Men who consume vegetable oils rich in monounsaturated fat: their dietary patterns and risk of prostate cancer (New Zealand)

Objectives: To investigate (i) dietary patterns associated with consumption of vegetable oils rich in monounsaturated fatty acids (MUFA), and (ii) the risk of prostate cancer associated with consumption of these oils. Methods: A population-based case-control study was conducted in Auckland, N ew Zealand, involving 317 prostate cancer cases and 480 controls. A food-fr equency questionnaire was used to collect data concerning consumption of MU FA-rich vegetable oils (including olive oil, canola or peanut oil) and othe r dietary variables. Biomarkers for fatty acids were measured in erythrocyt es. Results: The group of participants who reported regular consumption of grea ter than 5.5 ml of MUFA-rich vegetable oils per day had a diet relatively h igh in monounsaturated fat, vegetables, lycopene, vitamin E, selenium, and n-3 fish oils. Increasing levels of MUFA-rich vegetable oil intake were ass ociated with a progressive reduction in prostate cancer risk (multivariate relative risk = 0.5: 95% confidence interval 0.3-0.9; > 5.5 ml per day vs. non-consumption, p trend = 0.005), and similar trends were observed across all strata of socioeconomic status. Prostate cancer risk was not associated with intake of total MUFA or the major animal food sources of MUFA. Conclusion: This finding may be explained by the protective effect of an as sociated dietary pattern high in antioxidants and fish oils, an independent protective effect of MUFA-rich vegetable oils unrelated to the MUFA compon ent, or a combination of these factors.