Japan Diet Intake Changes Serum Phospholipid Fatty Acid Compositions in Middle-Aged Men: A Pilot Study

Aim: The Japan Diet nutritional education program effects on serum fatty acid compositions for prevention of atherosclerotic cardiovascular disease in middle-aged men brought up in the westernized dietary environment of modern Japan were examined. Methods: Thirty-three men, 30–49 years of age, attended a nutrition education class and were recommended to consume Japan Diet volumes (more fish, soybeans and soy products, vegetables, seaweed, konjak, mushrooms, and unrefined cereals and less animal fat, meat and poultry with fat, sweets, desserts and snacks, and alcoholic drinks) for 6 weeks. Three-day weighted dietary records were kept, and fatty acid intakes were calculated. Serum phospholipid fatty acid compositions were examined. Results: During the 6 weeks, fish, soy, and seaweed and/or mushrooms and/or konjak were consumed 1.0, 1.1, and 1.0 times daily on average, whereas daily fatty meat and poultry and sweet consumptions were 0.3 and 0.3, respectively. These changes were attributed to increased intake of n-3 polyunsaturated fatty acids (PUFAs) such as C20:5(n-3), C22:6(n-3), C18:4(n-3), and C20:4(n-3) and decreased intakes of all saturated fatty acids and unsaturated fatty acids such as C18:1 and C18:2(n-6). As to the phospholipid fatty acid composition, C18:0 decreased, whereas C15:0, C17:0, and C20:0 increased. Marked increases in C20:5(n-3) and C22:6(n-3) raised total n-3 PUFA from 10.30% to 13.20% along with n-6 PUFA decreasing from 33.92% to 31.16%. Despite decreases in C20:4(n-6) and C20:3(n-6), the C20:4(n-6)/C20:3(n-6) ratio used as an estimate of delta-5 desaturase activities increased and correlated positively with fish intake at completion of the intervention. Conclusions: The Japan Diet is effective for changing the fatty acids to an anti-atherosclerotic profile. The clinical trial registration number: UMIN000020639.