The effect of walnut intake on factors related to prostate and vascular health in older men

Background: Tocopherols may protect against prostate cancer and cardiovascular disease (CVD). Methods: We assessed the effect of walnuts, which are rich in tocopherols, on markers of prostate and vascular health in men at risk for prostate cancer. We conducted an 8-week walnut supplement study to examine effects of walnuts on serum tocopherols and prostate specific antigen (PSA). Subjects (n= 21) consumed (in random order) their usual diet +/- a walnut supplement (75 g/d) that was isocalorically incorporated in their habitual diets. Prior to the supplement study, 5 fasted subjects participated in an acute timecourse experiment and had blood taken at baseline and 1, 2, 4, and 8 h after consuming walnuts (75 g). Results: During the timecourse experiment, triglycerides peaked at 4 h, and gamma-tocopherol(gamma-T) increased from 4 to 8 h. Triglyceride-normalized gamma-T was two-fold higher (P=0.01) after 8 versus 4 h. In the supplement study, change from baseline was +0.83 +/- 0.52 mu mol/L for gamma-T, -2.65 +/- 1.30 mu mol/L for alpha-tocopherol (alpha-T) and -3.49 +/- 1.99 for the tocopherol ratio (alpha-T: gamma-T). A linear mixed model showed that, although PSA did not change, the ratio of free PSA: total PSA increased and approached significance (P=0.07). The alpha-T: gamma-T ratio decreased significantly (P=0.01), partly reflecting an increase in serum gamma-T, which approached significance (P=0.08). Conclusion: The significant decrease in the alpha-T: gamma-T ratio with an increase in serum gamma-T and a trend towards an increase in the ratio of free PSA: total PSA following the 8-week supplement study suggest that walnuts may improve biomarkers of prostate and vascular status.