Scientific opinion on the tolerable upper intake level for vitamin B6

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. 2023 May 17;21(5):e08006. doi: 10.2903/j.efsa.2023.8006

Reference Study Country Duration Funding	Design	Subject characteristics at baseline	Intervention	Results
Shahraki et al. (2016) NR Iran Start: wk 4–16 of gestation End: delivery NR	RCT, DB Inclusion: Primipara pregnant females; pregnancy‐related nausea and vomiting Exclusion: Multi‐gestational; refusal of antiemetic medication; drug allergy; underlying disorders; history of other types of antiemetic drugs in recent weeks; addiction; reproductive assisted technologies n = 200/188/188 G1: n = 88 (ondansetron) G2: n = 100 (B6)	Sex (% women): G1: 100 G2: 100 Age (y, [mean ± SD]): G1: 24.8 ± 3.3 G2: 24.9 ± 4.0	Nutrient form: G1: 2 tablets/d ondansetron G2: 2 tablets/d vitamin B6 Doses: G1: 4 mg × 2/d G2: 40 mg × 2/d Background nutrient intake: NR Compliance: NR	Birth weight (g): G1: 3,007 ± 442 G2: 2,950 ± 457 p = 0.67 Type of analysis: Chi‐square/Fisher's exact test T‐test/Mann–Whitney U‐Test No congenital anomalies in both groups
Schuster et al. (1984) NR USA Start: wk 15 ± 4 (range 6–21) End: wk 30 or delivery Public	RCT, DB Inclusion criteria: Good health at first visit; < 22 weeks pregnant; > 17 years; no B6 supplementation, no long‐term history (> 1 year) of oral contraceptives N = NR G1: (pregnant): n = 196 G2: (non‐pregnant control): n = 26	Sex (% women): 100 Age (y): G1: 17–38 G2: 19–34 PLP (pmol/mL): G1 (pregnant): 37.1 ± 25.3 – SubG1: 38.8 ± 17.3 – SubG2: 50.0 ± 32.5 – SubG3: 31.4 ± 10.0 – SubG4: 37.3 ± 6.2 – SubG5: 25.8 ± 13.5 – SubG6: 32.5 ± 31.3 – SubG7: 28.2 ± 12.8 G2 (non‐pregnant controls): 59.0 ± 19.0	Nutrient form: PyridoxineHCL (PNHCL) (mg/d) in tablets: Pregnant women received in random order: 0, 2.6, 5, 7.5, 10, 15, 20 SubG1‐3 (pregnant): 0–5 SubG4‐7 (pregnant): 7.5–20 Background dietary B6 intake (mg/d): 1.43 ± 1.28 (83% consumed less than RDA [2.6 mg/d]) B6 intake/energy intake (mg/1,000 kcal): 0.67 ± 0.63 Compliance: NR	Birth weight (g, mean ± SD) SubG1‐3 (pregnant): 3,240 ± 505 SubG4‐7 (pregnant): 3,287 ± 429 p > 0.05

Reference

Study

Country

Duration

Funding

Design

Subject characteristics at baseline

Intervention

Results

Shahraki et al. (2016)

Iran

Start: wk 4–16 of gestation

End: delivery

RCT, DB

Inclusion: Primipara pregnant females; pregnancy‐related nausea and vomiting

Exclusion: Multi‐gestational; refusal of antiemetic medication; drug allergy; underlying disorders; history of other types of antiemetic drugs in recent weeks; addiction; reproductive assisted technologies

n = 200/188/188

G1: n = 88 (ondansetron)

G2: n = 100 (B6)

Sex (% women):

G1: 100

G2: 100

Age (y, [mean ± SD]):

G1: 24.8 ± 3.3

G2: 24.9 ± 4.0

Nutrient form:

G1: 2 tablets/d ondansetron

G2: 2 tablets/d vitamin B6

Doses:

G1: 4 mg × 2/d

G2: 40 mg × 2/d

Background nutrient intake: NR

Compliance: NR

Birth weight (g):

G1: 3,007 ± 442

G2: 2,950 ± 457

p = 0.67

Type of analysis:

Chi‐square/Fisher's exact test

T‐test/Mann–Whitney

U‐Test

No congenital anomalies in both groups

Schuster et al. (1984)

USA

Start: wk 15 ± 4 (range 6–21)

End: wk 30 or delivery

Public

RCT, DB

Inclusion criteria:

Good health at first visit;

< 22 weeks pregnant;

> 17 years; no B6 supplementation, no long‐term history (> 1 year) of oral contraceptives

N = NR

G1: (pregnant): n = 196

G2: (non‐pregnant control): n = 26

Sex (% women): 100

Age (y):

G1: 17–38

G2: 19–34

PLP (pmol/mL):

G1 (pregnant): 37.1 ± 25.3

– SubG1: 38.8 ± 17.3

– SubG2: 50.0 ± 32.5

– SubG3: 31.4 ± 10.0

– SubG4: 37.3 ± 6.2

– SubG5: 25.8 ± 13.5

– SubG6: 32.5 ± 31.3

– SubG7: 28.2 ± 12.8

G2 (non‐pregnant controls): 59.0 ± 19.0

Nutrient form: Pyridoxine*HCL (PN*HCL) (mg/d) in tablets:

Pregnant women received in random order:

0, 2.6, 5, 7.5, 10, 15, 20

SubG1‐3 (pregnant): 0–5

SubG4‐7 (pregnant): 7.5–20

Background dietary B6 intake (mg/d):

1.43 ± 1.28

(83% consumed less than RDA [2.6 mg/d])

B6 intake/energy intake (mg/1,000 kcal): 0.67 ± 0.63

Compliance: NR

Birth weight (g, mean ± SD)

SubG1‐3 (pregnant): 3,240 ± 505

SubG4‐7 (pregnant): 3,287 ± 429 p > 0.05

Mean ± SD, unless specified otherwise.

d: day; DB: double blind; Gx: group x; NA: not applicable; NR: not reported; PLP: pyridoxal 5‐phosphate; PN*HCL: pyridoxine hydrochloride; RCT: randomised controlled trial; RDA: recommended dietary allowance; SD: standard deviation; SubGx: sub‐group x; USA: United States of America; wk: week; y: year.