Folic Acid Supplements Have No Effect on Colorectal Cancer Risk
Debate over whether folic acid supplements increase or decrease the risk of colorectal cancer has been ongoing, but a new study claims the nutrient does neither. Analysis of data from three large trials of folic acid and colorectal cancer risk show the B vitamin has no effect on development of the disease.
Folic acid may improve mortality, however
Folic acid is perhaps best known for helping to prevent the incidence of birth defects, but for many years there has also been a debate about whether folic acid supplementation could reduce or increase the risk of colorectal cancer. For example, a study published in the Journal of Clinical Nutrition reported that increased intake of folate (the form of the B vitamin found in food) may reduce women’s risk of colorectal cancer by about 50 percent.
However, other research has indicated that folic acid supplementation and high levels of folate in the blood may increase the risk of colorectal cancer, including a study from Dartmouth Medical School. In that study, investigators found that folic acid supplementation may heighten the cancer risk.
In the new study, which was published in the International Journal of Cancer, a research team led by John Baron, professor of medicine at Dartmouth Medical School, evaluated data from the three largest randomized clinical trials involving folic acid supplements taken for the prevention of colorectal tumors (adenomas) that may develop into cancer.
A total of 2,632 men and women who had a history of adenomas were randomized to receive either 0.5 or 1.0 mg per day of folic acid or placebo. The investigators found that among the participants who took folic acid supplements for up to 3.5 years, there was “no clear decrease or increase in the occurrence of new adenomas in patients with a history of adenoma.”
One interesting finding was there were more deaths among people who took placebo than those who took folic acid. The researchers also found no differences in the rates of myocardial infarction, stroke, and all cancer types combined when comparing the folic acid and placebo groups.
Results of this combined analysis of three large studies indicate that folic acid supplements neither increase nor decrease the risk of colorectal cancer. The reviewers added, however, that additional follow-up is needed “to assess the longer-term effects of folic acid use.”
Cole BF et al. JAMA 2007 Jun 6;p 297(21): 2351-59
Figueiredo JC et al. International Journal of Cancer 2011; 129(1): 192-203
Kim J et al. European Journal of Clinical Nutrition 2009; doi:10.1038/ejcn.2009.37