Just an anecdote -- in individuals without pyroluria, taking unnecessary B6 supplements can be dangerous. I would encourage anyone who suspects a deficiency to get a serum B6 test first. Symptoms of deficiency are similar to those of toxicity. The United States' upper tolerable limit is actually very high compared to other countries. Most of us get plenty of this vitamin from diet, especially if one eats meat. High, and even modestly high doses of B6 can cause toxicity symptoms in certain individuals, such as small fiber nerve damage. Generally this can be reversed, but it can take years to resolve after stopping supplementation. Just a word of caution, as this happened to me, and I've found many others through support groups who experienced devastating effects.