Friend takes vitamin b6, b12, and folic acid on a daily basis, he says it prevents heart disease, stroke and mental depression. is this true?

Yes for some-depends: B6, B12 & Folic Acid all lower homocysteine, a metabolite of methionine.High homocysteine is a better predictor of risk of heart disease & stroke than cholesterol, high BP & smoking! these vits. Are proven to lower stroke risk but not yet proven to reduce heart attack risk-but likely will for anyone with high homocysteine. See http://www.Patrickholford.Com/index.Php/blog/blogarticle/171/ & comment:.