Folic acid
Folic acid, also known as vitamin B9 or folate, is a vital water-soluble B vitamin essential for DNA synthesis and the production of normal red blood cells. It occurs naturally in various foods, including lentils, leafy greens, cereals, and citrus fruits, while its synthetic form is commonly used in dietary supplements and food fortification. Folic acid plays a significant role in cellular processes and is particularly important during pregnancy, as it helps reduce the risk of neural tube defects in developing fetuses. Research has shown that adequate intake of folate may lower the risk of certain cancers, such as colorectal and breast cancer, by preventing DNA damage.
However, findings on the relationship between folic acid and cancer risk are mixed, with some studies indicating that supplementation may actually increase the risk of tumor progression in cases where cancer has already developed. Consequently, the National Institutes of Health currently advises caution regarding the use of folic acid supplements for cancer prevention. Overall, while folic acid is crucial for overall health, understanding its complex role in cancer development is essential for making informed decisions about supplementation and dietary intake.
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Folic acid
ALSO KNOWN AS: Folate, pteroylglutamic acid, vitamin B9
DEFINITION: Folate is a water-soluble B vitamin found naturally in foods such as lentils, green leafy vegetables, broccoli, cereals, citrus fruits, and liver. It is an essential cofactor for deoxyribonucleic acid (DNA) synthesis and DNA replication and is necessary for the production of normal red blood cells. Folic acid is the synthetic, oxidized form used in commercial vitamin supplements and food fortification.
Cancers treated or prevented:Colorectal cancer, breast cancer
Delivery routes: Natural dietary sources, fortified foods, oral supplements
How this substance works: Folate is an essential cofactor in the de novo synthesis of purines and thymidylate and therefore plays a role in DNA synthesis, replication, stability, and repair. Evidence suggests that folate deficiency can lead to DNA damage and is associated with macrocytic anemia, neural tube defects, and cancer. In 1998, the US Food and Drug Administration (FDA) began requiring the fortification of all flour and cereal grains with folic acid. These products are thus a major source of folic acid in the US population. Large epidemiological studies that followed subjects for many years have found that higher dietary intake of folate and folic acid supplementation decreased the risk of colon and breast cancer. A possible explanation for its protective effect is that folate prevents DNA damage that may lead to the development of cancer. Folic acid is also highly recommended for pregnant people to reduce the risk of birth defects to the brain and spine.
Side effects: Research results on the benefits of folate in preventing cancer are inconsistent. Despite population studies showing positive effects of higher folate intake, studies in animals and humans also have shown that folic acid supplementation increased the risk of breast cancer, tumor growth, and the development of colon polyps. These mixed results suggest that folate has a dual role in the development of cancer. In normal tissues, folate appears to suppress the development of cancer, presumably by preventing mutations. Once early lesions or tumors have developed, however, folate appears to promote their progression in colorectal and breast cancers. In these cases, folic acid may provide a source of nucleotides for rapidly proliferating tissues, including tumors. Indeed, antifolate drugs are sometimes used in the treatment of cancer. Thus, the timing, dose, and form of folate appear to be critical in whether this substance prevents or actually promotes certain types of cancers. For these reasons, the National Institutes of Health (NIH) do not currently recommend folic acid supplements to reduce the risk of cancer.
Bibliography
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MedlinePlus. "Folic Acid." MedlinePlus. US NLM/NIH, 16 Sept. 2014. Accessed 22 Oct. 2014.
US Natl. Insts. of Health Office of Dietary Supplements. "Folate: Dietary Supplement Fact Sheet." Natl. Insts. of Health Office of Dietary Supplements. NIH/ODS, 14 Dec. 2012. Accessed 22 Oct. 2014.
Vollset, S. E., et al. "Effects of Folic Acid Supplementation on Overall and Site-Specific Cancer Incidence During the Randomised Trials: Meta-Analyses of Data on 50,000 Individuals." Lancet 381.9871 (2013): 1029–1036. PubMed.gov. Accessed 22 Oct. 2014.
Thabet, Romany H., et al. “Folic Acid: Friend or Foe in Cancer Therapy.” The Journal of International Medical Research, vol. 52, no. 1, 16 Jan. 2024. Sage Journals, doi.org/10.1177/03000605231223064.