The effects of folic acid are primarily due to the role that folate plays as a coenzyme in one-carbon metabolism — a series of metabolic pathways that are vital for normal cellular functioning. As a coenzyme, folate carries and donates one-carbon units that are required for processes like nucleic acid (DNA and RNA) synthesis and repair, amino acid metabolism (most notably the conversion of homocysteine to methionine), and cell division.[1] During pregnancy, folate is especially important to support the rapidly growing fetus and the increased blood volume of the mother.[2]
Folic acid supplementation can effectively reduce homocysteine levels by increasing the metabolism of homocysteine to methionine, which is proposed to be the mechanism by which folic acid can reduce inflammation and positively affect some aspects of cardiovascular health (e.g., stroke risk, endothelial function).[3] By increasing the production of methionine, folate increases levels of S-adenosylmethionine (SAMe), which is involved in the synthesis of neurotransmitters like serotonin and dopamine and regulates gene expression through DNA methylation.[4][5]