The effect of walnut intake on factors related to prostate and vascular health in men at increased risk for prostate cancer

Abstract

Tocopherols may protect against prostate cancer. We conducted a free-living feeding study to assess the effect of walnuts, a tocopherol-rich food, on markers of prostate and vascular health in men at risk for prostate cancer. We examined serum tocopherol levels, lipids, selected hormones, PSA, food records and urinary symptoms data. Subjects (n=21) were randomized to an 8-week walnut diet (75 g/d) or their usual diet (control) and switched to the other diet for the second 8-week period following a 2-week washout. Fasted subjects had blood drawn at baseline and at the end of each diet period. All analyses were adjusted for weight, and the tocopherol analyses were also adjusted for age and lipids. No sequence effects were detected. At baseline, average serum concentrations were 193 mg/dl (SD=28.2) for total cholesterol, 102 mg/dl (SD=48.5) for triglycerides, 19.2 % (SD=8.53) for percent free PSA (PFP), 139 ng/ml (SD=40.5) for IGF-1, 29.3 μM (SD=10.0) for α-tocopherol (αT), 4.14 μM (SD=1.99) for γ-tocopherol (γ T) and 11.0 (SD=9.91) for the tocopherol ratio (αT: γ T). A change score was used to measure differences in concentrations between baseline and the diet periods. During the walnut diet, decreasing trends were seen in the mean serum concentrations of several variables, including αT: γ T (Δ =−3.46), total cholesterol (Δ =−6.00), triglycerides (Δ =−6.00) and PFP (Δ =−0.40%). In addition, a decreasing trend in mean serum IGF-1 was seen when comparing the diets (Δ =−8.00). Walnut consumption may thus improve markers associated with prostate cancer and cardiovascular disease risks. Funded by the California Walnut Commission.