The whole tomato is cancer foe

Whole tomato products appear to be a better bet for inhibiting development of prostate cancer than the compound lycopene alone, according to a new animal study.

Rats fed diets containing whole tomato powder, which contains lycopene and other compounds, had a lower risk of death from prostate cancer than animals fed diets supplemented with pure lycopene or on a standard diet.

Lycopene is a carotenoid in tomatoes that gives them their red color. Consumption of lycopene in the diet has been associated with a reduced risk of prostate cancer in population studies, but it's been unclear whether the compound itself is responsible, or if it serves as a marker for other anti-cancer compounds in tomatoes.

"Our observations support the concept that tomato products contain components in addition to lycopene that may inhibit prostate cancer," said Thomas Boileau, University of Illinois, Urbana- Champaign, senior co-author of the study.

"The findings strongly suggest that risks of poor dietary habits cannot be reversed simply by taking a pill," said Dr. Steven Clinton of Ohio State University, the other lead author. "We must focus more on choosing a variety of healthy foods, exercising and watching our weight."

The researchers randomly assigned 194 male rats treated with a carcinogen that induces prostate cancer to one of three diets. After four weeks, the rats were further divided into subgroups on each diet that either had unlimited access to food or were restricted to 80 percent of the average daily intake.

Rats in the diet-restricted group had a 32 percent lower risk of dying with prostate cancer than rats with unlimited access to food. There appeared to be no interaction between type of diet and the amount of food the rats got.

Rats on the tomato powder diet had a 26 percent lower risk of prostate cancer death than the control rats, allowing for diet restriction. By comparison, the rats eating lycopene alone had a prostate cancer risk that was not statistically different from the control rats.

The researchers said more work is needed to understand the role of the various compounds in tomatoes and to determine if there are additive or synergistic effects between the compounds on cancer.

"Many men are consuming lycopene-containing supplements with the hope that they may prevent prostate cancer or enhance the treatment of their prostate cancer," the researchers concluded. "We suggest that a focus on interventions with whole tomato products and energy balance should be a priority while clinical studies simultaneously investigate risks and benefits of lycopene supplements."

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