Aim: We conducted a pilot study to clarify the effects of the Japan Diet nutritional education program on metabolic risk factors for atherosclerotic cardiovascular disease in middle-aged men who were brought up in the westernized dietary environment of modern Japan.Methods: Thirty-three men, 30–49 years of age, attended a nutrition education class to learn food items and recommended volumes comprising the Japan Diet (more fish, soybeans and soy products, vegetables, seaweed, mushrooms and unrefined cereals, and less animal fat, meat and poultry with fat, sweets, desserts and snacks, and alcoholic drinks), and were encouraged to consume the Japan Diet for 6 weeks. Anthropometric and biochemical parameters were measured and 3-day weighted dietary records were kept before and at completion of the intervention.Results: Ninety-one percent of participants showed improvements in more than one cardiovascular risk factor after 6 weeks. Body weight, serum low density lipoprotein (LDL) cholesterol, malondialdehyde modified (MDA)-LDL and triglyceride concentrations decreased significantly, while high density lipoprotein cholesterol was unchanged. Fish, soy, and sum of seaweed, mushrooms and konjak intakes doubled, and green and yellow vegetable intakes also increased as compared to baseline. Meanwhile, intakes of refined cereals, meat and poultry, sweets, desserts and snacks, and margarine and shortening decreased. Total energy, lipid, and saturated and monounsaturated fatty acid intakes decreased, while n-3 polyunsaturated fatty acid, dietary fiber, beta-carotene, vitamins D and K, potassium, and magnesium increased, with no change in sodium intake.Conclusions: The Japan Diet is suggested to improve atherosclerotic cardiovascular disease risk factors in middle-aged Japanese men.The clinical trial registration number: UMIN000020639.

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.