A Canadian research group measured the folate content of breast milk and found that those who consumed folic acid supplements had higher levels of unmetabolized folic acid, but lower levels of 5-methyl-tetrahydrofolate.
Both mother and child require high amounts of folate during pregnancy and lactation. Folic acid (FA), the synthetic form of folate, reduces the risk of neural tube defects in the periconceptional period and is therefore often added to food such as white flour. In addition, pregnant women are recommended to consume a multivitamin that contains at least 400μg of folic acid. However, multivitamins often contain the Tolerable Upper Intake Level of 1000μg. In breast milk, folate is usually present in the form of 5-methyl-tetrahydrofolate (THF), but in those who consume folic acid supplements, unmetabolized folic acid (UMFA) is also present.
A paper was recently published in the American Journal of Clinical Nutrition on the folate content of the breast milk of Canadian women as part of the MIREC (Maternal-Infant Research on Environmental Chemicals) study. Between 2008 and 2011, breast milk from 561 women was analyzed. 401 women consumed FA supplements, while 160 were non-consumers. Supplemented FA and dietary folate intake were calculated and breast milk total folate, reduced folate, UMFA, and THF were measured. FA supplement consumers were often older, had a higher level of education and greater annual income than non-consumers. Total folate and UMFA was higher, while reduced folates and THF was lower in supplement users than in non-users. Furthermore, the proportion of THF was higher in non-consumers than in those who consumed FA supplements. Furthermore, the level of UMFA in the breast milk was two times greater in those who consumed more than 400μg FA.
In conclusion, results show that breast milk total folate content is higher in FA supplement users, but without clear benefits, as only UMFA and not THF is increased, especially when FA supplementation exceeds 400μg of FA.
Written By: Dr. Fanni R. Eros