Although better diet quality is inversely related to the risk of geriatric disorders, the association of adherence to dietary guidelines with oral health-related quality of life (OHRQoL) is unclear. We aimed to investigate this association in older Japanese adults. This cross-sectional study included 7984 Japanese participants aged ≥ 65 years from the population-based Kyoto–Kameoka study. Dietary intake was estimated using a validated self-administered FFQ. The scores for adherence to the Japanese Food Guide Spinning Top (range: 0 (worst) to 80 (best)) were calculated. These scores were stratified into quartiles (Qs). Poor OHRQoL was defined as a score ≤ 50 using a 12-item Geriatric Oral Health Assessment Index. The OR and 95 % CI were calculated using multivariable logistic regression and the spline model. Higher adherence score was associated with a lower prevalence of poor OHRQoL (Q1–Q4:36·0 %, 32·1 %, 27·9 % and 25·1 %, respectively). An inverse association was found between the score for adherence to the food-based Japanese dietary guidelines and the OR of poor OHRQoL among all the participants (Q1: reference; Q2: OR, 0·87 (95 % CI: 0·75, 1·00); Q3: OR, 0·77 (95 % CI: 0·66, 0·90); Q4: OR, 0·72 (95 % CI: 0·62, 0·85); P for trend < 0·001). These relationships were similar to the results in the spline model. Higher adherence to the food-based Japanese dietary guidelines is inversely associated with the prevalence of poor OHRQoL in older adults. Our results may provide useful insights to improve and maintain oral health.

Only a few studies have focused on the association between overall diet, rather than intakes of individual nutrients or foods, and depressive symptoms in Japanese. This cross-sectional study examined associations between a diet quality score and depressive symptoms in 3963 young (age 18 years) and 3833 middle-aged (mean age 47·9 (sd 4·2) years) Japanese women. Dietary information was collected using a diet history questionnaire. A previously developed diet quality score was computed mainly based on the Japanese Food Guide Spinning Top. The prevalence of depressive symptoms was 22·0 % for young women and 16·8 % for middle-aged women, assessed as a Center for Epidemiologic Studies Depression (CES-D) score ≥23 and ≥19, respectively. As expected, the diet quality score was associated positively with intakes of ‘grain dishes’, ‘vegetable dishes’, ‘fish and meat dishes’, ‘milk’ and ‘fruits’ and inversely with intakes of energy from ‘snacks, confection and beverages’ and Na from seasonings. After adjustment for potential confounders, OR for depressive symptoms in the highest v. lowest quintiles of the diet quality score was 0·65 (95 % CI 0·50, 0·84) in young women (Pfor trend=0·0005). In middle-aged women, the corresponding value was 0·59 (95 % CI 0·45, 0·78) (Pfor trend<0·0001). Analyses where the diet quality and CES-D scores were treated as continuous variables also showed inverse associations. In conclusion, this cross-sectional study showed that a higher diet quality score was associated with a lower prevalence of depressive symptoms in young and middle-aged Japanese women. Prospective studies are needed to confirm a public health relevance of this finding.

While Japanese diets have attracted considerable attention because of, for example, the long-life expectancy in Japan, their health benefits have not been examined. In the present study, we cross-sectionally examined whether adherence to the food-based Japanese dietary guidelines is associated with metabolic risk factors in 1083 Japanese women aged 18–22 years. Based on the Japanese Food Guide Spinning Top, adherence to the food-based Japanese dietary guidelines was assessed using dietary information on consumed servings of grain dishes, vegetable dishes, fish and meat dishes, milk and fruits and energy from snacks and alcoholic beverages during the preceding month, which was derived from a comprehensive diet history questionnaire. Higher dietary adherence was associated with higher intakes of protein, carbohydrate, dietary fibre, Na, K and vitamin C, and lower intakes of total and saturated fat. There was also an inverse association between dietary adherence and dietary energy density. After adjustment for potential confounding factors, dietary adherence was inversely associated with waist circumference (P for trend = 0·002). It also showed an inverse association with LDL-cholesterol concentrations (P for trend = 0·04). There was no association with the other metabolic risk factors examined, including BMI, systolic and diastolic blood pressure, total and HDL-cholesterol, TAG, glucose, glycated Hb and insulin concentrations. In conclusion, higher adherence to the food-based Japanese dietary guidelines, which was characterised by favourable dietary intakes of foods and nutrients as well as lower energy density, was associated with lower waist circumference and LDL-cholesterol concentrations in this group of young Japanese women.