Studies show a slight increase in cancer risk with high doses of supplements
By Salynn Boyles
WebMD Health News
Review by Louise Chang, MD
November 17, 2009-There is new evidence that high intakes of folic acid can promote some cancers.
Norwegian heart disease patients who took folic acid and B12 supplements were found to have a slightly higher risk of cancer and death from all causes than heart disease patients who did not take the supplement. The·Journal of American Medical Association.
Unlike the United States, Norway does not fortify flour and cereal foods with folic acid, a synthetic form of B vitamins.
This makes Norwegians tend to have much lower blood folic acid levels than Americans, making the population suitable for studying the effects of folic acid supplementation on cancer risk, says Haukeland University, Norway. Hospital researcher Marta Ebbing, MD, told WebMD.
Folic acid, B12, and lung cancer
Ebbing et al. Analyzed data from two studies involving approximately 7,000 heart disease patients treated with B vitamin supplements or placebo for an average of three and a half years from 1998 to 2005.
The original purpose of the study was to determine if taking B vitamin supplements improved cardiovascular outcomes, but it did not.
During treatment, blood folic acid levels in patients who took 0.8 milligrams of folic acid and 0.4 milligrams of vitamin B12 daily increased more than 6-fold.
Patients were followed for an average of 3 years after the end of supplementation, during which time 341 patients (10%) who took folic acid and B12 and 288 patients who did not (8.4%) were diagnosed with cancer. It was.
Folic acid and B12 supplementation was associated with a 21% increase in cancer risk, a 38% increase in illness mortality, and an 18% increase in all-cause mortality.
This finding was primarily driven by an increased incidence of lung cancer in patients treated with folic acid and B12.
Of the 236 cancer-related deaths in the study, 75 (32%) were due to lung cancer, and the study group’s cancer incidence was 25% higher than the Norwegian population as a whole.
Approximately 70% of all patients in this study are current or former smokers, including more than 90% of patients who develop lung cancer.
In a statement released in response to the study, a spokesman for the Responsible Nutrition Council (CRN) of the supplement industry group said that no findings of lung cancer were found in other studies.
“The real headline for this study should be that smoking increases the risk of lung cancer. The study found that a total of 94% of subjects who developed lung cancer were current or former smokers.” Said Dr. Andrew Xiao, Vice President of Scientific Regulations at CRN, in a news release.
In the United States, forced folic acid fortification of wheat flour and grains has been in place for over a decade, and the fortification has been successful in dramatically reducing the incidence of neural tube birth defects.
Xiao says the fact that the incidence of lung cancer also decreased during this period in both men and women suggests that folic acid and B12 do not promote lung cancer.
Bettina F at the University of Washington, St. Louis School of Medicine. Dr. Drake says the enhancement is unlikely to have led to an increase in cancer in the United States. In fact, some studies suggest the exact opposite.
“We expect the cancer to become overkill within a few years of the onset of folic acid fortification, but we didn’t see it,” she told WebMD.
Drake says folic acid can protect against cancer at certain points in life and promote cancer growth at other times. It may also be true that too little folic acid in the blood or too much B vitamins both increase the risk of cancer.
In an editorial published in this study, Drake and Graham A. Corditz, MD, wrote that it may take decades to fully understand how folic acid fortification affects health. I will.
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Source: Ebbing, M. Journal of American Medical Association, November 18, 2009; Volume 302: pp. 2119-2126.
Malta Ebbing, Maryland, Department of Cardiology, Hawkland University Hospital, Bergen, Norway.
Dr. Bettina F. Drake, MPH, Washington University, St. Louis School of Medicine, Associate Professor of St. Louis.
news release, Journal of the American Medical Association.
News release, responsible nutrition council.
© 2009 WebMD, LLC. all rights reserved.
Folic acid, B12 may increase the risk of cancer
Source link Folic acid, B12 may increase the risk of cancer