Variations in diet quality across the lifespan remain insufficiently characterised, particularly in non-Western populations. We aimed to examine age-and sex-specific variation in diet quality and identify associated dietary components and socio-demographic and lifestyle factors in a Japanese population. In this cross-sectional study of 4455 Japanese individuals aged 1–79 years, dietary intake was assessed using 8-day weighed dietary records collected across four seasons. Diet quality was evaluated using the Healthy Eating Index-2020 (HEI-2020) and Nutrient-Rich Food Index 9·3 (NRF9·3). Associations with dietary components and lifestyle and socio-economic factors were examined separately in children and adults, with tests for interaction by age. Both indices showed marked age-and sex-specific variation. HEI-2020 scores reached estimated nadirs at 16·1 years in females and 23·4 years in males, whereas NRF9·3 scores were lowest in early adulthood (approximately 24 years) in both sexes; older adults consistently exhibited the highest scores. Across age-sex strata, the components contributing most to total score variation were dairy, fatty acids, Na and saturated fats for HEI-2020 and Na and added sugars for NRF9·3. Socio-economic disparities emerged early, with higher household income and parental education associated with better diet quality in children. In adults, lower diet quality was associated with lower income and education, smoking and breakfast skipping in both sexes and full-time employment in males. In conclusion, diet quality was lowest in adolescence and early adulthood in this Japanese population, with distinct socio-economic and lifestyle determinants across life stages, thereby highlighting critical periods for targeted, age-appropriate nutritional interventions.

The dietary phytochemical index (DPI), an alternative and practical marker for assessing dietary phytochemical intake, has not previously been investigated in relation to primary dysmenorrhoea (PD). This study aimed to investigate the association between the DPI and PD in women university students in Niğde, Türkiye. The sample of this cross-sectional study consisted of women university students aged 19–35 years. The study data were collected through face-to-face interviews using a questionnaire. The questionnaire included general information about the students, dietary intake, the short form of the International Physical Activity Questionnaire, and the Visual Analog Scale. The DPI was calculated from the participants’ food consumption records (DPI = energy from foods rich in phytochemicals (kcal/day)/total energy intake (kcal/day) × 100). Of the 362 women university students who participated in the study, the prevalence of PD was 83.9%. Those affected had higher waist circumference and dietary energy intake, but lower potassium and magnesium intake and DPI (p < 0.05). Students with severe pain were more likely to have a lower DPI (p < 0.05). The results of this study showed that the prevalence of PD a was quite high among students and that the DPI was associated with PD. These findings suggest a potential role of foods rich in dietary phytochemicals in alleviating PD, although causal relationships cannot be established due to the cross-sectional design of the study.

Epidemiologic evidence on the association between sugar-sweetened beverage (SSB) consumption and sleep-related symptoms or perceived stress remains limited, especially among middle-aged and older adults. This study examined the associations between SSB consumption and observed sleep apnoea, snoring, daytime tiredness and perceived stress among Korean adults aged 40 years and older. Cross-sectional data from the Korea National Health and Nutrition Examination Survey 2019–2023 were analysed (n 17 255). SSB consumption was assessed via 24-h dietary recall and categorised as non-consumers, moderate consumers (Q1–Q3) and high consumers (Q4). Multivariable logistic regression with complex survey design adjustment was used to estimate OR and 95 % confidence intervals (CI). Among 17 255 participants (mean age 60·2 years, 57·5 % women), 10 169 (58·9 %) were SSB consumers. Compared with non-consumers (n 7086), the highest intake group (Q4, n 2542) showed higher odds of observed sleep apnoea (OR 1·32; 95 % CI 1·09–1·60) and perceived stress (OR 1·23; 95 % CI 1·08–1·40). In sex-stratified analyses, the association with observed sleep apnoea was significant among men (OR 1·29; 95 % CI 1·04–1·60) but not women (OR 1·22; 95 % CI 0·89–1·67), although formal interaction analyses did not support significant effect modification by sex. Higher odds of perceived stress were observed in both men (OR 1·24; 95 % CI 1·02–1·50) and women (OR 1·22; 95 % CI 1·02–1·45). No significant associations were found for snoring or daytime tiredness. Higher SSB consumption was associated with observed sleep apnoea and perceived stress, and prospective studies are needed to clarify temporal relationships and underlying mechanisms.

Low dietary diversity is a predictor of depression in high-income countries, but evidence from low-income settings where poor nutrition and depression often co-occur is scarce. We examined the association between dietary diversity and depression in rural Western Kenya. We conducted a cross-sectional analysis of data collected between June and August 2025 from 311 participants enrolled in a group-based microfinance (‘BIGPIC’) program. Depression was measured using twenty-item Centre for Epidemiologic Studies for Depression Scale, and dietary diversity was assessed based on the consumption of five food groups in the previous 24 hours using a validated scale. We used linear regression models to estimate the association between high dietary diversity and depression scores and assessed effect measure modification by wealth status. Quantile regression was used to examine variation across the distributions of depression scores. Higher dietary diversity was associated with lower depression scores (adjusted β (95 % CI): −3·49 (–6·62, −0·38)). This association was stronger among individuals with lower wealth (adjusted β (95 % CI): −6·00 (–10·46, −1·42)), compared with those with high wealth (adjusted β (95 % CI): −0·53 (–4·76, 3·68); Wald P–value for interaction = 0·0003). Effect sizes were larger at higher quantiles across 75th (Q75: β = −7·56; 95 % CI: −12·82, −2·27) and 90th (Q90: β = −6·01; 95 % CI: −12·43, 0·43) quantiles, though estimates were imprecise. These findings suggest that greater dietary diversity may be associated with improved mental health, particularly among socio-economically vulnerable individuals, and those with severe depression. Future work using longitudinal and quasi-experimental designs are needed to strengthen causal inference and clarify underlying mechanisms.

Blood pressure (BP) variability is an independent risk factor for cardiovascular disease. Gut microbiome (GM) regulates BP, but its association with BP variability remains unclear. We examined the association of GM, determined by stool shotgun metagenomic sequencing, with 24-hour BP average real variability (ARV) assessed by ambulatory BP monitoring in 235 community-dwelling adults from Hong Kong (111 men and 124 women, mean age 54 ± 6 years) using covariate-adjusted statistical models. The GM alpha diversity was negatively associated with systolic BP (SBP) ARV in the full cohort, driven by women. In men, beta diversity of both GM species and function was associated with SBP ARV, while Bacteroides nordii and the steroid hormone biosynthesis pathway had a positive association with SBP ARV. Bacteroides nordii emerged as the key species driving the significant positive association of steroid hormone biosynthesis and other pro-pathogenic pathways with SBP ARV, including lipopolysaccharide biosynthesis, phenylalanine, and sulfur metabolism in men, warranting further investigation for its causal role. We demonstrated distinct signatures of GM dysbiosis, composition, and function with minimal overlap between men and women with increased 24-hour SBP variability. Our work suggests that sex differences should be an important consideration in mechanistic and therapeutic investigations of GM-mediated BP variability.

Using National Health and Nutrition Examination Survey data (2011–2020), we assessed the association between the nutritional risk index (NRI) and stroke risk among 22 839 adults (mean age, 49·61 (sd 17·07) years), including 910 individuals (3·98 %) with stroke. Weighted multivariable logistic regression and restricted cubic spline (RCS) analysis were used to characterise the association, with subgroup analyses to examine consistency across populations and mediation analyses to investigate the roles of lipid and inflammatory biomarkers. Higher continuous NRI was inversely associated with stroke, with each 1-unit increase associated with 4 % lower odds (OR = 0·96, 95 % CI: 0·95, 0·97), and participants in the highest NRI quartile (Q4) had a significantly lower stroke risk than those in the lowest NRI quartile (Q1) (OR 0·60, 95 % CI 0·42, 0·85). RCS analysis indicated a linear relationship (P for nonlinearity > 0·05), and the protective effect of higher NRI remained robust across nearly all subgroups examined. Mediation analyses revealed that total cholesterol, systemic immune-inflammation index, product of platelet and neutrophil count, neutrophil:lymphocyte ratio and lymphocyte:monocyte ratio each partially mediated the NRI–stroke association, with mediation effects ranging from 1·71 % to 13·65 %. These findings suggest that favourable nutritional status, reflected by higher NRI, is linked to lower stroke risk, with lipid metabolism and inflammation playing mediating roles in this association. Further longitudinal and mechanistic studies are warranted.

Prior research suggests that low-carbohydrate diets may reduce the frequency of headache attacks in individuals with migraine. However, the association between dietary carbohydrate intake and migraine in adults remains unclear. Given migraine’s significant public health burden and the modifiable nature of diet, understanding this relationship is vital for prevention. This study therefore investigated whether carbohydrate intake is associated with severe headache or migraine in a nationally representative sample of US adults. Using National Health and Nutrition Examination Survey (NHANES) data (1999–2004), this study examined the association between dietary carbohydrate intake and severe headache or migraine in adults aged over 20. Multivariable logistic regression was used, adjusting for demographics, socioeconomic status, lifestyle factors, and comorbidities. The study surveyed 10,413 participants, with 2062 reporting severe headache or migraine. Analysis of carbohydrate energy percentage revealed: compared to Q1 (≤42.7%), odds ratios (ORs) for severe headache or migraine were 1.04 for Q2 (42.7% to ≤50.5%, P = 0.642), 1.13 for Q3 (50.5% to ≤58.0%, P = 0.176), and 1.32 for Q4 (>58.0%, P = 0.008). A non-linear association was found between dietary carbohydrate intake and severe headache or migraine among U.S. adults (P for non-linearity = 0.002). The group with carbohydrate intake ≥51.1% of total energy had an OR of 1.22 (95% CI: 1.09–1.38, P = 0.002) compared to those below this level. The data suggest a significant association, with an important inflection point occurring at approximately 51.1%. This research uncovered a non-linear link between carbohydrate intake from diet and the chance of suffering from severe headache or migraine among American adults.

Depression affects over 280 million people worldwide. Long-chain n-3 fatty acids may relate to depression, but observational evidence is inconsistent. This cross-sectional analysis of the National Health and Nutrition Examination Survey 2021–2023 examined the association between dietary long-chain n-3 intake and depression severity in USA adults ≥ 18 years with complete dietary, Patient Health Questionnaire-9 (PHQ-9) and covariate data (n 3608). PHQ-9 severity categories (0–4 to 20–27) served as the main outcome. Total n-3 (α-linolenic acid (ALA), EPA, DPA and DHA) from 24-h recalls (Food and Nutrient Database for Dietary Studies 2021–2023) served as the exposure; supplements were excluded, and supplement use was a binary covariate. Survey-weighted ordinal logistic regression (svyolr) was used with all continuous variables centred/scaled (OR per 1 sd). Covariates included age, sex, race/ethnicity (collapsed for sparse cells), income:poverty ratio, BMI, smoking, alcohol, physical activity and n-3 supplement use. Higher total n-3 intake was inversely associated with depression severity (OR 0·865 per 1 sd, 95 % CI 0·761, 0·983, P = 0·026). EPA showed a significant inverse association (OR 0·907, 95 % CI 0·824, 0·998, P = 0·045); ALA, DPA and DHA were NS. No interaction by sex (P = 0·656) or race/ethnicity (P = 0·155). Sensitivity analyses: excluding supplement users (n 3093) OR 0·872 (95 % CI 0·773, 0·984, P = 0·026); two recalls only (n 3229) OR 0·847 (95 % CI 0·751, 0·955, P = 0·007). Dietary n-3 intake, particularly EPA, was modestly and inversely associated with depression severity. Residual confounding and reverse causation remain possible; longitudinal studies with biomarkers are needed.

Menopausal age represents the endpoint of the entire reproductive cycle of women, and it is a biological marker that indicates the overall health and ageing status of women. Flavonoids are the most common polyphenolic compounds in the daily diet, and their intake is related to reduced risks of certain diseases. Our study aimed to analyse the relationships between the intake of flavonoids and menopausal age. We selected 29 940 participants from National Health and Nutrition Examination Survey database from 2007–2008, 2009–2010 to 2017–2018. A total of 680 participants were included in our analysis after screening. Multiple logistic regression was used to explore the association between dietary flavonoid subclasses intake and menopausal delay (≥ 55 years old). Restricted cubic splines plots were generated to reveal the nonlinear relationships between the subclasses of flavonoids intake and menopausal age. According to the adjusted multiple factor logistic regression analysis, the top quartile intake (compared with bottom intake) of anthocyanidins was positively associated with delayed menopause (OR = 4·123; 95 % CI: 1·130, 15·041; Ptrend = 0·036), whereas the moderate intake of flavonols was negatively associated with delayed menopause (Q2 v. Q1, OR = 0·081 (95 % CI: 0·025, 0·261), Ptrend = 0·001; Q3 v. Q1, OR = 0·271 (95 % CI: 0·093, 0·791), Ptrend = 0·023). The restricted cubic splines revealed that non-linear association was observed between the intake of isoflavones, flavan-3-ols, flavonols and later menopause (P value for non-linearity < 0·05). Our findings suggest that specific dietary flavonoids intake may have potential roles in regulating menopausal timing.

This pilot cross-sectional study, conducted in two public hospitals in Malawi, assessed gestational diabetes mellitus (GDM) in pregnant women attending antenatal clinics and compared their dietary quality and food group consumption before and during pregnancy. The study targeted women aged 18 to 49 years within 24 to 28 weeks of gestation. GDM was diagnosed according to the International Association of Diabetes and Pregnancy Study Group criteria and assessed dietary quality before and during pregnancy using a 30-day qualitative food frequency questionnaire. We compared changes in dietary quality and specific food group mean scores using paired t-tests at p < 0.05. Of the 508 women enrolled, 22.7% were diagnosed with GDM. The overall diet quality significantly decreased during pregnancy compared to before; a similar trend was observed in women diagnosed with GDM compared to those without GDM (p < 0.0001). Among women with GDM, the mean score of the following food groups significantly (p < 0.05) decreased during pregnancy: cruciferous vegetables, deep orange vegetables and tubers, citrus fruits, deep orange fruits, other fruits, nuts and seeds, poultry, fish, low fat dairy, whole grains, and liquid oils and significantly (p < 0.05) increased in the following food groups; red meat, processed meat, sugar-sweetened beverages, sweets, sugary snacks and ice cream. In conclusion, GDM is prevalent in Malawian women enrolled in this study and is coupled with inadequate dietary quality, especially during pregnancy. Since dietary quality is pivotal to GDM management, more in-depth longitudinal dietary studies are needed to inform nutritional interventions to prevent and better manage GDM.

Suicidal ideation not only indicates severe psychological distress but also significantly raises the risk of suicide, whereas food insecurity may further increase this risk. To examine the relationship between food insecurity and suicidal ideation, we used the NHANES (National Health and Nutrition Examination Survey) data from 2007 to 2016. The association between the risk of suicidal ideation and food security status was examined using multivariate logistic regression models. To ensure the robustness of our findings, we also conducted subgroup and sensitivity analyses, which were crucial for assessing the consistency and precision of the research findings. This study included 22 098 participants, of whom 50·30 % were female and 49·70 % were male. In the comprehensive analysis of the population, after full adjustment, the OR were 1·14 (95 % CI 0·89, 1·46) for marginal food security, 1·40 (95 % CI 1·12, 1·76) for low food security and 1·59 (95 % CI 1·27, 1·99) for very low food security. In the subgroup analysis, we identified a significant interaction between depression and food security (P = 0·004). Additionally, the results of the sensitivity analysis were consistent with previous findings. Our study revealed that food insecurity significantly increased the risk of suicidal ideation, emphasising the importance of addressing food security to improve mental health. These findings support the need for national food assistance programmes integrated with mental health services. More longitudinal studies are needed to validate the long-term impact of food insecurity on suicidal ideation to optimise intervention measures and policy adjustments.

Low birth weight (LBW) and preterm birth (PTB) are primary factors contributing to morbidity and mortality among children aged under 5, resulting in a range of short- and long-term health consequences worldwide. Among the various risk factors, ambient air pollution poses a significant environmental risk and is a key determinant of child health. The prevalence of LBW and PTB among under 5 children sampled from the NFHS-5, 2019–2021, was combined with monthly PM2.5 data (2013–2021) obtained from the Atmospheric Composition Analysis Group at Washington University. Multivariable logistic regression models were used, and a stratified analysis was applied to understand the potential effect modifiers in LBW and PTB. Further, the geographical variation of LBW and PTB spatial autocorrelation (Moran’s I) was used. Geographically weighted regression and ordinary least square spatial regression were used to identify the spatial heterogeneity associated with selected variables. The study comprises a total of 208,181 under 5 children. Out of these children, the LBW rate was 17.41%, and the rate of PTB was 12.42%. The in-utero exposure to the mean concentration of PM2.5 was 56.01 μg/m3. The odds of suffering from LBW showed a non-linear shift when PM2.5 levels rose from the first octile (<28.02 μg/m3) to the last octile (>93.84 μg/m3) (adjusted odds ratio (AOR): 1.06, 95% CI: 1.01–1.12). While comparing the first octile of exposure to PM2.5 (>93.84 μg/m3) to the last octile, there was a 52% more likelihood of having PTB (AOR: 1.52, 95% CI: 1.43–1.61) after accounting for all relevant factors. These findings highlight the urgent need for a thorough strategy to control the air quality in India. Further, to reduce adverse birth outcomes, longitudinal studies and other co-pollutants can consider assessing the possible mechanisms mediating the relationship between maternal exposure and ambient air pollution.