Men who eat more fruits and vegetables are more likely to be diagnosed with prostate cancer. This finding from a large Los Angeles study to be published next month in the journal Cancer Causes Control suggests that well-nourished, health-conscious men are more likely to take PSA tests for early detection of this cancer. At the same time, diet did not protect them from developing this cancer nor did it affect the cancer grade.

To find out how intake of fruits, vegetables, and related vitamins and antioxidants relates to risk of cancer researchers at the USC/Norris Comprehensive Cancer Center asked 82,486 men to record their food and nutrient intakes in 1993-1996 by filling out detailed food frequency questionnaires. The men came from various ethnic backgrounds — African-American, Japanese-American, Native-Hawaiian, Latino and White males. The mens’ health and also how often they underwent health tests were measured over time.

“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. Notably, no significant protective associations of any foods were seen, including tomato intake; and intakes of two complex foods containing tomato sauce (pizza and Spanish rice) were associated with modest increases in risk. ”

“PSA test use was significantly and positively related to intake of some of these same items, implying a degree of disease detection-bias. Analysis of non-localized and high grade disease (1,345 cases) showed no significant protective associations with overall fruits and vegetables intake, related micronutrients, or with intake of selected complex food items.”

“CONCLUSIONS: We found no statistically significant evidence of a protective effect against prostate cancer of higher levels of intake of any of these foods, associated micronutrients or supplements. 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.”

Source: abstract
Cancer Causes Control. 2006 Nov;17(9):1193-207.
Prostate cancer incidence and intake of fruits, vegetables and related micronutrients: the multiethnic cohort study (United States).

Stram DO, et al. Department of Preventive Medicine, USC/Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.