Healthnotes Newswire (June 21, 2007)—For men who are trying to reduce their risk of prostate cancer by eating a diet high in lycopene—a carotenoid found in particularly high quantities in tomatoes—a new study in Cancer Epidemiology, Biomarkers, and Prevention questions the benefits of this action.
Prostate cancer is the most common internal cancer and the second leading cause of cancer-related deaths among men. The cancer is more prevalent in older men; more than 70% of prostate cancer cases are diagnosed in men over the age of 65. Since there are no symptoms early in the disease, routine screening can help detect the cancer before it spreads.
Several earlier studies have suggested that men who have high concentrations of lycopene in their blood are less likely to develop prostate cancer. An antioxidant carotenoid, which combats harmful free radicals in the body, lycopene has become a popular nutritional supplement, and manufacturers of lycopene-rich food products have funded research examining its health benefits.
The new study, which was part of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, examined the association between blood levels of carotenoids and prostate cancer risk. At the beginning of the study, more than 28,000 men—none of whom had prostate cancer—underwent testing for blood levels of carotenoids including alpha-carotene, beta-carotene, lutein, beta-cryptoxanthin, zeaxanthin, and lycopene.
During the eight-year study period, 692 men were diagnosed with prostate cancer. A high lycopene concentration in the blood did not seem to protect against prostate cancer; men who had the highest levels of lycopene were no less likely to develop the cancer than were those with the lowest levels. Of all the carotenoids, only beta-carotene was related to prostate cancer risk. Those men with the highest beta-carotene levels had a 1.7 times greater risk of aggressive prostate cancer than those men with the lowest levels.
“Our results do not support the use of lycopene, beta-carotene, or other carotenoids in prostate cancer prevention,” the authors concluded. “Simple and inexpensive approaches to prostate cancer prevention would be of great public health significance, and it is unfortunate that the initial results on lycopene and tomato products could not be replicated.”
Despite these negative results, it is too early to write off lycopene for prostate cancer prevention. It is possible that some of the men took lycopene supplements or ate large amounts of tomato products because they believed themselves to be at high risk of developing prostate cancer (perhaps because of a family history of the disease). If that is the case, then the study’s results could be invalid. Numerous other studies have shown that eating high amounts of tomato products is associated with a lower risk of prostate cancer, and some preliminary trials have suggested that lycopene supplements can slow the progression of existing prostate cancer.
(Cancer Epidemiol Biomarkers Prev 2007;16:962–8)
Kimberly Beauchamp, ND, earned her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She cofounded South County Naturopaths in Wakefield, RI. Dr. Beauchamp practices as a birth doula and lectures on topics including whole-foods nutrition, detoxification, and women’s health.
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