High intake of sweet foods such as cakes, cookies, chocolate and ice cream has been reported to be associated with depressive symptoms. However, prospective studies are scarce and no study has been conducted in Asian populations. We prospectively investigated the association between confectionery intake and depressive symptoms in a Japanese working population. Participants were 911 workers (812 men and 99 women; aged 19–68 years) without depressive symptoms at baseline who completed a 3-year follow-up survey. Dietary intake was assessed using a validated self-administered diet history questionnaire. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression (CES-D) scale. Multiple logistic regression was used to estimate the OR of depressive symptoms according to tertile of confectionery intake with adjustment for covariates. At the time of the 3-year follow-up survey, 153 (16·8 %) workers were newly identified as having depressive symptoms (CES-D score ≥ 16). Confectionery intake was significantly associated with increased odds of developing depressive symptoms. The multivariable-adjusted OR of depressive symptoms for the highest v. lowest tertile of confectionery intake was 1·72 (95 % CI 1·03, 2·86) after adjustment for covariates including dietary factors such as folate, vitamin B6, vitamin B12, n-3 PUFA, Mg, Zn and soft drink (Pfor trend = 0·012). Our results suggest that confectionery intake is associated with a higher risk of depressive symptoms in a Japanese working population predominantly comprised of men.

The relationship of chronotype differences with dietary habits and health-related outcomes among elderly people is not fully understood, although sex and generation differences are observed in human chronotype. Accordingly, we analysed the association of chronotype (as assessed by the midpoint of sleep) with dietary intake and health-related quality of life (HRQoL) in elderly Japanese women. The subjects in this cross-sectional study were 1618 women aged 65 years and older who were grandmothers or acquaintances of dietetics students. The subjects were classified into quintiles with respect to the midpoint of sleep, from the earliest to the latest quintile. HRQoL was assessed by the Japanese version of the short-form 36-item health survey score. Mental health was assessed by the Center for Epidemiologic Studies Depression (CES-D) Scale. Dietary intake was assessed by a brief-type self-administered diet history questionnaire. A later midpoint of sleep was associated with a lower intake of vitamin D and a higher intake of bread and caffeinated drinks. No correlations were observed between chronotype and other nutrient and food intake. The subjects with a late midpoint of sleep (eveningness) showed poor general health perception (GH) and high CES-D scores. Other HRQoL scores did not differ among groups with different midpoints of sleep. In conclusion, chronotype as assessed by the midpoint of sleep is associated with poor GH and depressive tendencies in elderly Japanese women. Additionally, a few associations were found between dietary intake and chronotype in elderly Japanese women.

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.

We aimed to examine the relationship between dietary glycaemic index (GI) and glycaemic load of foods consumed, intakes of carbohydrates, sugars and fibre, and the prevalence of depressive symptoms in older adults. Data collected from 2334 participants aged 55+ years and 1952 participants aged 60+ years were analysed. Dietary information was collected using a semi-quantitative FFQ. Depressive symptoms were based on antidepressant use or either the 36-Item Short-Form Survey, which included the Mental Health Index (MHI), or the Center for Epidemiologic Studies Depression-10 Scale. Participants in the highest v. lowest tertile of dietary GI intake had increased odds of depressive symptoms (assessed by the MHI scale), multivariable-adjusted OR 1·55 (95 % CI 1·12, 2·14). Participants in the highest compared with lowest tertile of fruit consumption had reduced odds of prevalent depressive symptoms, multivariable-adjusted OR 0·66 (95 % CI 0·46, 0·95). Total fibre, vegetable fibre and breads/cereal fibre intakes were all inversely associated with the prevalence of depressive symptoms, with global P values of 0·03, 0·01 and 0·03, respectively. Participants in the second v. first tertile of vegetable consumption had 41 % reduced odds of prevalent depressive symptoms, multivariable-adjusted OR 0·59 (95 % CI 0·40, 0·88). We show that dietary GI and fibre intakes as well as consumption of fruits and vegetables are associated with the prevalence of depressive symptoms.

Dietary factors and inflammation markers have been shown to play a role in the development of depression. However, there are very few studies that have explored the association between inflammatory potential of diet and risk of depression. In this study, we examined the association between the dietary inflammatory index (DII), which was developed specifically to measure the inflammatory potential of diet, and risk of depression in the middle-aged cohort of the Australian Longitudinal Study on Women’s Health. A total of 6438 women with a mean age of 52·0 (sd 1·4) years at baseline were followed-up at five surveys over 12 years (2001–2013). Depression was defined as a score of ≥10 on the Center for Epidemiologic Studies Depression-10 scale. The DII score, a literature-derived, population-based dietary index that has been validated against several inflammatory markers, was computed on the basis of dietary intake assessed using a validated FFQ. Generalised estimating equations were used to estimate relative risk (RR) of depression according to DII score. Models were adjusted for energy intake, highest education completed, marital status, menopause status and symptoms, personal illness or injury, smoking status, physical activity, BMI and depression diagnosis or treatment. In total, 1156 women (18 %) had scores≥10 on the CESD scale over the course of 9 years. Women with the most anti-inflammatory diet had an approximately 20 % lower risk of developing depression compared with women with the most pro-inflammatory diet (RRDII quartile 1 v. 4: 0·81; 95 % CI 0·69, 0·96; Ptrend=0·03). These results suggest that an anti-inflammatory diet is associated with lower risk of depression in middle-aged Australian women.