Distinct Gut Microbiota and Serum Metabolites in Response to Weight Loss Induced by Either Dairy or Exercise in a Rodent Model of Obesity

Metabolic effects of milk fatty acids: A literature review

Milk and dairy products are known to have a significant role in human development and tissue maintenance due to their high nutritional value. With the higher incidence of obesity and metabolic diseases, nutrition and public health authorities have recommended the intake of fat-free or low-fat dairy due to the saturated fatty acid content of whole-fat products and their effect on serum cholesterol levels. However, recent studies have questioned the association between milk fat consumption and cardiometabolic risk. This literature review aims to compile the scientific evidence of the metabolic effects of milk fatty acids in clinical and basic research studies, as well as their relationship with metabolic disorders and gut microbiota composition. Research shows that various milk fatty acids exert effects on metabolic alterations (obesity, type 2 diabetes and cardiovascular diseases) by modifying glucose homeostasis, inflammation and lipid profile-related factors. Additionally, recent studies have associated the consumption of milk fatty acids with the production of metabolites and the promotion of healthy gut microbiota. From mainly observational studies, evidence suggests that milk and dairy fatty acids are not directly linked to cardiometabolic risk, but further controlled research is necessary to clarify such findings and to assess whether dietary recommendations to choose low-fat dairy foods are necessary for the population for the prevention of obesity and cardiometabolic disease.

High fat diet reveals sex-specific fecal and liver metabolic alterations in C57BL/6J obese mice

Obesity is a major health concern that poses significant risks for many other diseases, including diabetes, cardiovascular disease, and cancer. Prevalence of these diseases varies by biological sex. This study utilizes a mouse (C57BL/6J) model of obesity to analyze liver and fecal metabolic profiles at various time points of dietary exposure: 5, 9, and 12 months in control or high fat diet (HFD)-exposed mice. Our study discovered that the female HFD group has a more discernable perturbation and set of significant changes in metabolic profiles than the male HFD group. In the female mice, HFD fecal metabolites including pyruvate, aspartate, and glutamate were lower than control diet-exposed mice after both 9th and 12th month exposure time points, while lactate and alanine were significantly downregulated only at the 12th month. Perturbations of liver metabolic profiles were observed in both male and female HFD groups, compared to controls at the 12th month. Overall, the female HFD group showed higher lactate and glutathione levels compared to controls, while the male HFD group showed higher levels of glutamine and taurine compared to controls. These metabolite-based findings in both fecal and liver samples for a diet-induced effect of obesity may help guide future pioneering discoveries relating to the analysis and prevention of obesity in people, especially for females.

Heritability and recursive influence of host genetics on the rumen microbiota drive body weight variance in male Hu sheep lambs

BACKGROUND

Heritable rumen microbiota is an important modulator of ruminant growth performance. However, no information exists to date on host genetics-rumen microbiota interactions and their association with phenotype in sheep. To solve this, we curated and analyzed whole-genome resequencing genotypes, 16S rumen-microbiota data, and longitudinal body weight (BW) phenotypes from 1150 sheep.

RESULTS

A variance component model indicated significant heritability of rumen microbial community diversity. Genome-wide association studies (GWAS) using microbial features as traits identified 411 loci-taxon significant associations (P < 10-8). We found a heritability of 39% for 180-day-old BW, while also the rumen microbiota likely played a significant role, explaining that 20% of the phenotypic variation. Microbiota-wide association studies (MWAS) and GWAS identified four marker genera (Bonferroni corrected P < 0.05) and five novel genetic variants (P < 10-8) that were significantly associated with BW. Integrative analysis identified the mediating role of marker genera in genotype influencing phenotype and unravelled that the same genetic markers have direct and indirect effects on sheep weight.

CONCLUSIONS

This study reveals a reciprocal interplay among host genetic variations, the rumen microbiota and the body weight traits of sheep. The information obtained provide insights into the diverse microbiota characteristics of rumen and may help in designing precision microbiota management strategies for controlling and manipulating sheep rumen microbiota to increase productivity. Video Abstract.

Impact of Calorie-Restricted Cafeteria Diet and Treadmill Exercise on Sweet Taste in Diet-Induced Obese Female and Male Rats

The goal of the present study was to evaluate the sweet taste function in obese rats fed with a 30% calorie-restricted cafeteria diet (CAFR) and/or subjected to moderate treadmill exercise (12-17 m/min, 35 min, 5 days per week) for 9 weeks. A two-bottle preference test, a taste reactivity test, and a brief-access licking test were carried out when animals were aged 21 weeks; biometric and metabolic parameters were also measured along the interventions. Two separate experiments for females and males were performed. Behaviorally, CAF diet decreased sucrose intake and preference, as well as perceived palatability, in both sexes and decreased hedonic responses in males. Compared to the CAF diet, CAFR exerted a corrective effect on sweet taste variables in females by increasing sucrose intake in the preference test and licking responses, while exercise decreased sucrose intake in both sexes and licking responses in females. As expected, CAF diet increased body weight and Lee index and worsened the metabolic profile in both sexes, whereas CAFR diet ameliorated these effects mainly in females. Exercise had no noticeable effects on these parameters. We conclude that CAF diet might diminish appetitive behavior toward sucrose in both sexes, and that this effect could be partially reverted by CAFR diet in females only, while exercise might exert protective effects against overconsumption of sucrose in both sexes.

Maternal Metabolites Indicative of Mental Health Status during Pregnancy

Approximately 25% of individuals report poor mental health during their pregnancy or postpartum period, which may impact fetal neurodevelopment, birth outcomes, and maternal behaviors. In the present study, maternal serum samples were collected from pregnancies at 28-32 weeks gestation from the All Our Families (Alberta, Canada) cohort and assessed using nuclear magnetic resonance spectroscopy (¹H-NMR) and inductively coupled plasma-mass spectrometry (ICP-MS). Individuals with poor mental health at 34-36 weeks gestation were age-matched with mentally healthy pregnant controls. Metabolites were examined against validated self-reported mental health questionnaires for associations with depressive symptoms (Edinburgh Perinatal Depression Scale) and anxiety symptoms (Spielberger State-Trait Anxiety Inventory). ¹H-NMR metabolites were identified for depression (alanine, leucine, valine, methionine, phenylalanine, glucose, lactate, 3-hydroxybutyrate, and pyruvate) and anxiety (3-hydroxybutyrate). For ICP-MS, antimony and zinc were significant for depression and anxiety, respectively. Upon false discovery rate (FDR) correction at 10%, five ¹H-NMR metabolites (alanine, leucine, lactate, glucose, and phenylalanine) for depression remained significantly increased. Although results warrant further validation, the identified metabolites may serve as a predictive tool for assessing mental health during pregnancy as earlier identification has the potential to aid intervention and management of poor mental health symptomology, thus avoiding harmful consequences to both mother and offspring.

Restricted cafeteria feeding and treadmill exercise improved body composition, metabolic profile and exploratory behavior in obese male rats

The aim of this study was to evaluate, in male Long-Evans rats, whether a restricted-cafeteria diet (CAFR), based on a 30% calorie restriction vs continuous ad libitum cafeteria (CAF) fed animals, administered alone or in combination with moderate treadmill exercise (12 m/min, 35 min, 5 days/week for 8 weeks), was able to ameliorate obesity and the associated risk factors induced by CAF feeding for 18 weeks and to examine the changes in circadian locomotor activity, hypothalamic-pituitary-adrenal (HPA) axis functionality, and stress response elicited by this dietary pattern. In addition to the expected increase in body weight and adiposity, and the development of metabolic dysregulations compatible with Metabolic Syndrome, CAF intake resulted in a sedentary profile assessed by the home-cage activity test, reduced baseline HPA axis activity through decreased corticosterone levels, and boosted exploratory behavior. Both CAFR alone and in combination with exercise reduced abdominal adiposity and hypercholesterolemia compared to CAF. Exercise increased baseline locomotor activity in the home-cage in all dietary groups, boosted exploratory behavior in STD and CAF, partially decreased anxiety-like behavior in CAF and CAFR, but did not affect HPA axis-related parameters.

Association between dairy consumption and the risk of diabetes: A prospective cohort study from the China Health and Nutrition Survey

Diet is closely related to the risk of diabetes; yet the relationship between dairy consumption and the risk of diabetes is unclear with conflicting evidence from previous studies. This study used data from the Chinese Health and Nutrition Survey to investigate the association between dairy consumption and diabetes. A total of 15,512 adults were included; dairy consumption at each survey was assessed by the 3-day 24-h recall and weighed food record methods, and diabetes occurrence was derived from self-reported information. The association between dairy consumption and diabetes was explored using Cox regression and further stratified with BMI and energy intake. Results indicated that 12,368 (79.7%) participants had no dairy consumption, while 2,179 (14.0%) and 947 (6.1%) consumed dairy at 0.1-100 and >100 g/day, respectively. After adjusting for potential confounders, dairy consumption of 0.1-100 g/day was associated with lower risk of diabetes in all participants (HR 0.53, 95% CI:0.38 -0.74; P < 0.001) and males (HR 0.50, 95% CI: 0.31-0.80; P = 0.004). According to the restricted cubic splines (RCS), the protective effect on diabetes was significant in the total population with dairy consumption ranging from 25 to 65 g/day (HR <1, P = 0.025). In the stratified analysis, consuming 30-80 g/day was associated with reduced diabetes risk among the ≤ 2,000 kcal/day energy intake group (HR <1, P = 0.023). In conclusion, dairy consumption was inversely associated with a reduced diabetes risk in Chinese population. Further studies are required to examine the optimal level of dairy consumption for preventing diabetes in the Chinese population.

The Harm of Metabolically Healthy Obese and the Effect of Exercise on Their Health Promotion

Obesity and obesity-related diseases [type 2 diabetes, cardiovascular disease (CVD), and cancer] are becoming more common, which is a major public health concern. Metabolically healthy obesity (MHO) has become a type of obesity, accounting for a large proportion of obese people. MHO is still harmful to health. It was discovered that MHO screening criteria could not well reflect health hazards, whereas visceral fat, adiponectin pathway, oxidative stress, chronic inflammation, and histological indicators at the microlevel could clearly distinguish MHO from health control, and the biological pathways involved in these micro indicators were related to MHO pathogenesis. This review reveals that MHO’s micro metabolic abnormality is the initial cause of the increase of disease risk in the future. Exploring the biological pathway of MHO is important in order to develop an effective mechanism-based preventive and treatment intervention strategy. Exercise can correct the abnormal micro metabolic pathway of MHO, regulate metabolic homeostasis, and enhance metabolic flexibility. It is a supplementary or possible alternative to the traditional healthcare prevention/treatment strategy as well as an important strategy for reducing MHO-related health hazards.

Moderate-Intensity Exercise Improves Endothelial Function by Altering Gut Microbiome Composition in Rats Fed a High-Fat Diet

BACKGROUND

Obesity changes gut microbial ecology and is related to endothelial dysfunction. Although the correlation between gut microbial ecology and endothelial dysfunction has been studied in obese persons, the underlying mechanisms by which exercise enhances endothelial function in this group remain unclear. This study investigated whether exercise improves endothelial function and alters gut microbiome composition in rats fed a high-fat diet (HFD).

METHODS

Obesity was induced by an HFD for 11 weeks. Whole-body composition and endothelium-dependent relaxation of mesenteric arteries were measured. Blood biochemical tests were performed, and gut microbiomes were characterized by 16S rRNA gene sequencing on an Illumina HiSeq platform.

RESULTS

Exercise training for 8 weeks improved body composition in HFD-fed rats. Furthermore, compared with the untrained/HFD group, aerobic exercise significantly increased acetylcholine-induced, endothelium-dependent relaxation in mesenteric arteries (P < 0.05) and circulating vascular endothelial growth factor levels (P < 0.01) and decreased circulating C-reactive protein levels (P < 0.05). In addition, exercise and HFD resulted in alterations in the composition of the gut microbiome; exercise reduced the relative abundance of Clostridiales and Romboutsia. Moreover, 12 species of bacteria, including Romboutsia, were significantly associated with parameters of endothelial function in the overall sample.

CONCLUSIONS

These results suggest that aerobic exercise enhances endothelial function in HFD-fed rats by altering the composition of the gut microbiota. These findings provide new insights on the application of physical exercise for improving endothelial function in obese persons.

Does the gut microbiota contribute to the antiobesity effect of exercise? A systematic review and meta-analysis

OBJECTIVE

The aim of this study was to assess gut microbiota modifications after exercise in humans and animal models with obesity or type 2 diabetes and their role in exercise-induced weight loss.

METHODS

A systematic search of six databases was conducted on July 31, 2021. The extracted data on body fat or body weight from human and animal studies were analyzed using random-effects meta-analysis.

RESULTS

A total of 28 studies were included, with all studies reporting exercise-induced gut microbiota modifications; however, the modified taxa varied among studies. Proteobacteria was the only taxa reported to be altered by exercise in more than one human and one animal study. Taxa belonging to Firmicutes were the most responsive to exercise in humans and mice, whereas Proteobacteria taxa were the most responsive to exercise in rats. A meta-analysis was conducted to examine the weight-lowering effect of exercise based on data subgrouped by altered or unaltered α-diversity or β-diversity. The association between the weight-lowering effect of exercise and altered β-diversity was observed in humans with obesity but not in animals.

CONCLUSIONS

These findings suggest that gut microbiota modifications contribute to exercise-induced weight loss in obesity; however, their precise contributions, especially those of taxon-level variations, remain to be investigated.

Cecal Butyrate (Not Propionate) Was Connected with Metabolism-Related Chemicals of Mice, Based on the Different Effects of the Two Inonotus obliquus Extracts on Obesity and Their Mechanisms

Obesity is a metabolic disease and causes significant changes in host and gut microbial metabolite levels. However, little research has been done on the relationship between host and gut microbial metabolites. Thus, this study investigated the connection of the chemicals, based on the different effects of two Inonotus obliquus extracts on high-fat-diet-induced mice and their mechanisms. In this study, C57BL6/J mice fed with a high-fat diet were given I. obliquus ethanol extract (IOE) and polysaccharide (IOP). ¹H NMR-based metabolomics, 16S rRNA sequencing, and real-time reverse transcription polymerase chain reaction (RT-PCR) were used to detect metabolites, cecal microbes, and expressions of genes in liver. IOE and IOP effectively improved the obesity of mice, including the adjustment of body weight gain, energy intake, energy efficiency, liver glucose metabolism and triglyceride metabolism, tricarboxylic acid (TCA) cycle, and degradation of three major nutrients (carbohydrate, lipid, and protein). IOE significantly increased cecal propionate based on Bacteroides and Akkermansia, thereby inhibiting energy intake and fat accumulation in mice. IOP remarkably improved the level of cecal butyrate by Lactobacillus and the Bacteroidales S24-7 group, resulting in increased energy consumption, and fat degradation by regulating the TCA cycle of the host. Two extracts containing different bioactive substances of I. obliquus improved obesity in mice through different effects on production of cecal microbial metabolites. Moreover, cecal butyrate (not propionate) was connected with chemicals of mice, including four metabolites of the TCA cycle and other metabolism-related chemicals.

Exercise training modulates the gut microbiota profile and impairs inflammatory signaling pathways in obese children

Childhood obesity has reached epidemic levels and is a serious health concern associated with metabolic syndrome, nonalcoholic fatty liver disease, and gut microbiota alterations. Physical exercise is known to counteract obesity progression and modulate the gut microbiota composition. This study aims to determine the effect of a 12-week strength and endurance combined training program on gut microbiota and inflammation in obese pediatric patients. Thirty-nine obese children were assigned randomly to the control or training group. Anthropometric and biochemical parameters, muscular strength, and inflammatory signaling pathways in mononuclear cells were evaluated. Bacterial composition and functionality were determined by massive sequencing and metabolomic analysis. Exercise reduced plasma glucose levels and increased dynamic strength in the upper and lower extremities compared with the obese control group. Metagenomic analysis revealed a bacterial composition associated with obesity, showing changes at the phylum, class, and genus levels. Exercise counteracted this profile, significantly reducing the Proteobacteria phylum and Gammaproteobacteria class. Moreover, physical activity tended to increase some genera, such as Blautia, Dialister, and Roseburia, leading to a microbiota profile similar to that of healthy children. Metabolomic analysis revealed changes in short-chain fatty acids, branched-chain amino acids, and several sugars in response to exercise, in correlation with a specific microbiota profile. Finally, the training protocol significantly inhibited the activation of the obesity-associated NLRP3 signaling pathway. Our data suggest the existence of an obesity-related deleterious microbiota profile that is positively modified by physical activity intervention. Exercise training could be considered an efficient nonpharmacological therapy, reducing inflammatory signaling pathways induced by obesity in children via microbiota modulation.

Physical fitness regimens could stimulate shifts in gut microbiome composition and metabolism that counteract health risks associated with childhood obesity. This condition can increase the risk of metabolic and cardiovascular disease later in life. Several studies have indicated that disturbances in the microbial populations in the digestive tract may contribute to these diseases. Researchers led by Sonia Sánchez-Campos of the Institute of Biomedicine, León,Spain, recently assessed the impact of exercise and endurance training on microbiome composition in obese children. They determined that these regimens can produce measurable shifts in the gut microbe population, yielding bacterial communities that are more similar to those seen in non-obese children. These shifts were accompanied by alterations in metabolic activity that may help mitigate inflammatory signaling and other processes that fuel obesity-related disease.