Antioxidant Supplements versus Food for Cancer Prevention
Despite studies that show antioxidants in fruits and vegetables can fight cancer, research again shows that Vitamin E, C, and beta-carotene supplements have no effect when it comes to fighting cancer. In fact, previous studies show supplements might promote cancer.
Past studies have shown that synergy between chemicals in the body and natural food sources, do indeed act as a defense against a variety of diseases, including cancer. Research has repeatedly failed to reproduce the same cancer fighting results with antioxidant health supplements, making the current study no real surprise.
The new study showing that antioxidant supplements do not prevent cancer, randomly assigned women to receive 500 mg of ascorbic acid daily, 600 IU of natural Vitamin E every other day, and 50mg. of beta-carotene every other day. During the treatment period, 624 women developed invasive cancer and 176 women died from cancer, leading researcher Jennifer Lin, PhD, and colleagues, to conclude that further studies are not needed. Dr. Lin, of the division of preventive medicine at Harvard Medical School and Brigham and Women's Hospital in Boston studied, 7627 women, an average of 9.4 years.
Demetrius Albanes, M.D., of the National Cancer Institute, in an accompanying editorial to the research, published in the Journal of the National Cancer Institute Advance Access published online on December 30, 2008, says we have valuable information that should not be disregarded. Vitamin E has been shown to reduce the incidence of colon cancer, as seen in other studies. Beta- carotene use has been associated with an increase in lung cancer.
A drawback of the study regarding whether antioxidant supplements can fight cancer involves the short-duration of the study and the age of the women. Cancer can take many years to develop, and the study may not have been conducted for a long enough period. The average age of the women enrolled was 60 at the beginning of the study. Though none had cancer, other health risks were present, including heart disease, high blood pressure, obesity and diabetes, all associated with inflammation - a biomarker for the development of cancer.
A newer study from Xianglin Shi, Ph.D., professor in the Graduate Center for Toxicology at the University of Kentucky, used commercially extracted grape extract , which eradicated 75% of cancerous leukemia cells in lab mice, likely showing us that foods have healing power, and may still be our best defense to fight cancer, rather than antioxidant supplements. (1)
High quality research, led by Goran Bjelakovic, MD, of the Copenhagen University Hospital in Denmark, published January 2008 in the Journal of the American Medical Association, revealed without a doubt that antioxidant supplements increase mortality from cancer and heart disease. Co-author of the study Christian Gluud, MD, also of the Copenhagen University Hospital in Denmark, at that time, warned, "The question has been thoroughly addressed and we now know the answer — these agents are harmful," referring specifically to beta-carotene, Vitamin E and Vitamin A. The Copenhagen study showed no harm, and no benefit from Vitamin C and selenium, also included in the research (2)
The newest study from Lin and colleagues concludes, "There is no basis for a recommendation that individuals increase dietary levels of antioxidants as a means of reducing cancer risk." The authors also write, "This study had very limited statistical power to investigate any effect of dietary antioxidants on the risk of specific cancers," such as prostate cancer in men.
No final word seems to exist on whether antioxidant supplements, versus food is best for fighting cancer - my money is on food.
(2) JAMA. 2007;297:842-857.