By David Liu, Ph.D. and editing by Aimee Keenan-Greene

Friday July 8, 2011 (foodconsumer.org) -- The total intake of folic acid, fortified and naturally occurring in foods, may help prevent colorectal cancer, according to a new study in the July 2011 issue of Gastroenterology.  

Some previous studies showed the form of folate used to fortify foods was linked with increased risk of  malignancy. 

This study was intended to determine whether manufactured folate would increase cancer risk.  Researchers ended up finding that high intake of total folate was associated with 19 percent reduced risk of colorectal cancer. The reduction in the risk was said to be statistically significant.

Victoria L. Stevens of  the American Cancer Society and colleagues analyzed data from 43,512 men and 56,011 women in the Cancer Prevention Study II to determine whether there was an association between high intake of folate and colorectal cancer.  Of the subjects, 1,023 developed the disease between 1999 and 2007.

The researchers found high intake of natural folate or folic acid was correlated with 14 or 16 percent reduced risk of colorectal cancer, respectively. But the associations were not statistically significant, according to the report.

However when total folate intake was considered, the researchers found those who had high intake were 19 percent less likely to be diagnosed with colorectal cancer.

Stevens et al. concluded that "Intake of high levels of total folate reduces risk of colorectal cancer; there is no evidence that dietary fortification or supplementation with this vitamin increases colorectal cancer risk."

It should be noted that this study was not a trial and its results did not establish a causal relationship between high intake of folate and risk of colorectal cancer. 

In fact, more solid evidence derived from a clinical trial conducted by Dr. Bernard F. Cole of Dartmouth Medical School in Hanover NH and colleagues suggests taking folate supplements did not reduce the risk of colorectal tumors.

Instead, the researchers found that those who took 1 mg per day of folate developed more adenomas, precursors to colorectal cancer, than those who did not take the supplement.

The study was reported in the June 6, 2009 issue of JAMA.

Folate is by law added to grain products like wheat flour to reduce the risk of birth defects.  As a result, men end up having to eat high amount of fortified folate and some studies suggest the added folate may cause adverse effects in both men and women.

University of Southern California researchers including Jane Figueiredo found that men who took folate supplements daily in a dose of 1 mg folate per day were twice as likely as those who did not use the supplement to develop prostate cancer.

Please note that this result came from a placebo-controlled randomized trial, which appears in the March 10, 2009 issue of the Journal of the Naitonal Cancer Institute.

Stevens and colleagues also published a study in the Oct 2010 issue of American Journal of Clinical Nutrition suggesting high intake of folate and other one-carbon metabolism related nutrients may increase risk of breast cancer in postmenopausal women.

This study shows high intake of folate was associated with significantly increased risk of breast cancer. 

Foods rich in folate include brewer's yeast, lentils, romaine lettuce, pinto beans, okra, black beans, black eyed peas, kidney beans, broccoli, Brussels sprouts, collard greens, garbanzo beans, asparagus, and beets.   These foods should be a sufficient source of natural folate to help prevent birth defects.

Fortified folate may help some women who do not have access to foods rich in this nutrient.

Photo credit: wikipedia

For more information on folic acid, read the following

Folic Acid - Dietary fortification

Dietary fortification In the USA many grain products are fortified with folic acid. See also: Food fortification Since the discovery of the link between insufficient folic acid and neural tube

Folic Acid - Health Issues Health issues [edit]Human reproduction Adequate folate intake during the periconception period, the time right before and just after a woman becomes pregnant, helps protect against a number ... 
Folic acid - basics Folic acid (also known as vitamin B9,[3] vitamin Bc[4] orfolacin) and folate (the naturally occurring form), as well aspteroyl-L-glutamic acid, pteroyl-L-glutamate, andpteroylmonoglutamic acid[5] are forms of the water-soluble vitamin B9. Folic acid is itself not biologically active, ...