Here’s something I’ve learned this week:
You can get vitamin B6 toxicity from over-the-counter supplements. To say I learned this today doesn’t do justice to my previous teachers. As I was reading about B6 toxicity, it reminded me vaguely of a lecture back in medical school that, unfortunately, over time, drifted out of the forefront of my mind. But it’s important to remember this is a thing.
Vitamin B6 is used to describe multiple similar compounds, of which pyridoxine is the most common. It’s found in a wide range of foods and has a high bioavailability, so deficiency is considered rare. Having a high oral bioavailability means that a high proportion of the vitamin enters the circulation after it has been ingested. The recommended daily dose is 0.7–2 mg, and intake of food-based sources won’t cause toxicity.[1] However, some products on shelves contain 50, 100, even 200 mg per tablet.[2]
The evidence suggests long-term high doses of over 250 mg/day can cause peripheral neuropathy. This can lead to tingling, burning, or numbness in the hands and feet, and sometimes even balance problems. What’s striking is that people often don’t realise their multivitamin or energy drink already has B6 in it, so they double up without knowing. Most cases improve once supplements are stopped, but in severe cases the nerve damage can be lasting.[3]
This is your reminder that “natural” doesn’t always mean harmless - especially when it comes to supplements
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[1] Public Health England. Government dietary recommendations. Nutritional and food based guidelines for UK institutions [Internet]. 2016 [cited 2025 Aug 29]. Available from: https://assets.publishing.service.gov.uk/media/5a749fece5274a44083b82d8/government_dietary_recommendations.pdf
[2] Sherley M. Pyridoxine toxicity from over-the-counter supplements. Aust J Gen Pract. 2025;54(8) [cited 2025 Aug 29]. Available from: https://www1.racgp.org.au/ajgp/2025/august/pyridoxine-toxicity-from-over-the-counter-suppleme
[3] Hemminger A, Wills BK. Vitamin B6 Toxicity [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan– [updated 2023 Feb 7; cited 2025 Aug 29]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554500/