Folic Acid, B12 May Increase Cancer Risk
Study Shows Slight Increase in Cancer Risk From Large Doses of Supplements
In a statement issued in response to the study, a spokesman for the supplement-industry trade association Council for Responsible Nutrition (CRN) noted that the lung cancer finding has not been seen in other studies.
"The real headline of this study should be that smoking increases the risk of lung cancer -- the study found that a total of 94% of the subjects who developed lung cancer were either current or former smokers," CRN Vice President for Scientific and Regulatory Affairs Andrew Shao, PhD, says in a news release.
In the U.S., mandatory folic acid fortification of flour and grains has been in effect for just over a decade, and fortification has succeeded in dramatically lowering the incidence of neural tube birth defects.
Shao says the fact that lung cancer rates have also dropped during this time in both men and women suggest folic acid and B12 do not promote lung cancer.
Bettina F. Drake, PhD, of Washington University in St. Louis School of Medicine, says it is not likely that fortification has led to an increase in cancers in the U.S. In fact, several studies suggest just the opposite.
"We would expect to see an excess in cancers within a few years after folic acid fortification began, and we have not seen that," she tells WebMD.
Drake says it is possible that folic acid protects against cancer at certain points in life and promotes the growth of cancers at other times. It may also be true that too little folate in the blood or too much of the B vitamin are both associated with an increased risk for cancer.
In an editorial published with the study, Drake and Graham A. Colditz, MD, write that it may take decades to fully understand how folic acid fortification affects health.