Understanding that deplin is the methyl folate (folic acid) needed to cross blood brain barrier, why is the dose so high 7.5 or 15mg? non script mf is a lot lower

L-methylfolate: I cannot answer for "why" a drug company chooses the specific doses it does, except that these were the doses used in positive pre-marketing studies. L-methylfolate is categorized as a "medical food, " and some question its validity: http://tinyurl.Com/lhel357 i've seen variable doses in available over-the-counter products -- from 1mg to 10mg, for instance.

Biological activity: The l-methyl folate (folic acid) is the biologically active form and will directly affect receptors. You need to know that as we age, fully 52% of adults start to lose the ability to chemically convert folate (folic acid) properly. Therefore, over the counter folate (folic acid) is not identical, and the "methyl folate (folic acid)" sold in health food stores is often the reverse optical isomer and would be fully inactive.