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High Doses of Vitamin B6 Could Cause Nerve Damage

High doses of vitamin B6 can lead to neuropathy instead of helping nerve pain heal. Why do these supplements backfire this way?

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 is it possible to get too much?

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 (Ghavanini & Kimpinski, Journal of Clinical Neuromuscular Disease, Sep. 2014).

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.

“On-line 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 (Vrolijk et al, Toxicology In Vitro, online July 14, 2017). Most vitamin pills supply pyridoxine, but it interferes with normal vitamin B6 activity in the body. That’s why taking high doses of vitamin B6 supplements can lead to neuropathy.

Revised 8/21/17

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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