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Vitamin B-6 Toxicity From a Multivitamin?
Question: I have been having neurological symptoms, and a blood test showed I have toxic levels of vitamin B-6. My multivitamin contains 75 mg of B-6, but this is below the upper limit of 100 mg per day. Could my vitamin contain more than it lists?
Answer: As noted in our B Vitamin Supplements Review, unless you are deficient, you only need to get slightly less than 2 mg of vitamin B6 per day from your diet (including supplements), while the daily upper tolerable intake level (UL) is 100 mg. [The Daily Value for B-6 was reduced in 2016 from 6 mg to 1.7 mg, but this change won't be reflected on most supplement labels until 2021.] When you exceed the UL, you start increasing your chances of side effects.
Since supplements are required to provide at least 100% of their listed amounts of ingredients at the time you purchase them and, if properly maintained, until a listed expiration date, it is customary and acceptable for companies to put in a bit more (an "overage") than the listed amount of an ingredient to compensate for normal degradation. In fact, according the USP, up to 50% more is permitted for B vitamins.
So, yes, it is possible that your multivitamin provided more than the daily upper limit of vitamin B6 -- putting you at some risk of toxicity with long-term use. This is because your supplement provided an amount of B6 close to the upper limit (and much more than normally needed) and there is an allowable manufacturing overage, as noted above. However, side effects have generally been reported with daily intakes above 200 mg and, more typically, above 1,000 mg, so, although possible, it would be unusual for the B6 in your supplement alone (if properly made) to cause the side effects you reported. Foods also contribute B6, but non-fortified foods would be unlikely to put you over the UL since foods naturally rich in B6 (like liver, other meats, potatoes, and bananas) provide about only about 0.25 to 1 mg of B6 per serving. Be aware that energy drinks may include large amounts of vitamin B6 and have been implicated in cases of vitamin B6 toxicity.
Be aware that Europe uses a more conservative daily upper limit (25 mg) than in the U.S., so even your "75 mg" B6 supplement would exceed the limit in Europe.
Unless you have been diagnosed with a deficiency in vitamin B6, there is no good reason to take more than 2 mg of B6 per day and certainly no more than 25 mg.