Increased Lung Cancer Risk Associated With Certain Vitamin Supplements

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Main Category: Lung Cancer
Also Included In: Public Health;  Nutrition / Diet;  Cancer / Oncology
Article Date: 29 Feb 2008 - 4:00 PDT

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A recent study published in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine reports that vitamin supplements do not protect against lung cancer, and may in fact increase the risk of developing it.

Dr. Christopher G. Slatore of the University of Washington and colleagues performed the analysis by selecting a prospective cohort of 77,126 people between 50 and 76 years of age who were all in the Washington State VITAL (VITamins And Lifestyle) program. The researchers analyzed the rate of lung cancer development over four years and how it correlates with current and past vitamin usage, smoking, and other characteristics pertaining to demography and medical history.

Slatore writes, "Our study of supplemental multivitamins, vitamin C, vitamin E and folate did not show any evidence for a decreased risk of lung cancer." In addition, he notes that participants who increased intake of supplemental vitamin E had slightly higher risks of lung cancer.

From the 77,126 people, 521 developed lung cancer; this is in line with the expected rate for this low-risk group. However, those who did develop lung cancer had a slight significant association between lung cancer and supplemental vitamin E in addition to the typical associations with smoking history, family history, and age.

According to the model, a person taking 100 mg/day of vitamin E for ten years increases the risk of lung cancer by seven percent. This is like a 28 percent increase in risk for a 400 mg/day dose for ten years. Slatore notes that this increase in risk was largely confined to current smokers.

Since so many people currently or used to smoke and so many people take vitamin supplements, the study findings can benefit public health. "Future studies may focus on other components of fruits and vegetables that may explain the decreased risk [of cancer] that has been associated with fruits and vegetables," notes Dr. Slatore. "Meanwhile, our results should prompt clinicians to counsel patients that these supplements are unlikely to reduce the risk of lung cancer and may be detrimental."

An editorial in the same journal issue by Dr. Tim Byers of the University of Colorado School of Medicine suggests people want to easily take a pill instead of eating a healthy diet, and this is why they believe that vitamin supplements are healthy or relatively harmless.

However, "fruits contain not only vitamins but also many hundreds of other phytochemical compounds whose functions are not well understood," writes Byers. One study found a 20 percent increase in cancer risk among people who ate the least amount of fruit, and this has led to the World Cancer Research Fund and the American Cancer Society to recommend two fruit servings each day.

Two servings of fruit per day "would likely lead to a reduced risk for lung cancer, as well as reduced risk of several other cancers and cardiovascular disease," writes Dr. Byers. "However, any benefit to the population of smokers from increasing fruit intake to reduce cancer risk by 20 percent would be more than offset if even a small proportion of smokers decided to continue tobacco use in favor of such a diet change."

Long-Term Use of Supplemental Multivitamins, Vitamin C, Vitamin E, and Folate Does Not Reduce the Risk of Lung Cancer
Christopher G. Slatore, Alyson J. Littman, David H. Au, Jessie A. Satia, and Emily White
American. Journal of Respiratory and Critical Care Medicine. 2008; 177: pp. 524-530.
doi:10.1164/rccm.200709-1398OC
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Written by: Peter M Crosta
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