What happens when you take high doses of vitamin B6? A deficiency of this crucial nutrient has been linked to nerve damage, particularly nerve pain. But scientists are unsure if supplements help. Moreover, taking too much could be dangerous.
Taking High Doses of Vitamin B6 for Sore Hands:
Q. I have been dealing with sore hands. I’ve had pain in the palm of my hand and been unable to touch my fingers to my thumb.
I started to take 200 mg of Vitamin B6, and after three weeks I am seeing a great deal of improvement. Is it safe to take this much B6?
A. Vitamin B6 (pyridoxine) has been used to treat a variety of conditions including carpal tunnel syndrome, PMS and muscle cramps. High doses of vitamin B6 may cause nerve damage.
Safe Upper Limit?
Although there is no evidence of harm at 200 mg a day, the Office of Dietary Supplements of the National Institutes of Health says that 100 mg of vitamin B6 is the safe upper limit. Some scientists who have reviewed the evidence believe that doses above 50 mg per day may be harmful ( Journal of Clinical Neuromuscular Disease, Sep. 2014). Scientists believe that we need approximately 2 mg per day, which is far below the levels in supplements.
Robert reported:
“I have experienced burning sensations in my feet from time to time – most evident in the winter time… A few weeks ago (early September) the burning started up again… What was different? Finally tracked it to taking too much B6. The B6 supplements from the Walmart Pharmacy are 100 or 200 mg tablets… I had been using a pill splitter to cut the 100mg tabs in half. The pill splitter broke and so I started taking 100 mg per day… This is when the burning started up.
“Online I saw that doses of 100mg & greater have been linked to such symptoms… I stopped the B6 supplement four days ago and within 48 hours the burning sensation was virtually gone… I wonder why they even sell 200mg tablets? (I see that would be 10 THOUSAND percent of the RDA.)”
Why Are High Doses of Vitamin B6 Risky?
Vitamin B6, like certain other vitamins, can occur in several different forms including pyridoxine, pyridoxamine, pyridoxal, pyridoxal-5′-phosphate or pyridoxamine-5-phosphate. Researchers recently determined that pyridoxine inhibits the enzymes that process the active form, pyridoxal-5′-phosphate (Toxicology In Vitro, online July 14, 2017). Most vitamin pills supply pyridoxine, but it interferes with normal vitamin B6 activity in the body. That might explain why taking high doses of vitamin B6 supplements can lead to neuropathy.
Are Some People More Susceptible to High Doses of Vitamin B6?
Q. I am a retired Registered Dietitian/Nutritionist and Certified Diabetes Educator writing to thank you, thank you, thank you for your letter on vitamin B6 toxicity. In my practice, I often found that patients were taking more than 50 mg vitamin B6. Sometimes they were on both a multivitamin plus a mega vitamin B supplement. I always advised them to stop gradually over several days.
Your report about possible toxicity at lower doses is concerning for personal reasons. I have been diagnosed with a MTHFR mutation and take methylcobalamin, methylfolate and pyridoxal-5′-phosphate (50 mg). Is this vitamin B6 dose of concern?
A. MTHFR stands for methylenetetrahydrofolate reductase, which is quite a mouthful. This enzyme is crucial for folate metabolism, but some people, like you, have a mutation that makes the enzyme less efficient.
A randomized controlled trial recently tested the supplements you are taking (Nutrients, May 21, 2024). Over six months, this combination lowered high homocysteine levels among people with genetic variants. As a result, we don’t think you need to worry about taking vitamin B6 as pyridoxal-5′-phosphate.
Stay vigilant, though, for any hint of numbness or tingling in hands or feet. That would suggest a need to stop the supplement or lower the dose.
