Sex as a Biological Variable in Nutrition Research: From Human Studies to Animal Models

Protein diversity, type 2 diabetes, and effect modifiers: a multi-country prospective study

BACKGROUND

Dietary diversity may affect type 2 diabetes (T2D) but no studies have examined protein diversity by source. We examined five diversity scores and the 10-year risk of T2D and effect modification.

METHODS

A prospective study of 10 363 incident T2D cases and a representative sub-cohort of 13 937 individuals sampled from a cohort of 340 234 participants in eight European countries (1993-2007). Five diversity scores were derived from self-reported diet data (gr/day): diversity of food groups (range: 0-5); and diversity within subtype of vegetables (0-4); meat/alternatives (0-6); animal-protein (0-8); and plant-protein sources (0-5). Country-specific hazard ratios (HRs) and 95% confidence intervals (CIs) were obtained by using Prentice-weighted Cox regression and combined by using mixed-effects models. Models were stratified by sex (male/female) and obesity status (body mass index ≥ 30 kg/m2; waist circumference ≥ 88 cm for females and ≥102 cm for males).

RESULTS

Daily intake of five food groups (versus up to three) was linked to lower T2D incidence overall [HR 0.86 (95% CI 0.75, 0.98)], in females [0.86 (0.77, 0.96)], and in people without central obesity [0.79 (0.70, 0.89)]. Three or more subtypes of plant protein were inversely associated with T2D overall [0.78 (0.65, 0.98)], in females [0.75 (0.62, 0.90)] and people without central obesity [0.82 (0.68, 1.00)]. Additionally, consuming three subtypes of vegetables was inversely associated with T2D overall [0.90 (0.83, 0.98)] and in males [0.85 (0.73, 0.99)].

CONCLUSION

Diabetes prevention may benefit not only from a diet consisting of five different food groups, but also from a diet that is diverse in plant-protein sources, with specific benefits for female Europeans and those without central obesity.

Is there a sex difference in response to FODMAP diet group education for IBS? A clinical practice service evaluation

Background: While the low fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet, low FODMAP diet (LFD) has demonstrated effectiveness in managing irritable bowel syndrome (IBS) symptoms, little is known about sex-specific responses to this dietary intervention. Aim: This study evaluates the role of sex differences in symptom improvement following a dietitian-led, group education session on the LFD for IBS patients. Methods: A total of 305 patients, including 249 with a diagnosis of IBS and 56 classified as having suspected IBS, were enrolled in this study (79.7% female). Patients attended two group education sessions on the LFD. Primary outcomes were measured using the IBS Symptom Severity Score (IBS-SSS) and the Global Symptom Question (GSQ). Secondary outcomes included stool frequency, stool consistency and individual symptoms assessed by the Gastrointestinal Symptom Rating Scale. Statistical analyses were performed to compare baseline and follow-up data within and between sexes. Results: Both male and female patients experienced significant reductions in IBS-SSS scores and improvements in GSQ satisfactory relief, stool frequency, stool consistency and individual gastrointestinal (GI) symptoms following the LFD (p < 0.05). There were no significant between-sex differences in the extent of symptom relief (p > 0.05). Conclusion: The study found no significant sex-based differences in symptom reduction or GI relief following the intervention. These findings suggest that, despite differing symptom profiles and IBS prevalence, both male and female patients achieve similar relief with the LFD group education.

Personalized Nutrition in Chronic Kidney Disease

A personalized approach to nutrition in patients with chronic kidney disease (CKD) represents a promising paradigm shift in disease management, moving beyond traditional one-size-fits-all dietary recommendations. Patients with CKD often have other comorbidities and face unique nutritional challenges, including protein-energy wasting (PEW), sarcopenia, and impaired renal excretion of nutrients, which complicate dietary planning. Current guidelines focus primarily on nutrient restrictions-such as limiting protein, sodium, potassium, and phosphorus. However, these generalized recommendations often result in suboptimal adherence and outcomes. Personalized nutrition, which adapts dietary recommendations to individual characteristics, such as genotype, phenotype, and socio-cultural preferences, has gained traction across various chronic diseases. However, its application in nephrology remains underexplored, and despite promising results from studies such as Food4Me, questions remain about the real-world impact of such strategies. The aims of this review are (1) to summarize the evidence on the current state of nutritional recommendations in CKD, (2) to discuss the emerging role of multi-omics approaches in informing personalized nutrition advice in CKD, and (3) to provide an opinion on nutritional challenges faced by patients with CKD and the importance of collaboration with the renal dietician. We conclude that despite barriers, such as the cost and data integration, personalized nutrition holds the potential to improve CKD outcomes, enhance quality of life, and empower patients through tailored dietary strategies for better disease management.

I eat, therefore I am? Revealing differences and incongruences in dietary identities among omnivores and flexitarians in Europe

Sustainable diets have been forwarded as initiatives to mitigate the impact of current food consumption towards health and the environment. For instance, adopting a flexitarian diet and reducing the consumption of animal-sourced food (ASF) are said to help limit the rate of food system greenhouse gas emissions. However, much remains to be explored on how individuals associate themselves with alternative diets. In filling this gap, self-declared omnivores and flexitarians from ten European countries (N = 5870) were surveyed to determine how they identify with a particular diet, considering their food preferences and consumption frequency of ASF and ASF substitutes. The analysis of the data revealed that flexitarians seemed to consume more plant-based alternatives than omnivores, yet their consumption of ASF remained comparable. A series of segmentation analyses likewise revealed that some individuals (N = 563, 34.2%) reporting as flexitarians seemed to behave similarly to conventional omnivores and conversely, some omnivores (N = 1202, 28.5%) behaved similarly to conventional flexitarians in terms of food consumption frequencies. Moreover, significant associations with consuming plant-based food were found when considering the current readiness level of the respondent to transform diets. Taken together, the findings of this study show that identifying with a particular dietary lifestyle is contingent on how individuals set personal thresholds to qualify for a particular diet, thereby providing implications to the way nutritional guidelines frame and define recommendations for dietary intake.

A researcher's guide to studying sex differences in immune aging

Sex differences in immune system aging significantly impact disease susceptibility and vaccine responses among older adults, but with notable disparities between men and women. This area has gained importance because vaccines can exhibit differential efficacy by sex in aging populations, underscoring the need for sex-specific strategies. As the global population ages, understanding these sex-based immune differences is crucial for developing targeted interventions for age-related diseases. Addressing these disparities requires robust preclinical models that mimic human immune aging to uncover mechanisms and inform personalized approaches. In this review we assess the translational potential of preclinical mouse models in studying sex differences in immune aging, and emphasize the urgency of sex-specific interventions to improve health outcomes in older adults.

Impact of Sexual Dimorphism on Therapy Response in Patients with Metabolic Dysfunction-Associated Steatotic Liver Disease: From Conventional and Nutritional Approaches to Emerging Therapies

Metabolic dysfunction-associated steatotic liver disease (MASLD) represents a spectrum of liver disease ranging from hepatic fat accumulation to steatohepatitis (metabolic dysfunction-associated steatohepatitis, MASH), fibrosis, cirrhosis, and potentially hepatocellular carcinoma in the absence of excessive alcohol consumption. MASLD is characterized by substantial inter-individual variability in terms of severity and rate of progression, with a prevalence that is generally higher in men than in women. Steroids metabolism is characterized by sexual dimorphism and may have an impact on liver disease progression; indeed, several therapeutic strategies targeting hormone receptors are under phase 2/3 development. Despite the fact that the importance of sexual dimorphism in the setting of MASLD is well recognized, the underlying molecular mechanisms that can potentially drive the disease toward progression are not clear. The aim of this review is to delve into the crosstalk between sexual dimorphism and steroid hormone perturbation under nutritional and pharmacological intervention.

Sex-Based Differences in the In Vitro Digestibility of MCT Emulsions Stabilized by Various Emulsifiers

Consumer sex influences phenotypic differences in digestive functions that may underlie variations in food disintegration. This study used an in vitro digestion model to test the hypothesis that emulsions follow distinct digestive pathways in men and women. Model emulsions were prepared using medium-chain triglycerides stabilized by beta-lactoglobulin, alpha-lactalbumin, or lactoferrin, and by three non-protein emulsifiers: Tween 80, lecithin, and sucrose esters. All emulsions were produced by high-pressure homogenization (0.57 MPa, 5 passes) and then subjected to in vitro digestion under simulated conditions of the male or female gastrointestine. Digesta samples were analyzed via confocal microscopy and laser-based particle sizing, revealing that protein-stabilized emulsions were responsive to physiological differences between males and females, whereas emulsions stabilized by non-protein emulsifiers remained mostly unaffected by sex-based differences. Absolute differential analyses of emulsion droplet size-distribution curves showed that changes in breakdown trajectories for emulsions were pronouncedly noticeable in gastric effluents. Further, SDS-PAGE analysis of digesta showed that breakdown patterns of protein-stabilized emulsions are consistent with prior evidence found for healthy adults; however, results under female gut conditions indicated variations in protein clotting that may alter bioaccessible levels of bioactive peptides. Thus, this study underscores the importance of considering consumer biological sex in food design, especially regarding emulsion-based products for targeted digestive responses.

Timing of standard chow exposure determines the variability of mouse phenotypic outcomes and gut microbiota profile

Standard chow diets influence reproducibility in animal model experiments because chows have different nutrient compositions, which can independently influence phenotypes. However, there is little evidence of the role of timing in the extent of variability caused by chow exposure. Here we measured the impact of different diets (5V5M, 5V0G, 2920X and 5058) and timing of exposure (adult exposure (AE), lifetime exposure (LE) and developmental exposure (DE)) on growth and development, metabolic health indicators and gut bacterial microbiota profiles across genetically identical C57BL/6J mice. Diet drove differences in macro- and micronutrient intake for all exposure models. AE had no effect on phenotypic outcomes. However, LE mice exhibited significant sex-dependent diet effects on growth, body weight and body composition. LE effects were mostly absent in the DE model, where mice were exposed to chow differences only from conception to weaning. Both AE and LE models exhibited similar diet-driven beta diversity profiles for the gut bacterial microbiota, with 5058 diet driving the most distinct profile. However, compared with AE, LE effects on beta diversity were sex dependent, and LE mice exhibited nine times more differentially abundant bacterial genera, the majority of which were inversely affected by 2920X and 5058 diets. Our findings demonstrate that LE to different chow diets has the greatest impact on the reproducibility of several experimental measures commonly used in preclinical mouse model studies. Importantly, weaning mice from different diets onto the same diet for maturation may be an effective way to reduce unwanted phenotypic variability among experimental models.

Anthropometric Measurements and Weight Management Nutrition Knowledge: A Cross-Sectional Study in Turkey

This study aimed to examine the relationships between academic programs, gender, anthropometric measurements, and the Weight Management Nutrition Knowledge Questionnaire (WMNKQ) score. Results indicated that 37.7% of male and 15.3% of female students were overweight, with significant gender differences in BMI, waist/height ratio, waist/hip ratio, and waist circumference (all p < .001, except waist circumference p = .024). WMNKQ scores also varied significantly by gender and BMI classification (p < .05). Students in health-related fields scored higher on nutrition knowledge than those in other faculties (p = .000). Findings emphasize the importance of weight management among university students, who may face lifestyle changes affecting healthy eating habits.

Sex-Specific Factors Associated With Diet Quality in Cancer Survivors: Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2019

Previous studies have shown the inverse association between diet quality and cancer mortality. Therefore, this study aims to discover the factors that affect diet quality among cancer survivors. We analyzed the 12 years of Korea National Health and Nutrition Examination Survey data, which included 2,756 cancer survivors. We analyzed 30 factors considered to be associated with diet quality. As a result, factors related to diet quality differed between males and females. A male cancer survivor who is aged < 65, living with members of the household, living without a spouse, having a lower household income, a blue-collar worker, a beneficiary of national basic livelihood, sleeping > 9 hours a day, unaware of a nutritional fact label, insecure in food, non-user of dietary supplements, not on diet therapy, limited in activity, perceiving stress, and obese, are more likely to have lower Korean Healthy Eating Index (KHEI) scores. On the other hand, a female cancer survivor who is aged < 65, a pink-collar worker, inexperienced in nutritional education, non-users of dietary supplements, obese, and has a lower education level, and cervical or stomach cancer is prone to have lower KHEI scores. In conclusion, factors associated with diet quality among cancer survivors are sex-specific. Therefore, sex-specific factors should be considered when identifying and intervening in cancer survivors at risk for lower diet quality scores.

Sex-based difference in immune responses and efficacy of the pneumococcal conjugate vaccine

Vaccine-mediated protection and susceptibility to Streptococcus pneumoniae (pneumococcus) infections are influenced by biological sex. The incidence of invasive pneumococcal disease remains higher in males compared to females even after the introduction of the pneumococcal conjugate vaccine. However, sex-based differences in the immune response to this conjugate vaccine remain unexplored. To investigate those differences, we vaccinated adult male and female mice with pneumococcal conjugate vaccine and assessed cellular and humoral immune responses. Compared to females, male mice displayed lower levels of T follicular helper cells, germinal center B cells, and plasmablasts, which are all required for antibody production following vaccination. This was linked to lower IgG and IgM levels against pneumococci and lower isotype switching to IgG3 in vaccinated males. Due to lower antibody levels, sera of vaccinated male mice had lower efficacy in several anti-pneumococcal functions, including neutralization of bacterial binding to pulmonary epithelial cells as well as direct cytotoxicity against S. pneumoniae. Importantly, while the vaccine was highly protective in females, vaccinated males succumbed to infection more readily and were more susceptible to both lung-localized infection and systemic spread following S. pneumoniae challenge. These findings identify sex-based differences in immune responses to pneumococcal conjugate vaccine that can inform future vaccine strategies.

Incidence and impact of food aversions among patients with cancer receiving outpatient chemotherapy: a one-year prospective survey

PURPOSE

To determine the current incidence and impact of chemotherapy-associated food aversions in a variety of cancer types.

METHODS

Cancer patients aged 18 years and older who received chemotherapy infusions at the outpatient chemotherapy unit of a university hospital between May 2022 and April 2023 were included in the study (n = 243). To monitor the occurrence of food aversions, participants were asked to complete a food preference questionnaire each time they visited the outpatient chemotherapy unit.

RESULTS

During the one-year survey period, one in four cancer patients receiving outpatient chemotherapy developed food aversions, and one in four of them complained of interference with daily life due to eating problems at the same time or later. The median time to the onset of food aversion was 46 (interquartile range 36-77) days after the start of chemotherapy. The incidence of food aversions was significantly higher in patients who were women, had a digestive, gynecologic, or breast cancer, and received more cytotoxic agents in chemotherapy. Patients who developed food aversions tended to lose more body weight than those who did not.

CONCLUSION

Food aversions were still common among cancer patients undergoing chemotherapy. Even an aversion to a single food may have affected the patient's nutritional status. Healthcare professionals should closely monitor the occurrence of food aversions, especially in the early days of chemotherapy induction, to detect an increasing risk of malnutrition.

TRIAL REGISTRATION

Not applicable.

Mapping the mitochondrial landscape in T2DM: key findings from 2003-2023

Backgound

T2DM, a chronic metabolic disorder, poses a significant threat to global public health. Mitochondria play a crucial role in the pathogenesis of T2DM. This study intends to investigate the correlation between mitochondria and T2DM over the past two decades (2003-2023) through bibliometric analysis. Its objectives are to pinpoint trends, emphasize research priorities, and establish a foundation for future investigations.

Methods

A literature search was conducted using the SCI-E database. All recorded results were downloaded in plain text format for further analysis. The following terms were analyzed using Vosviewer 1.6.18, citespace 6.3r1, bibliometrix in RStudio (v.4.4.1), and Microsoft Excel 2021: country, institution, author, journal, references, and keywords.

Results

From January 1, 2003 to December 31, 2023, a total of 2,732 articles were retrieved. The United States, China, and Italy contributed most of the records. UNIVERSITY OF CALIFORNIA SYSTEM, INSTITUT NATIONAL DE LA SANTE ET DE LA RECHERCHE MEDICAL INSERM, and US DEPARTMENT OF VETERANS AFFAIRS were the top 3 most productive institutions. rocha milagros, victor victor m had the most publications, followed by roden michael, and petersen kf had the most citations together. DIABETES published the most articles on research on this topic, followed by AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM, DIABETOLOGIA. The key points of this topic are the relationship between mitochondria and T2DM, the skeletal muscle mitochondrial changes observed in T2DM, and the impact of mitochondrial dysfunction on T2DM. Over the past five years, particle dynamics, mitochondrial dysfunction, and mechanism research have emerged as significant focal points in this field.

Conclude

This paper successfully identified the key areas and emerging trends in the relationship between mitochondria and T2DM, thereby offering valuable insights for future research.

Pooled and global burdens and trends of five common cancers attributable to diet in 204 countries and territories from 1990 to 2019: an analysis of the Global Burden of Disease Study

OBJECTIVE

Increasing evidence has shown that dietary behaviors are closely correlated with the carcinogenesis and progression of many types of cancer. However, few studies have assessed the global diet-related burden of cancer. This study aimed to estimate the pooled burdens and trends of five types of cancers attributable to dietary behaviors.

METHODS

Data regarding cancer attributable to dietary behaviors were extracted from the Global Burden of Disease study 2019, including the death cases and age-standardized death rates, and disability-adjusted life years (DALYs) estimated according to diseases, age, sex, the socio-demographic index (SDI) and location.

RESULTS

According to the Global Burden of Disease study 2019, five types of cancer were affected by dietary behaviors: colon and rectum cancer; tracheal, bronchus and lung cancer; stomach cancer; esophageal cancer and breast cancer. Unhealthy dietary behaviors for cancer caused a total of 605.4 thousand deaths and 13951.3 thousand DALYs globally. The burden of cancer attributable to dietary risks was higher for men than for women. The highest age-standardized death rates in 2019 were observed in southern Latin America, and the lowest rates were observed in North Africa and the Middle East. The greatest increases in the age-standardized death rates, from 1990 to 2019, were found in Western Sub-Saharan Africa, with the greatest decreases in Central Asia. The highest attributable proportions of death or DALYs were colon and rectum cancer. The greatest diet-related cancer burden was observed in regions with a high-middle SDI.

CONCLUSION

Global age-standardized deaths and DALYs rates attributable to diet-related cancer are considerable and cause a substantial burden. Successful population-wide initiatives targeting unhealthy dietary behaviors would reduce this burden.

Impact of Sex on the Therapeutic Efficacy of Rosiglitazone in Modulating White Adipose Tissue Function and Insulin Sensitivity

Obesity and type 2 diabetes mellitus are global public health issues. Although males show higher obesity and insulin resistance prevalence, current treatments often neglect sex-specific differences. White adipose tissue (WAT) is crucial in preventing lipotoxicity and inflammation and has become a key therapeutic target. Rosiglitazone (RSG), a potent PPARγ agonist, promotes healthy WAT growth and mitochondrial function through MitoNEET modulation. Recent RSG-based strategies specifically target white adipocytes, avoiding side effects. Our aim was to investigate whether sex-specific differences in the insulin-sensitizing effects of RSG exist on WAT during obesity and inflammation. We used Wistar rats of both sexes fed a high-fat diet (HFD, 22.5% fat content) for 16 weeks. Two weeks before sacrifice, a group of HFD-fed rats received RSG treatment (4 mg/kg of body weight per day) within the diet. HFD male rats showed greater insulin resistance, inflammation, mitochondrial dysfunction, and dyslipidemia than females. RSG had more pronounced effects in males, significantly improving insulin sensitivity, fat storage, mitochondrial function, and lipid handling in WAT while reducing ectopic fat deposition and enhancing adiponectin signaling in the liver. Our study suggests a significant sexual dimorphism in the anti-diabetic effects of RSG on WAT, correlating with the severity of metabolic dysfunction.

Ex Vivo Study of Colon Health, Contractility and Innervation in Male and Female Rats after Regular Exposure to Instant Cascara Beverage

Instant Cascara (IC) is a sustainable beverage made from dried coffee cherry pulp, a by-product of coffee processing. It is rich in nutrients and bioactive compounds and has a high concentration of antioxidants. This study explored the impact of regular IC consumption on colonic motor function and innervation. Over a period of 4 weeks, male and female healthy rats were given drinking water containing 10 mg/mL of IC. Thereafter, colon samples were obtained to evaluate the longitudinal (LM) and circular (CM) smooth muscle contractile response to acetylcholine (ACh) and electrical field stimulation (EFS) in an organ bath, before and after atropine administration (10-6 M). Histological and immunohistochemical analyses assessed colon damage, muscle thickness, and immunoreactivity to substance P (SP) and neuronal nitric oxide synthase (nNOS). ACh and EFS induced similar responses across groups, but the CM response to EFS was greater in females compared with males, despite their lower body weight. Atropine completely blocked the response to ACh but only partially antagonized the neural response to EFS, particularly that of CM in females treated with IC, which had a greater liquid intake than those exposed to water. However, in the myenteric ganglia, no statistically significant differences were observed in SP or nNOS. Our results suggest that regular IC exposure may enhance specific neural pathway functions, particularly in females, possibly due to their increased IC consumption.

Sex differences in sleep, circadian rhythms, and metabolism: Implications for precision medicine

The number of individuals experiencing sleep loss has exponentially risen over the past decades. Extrapolation of laboratory findings to the real world suggests that females are more affected by extended wakefulness and circadian misalignment than males are. Therefore, long-term effects such as sleep and metabolic disorders are likely to be more prevalent in females than in males. Despite emerging evidence for sex differences in key aspects of sleep-wake and circadian regulation, much remains unknown, as females are often underrepresented in sleep and circadian research. This narrative review aims at highlighting 1) how sex differences systematically impinge on the sleep-wake and circadian regulation in humans, 2) how sex differences in sleep and circadian factors modulate metabolic control, and 3) the relevance of these differences for precision medicine. Ultimately, the findings justify factoring in sex differences when optimizing individually targeted sleep and circadian interventions in humans.

Research priorities and considerations for nutrition research: methods of sex and gender analysis for biomedical and nutrition research

For some 20 years, science funding bodies have been asking for the integration of sex- and gender-related factors into the content of research and innovation. The rationale for those requirements has been the accumulated evidence that sex and gender are important determinants of health and disease. The European Commission (EC) has been the first, since 2002, to seriously ask for the integration of sex and gender into research and innovation in the context of their multi-annual framework programmes. When introduced, this condition was not immediately applauded by the research community, who perhaps lacked training in methods for the integration of sex- and gender-related factors. The EC Expert Group on Gendered Innovations sought to fill this gap. This review describes the work of this international collaborative project which has resulted in the development of general and field-specific methods for sex and gender analysis and 38 case studies for various research domains (science, health and medicine, environment, engineering) to illustrate how, by applying methods of sex and gender analysis, new knowledge could be created. Since 2010, science funding bodies in Canada, the USA and several EU member states have followed the example of the EC issuing similar conditions. Although the effects of nutritional patterns on a range of (physiological and health) outcomes may differ for men and women, sex and gender analyses are rarely conducted in nutrition research. In this review, we provide examples of how gender is connected to dietary intake, and how advancing gender analysis may inform gender-sensitive policies and dietary recommendations.

Sexual dimorphism in the context of nutrition and health

Diets and dietary constituents that we consume have a considerable impact on disease risk. Intriguingly these effects may be modulated to some extent by sex. Lack of female representation in nutritional studies as well as a lack of stratification by sex has and continues to limit our understanding of these sex × diet interactions. Here we provide an overview of the current and available literature describing how exposure to certain dietary patterns (Western-style diet, Mediterranean diet, vegetarian/vegan, ketogenic diet) and dietary constituents (dietary fibre, PUFA and plant bioactive) influences disease risk in a sex-specific manner. Interestingly, these sex differences appear to be highly disease-specific. The identification of such sex differences in response to diet stresses the importance of sex stratification in nutritional research.

Beneficial effects of time-restricted fasting on cardiovascular disease risk factors: a meta-analysis

BACKGROUND

Cardiovascular disease continues to be a leading cause of mortality worldwide, highlighting the need to explore innovative approaches to improve cardiovascular health outcomes. Time-restricted fasting (TRF) is a dietary intervention that involves limiting the time window for food consumption. It has gained attention for its potential benefits on metabolic health and weight management. This study aims to investigate the impact of TRF on key risk factors, including body weight, glucose metabolism, blood pressure, and lipid profile.

METHODS

We conducted a systematic search in five databases (Scopus, Embase, PubMed, Cochrane, and Web of Science) for relevant studies up to January 2023. After applying inclusion criteria, 12 studies were eligible for analysis. Quality assessment was conducted using the ROB-2.0 tool and ROBINS-I. Risk of bias was mapped using Revman 5.3, and data analysis included Hartung-Knapp adjustment using R 4.2.2.

RESULTS

The group that underwent the TRF intervention exhibited a significant decrease in body weight (SMD: -0.22; 95%CI: -0.41, -0.04; P < 0.05) and fat mass (SMD: -0.19; 95%CI: -0.36, -0.02; P < 0.05), while maintaining lean mass (SMD: -0.09; 95%CI: -0.08, 0.26; P > 0.05).

CONCLUSION

TRF has shown potential as a treatment strategy for reducing total body weight by targeting adipose tissue, with potential improvements in cardiometabolic function.

Sex-Dependent Metabolic Effects in Diet-Induced Obese Rats following Intermittent Fasting Compared with Continuous Food Restriction

Recently, intermittent fasting has gained relevance as a strategy to lose weight and improve health as an alternative to continuous caloric restriction. However, the metabolic impact and the sex-related differences are not fully understood. The study aimed to compare the response to a continuous or intermittent caloric restriction in male and female rats following a previous induction of obesity through a cafeteria diet by assessing changes in body weight, energy intake, metabolic parameters, and gene expression in liver hepatic and adipose tissue. The continuous restriction reduced the energy available by 30% and the intermittent restriction consisted of a 75% energy reduction on two non-consecutive days per week. The interventions reduced body weight and body fat in both sexes, but the loss of WAT in females was more marked in both models of caloric restriction, continuous and intermittent. Both caloric restrictions improved insulin sensitivity, but more markedly in females, which showed a more pronounced decrease in HOMA-IR score and an upregulation of hepatic IRS2 and Sirt1 gene expression that was not observed in males. These findings suggest the fact that females are more sensitive than males to reduced caloric content in the diet.

Cardiovascular Disease and the Mediterranean Diet: Insights into Sex-Specific Responses

Cardiovascular disease (CVD) is a leading cause of mortality and disease burden in women globally. A healthy diet is important for the prevention of CVD. Research has consistently favoured the Mediterranean diet as a cardio-protective diet. Several studies have evaluated associations between the Mediterranean diet and cardiovascular outcomes, including traditional risk factors like hypertension, type 2 diabetes mellitus, and obesity. In addition, consistent evidence suggests that the components of the Mediterranean diet have a synergistic effect on cardiovascular risk due to its anti-inflammatory profile and microbiome effects. While the benefits of the Mediterranean diet are well-established, health advice and dietary guidelines have been built on largely male-dominant studies. Few studies have investigated the beneficial associations of the Mediterranean diet in sex-specific populations, including those with non-traditional risk factors that are specific to women, for instance polycystic ovarian syndrome and high-risk pregnancies, or more prevalent in women, such as chronic inflammatory diseases. Therefore, this review aims to provide a comprehensive overview of the current evidence regarding the Mediterranean diet in women in relation to cardiovascular health outcomes.

Widespread sex dimorphism across single-cell transcriptomes of adult African turquoise killifish tissues

The African turquoise killifish (Nothobranchius furzeri), the shortest-lived vertebrate that can be bred in captivity, is an emerging model organism for aging research. Here, we describe a multitissue, single-cell gene expression atlas of female and male blood, kidney, liver, and spleen. We annotate 22 cell types, define marker genes, and infer differentiation trajectories. We find pervasive sex-dimorphic gene expression across cell types. Sex-dimorphic genes tend to be linked to lipid metabolism, consistent with clear differences in lipid storage in female vs. male turquoise killifish livers. We use machine learning to predict sex using single-cell gene expression and identify potential markers for molecular sex identity. As a proof of principle, we show that our atlas can be used to deconvolute existing bulk RNA sequencing (RNA-seq) data to obtain accurate estimates of cell type proportions. This atlas can be a resource to the community that could be leveraged to develop cell-type-specific expression in transgenic animals.

Metabolic impact of polyphenol-rich aronia fruit juice mediated by inflammation status of gut microbiome donors in humanized mouse model

Background

The Aronia melanocarpa fruit is emerging as a health food owing to its high polyphenolic content and associated antioxidant activity. Antioxidant-rich foods, such as Aronia fruit, may counter inflammatory stimuli and positively modulate the gut microbiome. However, a comprehensive study characterizing the impact of Aronia fruit supplementation has not been completed. Therefore, we completed analyses measuring the metabolic, microbial, and inflammatory effects of a diet supplemented with Aronia fruit juice.

Method

Humanized mice were generated by colonizing gnotobiotic mice with microbiomes from human donors presenting disparate inflammation levels. Blood and fecal samples were collected throughout the course of an 8-week dietary intervention with either Aronia juice or a carbohydrate-matched beverage alone (2 weeks) or in combination with a high-fat diet to induce inflammation (6 weeks). Samples were analyzed using 16S rRNA gene sequencing (stool) and liquid chromatography-mass spectrometry (serum).

Results

We demonstrated transfer of microbiome composition and diversity and metabolic characteristics from humans with low and high inflammation levels to second-generation humanized mice. Aronia supplementation provided robust protection against high-fat diet induced metabolic and microbiome changes that were dependent in part on microbiome donor. Aronia induced increases in bacteria of the Eggerthellaceae genus (7-fold) which aligns with its known ability to metabolize (poly)phenols and in phosphatidylcholine metabolites which are consistent with improved gut barrier function. The gut microbiome from a low inflammation phenotype donor provided protection against high-fat diet induced loss of microbiome β-diversity and global metabolomic shifts compared to that from the high inflammation donor.

Conclusion

These metabolic changes elucidate pathway-specific drivers of reduced inflammation stemming from both Aronia and the gut microbiota.

Microbiota in the oral cavity of school-age children with HIV who started antiretroviral therapy at young ages in South Africa

BACKGROUND

Infancy is an important developmental period when the microbiome is shaped. We hypothesized that earlier antiretroviral therapy (ART) initiation would attenuate HIV effects on microbiota in the mouth.

METHODS

Oral swabs were collected from 477 children with HIV (CWH) and 123 children without (controls) at two sites in Johannesburg, South Africa. CWH had started ART less than 3 years of age; 63% less than 6 months of age. Most were well controlled on ART at median age 11 years when the swab was collected. Controls were age-matched and recruited from the same communities. Sequencing of V4 amplicon of 16S rRNA was done. Differences in microbial diversity and relative abundances of taxa were compared between the groups.

RESULTS

CWH had lower alpha diversity than controls. Genus-level abundances of Granulicatella, Streptococcus, and Gemella were greater and Neisseria and Haemophilus less abundant among CWH than controls. Associations were stronger among boys. Associations were not attenuated with earlier ART initiation. Shifts in genus-level taxa abundances in CWH relative to controls were most marked in children on lopinavir/ritonavir regimens, with fewer shifts seen if on efavirenz ART regimens.

CONCLUSION

A distinct profile of less diverse oral bacterial taxa was observed in school-aged CWH on ART compared with uninfected controls suggesting modulation of microbiota in the mouth by HIV and/or its treatments. Earlier ART initiation was not associated with microbiota profile. Proximal factors, including current ART regimen, were associated with contemporaneous profile of oral microbiota and may have masked associations with distal factors such as age at ART initiation.

Considerations for reproducible omics in aging research

Technical advancements over the past two decades have enabled the measurement of the panoply of molecules of cells and tissues including transcriptomes, epigenomes, metabolomes and proteomes at unprecedented resolution. Unbiased profiling of these molecular landscapes in the context of aging can reveal important details about mechanisms underlying age-related functional decline and age-related diseases. However, the high-throughput nature of these experiments creates unique analytical and design demands for robustness and reproducibility. In addition, 'omic' experiments are generally onerous, making it crucial to effectively design them to eliminate as many spurious sources of variation as possible as well as account for any biological or technical parameter that may influence such measures. In this Perspective, we provide general guidelines on best practices in the design and analysis of omic experiments in aging research from experimental design to data analysis and considerations for long-term reproducibility and validation of such studies.

Widespread sex-dimorphism across single-cell transcriptomes of adult African turquoise killifish tissues

The African turquoise killifish (Nothobranchius furzeri), the shortest-lived vertebrate that can be bred in captivity, is an emerging model organism to study vertebrate aging. Here we describe the first multi-tissue, single-cell gene expression atlas of female and male turquoise killifish tissues comprising immune and metabolic cells from the blood, kidney, liver, and spleen. We were able to annotate 22 distinct cell types, define associated marker genes, and infer differentiation trajectories. Using this dataset, we found pervasive sex-dimorphic gene expression across cell types, especially in the liver. Sex-dimorphic genes tended to be involved in processes related to lipid metabolism, and indeed, we observed clear differences in lipid storage in female vs. male turquoise killifish livers. Importantly, we use machine-learning to predict sex using single-cell gene expression in our atlas and identify potential transcriptional markers for molecular sex identity in this species. As proof-of-principle, we show that our atlas can be used to deconvolute existing liver bulk RNA-seq data in this species to obtain accurate estimates of cell type proportions across biological conditions. We believe that this single-cell atlas can be a resource to the community that could notably be leveraged to identify cell type-specific genes for cell type-specific expression in transgenic animals.

The importance of reaction norms in dietary restriction and ageing research

Ageing research has progressed rapidly through our ability to modulate the ageing process. Pharmacological and dietary treatments can increase lifespan and have been instrumental in our understanding of the mechanisms of ageing. Recently, several studies have reported genetic variance in response to these anti-ageing interventions, questioning their universal application and making a case for personalised medicine in our field. As an extension of these findings the response to dietary restriction was found to not be repeatable when the same genetic mouse lines were retested. We show here that this effect is more widespread with the response to dietary restriction also showing low repeatability across genetic lines in the fly (Drosophila melanogaster). We further argue that variation in reaction norms, the relationship between dose and response, can explain such conflicting findings in our field. We simulate genetic variance in reaction norms and show that such variation can: 1) lead to over- or under-estimation of treatment responses, 2) dampen the response measured if a genetically heterogeneous population is studied, and 3) illustrate that genotype-by-dose-by-environment interactions can lead to low repeatability of DR and potentially other anti-ageing interventions. We suggest that putting experimental biology and personalised geroscience in a reaction norm framework will aid progress in ageing research.

Sexual dimorphism in selenium deficiency is associated with metabolic syndrome and prevalence of heart disease

BACKGROUND

Serum selenium levels have been associated with the incidence of heart failure (HF) and signs of the metabolic syndrome. In addition, notable differences have been reported between males and females in food intake and micronutrient metabolism, possibly explaining different health outcomes.

OBJECTIVE

Our objective was to elucidate sex-specific, cross-sectional phenotypic differences in the association of serum selenium concentrations with parameters of metabolic syndrome and HF.

METHODS

We investigated data from individuals from a community-based cohort (PREVEND; N = 4288) and heart failure cohort (BIOSTAT-CHF; N = 1994). In both populations, cross-sectional analyses were performed for potential interaction (p < 0.1) between sex and serum selenium with overlapping signs and clinical parameters of the metabolic syndrome and HF.

RESULTS

Baseline selenium levels of the total cohort were similar between PREVEND (85.7 μg/L) and BIOSTAT-CHF (89.1 μg/L). Females with lower selenium levels had a higher BMI and increased prevalence of diabetes than females with higher selenium, in both PREVEND (p_interaction < 0.001; p_interaction = 0.040, resp.) and BIOSTAT-CHF (p_interaction = 0.021; p_interaction = 0.024, resp.), while opposite associations were observed for males. Additionally, in females, but not in males, lower selenium was associated with a higher prevalence of myocardial infarction (MI) in PREVEND (p_interaction = 0.021) and BIOSTAT-CHF (p_interaction = 0.084).

CONCLUSION

Lower selenium was associated with a higher BMI and increased prevalence of diabetes in females, opposite to males, and was also associated with more MI in females. Interventional studies are needed to validate this observation.