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The prevalence of poor linear growth among African children with perinatally acquired HIV remains high. There is concern that poor linear growth may to lead to later total and central fat deposition and associated non-communicable disease risks. We investigated associations between height-for-age Z score (HAZ) and total and regional fat and lean mass measured by dual-energy X-ray absorptiometry, expressed as internal population Z scores, among 839 Zimbabwean and Zambian perinatally HIV-infected male and female adolescents aged 11–19 years. Stunting (HAZ < –2) was present in 37 % of males and 23 % of females. HAZ was strongly positively associated with total, trunk, arm and leg fat mass and lean mass Z scores, in analyses controlling for pubertal stage, socio-economic status and HIV viral load. Associations of linear growth with lean mass were stronger than those with fat outcomes; associations with total and regional fat were similar, indicating no preferential central fat deposition. There was no evidence that age of starting antiretroviral therapy was associated with HAZ or body composition. Non-suppressed HIV viral load was associated with lower lean but not fat mass. The results do not support the hypothesis that poor linear growth or stunting are risk factors for later total or central fat deposition. Rather, increased linear growth primarily benefits lean mass but also promotes fat mass, both consistent with larger body size. Nutritional and/or HIV infection control programmes need to address the high prevalence of stunting among perinatally HIV-infected children in order to mitigate constraints on the accretion of lean and fat mass.
The long-term impact of eating duration on the risk of all-cause mortality remains unclear, with limited exploration of how different levels of energy intake and physical activity might influence this impact. To investigate, 24 484 American adults from the National Health and Nutrition Examination Survey spanning 1999–2018 were included. Eating duration was assessed via 24-h dietary recall, and all-cause mortality data were sourced from the National Death Index. The relationship between eating duration and all-cause mortality was analysed using Cox proportional hazards regression models, restricted cubic splines and stratification analysis with complex weighted designs. The median (IQR) of eating duration for participants was 12·5 (11·0, 14·0) h. In this study, 2896 death events were observed, and the median follow-up time (IQR) was 125 (77, 177) months. After multivariable adjustment, compared with Q1, Q2, Q3 and Q4 had reduced risks of all-cause mortality by 17, 15 and 13 %, respectively. Furthermore, each additional hour of eating duration was correlated with a 2 % decrease in the risk of all-cause mortality. Additionally, a non-linear dose–response relationship was observed between eating duration and the risk of all-cause mortality, showing a U-shaped relationship from 8·9 h to 15·3 h (P for non-linearity < 0·05). Interestingly, the non-linear dose–response relationship was observed exclusively among individuals with high energy intake or a lightly active physical activity level. These findings suggest potential health benefits from adjusting eating duration, though further prospective studies are needed for validation.
Musculoskeletal disorders and age-related musculoskeletal decline are major contributors to the burden of ill health seen in older subjects. Despite this increased burden, these chronic disorders of old age receive a relatively small proportion of national research funds. Much has been learned about fundamental processes involved in ageing from basic science research and this is leading to identification of key pathways that mediate ageing which may help the search for interventions to reduce age-related musculoskeletal decline. This short review will focus on the role of reactive oxygen species in age-related skeletal muscle decline and on the implications of this work for potential nutritional interventions in sarcopenia. The key physiological role of reactive oxygen species is now known to be in mediating redox signalling in muscle and other tissues and ageing leads to disruption of such pathways. In muscle, this is reflected in an age-related attenuation of specific adaptations and responses to contractile activity that impacts the ability of skeletal muscle from ageing individuals to respond to exercise. These pathways provides potential targets for identification of logical interventions that may help maintain muscle mass and function during ageing.
Bariatric surgery has significantly increased globally as an effective treatment for severe obesity. Nutritional deficits are common among candidates for bariatric surgery, and follow-up of nutritional status is critically needed for post-surgery healthcare management. This observational prospective study was conducted at King Khalid University Hospital in Riyadh. Samples were collected pre- and post-laparoscopic sleeve gastrectomy (LSG), with the visit intervals divided into four visits: pre-surgery (0M), 3 months (3M), 6 months (6M) and 12 months (12M). Food intake and eating patterns significantly changed during the first year (P < 0·001). The mean energy intake at 3M post-surgery was 738·3 kcal, significantly lower than the pre-surgery energy intake of 2059 kcal. Then, it increased gradually at 6M and 12M to reach 1069 kcal (P < 0·00). The intake of Fe, vitamin B12 and vitamin D was below the dietary reference intake recommendations, as indicated by the 24-hour dietary recall. The prevalence of 25 (OH) vitamin D deficiency improved significantly from pre- to post-surgery (P < 0·001). Vitamin B12 deficiency was less reported pre-LSG and improved steadily towards a sufficient post-surgery status. However, 35·7 % of participants were deficient in Fe status, with 28·6% being female at higher levels than males. While protein supplementation decreased significantly over the 12M follow-up, the use of vitamin supplements dramatically increased at 3 and 6M before declining at 12M. Fe and vitamin B12 were the most popular supplements after vitamin D. This study confirms the necessity for individualised dietary plans and close monitoring of candidates’ nutritional status before and after bariatric surgery.
Folate metabolism is involved in the development and progression of various cancers. We investigated the association of single nucleotide polymorphisms (SNP) in folate-metabolising genes and their interactions with serum folate concentrations with overall survival (OS) and liver cancer-specific survival (LCSS) of newly diagnosed hepatocellular carcinoma (HCC) patients. We detected the genotypes of six SNP in three genes related to folate metabolism: methylenetetrahydrofolate reductase (MTHFR), 5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) and 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR). Cox proportional hazard models were used to calculate multivariable-adjusted hazard ratios (HR) and 95 % CI. This analysis included 970 HCC patients with genotypes of six SNP, and 864 of them had serum folate measurements. During a median follow-up of 722 d, 393 deaths occurred, with 360 attributed to HCC. In the fully-adjusted models, the MTRR rs1801394 polymorphism was significantly associated with OS in additive (per G allele: HR = 0·84, 95 % CI: 0·71, 0·99), co-dominant (AG v. AA: HR = 0·77; 95 % CI: 0·62, 0·96) and dominant (AG + GG v. AA: HR = 0·78; 95 % CI: 0·63, 0·96) models. Carrying increasing numbers of protective alleles was linked to better LCSS (HR10–12 v. 2–6 = 0·70; 95 % CI: 0·49, 1·00) and OS (HR10–12 v. 2–6 = 0·67; 95 % CI: 0·47, 0·95). Furthermore, we observed significant interactions on both multiplicative and additive scales between serum folate levels and MTRR rs1801394 polymorphism. Carrying the variant G allele of the MTRR rs1801394 is associated with better HCC prognosis and may enhance the favourable association between higher serum folate levels and improved survival among HCC patients.
Overweight and obesity now impact one-third of the entire adult population globally, and play a role in the development of 3 of the 4 more common causes of death. Accountability systems for obesity prevention centring on food environment policies and health system strengthening have been vital for raising awareness to the lack of progress in prevention. However, health systems have struggled to prevent and treat obesity – in part because critical food systems reforms largely lay outside the mandate of health sectors and with government agencies for agriculture, industry, infrastructure, trade and investment, and finance. In this commentary we highlight aspects of food systems that are driving poor diets and obesity, and demonstrate a powerful but largely overlooked opportunity for accountability mechanisms for obesity that better address food systems as a main driver. We draw on lessons generated in the Pacific Islands Region where they have demonstrated remarkable commitment to obesity prevention through food system reforms, and the adoption of accountability systems that bring leaders to account on these. We make recommendations for accountability mechanisms that facilitate greater cooperation of food systems sectors on obesity and NCD prevention.
Lipids play an important role in human nutrition. Although adequate lipid consumption is necessary for an optimal functioning of the human body, overconsumption of saturated fatty acids can lead to postprandial hypertriglyceridaemia, which triggers the development of atherosclerosis. Important parameters that impact postprandial lipaemia and inflammation are related to the matrix structure and the fat-soluble micronutrient profile of ingested foods/lipids, but the specific effect of these parameters should be further studied, as most of the available studies evaluate their effect at fasting state. This review specifically explores the effects of food structure and fat-soluble micronutrients, from either micronutrient-rich foods or supplements, on postprandial hypertriglyceridaemia and inflammation. The review also highlights the potential of emerging biomarkers such as miRNAs or circulating microvesicles, as an alternative to the widely use biomarkers (e.g. low-density lipoproteins or blood concentration of pro-inflammatory cytokines), to identify inflammation associated with postprandial hypertriglyceridaemia at early stages.
To determine the prevalence of overweight and obesity in patients with severe mental disorders (SMD) and the factors associated with their socio-demographic and disease characteristics in a cross-sectional population-based study.
Design:
This analysis examined the prevalence of overweight and obesity in 14 868 managed SMD patients in an urban area of Shenzhen city based on data from the health information monitoring system in 2021. Multivariate logistic regression were used to identify the factors associated with the prevalence of overweight and obesity in patients with SMD.
Setting:
China.
Participants:
14 868 patients with SMD.
Results:
The prevalence of overweight and obesity in patients with SMD in this study was 32·6 % and 16·1 %, respectively. In multivariate analysis, married status, Shenzhen household registration, management durations of 5–10 years and >10 years, participation in family physician services, taking clozapine or aripiprazole, FPG > 6·1 mmol/l, hypertension, TC ≥ 5·2 mmol/l, TG ≥ 1·7 mmol/l, and more frequent follow-ups in the past year were associated with higher odds of overweight and obesity. Compared to their respective reference categories, living with parents, spouse and children, taking risperidone, aripiprazole, amisulpride and perphenazine, FPG > 6·1 mmol/l, hypertension, TC ≥ 5·2 mmol/l, TG ≥ 1·7 mmol/l, and more frequent follow-ups in the past year were associated with higher odds of obesity.
Conclusion:
We observed a high prevalence of overweight and obesity in patients with SMD in this study. The findings highlight the need for integrated management of overweight and obesity risk factors among patients with SMD.
We have previously demonstrated that calcium plus vitamin D supplementation during adolescent pregnancy reduces the magnitude of transient postpartum bone mass loss. In the present post hoc analysis, we further investigated the effect of calcium plus vitamin D supplementation during pregnancy in hip geometry throughout one year postpartum in Brazilian adolescents with low daily calcium intake (∼600 mg/d). Pregnant adolescents (14–19 years) were randomly assigned to receive calcium (600 mg/d) plus vitamin D3 (200 μg/d) or a placebo from 26 weeks of gestation until parturition. Dual-energy X-ray absorptiometry images were obtained at 5 (n 30 and 26 for calcium plus vitamin D and placebo, respectively), 20 (n 26 and 21) and 56 (n 18 and 12) weeks postpartum, and hip geometry parameters were analysed by Advanced Hip Assessment software. The effects of the intervention, time point and their interaction were assessed using repeated-measures mixed-effects models. No significant intervention effects or intervention × time interactions were observed on hip geometry parameters (P > 0·05). Time effects were observed in cross-sectional area, cross-sectional moment of inertia and section modulus parameters with decreases from the 5th to the 20th week postpartum followed by recovery from the 20th to the 56th week (P < 0·05). Our findings indicate that the postpartum period is associated with transient changes in the hip geometry of lactating adolescent mothers, regardless of the low calcium intake and the supplementation offered during pregnancy, suggesting that a physiological adaptation of these adolescents to low calcium intake is at play.
The increasing demand for food and especially proteins leads to the search for alternative protein sources. Meat co-products, which are available but little used in human food, provide a potential solution to this challenge. The present study aimed to evaluate the nutritional quality of two beef protein ingredients (greasy greaves recovered proteins (GGRP) and water recovered proteins (WRP)), both co-products of the fat rendering process. Their true ileal digestibility (TID), digestible indispensable amino acid score (DIAAS) and kinetics of plasma amino acids (AA) were measured in ten growing pigs, each fed the two co-products and a protein-free diet. Titanium dioxide was used as an indigestible marker. Digesta samples were collected for 9 h after meal ingestion, and blood samples were collected at ten time points during the same period. Total nitrogen (N) and AA contents were determined. Data were statistically analysed using linear mixed models. The TID of total N was not different between WRP and GGRP (81–84 %, P > 0·05). The first-limiting AA was Trp for both ingredients, with a DIAAS much higher for GGRP than for WRP (74 and 10 % for adults, respectively; P < 0·001). Postprandial plasma AA concentration peaked earlier for WRP (3 h) than for GGRP (5 h). Plasma concentrations of total and essential AA were higher (P < 0·001) with GGRP diet than WRP diet. Overall, GGRP has a nutritional quality suitable to meet the needs of adults for AA, while WRP needs to be supplemented with other protein sources to fulfil the dietary requirements.
Multiple reviews have examined the impact of nutritional interventions in patients with burn injuries; however, discrepancies among results cast doubt about their validity. We implemented this review to assess the impact of various nutritional interventions in adult patients with burn injuries. We conducted a thorough search of PubMed, Scopus and Web of Science databases until 1 August 2024, to identify relevant meta-analyses of intervention trials, examining the impact of nutritional interventions on burn patients. We adopted the random-effect models to determine the pooled effect sizes while employing the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) to examine evidence certainty. Thirty-three original intervention trials from eleven meta-analyses were entered in our review. Early enteral nutrition could substantially reduce overall mortality (relative risk (RR): 0·36, 95 % CI: 0·19, 0·68, GRADE = moderate certainty), hospital stay (mean difference (MD): −15·3, 95 % CI: −20·4, −10·2, GRADE = moderate certainty) and sepsis risk (RR: 0·23, 95 % CI: 0·11, 0·45, GRADE = moderate certainty). Glutamine showed a notable decrease in the length of hospital stay (MD: −6·23, 95 % CI: −9·53, −2·94, GRADE = low certainty). However, other nutritional interventions, including combined immunonutrition, branched-chain amino acids, fish oil, ornithine α-ketoglutarate and trace elements, did not significantly affect the assessed clinical outcomes. Early enteral nutrition might impose a beneficial effect on mortality, hospital stay length and incidence of sepsis with moderate evidence. Lower length of hospital stay was also seen in burn patients supplemented with glutamine, although the evidence was weak.
Maternal iodine plays a central role in fetal neurodevelopment. It is recommended that pregnant women consume sufficient levels of iodine to accommodate increased need for mother and fetus. We examined associations among prenatal dietary and supplemental iodine intake and infant temperament.
Design:
The PRogramming of Intergenerational Stress Mechanisms (PRISM) study is an ongoing longitudinal pregnancy cohort. Data from 2011 to 2020 were used for this study. Women completed the Block98 FFQ ascertaining prenatal dietary and supplemental iodine intake and the Infant Behavior Questionnaire-Revised at infant age 6 months to ascertain infant temperament (Surgency/Extraversion, Negative Affectivity and Orienting/Regulation).
Setting:
USA.
Participants:
Mother–child dyads (n 892).
Results:
Women were primarily Black/Hispanic Black (44 %) and non-Black Hispanic (35 %) with 46 % reporting household income < $25 000/year. Nearly half had an estimated average requirement (EAR) < 160 µg/d (49 % based on dietary intake; 43 % based on diet and supplements). Girls born to women with an EAR ≥ 160 µg/d compared to girls born to women below this level had higher unadjusted extraversion scores for dietary plus supplemental intake (β = 0·23 (0·13, 0·33)); decreased to β = 0·05 (–0·08, 0·19) after adjusting for covariates. Boys born to women with an EAR ≥ 160 µg/d (based on diet and supplements) as compared to boys born to women below this level had statistically non-significant higher unadjusted negative affective score (β = 0·06 (–0·08, 0·20)) that became significantly lower upon covariate adjustment (β = –1·66 (–1·97, –1·35)).
Conclusions:
A significant proportion of these women reported suboptimal prenatal iodine intake. Suboptimal prenatal iodine intake may have implications for child neurodevelopment evident as early as infancy.
Dietary intake assessment is often complicated by intrinsic bias. This study investigated whether food purchase data could constitute a valid indication of dietary intake, by evaluating the extent to which diet quality as measured by supermarket food purchases is correlated with diet quality as measured by reported dietary intake. We used data from the Supreme Nudge cluster-randomised controlled supermarket trial (n 227). Data were collected at baseline from supermarket purchases (loyalty cards) and a dietary questionnaire (short forty-item FFQ) to compute two scores reflecting diet quality from purchasing data (purchased diet quality) and FFQ (consumed diet quality). Both scores constituted thirteen food groups and could theoretically range from 0 (low diet quality) to 130 (high diet quality). The relationship between purchased diet quality and consumed diet quality was assessed using correlation coefficients and the Bland–Altman limits-of-agreement method. Multiple linear regression was fitted between purchased diet quality and consumed diet quality, adjusted for age, sex, waist circumference, educational level and household size. Consumed and purchased diet qualities were modestly positively correlated (Pearson’s ρ = 0·31, 95 % CI 0·18, 0·42). A positive association from linear regression was found after confounding adjustments (βbaseline = 0·22, 95 % CI 0·10, 0·34). The purchased diet quality was systematically lower than the consumed diet quality. This study found that diet quality as measured by supermarket purchases provided a reasonable indication of diet quality as reported by short-FFQ, albeit modest.
This study aimed to explore the combined effects of serum vitamin-D level and tobacco exposure on the risk of overweight and obesity in children. This cross-sectional study analysed the data of 11 636 children aged 2–17 years from the National Health and Nutrition Examination Surveys database between 2007 and 2018. Univariable and multivariate weighted logistic regression models were used to analyse the associations of serum vitamin-D or cotinine levels with overweight and obesity in children as well as the combined effects of serum vitamin-D and cotinine on the risk of overweight and obesity in children. Subgroup analysis was performed in terms of gender, age, race and household smokers. OR with corresponding 95 % CI was presented. The elevated risk of overweight and obesity in children was found in those with serum vitamin-D < 20 ng/ml (OR = 1·44, 95 % CI: 1·29, 1·61). Also, the odds of overweight and obesity in children was 1·14 (OR = 1·14, 95 % CI: 1·01, 1·29) in children with cotinine ≥ 0·05 ng/ml. Relative to participants with serum vitamin-D ≥ 20 ng/ml and cotinine < 0·05 ng/ml, increased risk of overweight and obesity was identified in those with serum vitamin-D < 20 ng/ml and cotinine < 0·05 ng/ml (OR = 1·45, 95 % CI: 1·26, 1·68) and serum vitamin-D < 20 ng/ml and cotinine ≥ 0·05 ng/ml (OR = 1·62, 95 % CI: 1·38, 1·91). Serum vitamin-D and cotinine exposure had combined effects on the risk of overweight and obesity in children.
Tea is one of the most widely consumed beverages in the world. However, the association between tea and risk of pancreatic adenocarcinoma remains controversial. This study aimed to investigate the causal relationship between tea consumption and risk of pancreatic adenocarcinoma and to explore their mediating effects. The two-sample Mendelian randomisation (MR) analysis showed an inverse causal relationship between tea intake and pancreatic adenocarcinoma (OR: 0·111 (0·02, 0·85), P < 0·04). To examine the mediating effects, we explored the potential mechanisms by which tea intake reduces the risk of pancreatic adenocarcinoma. Based on the oral bioavailability and drug-like properties in Traditional Chinese Medicine Systems Pharmacology database, we selected the main active ingredients of tea. We screened out the fifteen representative targeted genes by Pharmmapper database, and the gene ontology enrichment analysis showed that these targeted genes were related to vascular endothelial growth factor (VEGF) pathway. The two-step MR analysis of results showed that only VEGF-D played a mediating role, with a mediation ratio of 0·230 (0·066, 0·394). In conclusion, the findings suggest that VEGF-D mediates the effect of tea intake on the risk of pancreatic adenocarcinoma.
Growing evidence indicates a link between diet and depression risk. We aimed to examine the association between an inflammatory diet index and depression utilising extensive data from UK biobank cohort. The energy-adjusted dietary inflammation index (E-DII) was calculated to quantify the potential of daily diet, with twenty-seven food parameters utilised. The E-DII scores were classified into two categories (low v. high) based on median value. To mitigate bias and ensure comparability of participant characteristics, propensity score matching was employed. To ascertain the robustness of these associations, sensitivity analyses were conducted. Subgroup analyses were performed to evaluate the consistency of these associations within different subpopulations. Totally, 152 853 participants entered the primary analyses with a mean age of 56·11 (sd 7·98) years. Employing both univariate and multivariate logistic regression models, adjustments were made for varying degrees of confounding factors (socio-demographics, lifestyle factors, common chronic medical conditions including type 2 diabetes and hypertension). Results consistently revealed a noteworthy positive correlation between E-DII and depression. In the context of propensity score matching, participants displaying higher E-DII scores exhibited an increased likelihood of experiencing incident depression (OR = 1·12, 95 % CI: 1·05, 1·19; P = 0·000316). Subgroup analysis results demonstrated variations in these associations across diverse subpopulations. The E-value for the point-estimate OR calculated from the propensity score matching dataset was 1·48. Excluding individuals diagnosed with type 2 diabetes or hypertension, the findings consistently aligned with the positive association in the primary analysis. These findings suggested that consumption of a diet with higher pro-inflammatory potential might associated with an increase of future depression risk.
The associations between obesity and liver diseases are complex and diverse. To explore the causal relationships between obesity and liver diseases, we applied two-sample Mendelian randomisation (MR) and multivariable MR analysis. The data of exposures (BMI and WHRadjBMI) and outcomes (liver diseases and liver function biomarker) were obtained from the open genome-wide association study database. A two-sample MR study revealed that the genetically predicted BMI and WHRadjBMI were associated with non-alcoholic fatty liver disease, liver fibrosis and autoimmune hepatitis. Obesity was not associated with primary biliary cholangitis, liver failure, liver cell carcinoma, viral hepatitis and secondary malignant neoplasm of liver. A higher WHRadjBMI was associated with higher levels of biomarkers of lipid accumulation and metabolic disorders. These findings indicated independent causal roles of obesity in non-alcoholic fatty liver disease, liver fibrosis and impaired liver metabolic function rather than in viral or autoimmune liver disease.
This study aimed to assess the effects of multi-strain probiotics on anthropometric and biochemical measures in Saudi adults with overweight or obesity.
Occupational Health Clinics at King Saud University Medical City, Riyadh, Saudi Arabia.
Participants:
Ninety-three Saudi participants with overweight or obesity were randomly assigned to receive twice-daily doses of either placebo (n 49) or 30 × 109 CFU/g of HEXBIO® containing three Lactobacillus and three Bifidobacterium species (n 44) in a double-blind manner over a 12-week period, respectively. Both groups adhered to a hypoenergetic diet. Anthropometric measurements, glycaemic indices and lipid profiles were evaluated at baseline and post-intervention.
Results:
Following the 12-week intervention, no statistically significant differences were found in all between the probiotic group and placebo group comparisons, except for fat intake, where the group*time interaction showed a significant decrease in favour of the probiotic group (P = 0·02). However, significant within-group reductions were observed in the probiotic group: body weight (–0·9 kg, P = 0·02), HC (–1·5 cm, P = 0·002), energy intake (–387·3 kcal/d, P = 0·002), fasting glucose (–0·7, P = 0·002) and LDL-cholesterol (–0·7, P = 0·02).
Conclusion:
Consumption of multi-strain probiotic supplementation over 12 weeks significantly decreased fat intake in Saudi adults with overweight or obesity, with the probiotic group highlighting improved anthropometric and biochemical parameters. Further research is needed to evaluate the long-term clinical significance of this dietary practice and whether it has a meaningful impact on overall health beyond the placebo effect.
We aimed at quantifying the effects of different tea and coffee on weight loss in adults. We searched PubMed, Scopus, CENTRAL and grey literature sources to July 2024. The study excluded cross-over trials without washout period, those in critically ill patients, pregnant or breast-feeding women, multicomponent interventions and active control groups with tea or coffee. A random-effects network meta-analysis with a Bayesian framework was performed to calculate the mean difference (MD) and 95 % credible intervals (CrIs). The certainty of evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation approach, and risk of bias was assessed using Cochrane tool. Twenty-two randomised controlled trials with 1710 participants (average intervention duration = 10 weeks) were included. Green tea was effective for weight loss compared with placebo (MD: −1·23 kg, 95 % CrI: −2·45, −0·02; low certainty evidence) or water (MD: −1·61 kg, 95 % CrI: −2·90, −0·35; very low certainty evidence), while other beverages (coffee, decaffeinated coffee, green coffee, black tea and sour tea) were not. Green tea was effective for weight loss compared with water in sensitivity analysis of healthy individuals (MD: −3·31 kg, 95 % CrI: −5·83, −1·04). Based on very low to low certainty evidence, green tea drinking may result in a small weight loss in adults. This study mainly focused on weight loss effects of green tea and coffee, with limited data on other teas. Only five trials had longer intervention durations, suggesting future research on long-term effects. Most trials had high bias risk and low certainty, requiring more high-quality trials.
The incidence of cognitive decline is rising, leading to increased attention on the preventive role of healthy foods on brain function. Previous reviews including primarily observational studies suggested that dietary proteins may improve cognitive performance, but evidence from individual randomised controlled trials (RCT) is less consistent. Therefore, this systematic review examined the long-term effects of dietary proteins from RCT, considering both their amount and type, on cognitive performance (psychomotor speed and attention, executive function, memory and global cognition). Alterations in cerebral blood flow (CBF) – a validated brain vascular function marker – were also considered. A total of 4747 studies were identified through a systematic search, resulting in twenty-three included papers reporting effects on cognitive performance (n = 23) and CBF (n = 3). Improvements were observed in three out of the nine studies that evaluated psychomotor speed which compared a dietary protein intervention with a non-protein or lower-protein control. Of the six beneficial observations on working memory (n = 12), declarative memory (n = 10) and visuospatial memory (n = 10), five were nut interventions from three different trials. Limited studies focusing on global cognition suggested that specific target populations, namely subacute stroke or dementia, may benefit more than healthy individuals from increased dietary protein intake. From the three studies involving CBF, improvements in regional blood flow were associated with most cognitive performance outcomes. The comparative effects of different protein types warrant further investigation. Overall, this review encourages additional research into protein-rich foods or supplements which could potentially prevent or mitigate cognitive decline.