Tomato Diet Can't Guarantee Prostate Health: Study

FRIDAY, Sept. 14 (HealthDay News) -- Men who've been adding vitamin E or the tomato nutrient lycopene to their diets to cut their risk of prostate cancer may need to think again.

According to a new study, neither carotenoids (such as lycopene), retinol, nor tocopherols (forms of vitamin E) appear to reduce the odds of prostate malignancy -- findings that are in line with two other recent publications.

"Our overall findings are null," said lead researcher Timothy Key, deputy director of the Cancer Research UK Epidemiology Unit at the University of Oxford, U.K.

"This large study does not support the hypothesis that consuming large amounts of these nutrients will reduce prostate cancer," he added. "That is disappointing, but that is the overall message."

The findings are published in the September issue of theAmerican Journal of Clinical Nutrition.

His team examined the effect of the blood levels of 10 micronutrients on the risk of developing prostate cancer for almost 2,000 males from eight European countries.

The research, which the authors call "the largest prospective study to date of plasma carotenoids, retinol, tocopherols, and prostate cancer risk," was part of the EPIC (European Prospective Investigation into Cancer and Nutrition) study, which includes more than half a million men and women.

The authors did find evidence to suggest that, once a cancer forms, high levels of lycopene (or of carotenoids in general, including lycopene) may reduce by about 60 percent the risk of the tumor progressing to an advanced-stage prostate cancer. Carotenoids appeared to have no effect on the rate of localized, earlier-stage disease, however.

According to Dr. Peter Scardino, head of the Prostate Cancer Program at Memorial Sloan-Kettering Cancer Center in New York City, prostate cancer is the most common cancer in men in the developed world. A Western male, he said, has about a 42 percent risk of developing cancerous cells in his prostate over his lifetime, a 16 percent risk of being diagnosed with the disease, and about a three percent risk of dying as a result. In other words, nearly one-quarter of Western males have a subclinical form of prostate cancer, which will never progress to more advanced disease.

Stopping progression is crucial. According to Scardino, for those whose diseasedoesprogress, the risk of death is much higher -- nearly 50 percent.

"I think it's an important study," Scardino said. That lycopene and bulk carotenoids reduced the risk of progressing to advanced disease without impacting the risk of developing prostate cancer overall, he said, "suggests maybe these micronutrients are not as important in [stopping] carcinogenesis as they are in [slowing] progression of a very small early tumor to one that becomes invasive and larger and develops the ability to metastasize."

"The study provides supportive evidence that lycopene and the carotenoids may have an effect on delaying the progression of prostate cancer, so, from that point of view, it is an interesting study," Scardino added.