Highly publicized studies in recent years show that lycopene, a carotenoid antioxidant, appears to help prevent prostate cancer. They argued that eating foods rich in lycopene, such as tomatoes, guava, watermelon and pink grapefruit, lowers the risk of prostate cancer by anywhere from 30 to 50 percent. Soon after the studies were published, lycopene became available as a dietary food supplement.
But a new study from researchers at the University of Illinois and Ohio State University shows that lycopene may be nothing more than a bit player in the drama of prostate-cancer prevention. Other naturally occurring phytochemicals in tomatoes may be more potent than lycopene alone.1
The study involved 194 rats that were exposed to a carcinogen linked to prostate cancer, along with testosterone, which speeds the progress of prostate cancer. The rats were then divided into groups, with one group getting whole tomato powder and another receiving isolated lycopene supplements. A third group got a placebo and served as the control group. Rats in each group were randomly assigned to either an eat-as-much-as-you-want group or a group that ate 20 percent fewer total calories.
After 14 months the rats in the whole-tomato group showed a 26 percent lower death rate from prostate cancer than the control rats. The rats given pure lycopene showed death rates similar to those in the control group. By the end of the study, 80 percent of the rats in the control group had died of prostate cancer; 72 percent of the lycopene group had died; and 62 percent of those in the whole-tomato group had died. Among the rats that ate as much as they wanted, 79 percent died. In contrast, 65 percent of those in the restricted-calorie group died. That last finding underscores what past studies have found: Eating excess calories appears to promote some types of cancer.
Still, there are several things to ponder about this study. First, past research clearly shows that lycopene is far better absorbed from a cooked-tomato source than from raw tomatoes. Lycopene itself is difficult to absorb and requires a fat source for uptake into the body. It’s unclear whether those limitations were considered in this rat study. Other research shows that lycopene, a potent antioxidant, appears to prevent DNA mutations induced by products of oxidation, which are thought to be one cause of most cancers.
Lycopene can also short-circuit the tumor-promoting effects of insulinlike growth factor 1 (IGF-1), a hormone familiar to bodybuilders because of its anabolic effects on muscle. If it did nothing more than that, it would be worth taking as a supplement or eating foods that contain it. Lycopene concentrates more in the testes than in any other part of a man’s body, which suggests that it must be there for a darn good reason. Testosterone is known to promote prostate cancer via increased oxidation in the testes that leads to cellular mutations. Perhaps nature places lycopene in the testes to keep testosterone honest.
On the other hand, countless natural protective elements exist only in foods and aren’t available in supplement form. Tomatoes, for instance, contain phytonutrients that defend the body against many degenerative diseases, including cancer’and few of them work alone. That’s how nature works, and for the best health it makes sense to work with nature, not against it. IM
1 Boileau, T.W., et al. (2003). Prostate carcinogenesis in N-methyl-N-nitrosourea (NMU)-tes- tosterone-treated rats fed tomato powder, lycopene, or energy-restricted diets. J Nat Cancer Instit. 95:1578-86.