Folic Acid Supplementation and Cancer

Some evidence associates low blood levels of folate with a greater risk of cancer. Folate is involved in the synthesis, repair, and function of DNA, our genetic map, and some evidence indicates that a deficiency of folate can cause damage to DNA that may lead to cancer.

Several studies have associated diets low in folate with increased risk of breast, pancreas, and colon cancer. Over 88,000 women enrolled in the Nurses' Health Study who were free of cancer in 1980 were followed from 1980 through 1994. Researchers found that women ages 55 to 69 years in this study who took multivitamins containing folic acid for more than 15 years had a markedly lower risk of developing colon cancer.

Findings from over 14,000 subjects followed for 20 years suggest that men who do not consume alcohol and whose diets provide the recommended intake of folate are less likely to develop colon cancer. However, associations between diet and disease do not indicate a direct cause.

Researchers are continuing to investigate whether enhanced folate intake from foods or folic acid supplements may reduce the risk of cancer. Until results from such clinical trials are available, folic acid supplements should not be recommended to reduce the risk of cancer.

Folic acid and methotrexate for cancer

Folate is important for cells and tissues that rapidly divide. Cancer cells divide rapidly, and drugs that interfere with folate metabolism are used to treat cancer. Methotrexate is a drug often used to treat cancer because it limits the activity of enzymes that need folate.

Unfortunately, methotrexate can be toxic, producing adverse effects such as inflammation in the digestive tract that may make it difficult to eat normally. Leucovorin is a form of folate that can help "rescue" or reverse the toxic effects of methotrexate. Many studies are underway to determine if folic acid supplements can help control the adverse effects of methotrexate without decreasing its effectiveness in chemotherapy. Anyone receiving methotrexate should follow his or her physician's advice on the use of folic acid supplements.

Folic acid and methotrexate for noncancerous diseases

Low-dose methotrexate is used to treat a wide variety of noncancerous diseases, such as rheumatoid arthritis, lupus, psoriasis, asthma, sarcoidosis, primary biliary cirrhosis, and inflammatory bowel disease. Low doses of methotrexate can deplete folate stores and cause adverse effects that are similar to those of folate deficiency. Both high-folate diets and supplemental folic acid may help reduce the toxic effects of low-dose methotrexate without decreasing its effectiveness. Anyone taking low-dose methotrexate for the health problems listed above should consult with his or her physician about the need for a folic acid supplement.