L-Methylfolate is the bioavailable form of folate and is the only form able to cross the blood-brain barrier. L-Methylfolate is important for normal production of serotonin, norepinephrine and dopamine, and is essential for converting homocysteine to methionine. Almost half of all people have genetic variations that reduce their ability to convert folate to its usable form. For this population, L-methylfolate supplementation is far more effective in providing this form of folate.