According to the Centers for Disease Control and Prevention, colon cancer ranks second among cancer-related deaths in the United States; risks vary due to race, ethnicity, sex, age and geographic location. The American Cancer Society states that colon cancer has been linked with low levels of folic acid in the blood; recent studies reveal new evidence that more is not necessarily better, but additional research is needed. The CDC reports that the best preventative measure is early detection.
The Colon
The colon is a muscular, tube-like structure in the large intestines. The function of the colon is to absorb sodium and water from food and store waste products until elimination. Colon cancer begins in one of the four layers of the colon's walls and its depth determines the stage of cancer present. The presence of tumors, or polyps, in the colon develop first and some, but not all, can become cancerous. The development occurs slowly over several years, says the American Cancer Society.
Folic Acid
Folic acid, also referred to as B-9, is found naturally in various fruits, vegetables, legumes and fortified grains. The synthetic form of folic acid, reportedly, is easier to absorb. It is responsible for DNA maintenance and cell -- particularly red blood cell -- production. The cell producing properties of folic acid were identified as important in preventing birth defects as well. It was discovered in the 1930s and used in preventing anemia, a disease characterized by low levels of red blood cells. It wasn't until the 1990s that an association was made between low levels of folic acid and the development of certain types of cancer, specifically cervical and colon.
1998 Study
A large study conducted by Brigham and Women's Hospital was published in the October 1998 issue of the "Annals of Internal Medicine," that measured 88,756 women free of cancer over a 14-year period. The women regularly reported on their own diet and supplement use. The researchers found that the use of folic acid supplementation may reduce the risk of colon cancer over the long term. The FDA, in response, required certain processed grains and supplements be enriched with folic acid.
2007 Study
"The Journal of the American Medical Association" published a study in the June 2007 issue that compared folic acid supplementation with a placebo. The participants included 1,021 men and women with a prior history of colorectal adenomas, or benign glandular tumor, but without evidence of cancer. The results showed that folic acid did not reduce the risk of subsequent adenomas. The authors add that research is needed to evaluate whether folic acid supplementation may increase the risk of cancer.
2009 Study
Published in the October 2009 issue of "The American Journal of Clinical Nutrition" was a subsequent study evaluating folic acid supplementation and the risk of recurrence of colon cancer. The study involved 672 participants randomly selected to receive either folic acid or placebo to determine if any new cases of adenoma developed. The conclusion was that supplementation was beneficial for people with lower levels of folic acid but not effective in preventing a recurrence in those with already high levels. Therefore, more did not mean better.
Considerations
According to the American Cancer Society, or ACS, the effectiveness of folic acid may be dependent on when it is taken and whether or not there is a history of cancer. Although more research is needed, the ACS promotes diets high in vegetables and low in fat and calories. Their official recommendation is to eat a balanced diet high in plant-derived foods and not to rely on supplementation. However, they add that some people, such as pregnant women or people on restricted diets, may need supplementation but should not exceed the recommended daily value.
References
- American Cancer Society: Colorectal Cancer; 2010
- American Cancer Society: Folic Acid; 2008
- "Annals of Internal Medicine"; Multivitamin Use, Folate, and Colon Cancer in Women in the Nurses' Health Study; E. Giovannucci, et al; October 1998
- "The American Journal of Clinical Nutrition"; A Randomized Trial on Folic Acid Supplementation and Risk of Recurrent Colorectal Adenoma; Kanu Wu, et al; October 2009
- Centers for Disease Control and Prevention: Colorectal Cancer; 2011
- "The Journal of the American Medical Association"; Folic acid for the prevention of colorectal adenomas: a randomized clinical trial; B.F. Cole, et al; June 2007
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