The only function of vitamin B9 (folate) coenzymes in the body appears to be acting as acceptors and donors of one-carbon units (e.g., methyl, -CH3, and methylene, -CH2-) in a variety of reactions critical to the metabolism of nucleic acids and amino acids (2, 3).

 

Vitamin B9 (folate) coenzymes play a vital role in DNA metabolism through the synthesis of DNA from its precursors (‘thymidine’ and ‘purines’), and the synthesis of the amino acid ‘methionine’, which is required for the synthesis of a ‘methyl group donor’ used in many biological reactions. The addition of a methyl (-CH3) group (‘methylation’) to a number of sites within DNA may be important in cancer prevention.

 

Folate coenzymes are required for the metabolism of several important amino acids, such as the synthesis of methionine from homocysteine. Vitamin B9 (folate) deficiency can therefore result in decreased synthesis of methionine and a buildup of homocysteine; a risk factor for heart disease as well as several other chronic diseases.

 

In addition to vitamin B9, the amount of homocysteine in the blood is regulated by vitamin B12 and vitamin B6 (4). Vitamin B9 (folic acid) has been shown to have the greatest effect in lowering basal levels of homocysteine in the blood when there is no coexisting deficiency of vitamin B12 or vitamin B6.

 

The European Food Safety Authority (EFSA), which provides scientific advice to assist policy makers, has confirmed that clear health benefits have been established for the dietary intake of folate (vitamin B9) in contributing to:

 

• normal blood formation;
• normal homocysteine;
• a normal metabolism of the immune system;
• normal cell division;
• normal maternal tissue growth during pregnancy;
• normal amino acid synthesis;
• normal psychological functions;
• the reduction of tiredness and fatigue.