Medically reviewed by Jamie Johnson, RDN Key Takeaways Taking too much vitamin B6 can cause nerve damage and numbness in hands and feet.Niacin at high doses can cause flushing and, in extreme cases, ...

How timing and lifestyle factors impact the benefits of your B-complex supplement. Reviewed by Dietitian Maria Laura Haddad-Garcia Many people take B-complex supplements for energy—but are you taking ...