Vitamin B9 (aka: folate, folicin, folic-acid) is a water-soluble B vitamin with many rich natural sources. Folic acid is the synthetic form of vitamin B9 found in fortified foods and supplements. As with most vitamins, the natural form of vitamin B9 (folate) is preferred, and better for absorption. Vitamin B9 (folate) is required for numerous body functions including DNA synthesis and repair, cell division, and cell growth. A deficiency of folate can lead to anemia in adults, and slower development in children. For pregnant women, folate is especially important for proper fetal development. Folate, Vitamin B9, is a water soluble vitamin that is well regulated by the body, thus overdose is rare in natural food sources, and can only occur from supplements. The current DV for Folate (Vitamin B9) is 400μg.
One of the advances that changed the way we look at vitamins was the discovery that too little folate, one of the eight B vitamins, is linked to birth defects such as spina bifida and anencephaly.
Many foods are excellent sources of folate—fruits and vegetables, whole grains, beans. It’s best to avoid foods that are heavily fortified with folic acid.
How do B vitamins fit into the homocysteine picture? Folate, vitamin B6, and vitamin B12 play key roles in converting homocysteine into methionine, one of the 20 or so building blocks from which the body builds new proteins. Without enough folate, vitamin B6, and vitamin B12, this conversion process becomes inefficient and homocysteine levels increase. In turn, increasing intake of folate, vitamin B6, and vitamin B12 decreases homocysteine levels.
Several large randomized trials of B vitamins to lower homocysteine and prevent heart disease and stroke have failed to find any benefit. (13–16) These trials had similar designs: Adults who had a history of heart disease or stroke, or who were at a very high risk of heart disease were given a pill containing high doses of vitamins B6, B12, and folic acid or a placebo. The studies found that taking high doses of the three B vitamins lowered homocysteine levels but did not lead to a reduction in coronary heart events.
Ultimately, folic acid supplementation may only reduce the risk of heart disease in people who have lower levels of folate intake, most likely in countries that do not fortify their food supply with folic acid. In people who already get enough folate in their diets, further supplementation with high doses of folic acid supplements—much higher than what is found in a standard multivitamin—has not been found to be beneficial and might actually cause harm.