Dietary intakes and plasma 8-iso-prostaglandin F_2α concentrations in community-dwelling elderly Japanese: The Tsurugaya Project

We examined the association between dietary intakes and oxidative stress status in elderly Japanese. We analyzed cross-sectional data from a community-based Comprehensive Geriatric Assessment conducted in 2002. The subjects included 961 Japanese subjects aged 70 years or older who were non-daily antioxidant supplements users. We measured plasma total 8-iso-prostaglandin (PG)F_2α concentrations, a measurable lipid peroxidation biomarker, using a specific enzyme immunoassay kit. Dietary intakes were assessed through a food frequency questionnaire. Subjects were divided into three groups according to their dietary intake frequencies. Logistic regression was applied to calculate the odds ratios (ORs) for being in the highest tertile of plasma 8-iso-PGF_2α concentration. Frequent intake of orange or other citrus fruits, or persimmon, strawberry, or kiwi fruit was associated with lower plasma 8-iso-PGF_2α concentrations, respectively. After adjustment for potential confounders, the ORs and 95% confidence intervals (CIs) for orange or other citrus fruits were 1.00 (reference), 0.66 (0.47, 0.92), and 0.58 (0.39, 0.87) (p for trend, 0.009). Intake of persimmon, strawberry, or kiwi fruit showed similar results. These associations were partly explained by vitamin C intake. Other dietary intakes had no association. Intake of fruits may have a beneficial effect against oxidative stress in elderly Japanese.