 Because one out of three people do not break down the synthetic folic acid in the B-complex vitamins. And not only that, the B-complex vitamins, a lot of times they include cobalamin instead of methylcobalamin, the right form, the more absorbable, more assimilable kind. So get a good methylated B-complex. There is one on the market that I'm aware of called BioCoEnzymated Active.