Tryptophan is an essential amino acid required for protein synthesis, immune regulation and the production of serotonin, melatonin and kynurenine. Its metabolism proceeds through three major pathways – the kynurenine, serotonin and gut microbiota–derived indole pathways – which are influenced by diet, microbiota and inflammation. The Mediterranean diet generally improves tryptophan bioavailability, enhances serotonin synthesis and limits excessive kynurenine activation through anti-inflammatory and microbiota-mediated mechanisms. In contrast, Western diets promote systemic inflammation, increase kynurenine production and reduce serotonin and beneficial indole metabolites. High-protein and ketogenic diets elevate substrate availability but may increase microbial production of indoles such as skatole and alter the balance of tryptophan utilisation, while calorie-restricted diets appear to downregulate pro-inflammatory tryptophan degradation and improve serotonin-related satiety regulation. Collectively, these findings demonstrate that diet is a key regulator of tryptophan metabolism, with implications for mood, sleep, inflammation, cancer progression and cardiometabolic health. Despite these advances, several knowledge gaps remain, including limited standardisation of dietary assessment methods, insufficient databases on the tryptophan content of foods and a lack of controlled comparative trials. Addressing these limitations may enable the development of nutritional strategies that optimise tryptophan metabolism and improve health outcomes.

Sessile serrated lesions (SSL) are recognised precursors to colorectal cancer. Little is known about risk factors for SSL due to their relatively recent clinical recognition as a cancer precursor and routine documentation of cases. Lifestyle and diet-related information were collected using validated questionnaires in a colonoscopy-based case–control study in Australia (257 SSL cases, 239 conventional adenoma (CA) cases, 180 polyp-free controls). A posteriori dietary patterns were derived from self-reported dietary intake in the past 12 months using principal component analysis. Multivariable-adjusted OR and 95 % CI were used to examine associations between lifestyle factors and dietary patterns on risk of SSL and CA v. polyp-free controls and SSL v. CA using logistic regression modelling. Use of anti-inflammatory medications was associated with reduced SSL risk (OR = 0·61; 95 % CI 0·38, 1·00), while current smoking was associated with increased SSL risk (OR = 1·96; 95 % CI 1·09, 3·53). Unlike CA, SSL risk was not increased by hormone replacement therapy use and current alcohol consumption but was increased by taller height. Higher adherence to a dietary pattern featuring processed meats, ready-made convenience foods and high-energy drinks was associated with increased SSL risk (OR = 2·13; 95 % CI 1·13, 4·00; Ptrend = 0·03) and CA (OR = 2·60; 95 % CI 1·32, 5·09; Ptrend = 0·005). Compared with CA, a dietary pattern featuring wholegrains, low-fat dairy products, nuts, seeds and oily fish was associated with reduced SSL risk (OR = 0·60; 95 % CI 0·36, 0·98; Ptrend = 0·04). This study supports a healthy diet as primary prevention for both SSL and CA and reinforces smoking as a risk factor for SSL.

Type 2 diabetes (T2D) incidence has been steadily increasing over the past few decades. Several studies have evaluated the effect of plant-based, vegetarian or vegan diets on the risk of T2D, although their potential benefits need to be confirmed and characterised. We performed a literature search up to 10 July 2025, using the terms/keywords related to plant-based index (PDI), vegetarian/vegan diets and T2D. We included observational non-experimental studies evaluating adherence to such diets in adult subjects assessing T2D risk. We specifically considered overall PDI and related healthy PDI (hPDI) and unhealthy PDI (uPDI), assessing intake of different food groups. We included 36 studies published between 1999 and 2025. We found an inverse association between adherence to vegetarian/plant-based dietary patterns and T2D risk. This association was stronger, though statistically imprecise, for the vegan diet (RR = 0·65, 95 % CI 0·42, 1·00) and for lacto-ovo-vegetarian diet (RR = 0·68, 0·57, 0·82). For studies using plant-based indices, the RR were 0·82 (0·69, 0·82), 0·76 (0·69, 0·82) and 1·13 (0·98, 1·30) for overall PDI, hPDI and uPDI, respectively. In the dose–response meta-analysis, overall PDI and hPDI showed an inverse and almost linear association with T2D risk. Conversely, adherence to uPDI directly correlated with T2D risk. Overall, adherence to vegan/vegetarian diets may reduce T2D risk, while an unhealthy plant-based diet appears to linearly increase disease risk, indicating caution in the consumption of such unhealthy foods even if of plant origin. The beneficial association between vegetarian and healthy plant-based diets may have major public health implications.

Adherence to healthy dietary patterns, including fruits, vegetables and whole grains, is linked to improved health outcomes. However, limited research has explored this association in Latin American populations. This study aimed to investigate the association between adherence to a healthy eating score (unweighted and weighted) and all-cause mortality risk in a Chilean population. This longitudinal study included 5336 Chilean participants from the Chilean National Health Survey 2016 and 2017. Six healthy eating habits were considered to produce the healthy eating score (range: 0–12): consumption of seafood, whole grains, dairy products, fruits, vegetables and legumes. A weighted score was also developed. Participants were categorised into quartiles based on their final scores, with the healthiest quartile used as the reference group. Associations between healthy eating score and all-cause mortality were performed using Cox proportional hazard models adjusted for confounders. After a median follow-up of 5·1 years, 276 (5·2 %) participants died. In the fully adjusted model, compared with participants in the healthiest quartile of the score (Q4), those in the unhealthiest quartile (Q1) had 1·61 (95 % CI: 1·14, 2·27) times higher all-cause mortality risk. A similar association was observed for the weighted healthy eating score (1·52 (95 % CI: 1·03, 2·23)). An inverse trend was observed for both scores (P < 0·05). Sensitivity analyses excluding participants who died within the first 2 years showed consistent results 1·63 (95 % CI: 1·09, 2·42). Individuals with the lowest healthy eating score (unweighted or weighted) had a higher mortality risk compared with their counterparts. A healthy eating score is associated with mortality risk in the Chilean population.

This study aimed to evaluate adherence to the Mediterranean diet, a recognised healthy eating pattern, and the tendency towards orthorexia nervosa in professional athletes, and to examine their relationship with physical activity levels. The study was conducted with athletes (n 134) at the Turkish Olympic Preparation Center (TOHM). Data were collected using a questionnaire covering sociodemographic information, dietary habits, anthropometric measurements, the Mediterranean Diet Quality Index (KIDMED), the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and the Orthorexia-11 (ORTO-11) scale assessing orthorexic tendencies. Of the participants, 17·2 % had poor dietary quality, 60·4 % moderate and 22·4 % good dietary quality. According to the ORTO-11 (cut-off ≤ 25 points), 30·6 % of athletes exhibited orthorexic tendencies. Athletes adhering to a diet had significantly higher orthorexia tendencies compared with non-dieters (P < 0·05). A significant association was found between athletic experience and orthorexic tendencies, particularly among those with 4–8 years and ≥8 years of experience (P < 0·05). Moreover, athletes consuming three main meals had significantly higher KIDMED and ORTO-11 scores than those consuming two meals (P < 0·05). No statistically significant correlation was found between the KIDMED score, ORTO-11 score and physical activity level (P > 0·05). Professional athletes showed moderate adherence to the Mediterranean diet, while certain groups displayed higher orthorexia tendencies. Diet quality and orthorexic tendencies differed significantly with eating habits such as athletic experience and meal patterns, whereas physical activity level had no effect. These findings highlight the importance of multidisciplinary nutrition strategies focusing on both performance and sustainable healthy eating behaviours.

Despite observed ethnic differences in eating patterns and obesity, evidence in China is limited. This study examined ethnic differences in eating patterns and their associations with weight outcomes among multi-ethnic adults in West China. A cross-sectional survey collected self-reported data on demographics, eating behaviours, weight and height in 2021. Principal component analysis and multivariate regression were conducted to identify eating patterns and examine their associations with weight outcomes. In total, 4407 subjects aged ≥ 18 years were recruited across seven provinces in West China. Four eating patterns were identified: ‘meat-lover’ – characterised by frequent consumption of meat and dairy products, ‘indulgent’ – by frequent intakes of added salt, sugar, alcohol and pickled food, ‘diversified-eating’ – by frequently consuming food with diversified cooking methods and eating out and ‘nutri-health-concerned’ – by good food hygiene behaviours and reading food labels. Ethnic differences in eating patterns were observed. Compared with Han, Hui were less likely to exhibit meat-lover or diversified-eating patterns; Tibetans were less likely to have meat-lover or nutri-health-concerned patterns; Mongolians were more likely to have indulgent pattern. BMI was positively associated with meat-lover pattern in both genders (exp(β): 1·029; 95 % CI: 1·001, 1·058 for men; 1·018; 1·000, 1·036 for women) and negatively associated with nutri-health-concerned pattern in women (0·983; 0·966, 1·000). Mongolians were two times more likely to be overweight/obese than Han (OR: 3·126; 1·688, 5·790). Considerable ethnic differences existed in eating patterns in West China. Mongolians were more likely to be overweight/obese, which was associated with their indulgent eating patterns. Ethnic-specific healthy eating intervention programs are needed.

Evidence-based diet quality screeners that can be completed within a few minutes are suitable tools for evaluating diet quality in time-limited settings; however, no such tool has yet been developed in Japan. This study aimed to develop a screener to assess adherence to the Diet Quality Score for Japanese (DQSJ) and to describe its development process. The DQSJ is a 10-component index that was previously developed. The present study developed questions and assigned scores based on dietary data analysis and evidence on diet-health associations. Dietary data from 392 Japanese adults were analysed to identify the intake of food groups in the DQSJ. The mean intakes of 4-non-consecutive-day dietary records were described for each food group across the consumption frequencies in dietary questionnaires. Questions about sodium intake were derived from a sodium screener. Consequently, the DQSJ screener comprised 12 questions: two for red and processed meat, two for sodium and one for each of the other eight food groups (fruits, vegetables, whole grains, nuts, legumes, dairy, fish and sugar-sweetened beverages). The screener asked about the number of servings consumed for vegetables, dairy and sugar-sweetened beverages and the consumption frequencies for the other food groups. The maximum scores were assigned with consideration of optimal and feasible consumption for health outcomes. The total DQSJ was calculated by summing all item scores, resulting in a range of 0–30. The DQSJ screener has the potential to facilitate the assessment of diet quality in time-limited settings in Japan; the next step is to examine its validity.

This study aimed to investigate (1) the longitudinal associations between food patterns and body weight in young adulthood and (2) how food patterns of young adults relate to food consumption in early, middle and late childhood. The study sample includes 700 participants of the Québec Longitudinal Study of Child Development. During childhood, frequency of consumption of various foods was reported on ten occasions between 1·5 and 13 years. At age 22 years, food frequency questions (with quantities) were used to derive four food patterns (labelled healthy, beverage rich, protein rich and high energy density) through exploratory factor analysis. Self-reported height and weight were collected at 22 and 23 years. Regression analyses were performed to assess the associations between (1) food patterns and weight outcomes a year later (BMI, BMI change and overweight status) and (2) frequency of consumption of eight food groups in childhood and food patterns in adulthood. Dietary habits characterised by the consumption of vegetables, fruit, plant-based sources of protein and whole-grain cereal products were related to a lower risk of obesity a year later. Conversely, dietary habits characterised by a high consumption of energy-dense foods, of animal sources of proteins and, among women, of high quantities of liquids were associated with higher risk of excess weight a year later. Healthier food choices in childhood were associated with healthier food patterns in young adulthood. These findings reinforce the value of preventive dietary interventions in the early years to foster eating environments that favour healthy eating and healthy weights in adulthood.

Globally, more than 13 % of adolescents have clinically significant mental health problems, with anxiety and depression comprising over 40 % of cases. Despite the high prevalence of anxiety disorders among youth, dietary research has been focused on youth with depression, resulting in a significant knowledge gap regarding the impact of anxiety on adolescent diet quality. Adolescents with diagnosed anxiety disorders and healthy controls were included in this study. Anxiety symptoms were measured using the Screen for Child Anxiety-Related Disorders. Diagnosis of anxiety disorder was determined using the Kiddie Schedule for Affective Disorders and Schizophrenia interview. Five diet quality indices were scored from FFQ. Diet quality indices associated with anxiety symptoms in the correlation matrix were interrogated using multiple linear regression modelling. All models were adjusted for depression. One hundred and twenty-eight adolescents (mean age 14·8 years (sd: 2·1); 66·4 % female) were included in this cross-sectional analysis. Although healthy controls and outpatient participants had similar unhealthy dietary index subscale scores, outpatient participants had lower healthy index scores. Higher anxiety symptoms were associated with lower healthy dietary indices in univariate analysis; after adjusting for comorbid depression; however, anxiety symptoms were no longer associated with dietary indices following adjustment for multiple testing (P = 0·038 to P = 0·077). The association between anxiety symptoms and a poor diet is attenuated by depression. The results of this study support the need for an integrated approach to the assessment of mental and physical well-being and further research aimed at understanding the unique contribution of depression to healthy dietary patterns.

Psoriasis is a chronic immune-inflammatory skin disease. Cross-sectional research examining diet quality indices in psoriasis has focused on the Mediterranean diet and is confined to Mediterranean populations, thereby lacking generalisability to other populations. We explored associations between diet quality indices and the likelihood of reporting a higher psoriasis severity. This was an online cross-sectional study recruiting adult volunteers with psoriasis (n 257). A 147-item FFQ evaluated adherence to the Mediterranean diet score, the Dietary Approaches to Stop Hypertension score and the Plant-based Diet Index (PDI), including its original (oPDI), healthy (hPDI) and unhealthy (uPDI) subtypes. Psoriasis severity was determined with the self-assessed Simplified Psoriasis Index. When adjusted for age, sex, smoking, alcohol overconsumption, energy intake and psychological morbidity, multinomial logistic regression analyses revealed an increased likelihood of reporting a higher psoriasis severity in participants with a very low adherence to Dietary Approaches to Stop Hypertension (OR = 3·75; 95 % CI 1·313, 10·700; P = 0·01) and hPDI (OR = 4·04; 95 % CI 1·251, 13·064; P = 0·02) patterns. A reduced likelihood of reporting a higher psoriasis severity was shown in participants with low adherence to the uPDI (OR = 0·25; 95 % CI 0·085, 0·716; P = 0·01). With further adjustment for BMI, a very low adherence to the oPDI was significantly associated with an increased likelihood of reporting a higher psoriasis severity (OR = 3·46; 95 % CI 1·029, 11·656; P = 0·05). Dietary interventions and assessment should be introduced in the care pathway for psoriasis management.

Various individual diet and lifestyle factors are associated with mortality. Investigating these factors collectively may help clarify whether dietary and lifestyle patterns contribute to life expectancy. We investigated the association of previously described evolutionary-concordance and Mediterranean diet pattern scores and a novel evolutionary-concordance lifestyle pattern score with all-cause and cause-specific mortality in the prospective Iowa Women’s Health Study (1986–2012). We created the diet pattern scores from Willett FFQ responses, and the lifestyle pattern score from self-reported physical activity, BMI and smoking status, and assessed their associations with mortality, using multivariable Cox proportional hazards regression. Of the 35 221 55- to 69-year-old cancer-free women at baseline, 18 687 died during follow-up. The adjusted hazard ratios (HR) and 95 % CI for all-cause, all CVD, and all-cancer mortality among participants in the highest relative to the lowest quintile of the evolutionary-concordance lifestyle score were, respectively, 0·52 (95 % CI 0·50, 0·55), 0·53 (95 % CI 0·49, 0·57) and 0·51 (95 % CI 0·46, 0·57). The corresponding findings for the Mediterranean diet score were HR 0·85 (95 % CI 0·82, 0·90), 0·83 (95 % CI 0·76, 0·90) and 0·93 (95 % CI 0·84, 1·03), and for the evolutionary-concordance diet score they were close to null and not statistically significant. The lowest estimated risk was among those in the highest joint quintile of the lifestyle score and either diet score (both Pinteraction <0·01). Our findings suggest that (1) a more Mediterranean-like diet pattern and (2) a more evolutionary-concordant lifestyle pattern, alone and in interaction with a more evolutionary-concordant or Mediterranean diet pattern, may be inversely associated with mortality.

This study examined the relationship between childhood diet quality and arterial stiffness and thickness during adolescence/early adulthood. Participants were from the Avon Longitudinal Study of Parents and Children (ALSPAC) with dietary data at ages 7, 10 and 13 years and pulse wave velocity (PWV) and carotid intima-media thickness (cIMT) at ages 17 and/or 24 years. Diet quality (DQ) was assessed using five scores: a children’s Mediterranean-style diet (C-rMED) Z-score, a children’s Dietary Inflammatory Z-score (C-DIS), a DASH diet Z-score, a children’s Eatwell Guide (C-EWG) Z-score reflecting UK dietary guidelines and a data-driven obesogenic Z-score. Adjusted regression models examined the associations between DQ scores at 7–13 years and PWV and cIMT at 17 and 24 years. In adjusted models, a high v. low Obesogenic Z-score at 7 and 10 years was associated with higher PWV at 17: β 0.07 (95 % CI 0.01, 0.13) and β 0.10 (95 % CI 0.04, 0.16), respectively. A high v. low C-rMED Z-score at 7 years was associated with lower PWV at 17 (β −0.07; 95 % CI −0.14, −0.01). A high (more anti-inflammatory) vs low C-DIS Z-score at 10 years was associated with a lower PWV at 17 years: β −0.06 (95 % CI −0.12, −0.01). No other associations were observed. In conclusion, an Obesogenic dietary pattern in childhood (7–10 years) was related to increased arterial stiffness, while Mediterranean-style and anti-inflammatory diets were related to decreased arterial stiffness in adolescence. This highlights the importance of establishing healthy dietary habits early in life to protect against vascular damage.

Autism spectrum disorder (ASD) has been frequently associated with an increased risk of obesity and metabolic disorders, including dyslipidaemia. However, research on lipid profiles and dietary intake in this population remains scarce. This cross-sectional study aimed to evaluate dietary patterns and their association with serum lipid profile in children and adolescents diagnosed with ASD. The study included 233 individuals from 2 to under 19 years assisted by the public health system in Pelotas, Brazil. Fasting blood samples were collected and analysed for serum concentrations of total cholesterol, HDL-cholesterol, LDL-cholesterol and TAG. Dietary intake was assessed using three non-consecutive 24-h food recalls (two weekdays and one weekend day). Dietary patterns were derived through reduced rank regression, using food group intakes as predictors and fibre density, energy density, carbohydrate and saturated fat intakes as response variables. Standardised pattern scores were calculated to assess individual adherence, and linear regression models, adjusted for potential confounders, were applied to examine the association between the dietary pattern scores and lipid profiles. Elevated TAG concentrations were observed in 48·9 % of the participants. Four dietary patterns were identified: Healthy, sugar and starches, mixed and dairy and biscuits. After adjustment, no significant associations were observed between dietary pattern scores and lipid profile. These findings underscore the complex nature of lipid metabolism in individuals with ASD and suggest that dietary patterns alone may not fully explain variations in lipid profiles. This reinforces the need for further research and development of appropriate nutritional interventions for this population.

This prospective study investigated the associations of various diet quality indices with mortality in Japan. Participants were 13 355 men and 15 724 women from the Takayama study. Eight diet quality indices were assessed using an FFQ: the Dietary Approaches to Stop Hypertension, alternative Mediterranean diet scores, Healthy Eating Index-2015, Alternate Healthy Eating Index-2010, Nutrient Rich Food Index 9.3, Diet Quality Score for Japanese, Japanese Food Guide Spinning Top and twelve-item Japanese Diet Index. Cox proportional models estimated hazard ratios and 95 % CI for all-cause and cause-specific mortality in a 1 sd difference for each index, with adjustment for confounders. During a mean follow-up of 14·1 years, 5339 deaths were recorded. Hazard ratios (95 % CI) per 1 sd higher index were 0·90 (0·87, 0·93) for Alternate Healthy Eating Index-2010, 0·92 (0·89, 0·95) for Diet Quality Score for Japanese, 0·93 (0·91, 0·96) for Nutrient Rich Food Index 9.3, 0·94 (0·92, 0·97) for alternative Mediterranean diet and Dietary Approaches to Stop Hypertension, 0·94 (0·91, 0·97) for Japanese Food Guide Spinning Top, 0·94 (0·91, 0·98) for twelve-item Japanese Diet Index and 0·97 (0·94, 0·996) for Healthy Eating Index-2015. Similar protective associations were observed for CVD mortality, but not for cancer mortality. These findings suggest that all eight indices are associated with lower mortality and that the strength of associations varies across indices; the Alternate Healthy Eating Index-2010 showed relatively strong associations, followed by the Diet Quality Score for Japanese, whereas the associations of the Healthy Eating Index-2015 appeared relatively weaker in this Japanese population.

Adopting a healthy dietary pattern may be an initial step in combating inflammation-related chronic diseases; however, a comprehensive synthesis evaluating current evidence is lacking. This umbrella review aimed to summarise the current evidence on the effects of dietary patterns on circulating C-reactive protein (CRP) levels in adults. We conducted an exhaustive search of the Pubmed, Scopus and Epistemonikos databases, spanning from their inception to November 2023, to identify systematic reviews and meta-analyses across all study designs. Subsequently, we employed a random-effects model to recompute the pooled mean difference. Methodological quality was assessed using the A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) checklist, and evidence certainty was categorised as non-significant, weak, suggestive, highly suggestive or convincing (PROSPERO: CRD42023484917). We included twenty-seven articles with thirty meta-analyses of seven dietary patterns, fifteen of which (50 %) exhibited high methodological quality. The summary effects of randomised controlled trials (RCT) found that the Mediterranean diet was the most effective in reducing circulating CRP levels, followed by Vegetarian/Vegan and Energy-restricted diets, though the evidence was of weak quality. In contrast, Intermittent Fasting, Ketogenic, Nordic and Paleolithic diets did not show an inverse correlation with circulating CRP levels. Some results from combined interventional and observational studies, as well as solely observational studies, also agreed with these findings. These dietary patterns show the potential in reducing CRP levels in adults, yet the lack of high-quality evidence suggests future studies may alter the summary estimates. Therefore, further well-conducted studies are warranted.

The relationship between dietary habits and microbiota composition during adolescence has not been well examined. This is a crucial knowledge gap to fill considering that diet–microbiota interactions influence neurodevelopment, immune system maturation and metabolic regulation. This study examined the associations between diet and the gut microbiota in a school-based sample of 136 adolescents (Mage = 12·1 years; age range 11–13 years; 48 % female; 47 % Black, 38 % non-Hispanic White, 15 % Hispanic or other minorities) from urban, suburban and rural areas in the Southeast USA. Adolescents completed the Rapid Eating Assessment for Participants and provided stool samples for 16S ribosomal RNA gene sequencing. Parents reported their child and family socio-demographic characteristics. The associations between diet and socio-demographics with gut microbiota diversity and abundance were analysed using multivariable regression models. Child race and ethnicity, sex, socio-economic status and geographic locale contributed to variation within microbiota composition (β-diversity). Greater consumption of processed meat was associated with a lower microbial α-diversity after adjusting for socio-demographic variables. Multi-adjusted models showed that frequent consumption of nutrient-poor, energy-dense foods (e.g. sugar-sweetened beverages, fried foods, sweets) was negatively associated with abundances of genera in the family Lachnospiraceae (Anaerostipes, Fusicatenibacter and Roseburia), which are thought to play a beneficial role in host health through their production of short-chain fatty acids (SCFAs). These results provide new insights into the complex relationships among socio-demographic factors, diet and gut microbiota during adolescence. Adolescence may represent a critical window of opportunity to promote healthy eating practices that shape a homoeostatic gut microbiota with life-long benefits.