Development of a food-based diet quality score for Japanese: associations of the score with nutrient intakes in young, middle-aged and older Japanese women

Several previous studies have shown that a diet score based on the Japanese food guide Spinning Top (the original score) is associated with both favourable and unfavourable dietary intake patterns. We developed a food-based diet quality score (the modified score) and examined associations with nutrient intakes. Subjects were 3963 young (all aged 18 years), 3800 middle-aged (mean age 47·7 (sd 3·9) years) and 2211 older (mean age 74·4 (sd 5·2) years) Japanese women. Dietary intakes were assessed using comprehensive (for the young and middle-aged) and brief-type (for the older) diet history questionnaires. The original score was calculated based on intakes of grains, vegetables, fish/meat, milk, fruits, and snacks/alcoholic beverages. The modified score was similarly calculated, but included Na from seasonings and without applying the upper cut-off values for dietary components where increased consumption is advocated for Japanese women (grains, vegetables, fish/meat, milk, and fruits). The original score was positively associated with intakes of carbohydrate, dietary fibre, and all the vitamins and minerals examined including Na and inversely with intakes of fats and alcohol in young and middle-aged women. In older women, the original score was inversely associated with intakes of all nutrients except for carbohydrate and vitamin C. However, the modified score was associated positively with intakes of protein, carbohydrate, dietary fibre, K, Ca, Mg, Fe, vitamins A, C and E, and folate and inversely with intakes of fats, alcohol and Na in all generations. In conclusion, the modified diet score was positively associated with favourable nutrient intake patterns in Japanese women.