Folic acid also known as vitamin B9, are forms of the water-soluble vitamin B9. Folic acid is itself not biologically active, but its biological importance is due to tetrahydrofolate and other derivatives after its conversion to dihydrofolic acid in the liver.
Vitamin B9 is essential to numerous bodily functions. The human body needs folate to synthesize DNA, repair DNA, and methylate DNA as well as to act as a cofactor in biological reactions involving folate. It is especially important in aiding rapid cell division and growth, such as in infancy and pregnancy, as well as in “feeding” some cancers. While a normal diet also high in natural folates may decrease the risk of cancer, there is diverse evidence that high folate intake from supplementation may actually promote some cancers as well as precancerous tumors and lesions. Children and adults both require folic acid to produce healthy red blood cells and prevent anemia.

A lack of dietary folic acid leads to folate deficiency which is uncommon in normal Western diets. Failures to replenish one’s folates might not manifest themselves as folate deficiency for 4 months because a healthy individual has about 500–20,000 µg of folate in body stores.This deficiency can result in many health problems, the most notable one being neural tube defects in developing embryos. Common symptoms of folate deficiency include diarrhea, macrocytic anemia with weakness or shortness of breath, nerve damage with weakness and limb numbness (peripheral neuropathy)[citation needed], pregnancy complications, mental confusion, forgetfulness or other cognitive declines, mental depression, sore or swollen tongue, peptic or mouth ulcers, headaches, heart palpitations, irritability, and behavioral disorders. Low levels of folate can also lead to homocysteine accumulation

Daily dose for Vitamin B9 800mcg Food that contains vitamin B9: eggs, dairy products, tuna, mixed vegetables