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Key words: carotenoids, case-control study, diet, fatty acids, prostate cancer.
Abstract
Objective: To examine the risk of prostate cancer associated with foods and nutrients, including individual fatty acids and carotenoids.
Methods: Population-based case-control study of 858 men aged <70 years at diagnosis with histologically confirmed prostate cancer of Gleason Grade 5 or greater, and 905 age-frequency-matched men, selected at random from the electoral rolls. Dietary intakes were assessed with a 121-item food frequency questionnaire.
Results: Inverse associations with prostate cancer were observed for (Odds ratio, OR, 95% confidence intervals, 95% CI for tertile III compared with tertile I) allium vegetables 0.7, 0.5-0.9; p trend 0.01, tomato-based foods 0.8, 0.6-1.0; p trend 0.03 and total vegetables 0.7, 0.5-1.0; p trend 0.04. Margarine intake was positively associated with prostate cancer 1.3, 1.0-1.7; p trend 0.04. The only statistically significant associations observed with nutrients were weak inverse associations for palmitoleic acid (p trend 0.04), fatty acid 17:1 (p trend 0.04), and 20:5 n-6 (p trend 0.05); and a non-significant trend for oleic acid (p trend 0.09). Neither total, nor beverage-specific, intake of alcohol was associated with risk.
Conclusions: Based on these findings, diets rich in olive oil (a source of oleic acid), tomatoes and allium vegetables might reduce the risk of prostate cancer.
Introduction
Prostate cancer has become the most commonly diagnosed male cancer in many Westernized populations including Australia [1]. Yet despite the importance of prostate cancer globally, only a few risk factors have been well-established, age and family history being the most important. International differences in incidence and mortality rates, changes in rates among migrants, and rapid temporal changes in rates in some populations are seen as evidence for environmental effects on prostate cancer promotion. In the Australian context, men from southern Europe and Asia have experienced significantly lower incidence and mortality rates compared with the Australian born [2]. Diet is potentially an important factor in explaining some of these differences.
Two recent reviews of food and nutrition policy concluded that consumption of red meat, all meat, all fat and saturated/animal fat could be associated with increased risk of prostate cancer, while vegetable consumption appeared to reduce risk [3, 4]. Associations with other foods and nutrients have been much less consistent, possibly because of problems...