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Nagano diet, oleic acid, omega-3 fatty acids
Aim: Increased life expectancy has long been linked to a healthy diet. Although individuals from the Nagano Prefecture have the longest life expectancy in Japan, the characteristics of the Nagano diet are unclear. While marine-derived n-3 free fatty acids (FFA) have traditionally been thought to decrease mortality, Nagano has no seashore; hence, we hypothesized that non-marine dietary constituents in the diet may contribute to the decreased death rate. We thus aimed to characterize the Nagano diet with respect to serum triglycerides, FFA, cholesterol, and lipoprotein concentrations. Methods: This was a cross-sectional study, where 106 Nakano city residents completed a health and lifestyle questionnaire. Additionally, we calculated body mass index and analyzed non-fasting blood samples for triglycerides, FFA, total cholesterol, high-density lipoprotein, and low-density lipoprotein concentrations. Results: Participants had significantly higher oleic acid and alpha-linolenic acid concentrations, and significantly lower docosahexaenoic and linoleic acid concentrations than Japanese reference values. Conclusions: Our results suggest that the Nagano diet may alter FFA composition in Nagano residents, potentially contributing to better maintenance of health.