Folic acid (vitamin B-9) is an important water-soluble B-complex vitamin that is often deficient in the diet. It helps iron function properly and it regulates red blood cell formation. It works in conjunction with vitamins B-12 and C to metabolize protein. Folic acid helps to form the nucleic acid of RNA and DNA. It is a vital nutrient for women who are pregnant or may be pregnant. Along with Vitamins B-6 and B-12, it helps to break down homocysteine, a harmful amino acid.