Growth Inhibitory Effect of Low Fat Diet on Prostate Cancer Cells: Results of a Prospective, Randomized Dietary Intervention Trial in Men With Prostate Cancer

Purpose: A high fat Western diet and sedentary lifestyle may predispose men to prostate cancer through changes in serum hormones and growth factors. We evaluated the effect of a low fat diet on serum factors affecting prostate cancer cell growth by performing a prospective, randomized dietary intervention trial in men with prostate cancer. Materials and Methods: We randomized 18 men with prostate cancer who did not receive prior therapy to a low fat (15% kcal), high fiber, soy protein supplemented diet or a Western (40% kcal fat) diet for 4 weeks. Fasting serum was collected at baseline and after the intervention to measure prostate specific antigen, sex hormones, insulin, insulin-like growth factor I and II, insulin-like growth factor binding proteins, lipids and fatty acids. LNCaP cells (ATCC (R)) were cultured in medium containing pre-intervention and post-intervention human serum to assess the in vitro effect of the diet on prostate cancer cell proliferation. Results: Subjects in each group were highly compliant with the dietary intervention. Serum from men in the low fat group significantly decreased the growth of LNCaP cells relative to Western diet serum (p = 0.03). There were no significant between group changes in serum prostate specific antigen, sex hormones, insulin, insulin-like growth factor I and II, and insulin-like growth factor binding proteins. Serum triglyceride and linoleic acid (omega-6) levels were decreased in the low fat group (p = 0.034 and 0.005, respectively). Correlation analysis revealed that decreased omega-6 and increased omega-3 fatty acid correlated with decreased serum stimulated LNCaP cell growth (r = 0.64, p = 0.004 and r = -0.49, p = 0.04, respectively). Conclusions: In this prospective, randomized dietary intervention trial a low fat diet resulted in changes in serum fatty acid levels that were associated with decreased human LNCaP cancer cell growth. Further prospective trials are indicated to evaluate the potential of low fat diets for prostate cancer prevention and treatment.