We like to have simple solutions to complex problems. Want to reduce the risk of prostate cancer? Why, just pop a lycopene pill! Many men are doing just that, prompted by ads in magazines and sales pitches in health food stores. But things may not be that simple. Why should we think that lycopene, the red pigment responsible for the color of tomatoes, should have any effect on prostate cancer in the first place? Because studies have shown that men who consume lots of tomato products have a lower incidence of the disease. Lycopene is a good candidate for biological activity because the tomato does actually use the compound to maintain its own health. The compound protects the seeds in the fruit from damage by oxygen and light. It can absorb excess ultraviolet light and react with the potentially damaging free radicals produced by exposure to oxygen.
But tomatoes, like other plants are very complex chemically. They contain literally hundreds of compounds. Now researchers at Ohio State University have designed and experiment to investigate if lycopene is really the anti-cancer ingredient in tomatoes. Of course one cannot ethically trigger cancer in humans, so the researchers focused on rats, which actually are very good models for human prostate cancer. They induced prostate cancer in about 200 rats by treating them with a mix of testosterone and N-methyl-N- nitrosourea, a potent combo for prostate carcinogenesis. Some of the rats were then fed diets that contained whole tomato powder while others were treated to rat chow fortified with lycopene. The lycopene fortified rats were getting more lycopene than the tomato powder rats. That’s what made the results of the experiment so surprising. The risk of death from prostate cancer was significantly greater in the rats that were fed the pure lycopene extract! This would seem to suggest that there are other components in tomatoes that have a protective effect and that the whole food is beneficial while isolated components may not be. True, the study was done in rats, but it does send us a message. Eat a balanced diet, with lots of vegetables and fruits because short cuts may not work.
But there was another significant finding in this study. The researchers also put some of the rats in each group on a calorie restricted diet. While their colleagues were allowed to eat as much as they wanted, these rats were given a diet that contained 20% fewer calories than the usual rat consumption. And guess what. These hungry rats experienced longer prostate cancer-free survival than the rats who ate freely. So, just eating less food reduces the risk of prostate cancer. What’s the overall message for us? Reduce our calorie intake and eat lots of tomato products. And exercise skepticism when we hear claims of lycopene reducing the risk of cancer.
