Folate (vitamin B9) is a key B vitamin that is essential for making DNA, for repairing DNA, for detoxification, for making red blood cells, for mental health, for histamine metabolism, for muscle growth, and for prevention of neural tube defects. Not getting enough can lead to depression and obsessive thinking (deficiency is quite common in depression), recurrent allergies, or unexplained cardiovascular disease. Good sources of folate are liver, legumes (preferably sprouted), and leafy greens. The RDA for folate is 400 mcg DFE per day; there is some concern that doses over 1000 mcg DFE per day can cause problems. You need just the right amount!