Brown and Beige Adipose Tissue and Aging

Across aging, adipose tissue (AT) changes its quantity and distribution: AT becomes dysfunctional with an increase in production of inflammatory peptides, a decline of those with anti-inflammatory activity and infiltration of macrophages. Adipose organ dysfunction may lead to age-related metabolic alterations. Aging is characterized by an increase in adiposity and a decline in brown adipose tissue (BAT) depots and activity, and UCP1 expression. There are many possible links to age-associated involution of BAT, including the loss of mitochondrial function, impairment of the sympathetic nervous system, age-induced alteration of brown adipogenic stem/progenitor cell function and changes in endocrine signals. Aging is also associated with a reduction in beige adipocyte formation. Beige adipocytes are known to differentiate from a sub-population of progenitors resident in white adipose tissue (WAT); a defective ability of progenitor cells to proliferate and differentiate has been hypothesized with aging. The loss of beige adipocytes with age may be caused by changes in trophic factors in the adipose tissue microenvironment, which regulate progenitor cell proliferation and differentiation. This review focuses on possible mechanisms involved in the reduction of BAT and beige activity with aging, along with possible targets for age-related metabolic disease therapy

Mediterranean diet increases endothelial function in adults: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND: The endothelium plays a key role in the maintenance of vascular health and represents a potential physiological target for dietary and other lifestyle interventions designed to reduce the risk of cardiovascular diseases (CVD) including stroke or coronary heart disease. OBJECTIVE: To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the effects of the Mediterranean dietary pattern (MedDiet) on endothelial function. METHODS: Medline, Embase, and Scopus databases were searched from inception until January 2019 for studies that met the following criteria: 1) RCTs including adult participants, 2) interventions promoting the MedDiet, 3) inclusion of a control group, and 4) measurements of endothelial function. A random-effects meta-analysis was conducted. Metaregression and subgroup analyses were performed to identify whether effects were modified by health status (i.e., healthy participants versus participants with existing comorbidities), type of intervention (i.e., MedDiet alone or with a cointervention), study duration, study design (i.e., parallel or crossover), BMI, and age of participants. RESULTS: Fourteen articles reporting data for 1930 participants were included in the meta-analysis. Study duration ranged from 4 wk to 2.3 y. We observed a beneficial effect of the MedDiet on endothelial function [standardized mean difference (SMD): 0.35; 95% CI: 0.17, 0.53; P 0.05). CONCLUSIONS: MedDiet interventions improve endothelial function in adults, suggesting that the protective effects of the MedDiet are evident at early stages of the atherosclerotic process with important implications for the early prevention of CVD. This study has the PROSPERO registration number: CRD42018106188

Acceptability and Feasibility of a 13-Week Pilot Randomised Controlled Trial Testing the Effects of Incremental Doses of Beetroot Juice in Overweight and Obese Older Adults

Nitrate-rich food can increase nitric oxide production and improve vascular and brain functions. This study examines the feasibility of a randomised controlled trial (RCT) testing the effects of prolonged consumption of different doses of dietary nitrate (NO3-) in the form of beetroot juice (BJ) in overweight and obese older participants. A single-blind, four-arm parallel pilot RCT was conducted in 62 overweight and obese (30.4 ± 4 kg/m2) older participants (mean ± standard deviation (SD), 66 ± 4 years). Participants were randomized to: (1) high-NO3- (HN: 2 × 70 mL BJ/day) (2) medium-NO3- (MN: 70 mL BJ/day), (3) low-NO3- (LN: 70 mL BJ on alternate days) or (4) Placebo (PL: 70 mL of NO3--depleted BJ on alternate days), for 13 weeks. Compliance was checked by a daily log of consumed BJ, NO3- intake, and by measuring NO3- and NO2- concentrations in plasma, saliva, and urine samples. Fifty participants completed the study. Self-reported compliance to the interventions was >90%. There were significant positive linear relationships between NO3- dose and the increase in plasma and urinary NO3- concentration (R2 = 0.71, P 0.001 and R2 = 0.46 P 0.001, respectively), but relationships between NO3- dose and changes in salivary NO3- and NO2- were non-linear (R2 = 0.35, P = 0.002 and R2 = 0.23, P = 0.007, respectively). The results confirm the feasibility of prolonged BJ supplementation in older overweight and obese adults

Sarcopenia and obesity

Purpose of reviewTogether with age-related body composition changes, the increased prevalence of obesity observed in the past few decades in older individuals has led to a condition called sarcopenic obesity, characterized by a mismatch between muscle mass and fat mass. The operative definition of sarcopenic obesity is still under discussion and creates difficulties in clinical practice. Muscle weakness, rather than low muscle mass, was previously proposed as an alternative criterion and, more recently, the dynapenic abdominal obese phenotype is of increasing interest because of its unfavorable health consequences and usability in clinical practice.Recent findingsThis review focuses on the most recent findings of pathogenic inter-relationships between adipose tissue and muscle. Recent studies on health consequences of sarcopenic obesity and dynapenic abdominal obesity are also examined. Despite the lack of consensus on a definition for sarcopenic obesity, progress has been made in the delineation of the treatment principles for this condition.SummaryFurther research is needed to compare different definitions of sarcopenic/dynapenic obesity to clarify the relationship between obesity and the most important adverse outcomes in the elderly. The next step will be the definition of best possible therapeutic approaches for this condition

The Potential of \u3b2-Hydroxy-\u3b2-Methylbutyrate as a New Strategy for the Management of Sarcopenia and Sarcopenic Obesity

Sarcopenia is defined as an age-related loss of skeletal muscle mass and function and is recognized as a major clinical problem for older people. Essential amino acid supplementation, particularly beta-hydroxy-beta-methylbutyrate (HMB), a metabolite of leucine that is produced in skeletal muscle, has been evaluated in several studies as a nutritional approach to enhancing muscle protein synthesis in healthy or frail elderly subjects. Studies performed in in vitro conditions show that HMB may be effective in the treatment of muscle wasting, increasing myogenesis, reducing muscle apoptosis, and having a positive effect on muscle protein turnover; however, studies of the effects of HMB conducted in old animals have reported conflicting results. Clinical trials performed in older adults confirm that HMB can attenuate the progression of sarcopenia in elderly subjects. HMB supplementation results in an increase in skeletal muscle mass and strength in the elderly and its effect is even greater when combined with physical exercise. The role of HMB in sarcopenic obesity management is still under debate and a general lack of intervention studies in this population must be recognized. In conclusion, HMB appears to be effective for enhancing muscle mass and strength in the elderly. Less certain is the role of HMB supplementation in reducing fat mass and, thus, in the treatment of sarcopenic obesity

Weight Cycling as a Risk Factor for Low Muscle Mass and Strength in a Population of Males and Females with Obesity

Objective This study aimed to determine whether multiple weight cycles in adulthood are an independent predictor of lower muscle mass and reduced strength, with potential implication for sarcopenia in adults with obesity. Methods A total of 60 males and 147 females with obesity were included, with a mean BMI of 37.9 +/- 6.0 kg/m(2) and a mean age of 52.6 +/- 12.4 years. Muscle strength was evaluated with handgrip and appendicular skeletal muscle mass was measured with dual-energy x-ray absorptiometry. Results Participants were categorized into the following three groups: non-weight cyclers, mild weight cyclers, and severe weight cyclers. From a binary logistic regression that considered muscle mass categories as a dependent variable and weight cycling categories, age, and sex as independent variables, severe weight cyclers showed a 3.8-times increased risk of low muscle mass (95% CI: 1.42-10.01). Considering handgrip strength categories as a dependent variable and weight cycling categories, age, sex, and BMI as independent variables, severe weight cycling was associated with an increased risk of low muscle mass (about 6.3 times, 95% CI: 1.96-20.59). Severe weight cyclers showed a 5.2-times greater risk of developing sarcopenia. Conclusions In adults with obesity, weight cycling is associated with lower muscle mass and strength and a greater likelihood of developing sarcopenic obesity

Prevalence of sarcopenic obesity and association with metabolic syndrome in an adult Iranian cohort: the Fasa PERSIAN cohort study

Sarcopenic obesity (SO) is characterised by a concomitant high fat mass (FM) and low fat free mass (FFM) leading to an increased cardio-metabolic risk. This analysis aims to estimate the SO prevalence in Iranian adults and evaluate the association of SO with metabolic syndrome (MetS) risk. This cross-sectional analysis included 4296 subjects (age 35-70 years, 55.2% females). Body composition parameters, measured by bioelectrical impedance included: FM, FFM, appendicular lean mass (ALM) and skeletal mass index. SO was classified according to five criteria: (1) FM%-SMI; (2) FM%-ALM/% weight (wt%); (3) FM%-ALM/body mass index (BMI); (4) Residuals of ALM and FM and (5) FM/FFM Ratio. Multivariate logistic regression was applied to explore the association between SO models with MetS risk stratified by gender. Receiving operating characteristic (ROC) curves were used to identify the best FM/FFM ratio cut-off value for detecting MetS cases in males and females. The prevalence of SO varied between 4% and 26% depending upon the classification method. The prevalence of MetS was 12.8% and 31.6% in males and females, respectively. SO models based on ALM/wt% and FM/FFM ratio showed the strongest association with MetS risk in males (OR: 11.5, 95%CI: 7.5-17.7, p < 0.001 and OR: 10.1, 95%CI: 6.9-14.7, p < 0.001, respectively) and females (OR: 4.1, 95%CI: 3.0-5.6, p < 0.001 and OR: 4.6, 95%CI: 3.5-5.9, p < 0.001, respectively). SO is a prevalent condition in an adult Iranian population and the ALM/wt% and the FM/FFM ratio models of SO appeared to be associated with higher MetS risk

Protocol and recruitment results from a 13-week randomized controlled trial comparing the effects of different doses of nitrate-rich beetroot juice on cognition, cerebral blood flow and peripheral vascular function in overweight and obese older people

Background: Nitrate-rich food can increase NO production and may induce positive effects on brain function. This study examined the feasibility of a randomized clinical trial (RCT) testing the effects of prolonged consumption of incremental doses of dietary nitrate (NO ) in overweight and obese older participants. Secondary aims tested dose-dependent changes in cognitive, vascular and pulmonary functions and cerebral blood flow (CBF). Methods: This was a single blind, four-arm parallel RCT conducted in 60 overweight and obese older participants. Eligible participants were randomized to:1) high NO (140 ml of beetroot juice (BJ) per day, ~800 mg of NO /day), 2) moderate NO (70 ml of BJ per day, ~400 mg of NO /day), 3) low NO (70 ml on alternate days, ~400 mg of NO ) or 4) NO depleted (70 ml on alternate days, ~0.001 mg of NO). Measurements of cognitive, vascular and pulmonary functions and CBF were conducted at baseline and 13-weeks NO intake was assessed by six 24-h recalls, and by measuring NO intake biomarkers. Feasibility was assessed by obtaining qualitative feedback and evaluating trial recruitment, retention, compliance with study visits and measurement protocols. Results: Participant recruitment started in July 2018 and ended in April 2019. Of all the recruitment strategies that were used, advertisement of the study via Facebook generated the highest response rate. Sixty-two participants consented and were enrolled. Overall, characteristics of included participants matched our recruitment criteria. Conclusion: The findings from this study provide evidence of the acceptability and feasibility of an intervention investigating the effects of incremental doses of high-nitrate BJ over a prolonged period. Trial registration: The intervention study was registered with clinical trial ISRCTN registry (ISRCTN14746723) on 27 December 2018