Scientific opinion on the tolerable upper intake level for selenium

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. 2023 Jan 20;21(1):e07704. doi: 10.2903/j.efsa.2023.7704

Reference Study Country	Design N randomised/completed Duration^(a) Recruitment criteria	Subject characteristics at baseline^(b)	Intervention^(b)	Outcomes assessed	Results^(b)
Stranges et al. (2019) DK PRECISE Denmark	RCT G1, placebo: 126/108/99^# G2, 100 μg Se/d:* 124/113/90^# G3, 200 μg Se/d:* 122/110/86^# G4, 300 μg Se/d:* 119/104/94^# Duration:* 5 yr SWOG performance‐status score ≤ 1; no active liver or kidney disease; no previous diagnosis of cancer (excluding NMSC); no diagnosed HIV infection; no immunosuppressive therapy; no use of Se supplements ≥ 50 μg/d in the previous 6 mo. *6‐mo HbA1c measurement available ^#2‐yr HbA1c measurement available	Sex (% F): 48.1 Age (yr) G1: 65.4 ± 3.8 G2: 66.4 ± 4.2 G3: 66.3 ± 4.4 G4: 66.5 ± 4.1 BMI (kg/m ² ) G1: 26.5 ± 4 G2: 27.1 ± 4 G3: 27.2 ± 4.3 G4: 26.5 ± 4 Ethnicity: NR Plasma Se (ng/g) G1: 86.0 ± 15.2 G2: 87.5 ± 16.4 G3: 88.3 ± 16.2 G4: 83.9 ± 17.1 Se intake: NR Diabetes at baseline (%): 1.2	Selenised yeast (100 or 200 or 300 μg Se/d) vs placebo Adherence NR Plasma Se (ng/g) at 6 mo G1: 85.3 ± 14.2 G2: 152.4 ± 23.7 G3: 209.1 ± 41.5 G4: 253.7 ± 54.1	HbA1c measured in red blood cells collected at baseline, 6 mo and 2 yr Number of incident cases of T2DM at 2 years based on use of diabetes medications (insulin or hypoglycaemic drugs)^(c)	HbA1c (mmol/mol) Baseline G1: 35.7 ± 5.7 G2: 37.4 ± 7.4 G3: 36.6 ± 7.9 G4: 36.7 ± 7.0	HbA1c (mmol/mol) 6 mo G1: 36.4 ± 5.2 G2: 37.1 ± 8.3 (p = 0.02) G3: 36.9 ± 7.3 (p = 0.32) G4: 36.5 ± 4.8 (p = 0.30) 2 yr G1: 34.0 ± 7.2 G2: 34.8 ± 7.2 (p = 0.35) G3: 34.9 ± 7.7 (p = 0.88) G4: 33.8 ± 7.8 (p = 0.80) The exclusion of visits after participants received diabetes medications did not materially alter the results at 2 years N incident cases of T2DM at 2 yr, after exclusion of prevalent cases at baseline ^(c) G1: 1 l G2: 5 l G3: 3 l G4: 0

Reference

Study

Country

Design

N randomised/completed

Duration^(a)

Recruitment criteria

Subject characteristics at baseline^(b)

Intervention^(b)

Outcomes assessed

Results^(b)

Stranges et al. (2019)

DK PRECISE

Denmark

RCT

G1, placebo: 126/108*/99^#

G2, 100 μg Se/d: 124/113*/90^#

G3, 200 μg Se/d: 122/110*/86^#

G4, 300 μg Se/d: 119/104*/94^#

Duration: 5 yr

SWOG performance‐status score ≤ 1; no active liver or kidney disease; no previous diagnosis of cancer (excluding NMSC); no diagnosed HIV infection; no immunosuppressive therapy; no use of Se supplements ≥ 50 μg/d in the previous 6 mo.

*6‐mo HbA1c measurement available ^#2‐yr HbA1c measurement

available

Sex (% F): 48.1

Age (yr)

G1: 65.4 ± 3.8

G2: 66.4 ± 4.2

G3: 66.3 ± 4.4

G4: 66.5 ± 4.1

BMI (kg/m ² )

G1: 26.5 ± 4

G2: 27.1 ± 4

G3: 27.2 ± 4.3

G4: 26.5 ± 4

Ethnicity: NR

Plasma Se (ng/g)

G1: 86.0 ± 15.2

G2: 87.5 ± 16.4

G3: 88.3 ± 16.2

G4: 83.9 ± 17.1

Se intake: NR

Diabetes at baseline (%): 1.2

Selenised yeast (100 or 200 or 300 μg Se/d) vs placebo

Adherence

Plasma Se (ng/g) at 6 mo

G1: 85.3 ± 14.2

G2: 152.4 ± 23.7

G3: 209.1 ± 41.5

G4: 253.7 ± 54.1

HbA1c measured in red blood cells collected at baseline, 6 mo and 2 yr

Number of incident cases of T2DM at 2 years based on use of diabetes medications (insulin or hypoglycaemic drugs)^(c)

HbA1c (mmol/mol)

Baseline

G1: 35.7 ± 5.7

G2: 37.4 ± 7.4

G3: 36.6 ± 7.9

G4: 36.7 ± 7.0

HbA1c (mmol/mol)

6 mo

G1: 36.4 ± 5.2

G2: 37.1 ± 8.3 (p = 0.02)

G3: 36.9 ± 7.3 (p = 0.32)

G4: 36.5 ± 4.8 (p = 0.30)

2 yr

G1: 34.0 ± 7.2

G2: 34.8 ± 7.2 (p = 0.35)

G3: 34.9 ± 7.7 (p = 0.88)

G4: 33.8 ± 7.8 (p = 0.80)

The exclusion of visits after participants received diabetes medications did not materially alter the results at 2 years

N incident cases of T2DM at 2 yr, after exclusion of prevalent cases at baseline ^(c)

G1: 1 l G2: 5 l G3: 3 l G4: 0

BMI: body mass index; d: day; DK PRECISE: The Denmark PREvention of Cancer by Intervention with SElenium pilot trial; F: females; Gx: group x; HbA1c: glycated haemoglobin; mo: month; N: number; NMSC: non‐melanoma skin cancer; NR: not reported; RCT: randomised controlled trial; Se: selenium; SWOG: Southwest Oncology Group; T2DM: type 2 diabetes mellitus; USA: United states of America; yr: year.

(a) Duration = duration of the treatment phase, unless specified otherwise.

(b): Mean ± SD, unless specified otherwise.

(c): Data provided by the authors. The authors also provided data regarding the UK PRECISE trial: after exclusion of prevalent cases at baseline (identified based on self‐reported use of diabetes medications), the number of cases of T2DM at 6 months were 0/107, 0/117, 0/120 and 1/112 in the control group and the groups receiving 100, 200 and 300 ug Se/day, respectively.