the outcome of hypercalcaemia; study pills were stopped, and the participant was referred to their health care provider.

If the first measurement of serum calcium was > the upper level of normal plus 1 mg/dL [0.25 mmol/L], no repeat testing was required and the participant was considered to have met the outcome of hypercalcaemia; study pills were stopped, and the participant was referred to their health care provider.

Hypercalciuria:

‐ secondary outcomes

‐ urine Ca/Cr ratio was measured at month 3, and annually thereafter

‐ defined as >0.375

If urine Ca/Cr ratio was >0.375, testing was repeated within 4 weeks. If repeat urine Ca/Cr ratio remained >0.375, then the participant was considered to have met the outcome of hypercalciuria; study pills were stopped, and the participant was referred to their health care provider.

Hypercalcaemia, n of participants

There were 16 cases in G1 and 20 cases in G2 with new‐onset hypercalcaemia on initial testing; on repeat testing, only 10 cases were confirmed, 4 in G1 and 6 in G2.

Hypercalcaemia, IRR (95% CI)

G2 vs G1: 1.49 (0.42, 5.27)

Hypercalciuria, n of participants

There were 10 cases in G1 and 11 cases in G2 with new‐onset hypercalciuria on initial testing; on repeat testing, only 2 cases were confirmed, 1 in each group

Hypercalciuria, IRR (95% CI)

G2 vs G1: 0.99 (0.06, 15.86)

 2

Jorde et al. (2008); Sneve et al. (2008)

Norway

Latitude [assumed] 69.6° N

1 yr

Mixed funding

(RCT parallel)

Inclusion criteria:

Males and females, 21–70 years old, with BMI between 28.0 and 47.0 kg/m2 were included.

If the serum calcium was in the range 2.50–2.55 mmol/l, serum PTH had to be below 5.0 pmol/l.

Exclusion criteria:

Subjects with diabetes or a history of coronary infarction, angina pectoris, stroke, renal stone disease, or sarcoidosis were excluded. Subjects with a weight loss of more than 10% of total body weight during the last 6 months, those using anti‐depressant drugs or weight reducing drugs, those participating in an organized weight loss program, pregnant or lactating women, women planning to become pregnant in the next 12 months, women below the age of 50 years without adequate contraception contraceptive pills, implantable subdermal contraceptive rods, contraceptive dermal patches, injectable contraceptives, vaginal contraceptive rings, or intrauterine devices, with pearl index <1.0), subjects with serum calcium >2.55 mmol/l, males with serum creatinine >129 mmol/l, and females with serum creatinine >104 mmol/l were not included.

N participants, randomised/completed/analysed:

G1: 149/112/112

G2: 143/106/106

G3: 153/116/116

Sex (% Females)

G1: 65.8

G2: 64.3

G3: 62.7

Age (y)

G1: 48.9 ± 11.0

G2: 47.6 ± 11.9

G3: 46.4 ± 11.3

Serum 25(OH)D (nmol/L)

G1: 53.2 ± 15.4

G2: 51.4 ± 18.4

G3: 54.5 ± 16.7

Assay: ECLIA, using an automated clinical chemistry analyser (Modular E170; Roche

Diagnostics)

BMI (kg/m2)

G1: 35.1 ± 3.8

G2: 34.4 ± 3.9

G3: 35.0 ± 4.1

Ethnicity [assumed]: Caucasian

Smoking status (%)

Current smokers:

G1: 21.5

G2: 21.7

G3: 22.9

Alcohol use: NR

Health status: Healthy overweight and obese men and women

Season: Summer and winter

Vitamin D3

Doses

G1: Double placebo + calcium 500 mg/d

G2: Vitamin D3 20 000 IU/wk [500 μg/wk = 71.43 μg/d] + placebo + calcium 500 mg/d

G3: Double vitamin D3 20 000 IU/wk [1000 μg/wk = 142.86 μg/d] + calcium 500 mg/d

Background vitamin D intake μg/d

G1: 8.9 ± 6.2

G2: 9.1 ± 7.0

G3: 9.0 ± 6.7

Background dietary calcium intake (mg/d)

G1: 955 ± 390

G2: 943 ± 438

G3: 922 ± 368

Compliance

Pill count method – vitamin D3/placebo (%)

All: 95

Pill count method ‐calcium (%)

G1: 83

G2: 85

G3: 81

Serum 25(OH)D at 12 mo (nmol/L)

G1: 50.0 (20.3–99.8)

G2: 87.8 (51.5–162.3)

G3: 112.1 (46.7–193.4)

Hypercalcaemia:

‐ safety measure

‐ serum calcium drawn after 3, 6, and 9 mo

‐ defined as >2.59 mmol/L

One participant in G2 had an increased serum calcium level to 2.62 mmol/L after 6 mo, and the retest value was 2.60 mmol/L. The participant was excluded from the study. Serum calcium then normalised.

1 participant in G1 and 3 participants in G3 had transient increases in serum calcium at 6 mo (for 2 of them, as follows and they completed the study:

”During the study, only seven subjects reached a serum calcium value above 2.59 mmol/l, which was our predefined hypercalcaemia threshold. Two subjects, one given placebo, developed PHPT and, in retrospect, their baseline serum calcium and PTH levels, although not outside the present limits for inclusion, indicated a disturbed calcium metabolism.”).

Serum calcium levels (mmol/L) in each hypercalcaemic cases by their respective groups

G1: at screening 2.46; at 6 mo 2.60; retest 2.50

G2: at screening 2.30; at 6 mo 2.62; retest 2.60

G3: at screening 2.24; at 9 mo 2.61; retest 2.38

G3: at screening 2.31; at 3 mo 2.61; retest 2.39

G3: at screening 2.29; at 3 mo 2.61; retest 2.53

 2

Mastaglia et al. (2006)

Argentina

Latitude 34° S

3 mo

Private funding

RCT (parallel)

Inclusion criteria:

50–70 years old; menopause had started at least 1 year prior to the study; lived in Buenos Aires

Exclusion criteria:

treatment with vitamin D or any other medication known to affect mineral metabolism, within 12 months prior to the study; a health condition which rendered administration of vitamin D unadvisable (renal lithiasis, tumors) or affecting vitamin D metabolism (hepatic disease, renal insufficiency).

N participants, randomised/completed/analysed:

All: 45

G1: NR/13/13

G2: NR/13/13

G3: NR/12/12

Sex: Females

Age (y)

G1: 61.9 (54.5–67.0)

G2: 65.0 (57.0–67.0)

G3: 60.0 (56.2–66.2)

Serum 25(OH)D (nmol/L)

G1: 45.0 (31.2–61.2)

G2: 42.0 (23.7–45.0)

G3: 32.5 (27.5–37.5)

Assay: RIA (Diasorin)

BMI (kg/m2):

G1: 25.8 (23.2–28.6)

G2: 27.4 (25.0–31.7)

G3: 25.9 (22.4–30.4)

Ethnicity [assumed]: Caucasian

Smoking status: NR

Alcohol use: NR

Health status: Osteopenic/osteoporotic women

Season: winter and spring

Vitamin D2

Doses (labeled)

G1: calcium 500 mg/d

G2: vitamin D2 125 μg/d + calcium 500 mg/d

G3: vitamin D2 250 μg/d + calcium 500 mg/d

Analysed vitamin D2 doses:

62.5 μg per drop

(patients in G2 received two daily drops (131 μg/d) and those in G3 received four daily drops (262 μg/d)).

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method (%)

G1: NR

G2: 89 ± 11

G3: 92 ± 10

Serum 25(OH)D at 3 mo (nmol/L):

G1: 55.0 (72.5–68)

G2: 77.5 (66.2–156.2)

G3: 97.7 (79.3–123.1)

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 1, 2 and 3 mo

‐ defined as >10.5 mg/dl [>2.625 mmol/L]

Hypercalciuria:

‐ safety measure

‐ 24‐h urine collected at baseline and at 1, 2 and 3 mo

‐ defined as 24‐h urine calcium >250 mg or Ca/Cr ratio >0.37 mg/mg.

Hypercalcaemia

No individual value in any of the three groups was above the upper limit of the normal range (10.5 mg/dl [2.625 mmol/L]).

Hypercalciuria

One patient in G2 exhibited values >250 mg/24 h at 2 and 3 mo.

One patient in G3 showed an increase from a baseline value of 229–278 mg/24‐h after 3 mo treatment.

One patient in G1 exhibited hypercalciuria (>250 mg/24 h) at 3 mo.

Urinary calcium excretion was below 250 mg/24‐h in all the remaining cases.

There were no differences among groups at any of the studied times points when comparing the number of patients with urinary calcium levels >250 mg/24‐h. None of the subjects showed a calciuria/creatininuria ratio >0.37 mg/mg during the follow‐up.

 2

Ponda et al. (2012)

USA

Latitude [assumed] 40.7° N

8 wk

Public funding

RCT (parallel)

Inclusion criteria:

Age 18–85 y; 25(OH)D level ≤ 20 ng/mL [50 nmol/L] and at least 1 of the following cardiovascular risk factors: BMI >30 kg/m2, HDL <40 mg/dL for men or < 50 mg/dL for women, hsCRP >2 mg/L, glomerular filtration rate 30 to 59 mL/min per 1.73 m2, a history of coronary artery disease, diabetes mellitus, or a 10‐year Framingham risk score > 10%.

Exclusion criteria:

Taking >400 IU of vitamin D2 or D3, or any dose of activated vitamin D (1,25(OH)D or its analogues) within 1 mo; triglycerides >400 mg/dL; serum calcium >10.5 mg/dL; serum phosphorus >5.5 mg/dL, a change in any lipid therapy within 1 month; glomerular filtration rate < 30 mL/min per 1.73 m2.

N participants, randomised/completed/analysed:

All: NR/151/151

G1: NR/NR/75

G2: NR/NR/76

Sex (% Females)

G1: 45

G2: 45

Age (y)

G1: 47.4 ± 12.8

G2: 48.4 ± 11.3

Serum 25(OH)D (ng/ml):

G1: 14.1 ± 5.7 [35.25 ± 14.25 nmol/L]

G2: 13.4 ± 5.3 [33.5 ± 13.25 nmol/L]

Assay: CLIA (LIASON, Diasorin)

BMI (kg/m2): NR

Ethnicity (%)

Blacks:

G1: 47

G2: 45

Other ethnicities: NR

Smoking status: NR

Alcohol use: NR

Health status: Vitamin D‐deficient; elevated risk for cardiovascular disease

Season: NR

Vitamin D3

Doses

G1: placebo

G2: vitamin D3 5 x 10 000 IU/wk [5 x 250 μg/wk = 178.6 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method: NR

Serum 25(OH)D at 8 wk (ng/mL)

G1: 14.6 ± 6.2 [36.5 ± 15.5 nmol/L]

G2: 43.0 ± 12.3 [107.5 ± 30.75 nmol/L]

Serum calcium:

‐ secondary outcome

‐ measured at baseline and at 4 and 8 weeks

‐ cut‐off for elevated levels defined as >10.5 mg/dl [>2.625 mmol/L].

Serum calcium levels remained below the upper limit of normal for all subjects throughout the study.

 2

Rafii et al. (2019)

USA

Latitude [assumed] 40.6° N

1 yr

Private funding

RCT (parallel)

Inclusion criteria:

25–85 years; documented 25(OH)D < 30 ng/ml [75 nmol/L] within the preceeding 2 mo; not on vitamin D supplementation (other than what is contained in a daily multivitamin, which is around 600 IU).

Exclusion criteria:

History of malabsorption, chronic kidney disease stages 3 to 5, end‐stage renal disease, hypercalcaemia, nephrolithiasis, alcohol/drug abuse, steroid use, androgen deprivation therapy; active hyper‐ or hypothyroidism; active malignancy (other than nonmelanoma skin cancer; inability to comply with study requirements; use of immunomodulators, anticonvulsants, teroparatide, orlistat, or reinoids; pregnancy; contemplating pregnancy.

N participants, randomised/completed/analysed:

G1: 25/16/24

G2: 25/17/24

G3: 25/16/25

G4: 25/16/25

Sex (% Females)

G1: 20

G2: 25

G3: 20

G4: 20

Age (y)

G1: 53.48 ± 12.53

G2: 56.00 ± 12.47

G3: 56.64 ± 11.06

G4: 52.40 ± 13.00

Serum 25(OH)D (ng/mL)

G1: 17.5 ± 5.5 [43.75 ± 13.75 nmol/L]

G2: 18.7 ± 6.2 [46.75 ± 15.5 nmol/L]

G3: 14.4 ± 5.9 [36 ± 14.75 nmol/L]

G4: 14.8 ± 5.7 [37 ± 14.25 nmol/L]

Assay: CLIA (LIAISON, Diasorin)

BMI (kg/m2)

G1: 32.33 ± 6.78

G2: 29.86 ± 6.13

G3: 32.06 ± 4.81

G4: 32.02 ± 4.86

Ethnicity (%)

White:

G1: 32

G2: 38

G3: 20

G4: 24

Black:

G1: 40

G2: 54

G3: 64

G4: 56

Hispanic:

G1: 16

G2: 8

G3: 16

G4: 16

Asian:

G1: 8

G2: 0

G3: 0

G4: 4

Other:

G1: 4

G2: 0

G3: 0

G4: 0

Smoking status: NR

Alcohol use: NR

Health status: Vitamin D insufficient

Season: NR

Vitamin D2 and D3

Doses

G1: vitamin D3 2000 IU/d [50 μg/d] + calcium 500 mg/d

G2: vitamin D3 3000 IU/d [75 μg/d] + calcium 500 mg/d

G3: vitamin D2 50 000 IU/wk [1250 μg/wk = 178.6 μg/d] + calcium 500 mg/d

G4: vitamin D2 50 000 IU two times/wk [2500 μg/wk = 57.1 μg/d] + calcium 500 mg/d

Background vitamin D intake: NR

Background calcium intake (mg/d)

All: 300 on average.

Compliance

Pill count method (%)

G1: 78.6

G2: 72.8

G3: 89.5

G4: 87.7

Serum 25(OH)D, mean change over 12 mo (ng/mL):

G1: 13.04 [32.6 nmol/L]

G2: 33.58 [83.95 nmol/L]

G3: 38.46 [96.15 nmol/L]

G4: 56.76 [141.88 nmol/L]

Hypercalcaemia:

‐ secondary outcome

‐ serum calcium was measured at baseline and at 1, 3, 5, 7, 9 and 12 mo

‐ clinically significant hypercalcaemia defined as serum calcium level >1 ng/mL[1 mg/dl; 0.25 mmol/L] above the upper limit of normal; as reference range of 8.4–10.2 mg/dL [2.1–2.55 mmol/L] was provided, the cut‐point was 2.7 mmol/L

Elevated Ca/Cr ratio:

‐ secondary outcome

‐ urine Ca/Cr ratio from spot urine measured at baseline and at 1, 3, 5, 7, 9, and 12 mo

‐ defined as Ca/Cr ratio >0.14 and >0.20.

Hypercalcaemia

None of the subjects developed clinically significant hypercalcaemia. The highest calcium attained was 10.8 ng/mL[2.7 mmol/L], which occurred at visit 2 in an individual in G2.

Elevated urine Ca/Cr ratio

The percentage of subjects with Ca/Cr ratio >0.14 fluctuated throughout the study without a clear trend.

G1 had the highest Ca/Cr ratio in all but the second visit. 23% of participants had a Ca/Cr ratio of >0.14 at baseline: this rose to 31% by 12 mo.

The percentage of participants with Ca/Cr ratio >0.2, a value seen in those with hypercalciuria, rose from 9.4% at baseline to 12.9% at 12 mo. The highest Ca/Cr ratios were inexplicably seen with G1.

 3

Rorie et al. (2014)

USA

Latitude [assumed] 41.2° N

12 wk

Private funding

RCT (parallel)

Inclusion criteria:

A history of urticarial and/or angioedema daily or almost daily for longer than 6 week; chronic urticaria having signs of dermatographism and/or

delayed‐pressure urticaria history of intolerance to nonsteroidal anti‐inflammatory drugs were included but warned not to take this drug class (acetaminophen was allowed). Patients with a history of alcohol‐exacerbating hives were included but were counselled to avoid alcohol.

Exclusion criteria:

Diagnosed with a pure physical urticaria, hereditary or acquired angioedema, hypercalcaemia (>10.3 mg/dL[2.5757.49 mmol/L]), renal insufficiency (glomerular filtration rate < 50 mL/min/1.73 m2), primary hyperparathyroidism, sarcoidosis, granulomatous disease, or malignancy or were pregnant or lactating.

N participants,

randomised/completed/analysed:

G1: 21/17/17

G2: 21/21/21

Sex (% Females)

G1: 71.4

G2: 85.7

Age (y); mean, range

G1: 43.1, 19–79

G2: 43.9, 20–72

Serum 25(OH)D (ng/mL), mean ± SE

G1: 37.1 ± 3.4 ng/mL

[92.8 ± 8.5 nmol/L]

G2: 28.8 ± 2.2) ng/mL

[72.0 ± 2.5 nmol/L]

Assay: MS/MS

BMI (kg/m2)

G1: 30.5 ± 6.32

G2: 30.6 ± 9.42

Ethnicity (%)

White:

G1: 90.4

G2: 95.2

African American:

G1: 4.7

G2: 4.7

Asian:

G1: 4.7

G2: 0

Smoking status (%)

Current smokers:

G1: 23.8

G2: 28.5

Former smokers:

G1: 52.3

G2: 47.6

Alcohol users (%)

G1: 42.8

G2: 14.2

Health status: Adult patients with physician‐diagnosed Chronic urticaria with or without angioedema

Season: NR

Vitamin D3

Doses

G1: vitamin D3 600 IU/d [15 μg/d]

G2: vitamin D3 4000 IU/d [100 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – vitamin D3 (%)

All: >80

Stated: Excellent compliance, with only 1 subject in G1 showing <80% compliance.

Serum 25(OH)D at 12 wk (ng/mL), mean ± SE

G1: 35.8 ± 2.3 ng/mL [89.5 ± 5.8 nmol/L]

G2: 56.0 ± 3.9) ng/mL [140.0 ± 9.8 nmol/L]

Hypercalcaemia:

‐ safety measure

‐ blood was collected at enrollment and at 6 and 12 wk and processed for calcium

‐ defined as serum calcium >10.3 mg/dL [2.575 mmol/L]

Hypercalciuria:

‐ safety measure

‐ spot urine for urine calcium was collected for safety end points

‐unclear at which time points.

‐ defined as spot urine calcium >30 mg/dL [7.49 mmol/L].

Specific stopping rules and discontinuation of the study included a serum calcium level > 10.3 mg/dL [2.575 mmol/L].

Safety guidelines were implemented if the spot urine calcium level was > 30 mg/dL.

Hypercalcaemia

There was no evidence of hypercalcaemia.

Hypercalciuria

The 3 participants (2 in G1 and 1 in G2) had 1‐time spot urine calcium level > 30 mg/dL [7.49 mmol/L], which resolved on repeat measurement.

 2

Schwartz et al. (2016)

USA

Latitude [assumed] 37.7° N

16 wk

Mixed funding

(RCT parallel)

Inclusion/exclusion criteria:

No hypercalcaemia,

history of hypercalcaemia, uncontrolled thyroid or parathyroid disorders, severe renal failure (estimated glomerular filtration rate (eGFR) <30 mL/min per 1.73 m2), active malignancies (except nonmelanoma skin cancer), intestinal bypass surgery or small bowel resection, granulomatous diseases, contraindications or allergy to vitamin D, osteoporosis, or a history of fractures; not receiving more than 800 IU/d [20 μg/d] of vitamin D, or treatment for severe vitamin D deficiency or an investigational agent in the prior 6 months. They received no vitamin D supplements (vitamin D naive) or had stable vitamin D doses for longer than 2 months before entry.

N participants,

randomised/completed/analysed:

G1: 23/20/20

G2: 20/19/19

G3: 24/20/20

G4: 14/13/13

Sex (% Females)

G1: 70.0

G2: 63.2

G3: 65.0

G4: 76.9

Age (y)

G1: 84.9 ± 8.7

G2: 85.9 ± 8.5

G3: 89.5 ± 6.6

G4: 90.1 ± 6.6

Serum 25(OH)D (ng/mL)

G1: 29.4 ± 10.4 ng/mL

[73.5 ± 26.0 nmol/L]

G2: 28.9 ± 10.4 ng/mL

[72.3 ± 26.0 nmol/L]

G3: 29.0 ± 9.9 ng/mL

[72.5 ± 24.8 nmol/L]

G4: 32.3 ± 6.0 ng/mL

[80.8 ± 15.0 nmol/L]

Assay:

LC–MS/MS (Mayo Clinical Laboratories, Rochester, MN).

BMI (kg/m2)

G1: 27.5 ± 6.8

G2: 27.6 ± 5.3

G3: 27.0 ± 5.4

G4: 28.2 ± 5.7

Ethnicity (%)

White:

G1: 95

G2: 100

G3: 100

G4: 100

Asian:

G1: 5

G2: 0

G3: 0

G4: 0

Smoking status: NR

Alcohol use: NR

Health status: Clinically stable long‐term stay nursing home residents

Season: NR

Vitamin D3

Doses (labeled)

G1: vitamin D3 800 IU/d [20 μg/d]

G2: vitamin D3 2000 IU/d [50 μg/d]

G3: vitamin D3 4000 IU/d [100 μg/d]

G4: vitamin D3 50 000 IU/wk [1250 μg/wk = 178.6 μg/d]

Analysed doses

G1: 858 ± 29 IU [21.5 ± 0.73 μg/d] and 861 ± 45 IU [21.5 ± 1.1 μg/d]

G2: 2467 ± 69 [61.7 ± 1.7 μg/d] and 2482 ± 73 IU [62.0 ± 1.8 μg/d]

G3: 4839 ± 202 [121.0 ± 5.1 μg/d] and 4807 ± 108 IU [120.2 ± 2.7 μg/d]

G4: 68 354 ± 2296 IU [1 708 ± 57.4 μg/d] and 57 542 ± 356 IU [1 439 ± 8.9 μg/d];

at study initiation and end, respectively.

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – vitamin D3 (%)

All: 96 ± 7

Serum 25(OH)D at 16 wk (ng/mL)

G1: 33 ± 6 ng/mL

[82.5 ± 15.0 nmol/L]

G2: 34 ± 6 ng/mL

[85.0 ± 15.0 nmol/L]

G3: 43 ± 10 ng/mL

[107.5 ± 25.0 nmol/L]

G4: 61 ± 14 ng/mL

[152.5 ± 35.0 nmol/L]

Hypercalcaemia:

‐ safety measure

‐ unclear measurement frequency of albumin‐adjusted serum calcium

‐ no cut‐off provided.

However, chemistry panels were analysed at baseline, midstudy, and study end, probably including serum calcium

Hypercalcaemia

In the interim safety analysis, hypercalcaemia

did not occur, nor were corrected calcium concentrations

changed by more than 5% (maximum changes were 0.5 and 0.6 mg/dL [0–125 ‐ 0.15 mmol/L] in two participants).

Adverse effects over intervention period: Hypercalcaemia occurred in one participant assigned to 4 000 IU/d [100 μg/d] that resolved with discontinuation of supplemental calcium.

 2

Shirvani et al. (2020)

USA

Latitude [assumed] 42.3° N

6 mo

Unclear funding

(RCT parallel)

Inclusion criteria:

Healthy young black and white adults with a BMI < 30 kg/m2 without disorders or medications affecting vitamin D metabolism.

Exclusion criteria:

History of elevated serum calcium (>10.5 mg/dL [2.625 mmol/L]); vitamin D

supplementation with a dose of 600 IU/day or more; direct exposure to UV during the past month for greater than eight hours; any kind of malabsorption; history of chronic or acute renal or hepatic disease; current antiseizure medications or glucocorticoids; pregnant/lactating women; and reluctance to consent to the study.

N participants, randomised/completed/analysed:

All: 33

G1: NR/9/9

G2: NR/13/13

G3: NR/8/8

Sex (% Females)

G1: 66.7

G2: 61.5

G3: 62.5

Age (y)

G1: 26.3 ± 2.0

G2: 25.3 ± 2.1

G3: 26.1 ± 2.0

Serum 25(OH)D (ng/mL)

G1: 17.1 ± 5.9 ng/mL [42.8 ± 14.8 nmol/L]

G2: 22.5 ± 5.7 [56.3 ± 14.3 nmol/L]

G3: 17.8 ± 3.3 [44.5 ± 8.3 nmol/L] Assay: LC–MS/MS

BMI: NR

Ethnicity (%)

Non‐White:

G1: 66.7

G2: 38.5

G3: 50.0

Smoking status: NR

Alcohol use: NR

Health status: Healthy adults with insufficient serum 25(OH)D

Season: Recruitment occurred from Oct to March

Vitamin D3

Doses

G1: vitamin D3 600 IU/d [15 μg/d]

G2: vitamin D3 4000 IU/d [100 μg/d]

G3: vitamin D3 10 000 IU/d [250 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – vitamin D3: NR

Serum 25(OH)D, average increase at 24 wk (ng/mL)

G1: 7 ng/ml (18 nmol/l)

G2: 18 ng/ml (45 nmol/l)

G3: 61 ng/ml (153

nmol/l)

Elevated serum calcium

‐ safety measure

‐ serum calcium measured at baseline and every 8 wk

‐ defined as serum calcium >10.5 mg/dL [2.625 mmol/L]

‐ the participation of an individual who discovered to have elevated serum calcium

was immediately discontinued and the primary care physician was informed.

Serum calcium levels remained normal for all study participants and no untoward toxicity was observed.

 2

Vieth et al. (2001)

Canada

Latitude: 43° N

2–5 mo

Private funding

(RCT parallel)

Inclusion/exclusion criteria:

Generally healthy volunteers, most of whom worked in the clinical laboratory departments of 2 Toronto hospitals.

N participants, randomised/completed/analysed:

All:73

G1: NR/33 ≥ 1 mo; 26 at ≥3 mo; 15 at 5 mo/NR

G2: NR/28 ≥ 1 mo; 25 ≥ 3 mo; 15 at 5 mo/NR

[those who completed ≥1 mo were considered as the baseline population by the authors]

Sex: % (Females)

G1: 69.7

G2: 64.3

Age (y)

G1: 41.6 (18–53)

G2: 39.9 (23–56)

Serum 25(OH)D (nmol/L):

G1: 43.3 ± 16.8

G2: 37.9 ± 13.4

Assay: RIA (DiaSorin, Stillwater, MN)

BMI: NR

Ethnicity (%)

White:

G1: 66.6

G2: 71.4

Black:

G1: 6.1

G2:10.7

Asian:

G1: 27.3

G2: 17.9

Smoking status: NR

Alcohol use: NR

Health status: Healthy men and women.

Season: Winter and summer; the study began between Jan and Feb.

Vitamin D3

Doses

G1: vitamin D3 25 μg/d / 1000 IU/d

G2: vitamin D3 100 μg/d / 4000 IU/d

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Vials that contained the vitamin D3 solutions were collected and

subjects were given fresh vials: NR

Peaked serum 25(OH)D at 3 mo (nmol/L)

G1: 68.7 ± 16.9

G2: 96.4 ± 14.6

Stated that the concentrations remained relatively stable for the remainder of the study.

Hypercalcaemia:

‐ primary outcome

‐ serum calcium measured at baseline and at 0.5, 1, 2, 3, 4, and 5 mo

‐ defined as serum calcium concentration >2.75 mmol/L

Hypercalciuria:

‐ primary outcomes

‐ second void urine sample for calcium was collected at baseline and at 0.5, 1, 2, 3, 4, and 5 mo

‐ defined as a mean urinary Ca/Cr ratio >1.0 mmol or >0.37 mg

Hypercalcaemia

Serum calcium concentrations remained within the reference range (2.2–2.6 mmol/L) during the study in all subjects in G1 and G2.

Hypercalciuria

There were more urinary Ca/Cr excretion ratios >1.0 mmol/L in G2 (in one subject, 2 of 6 values were >1.0 during treatment) than in G1.

The relative number of occurrences of hypercalciuria across the entire follow‐up period was not significantly different between the 2 dosage groups.

 1

Wagner et al. (2016)

Sweden

Latitude [assumed] 59.3° N

8 wk

Mixed funding

RCT (parallel)

Inclusion criteria:

1) IFG, IGT, IFG + IGT, or drug‐naïve diabetes at the screening OGTT (IFG = fasting plasma glucose [p‐glucose] 6.1–6.9 mmol/L; IGT = 2‐h p‐glucose 7.8–11.0 mmol/L; diabetes = fasting p‐glucose ≥7.0 mmol/L and/or 2‐h p‐glucose ≥11.1 mmol/L) (22); 2) age ≥ 45 and ≤ 75 years, female or male; 3) BMI ≤32 kg/m2; 4) glycosylated haemoglobin (HbA1c) ≤7.9% (63 mmol/mol); 5) fasting p‐glucose <9 mmol/L; 6) serum 25(OH)D < 75 nmol/L (below normal lab reference); and 7) able and willing to perform tests and examinations specified in the protocol.

Exclusion criteria:

1) antidiabetic medication of any kind; 2) anticipated change of concomitant medication that may interfere with glucose metabolism, such as systemic

corticosteroids, nonselective b‐blockers, monoamine oxidase inhibitors, and anabolic steroids; 3) treatment with any vitamin D preparation; 4) regular sunbathing in solarium; 5) hypercalcaemia at screening, defined as ionized s‐calcium

>1.35 mmol/L; 6) hyperphosphatemia at

screening, defined as s‐phosphate >1.5 mmol/L; 7) sarcoidosis or other granulomatous disease; 8) treatment with phenytoin, barbiturates, rifampicin, isoniazid, cardiac glycosides, orlistat, or colestyramin (known to interfere with vitamin D metabolism); 9) impaired hepatic function, defined as alanine aminotransferase (ALT) three or more times the upper reference limit; 10) impaired renal function, defined as s‐creatinine

>133 mmol/L for males and > 115 mmol/L for females; 11) cardiac disease, defined as a) unstable angina pectoris,

b) myocardial infarction within the last 6 months, or c) congestive heart failure New York Heart Association class III and IV; 12) cerebral stroke within the last 6 months; 13) uncontrolled treated/ untreated hypertension (systolic blood pressure ≥ 180 mmHg and/or diastolic blood pressure ≥ 110 mmHg); 14) cancer (except basal cell skin cancer or squamous cell skin cancer); 15) females of childbearing potential who were pregnant, breast‐feeding, or intended to become pregnant or were not using

adequate contraceptive methods; 16) known or suspected abuse of alcohol or narcotics; or 17) mental incapacity, unwillingness, or language barrier precluding adequate understanding or cooperation.

N participants,

randomised/completed/analysed:

G1: 22/21/21

G2: 22/22/22

Sex: % (Females)

G1: 50.0

G2: 42.9

Age (y)

G1: 67.0 (64.7–68.5)

G2: 67.6 (63.4–68.8)

Serum 25(OH)D (nmol/L)

G1: 47 (42–53)

G2: 42 (35–55)

Serum 25(OH)D (nmol/L), season‐adjusted

G1: 43 (37–54)

G2: 43 (36–50)

Assay: CLIA (LIAISON, intra‐ and interassay coefficient of variation of 5 and 8–11%,

respectively)

BMI (kg/m2)

G1: 28.6 (26.4–29.9)

G2: 28.3 (24.5–29.4)

Ethnicity: White

Smoking status NR

Alcohol use: NR

Health status: Participants with prediabetes or diet‐treated type 2 diabetes.

Season: Feb 2012 to May 2013

Vitamin D3

Doses

G1: placebo

G2: vitamin D3 30 000 IU μg/wk [750 μg/wk = 107.1 μg/d]

Background vitamin D intake: NR

Background calcium intake: NR

Compliance

Pill count method – vitamin D3/placebo (%): NR although stated in the method section that it was assessed.

Serum 25(OH)D, change at 8 wk (nmol/L)

G1: −1 (−3–5)

G2: 41 (27–50)

Adjusted serum 25(OH)D, change at 8 wk (nmol/L)

G1: 0 (−7–11)

G2: 42 (32–50)

Hypercalcaemia:

‐ secondary outcome

‐ serum calcium measured at baseline and at 4 and 8 wk

‐ defined as ionized serum calcium >1.35 mmol/L.

No events of hypercalcaemia occurred in the study.

 2

Wamberg et al. (2013)

Denmark

Latitude [assumed] 56.1° N

26 wk

Unclear funding

(RCT parallel)

Inclusion criteria:

Women not planning pregnancy and reporting the use of safe contraception.

Exclusion criteria:

A history of diabetes, a fasting plasma glucose [7.0 mmol/L, hypercalcaemia, or impaired renal plasma creatinine [130 lmol/L) or hepatic function alanine aminotransferase [135 U/L); treatment with vitamin D within the last 3 mo; a history of sarcoidosis, osteomalacia, or alcohol or substance abuse.

N participants, randomised/completed/analysed:

G1: 26/21/NR

G2: 26/22/NR

Sex: % (Females)

G1: 73

G2: 69

Age (y)

G1: 41.2 ± 6.8

G2: 39.5 ± 8.0

Serum 25(OH)D (nmol/L)

G1: 34.6 ± 10.3

G2: 34.5 ± 10.8

Assay: LC–MS/MS

BMI (kg/m2)

G1: 35.0 ± 3.2

G2: 36.1 ± 3.4

Ethnicity [assumed]: Caucasian

Smoking status (%)

Current smokers:

G1: 19

G2: 27

Ex‐smokers:

G1: 27

G2: 31

Non‐smokers

G1:54

G2: 42

Alcohol use: Alcohol abusers were excluded.

Health status: Healthy obese men and women

Season: NR

(Recruited from February 2010 until May 2011)

Vitamin D3

Doses

G1: placebo

G2: vitamin D3 7000 IU (175 μg/d)

Background vitamin D intake (μg/d)

G1: 1.7 (1.4–3.1)

G2: 2.1 (1.5–4.0)

Background dietary calcium intake (mg/d)

G1: 936 ± 389

G2: 992 ± 400

Compliance

Pill count method – vitamin D3/placebo (%)

G1: 94 ± 8

G2: 95 ± 6

Serum 25(OH)D at 26 wk (nmol/L)

G1: 46.8 ± 21.2

G2: 110 ± 17.3

Hypercalcaemia:

‐ safety measure

‐ serum calcium measured at baseline and at 26w; safety measures and adverse events measured at 2, 10, and 18 wk, apparently including serum ionized calcium

‐ reference range for serum ionized calcium defined as 1.18–1.32 mmol/L

 No subjects developed symptomatic hypercalcaemia during the study. Only one subject in G2 had plasma calcium just above the upper reference limit at one occasion. 1

Abbreviations: BEST‐D; the Biochemical Efficacy and Safety Trial of vitamin D; Ca/Cr: calcium to creatinine; CPBA: competitive protein binding assay; CI: confidence interval; CLIA: chemiluminescence immunoassay; CT: clinical trial; D2d: the Vitamin D and Type 2 Diabetes; G: group; ECLIA: electrochemiluminescence immune assay; HPLC–MS/MS: high performance liquid chromatography tandem mass spectrometry; IQR: inter quartile range; IRR: incidence rate ratio; LC–MS: liquid chromatography mass spectrometry; LC–MS/MS: liquid chromatography tandem mass spectrometry; MIDG, Maternal Vitamin D for Infant Growth; MS/MS: tandem mass spectrometry; RCT: randomised controlled trial; SE: Standard error; STURDY: Study To Understand Fall Reduction and Vitamin D in You; NR: not reported; OR: odds ratio; RIA: radioimmunoassay; ViDOS: Vitamin D Supplementation in Older Women; 25(OH)D: 25‐hydroxyvitamin D.

a

the values have been reported as mean ± standard deviation or median (IQR) unless otherwise indicated; IQR = the 25th–75th percentiles or the length between the percentiles