Can taking folic acid reduce my risk of cancer?

Folate (or folic acid, in its synthetic form) is part of the B-complex of vitamins, and is often prescribed for pregnant women because it's essential for the normal development of the brain and spinal cord of the fetus. But when mothers started taking folate to prevent spina bifida (a specific birth defect), we also saw a 60-percent reduction in childhood cancers. But folate is important for adults, too. If you don't get enough folate as an adult, that deficiency can lead to cancer.

In four studies, folate supplementation decreased colon cancer rates by 20 to 50 percent, but more than 50 percent of Americans don't even get the recommended amount-and 90 percent don't get the amount that seems best to reduce colon cancer (800 micrograms a day).

Research shows that a deficiency of folate, part of the B complex of vitamins, is linked to cancer. Folate supplementation decreases colon cancer rates by 20 percent to 50 percent, but more than 50 percent of Americans don't even get the recommended amount, and 90 percent don't get the amount that seems to reduce colon cancer (800 micrograms a day).

Lots of foods—like spinach, tomatoes, and orange juice—contain folate, but folate from food is absorbed less well than folic acid from supplements. The average intake of folate through food is 275 to 375 micrograms, so you need a supplement of about 400 micrograms to reduce your risk of cancer. That's especially important if you're allowing sun exposure to deplete your folate levels, which happens when you get more than twenty minutes of sun exposure a day. Be sure to add B6 and crystalline B12.

A number of studies have found that people with low blood levels of folic acid are at increased risk for cervical and colorectal cancer.

Some research also suggests that folic acid may protect women who drink alcohol regularly from an increased risk of breast cancer. (Drinking alcohol is known to increase breast cancer risk, but folic acid may buffer this effect.) Folic acid -- or folate, which is the natural form of this B vitamin -- plays a role in DNA function and repair, and experts theorize that low levels of folic acid may increase the chances of DNA being damaged. 

However, experts say there's not enough evidence to recommend taking folic acid supplements to reduce cancer risk. In fact, some studies suggest that if a person already has cancer, taking folic acid may actually promote cancer growth.