Phytoestrogens May Reduce Lung Cancer Risk

Eating a diet rich in phytoestrogens may reduce the risk of lung cancer, reports the Journal of the American Medical Association (2005;294:1493–504). The results of this study suggest that both smokers and nonsmokers can reduce their chances of developing this often fatal type of cancer by modifying their diet.

Phytoestrogens are a group of chemicals present in various plant foods that have weak estrogen-like effects. Previous studies have shown that high phytoestrogen intake is associated with a reduced risk for cancer growth in the breast, uterus, and prostate. Other studies have found that blood levels of phytoestrogens are high in people living in areas with a relatively low cancer incidence. A specific group of phytoestrogens—isoflavones, which are present in soy products and some other foods—also appear to be useful for preventing menopausal hot flashes and postmenopausal osteoporosis.

Lung cancer is one of most common and most serious types of cancer in the United States. As the vast majority of lung cancer cases result from cigarette smoking, avoiding cigarette smoke is the most effective prevention measure. Other risk factors include exposure to air pollution, radon, asbestos, or other industrial chemicals, and a family history of lung cancer. Diets low in fruits and vegetables also appear to increase lung cancer risk.

In the new study, the dietary histories of 1,674 American patients with lung cancer were compared with those of 1,735 healthy people. After controlling for smoking status and other risk factors, the risk of lung cancer decreased with increasing phytoestrogen intake. People with the highest levels of intake had a 46% reduction in lung cancer incidence, compared with those with the lowest phytoestrogen intake. The benefits of high phytoestrogen intake were seen both in smokers and in those who had never smoked, although they were not as evident in former smokers.

Good food sources of phytoestrogens include legumes (particularly soy products), whole grains, oranges, bananas, strawberries, carrots, broccoli, lettuce, flaxseed, and onions. In addition to their potential protective effect against lung cancer, some of these foods may also help prevent other types of cancer, diabetes, heart disease, and osteoporosis. While avoiding cigarette smoke, radon, and various pollutants and industrial chemicals are the most important components of a lung cancer–prevention program, it is encouraging that consuming a healthful diet is likely to provide additional protection.

An expert in nutritional therapies, Chief Medical Editor Alan R. Gaby is a former professor at Bastyr University of Natural Health Sciences, where he served as the Endowed Professor of Nutrition. He is past-president of the American Holistic Medical Association and gave expert testimony to the White House Commission on Complementary and Alternative Medicine on the cost-effectiveness of nutritional supplements. Dr. Gaby has conducted nutritional seminars for physicians and has collected over 30,000 scientific papers related to the field of nutritional and natural medicine. In addition to editing and contributing to The Natural Pharmacy (Three Rivers Press, 1999), and the A–Z Guide to Drug-Herb-Vitamin Interactions (Three Rivers Press, 1999), Dr. Gaby has authored Preventing and Reversing Osteoporosis (Prima Lifestyles, 1995) and B6: The Natural Healer (Keats, 1987) and coauthored The Patient's Book of Natural Healing (Prima, 1999).

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