Tomatos Impact on Prostate Health Questioned

LOS ANGELESIn a multiethnic cohort study published in Cancer Causes and Control (17,9: 1193-1207, 2006), researchers found no statistically significant evidence of a protective effect of tomato, two meals containing tomato (pizza, Spanish rice) or leafy vegetables against prostate cancer.
Food and nutrient intakes from 1993 to 1996 were calculated from a detailed food frequency questionnaire (FFQ), designed to account for the food and nutrient intake of several ethnic groups including Japanese-American, Native-Hawaiian, Latino, black and white malestotaling 82,486 surveys.
Follow-up was done for incident cancers using the local Surveillance Epidemiology and End Results (SEER) registries; vital status was ascertained using state death files; and data on PSA utilization from a later questionnaire was also examined. Results showed a total of 3,922 incident cancer cases during follow-up. Modestly increased risks of prostate cancer were observed in relation to higher intakes of several food items including light green lettuce and dark leafy green vegetables.
Researchers did not note any significant protective associations with any foods, including tomato intake, but two complex foods containing tomato sauce (pizza and Spanish rice) were associated with modest increases in risk. Prostate-specific antigen (PSA) test use was significantly and positively related to intake of some of these same items, implying a degree of disease detection-bias. Analysis found intake of overall fruits and vegetables, related micronutrients, or intake of selected complex food items had no significant protective associations with non-localized, high grade disease (in 1,345 cases). Researchers at the University of Southern California, Los Angeles, concluded there was no statistically significant evidence of a protective effect against prostate cancer after consumption of these foods, their associated micronutrients or supplements. However, a possible explanation for the positive associations with risk of several of the foods normally considered to be healthy is detection bias, since healthy dietary intake was related to greater use of the PSA test.