How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Vitamin B6
Vitamin B6: slightly relieves premenstrual syndrome and early pregnancy nausea in older trials. Tested doses exceed EFSA's safe upper limit (12 mg per day): beyond that, nerve risk.
Benefits
- Premenstrual syndrome: across nine trials (940 women), B6 multiplies the chances of symptom improvement by 2.32 compared to placebo, and by 1.69 for depression (four trials, 541 women); most trials are of low quality.
- Pre-menstrual mood: in 32 women followed for seven months, 50 mg per day reduced depression, irritability, and fatigue, with no effect on other symptoms.
- Severe pregnancy nausea: 25 mg every 8 hours for 3 days reduced nausea by 4.3 points out of 10, compared to 1.8 with placebo, in women with severe nausea (nothing clear in others); at the end, 8 women out of 31 were still vomiting under B6, compared to 15 out of 28 on placebo.
- Pregnancy nausea: in 342 women in early pregnancy, 30 mg per day reduced nausea compared to placebo, without a significant decrease in vomiting.
- Anxiety: in young adults, one month of high-dose B6 reduced reported anxiety compared to placebo (265 participants evaluated).
- Severe stress, with magnesium: in 162 highly stressed adults with low magnesium, 30 mg of B6 added to 300 mg of magnesium improved stress by 24% more than magnesium alone over 8 weeks.
- B6 status: in patients with rheumatoid arthritis, 50 mg per day for 30 days corrected deficient B6 status.
Precautions
Nerves: at high doses, B6 can damage nerves (primarily sensory neuropathy: tingling, numbness); symptoms improve upon cessation. Safe limit: in 2023, the EFSA set the limit at 12 mg per day for adults, including pregnancy and breastfeeding; only regular users of high-dose supplements exceed it. Trial doses: 50 to 150 mg per day for premenstrual syndrome, well beyond this limit; a 1987 trial already called for caution for this reason. Extreme case: a man taking 9.6 g per day developed severe neuropathy with muscle weakness. Children: the EFSA sets lower limits, from 2.2 mg per day under one year old to 10.7 mg per day at 17 years old. Limitations: ginger: in two trials involving pregnant women, ginger (1 g per day in one, 650 mg three times a day in the other) relieved nausea slightly better than B6. Stress: in 264 adults with low magnesium, adding B6 to magnesium did not perform better overall; the benefit is only seen in the most stressed individuals. Premenstrual syndrome: a vitamin and mineral blend performed at least as well as 80 mg of B6 in 72 women. Memory: three trials of B6 alone and six of combined B vitamins find no effect on cognitive functions. Cancer: in 5,442 women followed for 7.3 years, 50 mg of B6 with folic acid and B12 did not change cancer risk. Heart and inflammation: after angioplasty, a blend of folic acid, B12, and 10 mg of B6 reduced complications at one year (15.4% versus 22.8%); but in 285 patients after a stroke, a similar blend changed neither inflammation nor coagulation, and B6 alone did not reduce rheumatoid arthritis inflammation.
Recommended dosage
Trials: 50 to 150 mg per day (premenstrual syndrome); 30 mg per day to 25 mg every 8 hours (nausea). EFSA safe limit: 12 mg per day.
How to take it
- Who it is for: trials involve women with premenstrual syndrome, nauseous pregnant women, and patients; none involve sport.
- Premenstrual syndrome: up to 100 mg per day in the review of nine trials; 50 to 80 mg per day in two trials followed over three cycles or more.
- Pregnancy nausea: 25 mg every 8 hours for 3 days, or 40 mg per day for 4 days; first ask your doctor or midwife for advice.
- With magnesium: 50 mg of B6 and 200 mg of magnesium per day slightly reduced premenstrual anxiety in 44 women over one cycle; the effect only appeared with both together.
- Rapid effect on the blood: in 90 patients, 40 mg per day multiplied the active form of B6 in the blood by about 10 after just 3 days, then the level stopped rising.
- Form: pyridoxine (pyridoxine hydrochloride) is the form named by the trials on this page that specify the form.
Did you know?
B6 is quickly seen in the blood: in 90 patients, 40 mg per day multiplied its active form by about 10 from the third day, then the level did not rise further, even after 84 days.
What the studies say
This systematic review examines the role of vitamin B6 in peripheral neuropathy, a condition that can be caused by a deficiency or, more often, by high levels of B6 from dietary supplements. High doses can lead to sensory neuropathy, which often improves after stopping the supplement. Although low levels are observed in some patients with neuropathy, a direct causal link is not firmly established, and the therapeutic role of B6 alone remains to be confirmed.
Muhamad R, Akrivaki A, Papagiannopoulou G, Zavridis P, Zis P. — Nutrients (2023) — View the source study
Pairs well with
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more