Folic Acid, B12 May Increase Cancer Risk
Study Shows Slight Increase in Cancer Risk From Large Doses of Supplements
WebMD News Archive
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
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
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