Vitamin B6 poisoning is extremely rare, but cases have increased by about 40% in the last decade, according to reports from America's Poison Centers. High doses of vitamin B6 can cause nerve damage and numbness.
This vitamin is present in foods such as nuts, chickpeas, fish, and fortified cereals, but it's also an increasingly popular ingredient in supplements and energy drinks. In Australia, drug regulators have removed supplements with high levels of vitamin B6 from the market due to reports of toxicity.
High Doses of B6 in Supplements and Energy Drinks
Most adults need 1.3 to 1.7 mg of vitamin B6 per day to support metabolism and nerve function. Slightly higher doses are unlikely to cause harm, and it’s hard to reach toxic levels from food alone.
Vitamin B6 toxicity is rare unless someone consumes about 20 times the recommended daily amount consistently, said Kelly Krisna Johnson-Arbor, MD, a medical toxicologist at MedStar Georgetown University Hospital.
Many supplements and energy drinks market vitamin B6 as a way to boost energy and support the nervous system. Some B6 supplements may contain up to 100 mg of B6, while energy drinks often have as much as 40 mg per serving.
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Too Much Vitamin B6 Can Damage Nerve Cells
Taking high doses of B6 may cause numbness, a pins-and-needles sensation, or pain in your legs, impairing your ability to walk.
“Basically, it’s toxic to nerve cells,” Johnson-Arbor said.
These symptoms are associated with more than 100 causes, not just vitamin B toxicity. If you do experience these symptoms, it is especially important to mention your B6 regimen to your healthcare provider because they might not initially think about B6 as the culprit, she added.
The treatment for B6 toxicity is to stop taking the high-dose supplements. However, these symptoms don’t always reverse right away.
“There are many reports of people whose symptoms have gotten better after they stopped taking the high doses of B6, but there's also a phenomenon called ‘coasting,’ where people stop taking the B6 but then their symptoms actually keep getting worse for a couple of weeks, until they slowly start to get better,” Johnson-Arbor said.
Most People Can Get Enough B6 From Food Alone
Most people can get enough vitamin B6 through a balanced diet and do not need a supplement. However, if you take a multivitamin or a standalone B6 supplement, check the label to see how much vitamin B6 it contains so you can track your total daily intake.
If you consume “reasonable levels” of B6, you likely won’t have any issues besides some potential gastrointestinal upset, said Jamie Alan, RPh, PharmD, PhD, an associate professor of pharmacology and toxicology at Michigan State University.
"If you are experiencing the [neurological] symptoms, talk to your healthcare provider right away to see if you are experiencing a [B6] overload that's causing the symptoms," Alan said. "Because this is so rare, exploring other reasons for those symptoms is equally important."
