Sarcopenia is a progressive age-related skeletal muscle disorder characterized by the decline of muscle mass and function, driven by mitochondrial dysfunction, oxidative stress, and chronic low-grade inflammation. Polyphenols have been proposed as candidate modulators of these pathways on mechanistic and preclinical grounds, but whether this plausibility translates into measurable structural and functional benefit in clinical trials remains unresolved. A systematic review following PRISMA 2020 guidelines and the Cochrane Handbook (PROSPERO CRD420251183284) was conducted. Eligible studies were randomized controlled trials evaluating polyphenol supplementation in adults aged ≥ 55 years for outcomes related to skeletal muscle mass, strength, or physical function. Risk of bias was assessed using the Cochrane RoB 2 tool, and because a formal meta-analysis was not feasible given the small number of trials and substantial clinical heterogeneity, effect estimates and measures of uncertainty were tabulated alongside a structured direction-of-effect synthesis, following recommended practice for reviews that cannot pool data quantitatively. Six randomized controlled trials were identified; five had reported outcome data and were included in the synthesis, while a sixth remains an ongoing registered protocol with no results yet available and is reported separately. Interventions included quercetin, epicatechin-rich extracts, tea catechins, cocoa flavonoids, and marine-derived polyphenols, with durations ranging from 4 to 24 weeks among completed trials. Muscle strength improved significantly on between-group comparison in two of five completed trials; effects on muscle mass were inconsistent, with one trial showing a significant group-by-time interaction under a combined polyphenol, amino-acid, and exercise intervention, another showing an attenuated loss without a significant between-group difference, and others showing null or less clearly attributable effects; functional and balance outcomes improved in two of three trials that assessed them. Polyphenol supplementation shows biologically plausible but currently inconsistent effects on skeletal muscle outcomes in older adults; the evidence base remains too small, heterogeneous, and methodologically limited to support therapeutic recommendations. Larger, standardized randomized trials in populations with confirmed sarcopenia, incorporating direct neuromuscular assessment, are required before clinical translation.
Age-related loss of muscle and bone mass and increased adiposity contribute to frailty, disability, falls, and fractures. The hallmarks of aging framework provide a biological model to investigate mechanisms underlying body composition remodeling. However, whether hallmark-related biomarkers are associated with longitudinal body composition changes remains unclear. We conducted a narrative review of longitudinal human studies examining associations between biomarkers and body composition changes. Eligible studies included adults aged 50 years and older with repeated body composition assessment. We found 50 articles: 3 investigated primary, 20 antagonists, and 24 integrative hallmarks. Body composition was mainly measured using Dual-energy X-ray Absorptiometry. Chronic inflammation emerged as the most commonly investigated hallmark. No study was found for genomic instability, epigenetic alterations, proteostasis, macroautophagy, cellular senescence, stem cell exhaustion, or dysbiosis. Primary hallmarks were underrepresented: telomere length was the only primary hallmark identified, with no consistent association with body composition changes. Among antagonistic hallmarks, deregulated nutrient sensing provided consistent evidence: insulin resistance, hyperinsulinemia, impaired glucose homeostasis, and related indices were associated with adverse muscle and adipose changes. Evidence for mitochondrial dysfunction relied on indirect biomarkers and was more suggestive for adiposity than muscle or bone. Among integrative hallmarks, altered intercellular communication and chronic inflammation were most investigated. Hormonal markers including vitamin D, trace elements, inflammatory indices, and systemic biomarkers showed biomarker-specific, sex-specific, and compartment-specific associations. Evidence remains limited and heterogeneous. Current findings support insulin-related nutrient sensing in adverse muscle and adipose remodeling. Studies combining repeated biomarker assessment with precise phenotyping are needed.
The precise nature and magnitude of the longitudinal association between cardiorespiratory fitness (CRF) and the risk of dementia remain incompletely characterized. Using a systematic review and meta-analysis of published observational cohort studies in the general population, we sought to assess the association between CRF and the risk of incident dementia and related cognitive outcomes. Relevant studies with at least 1 year of follow-up were identified through searches of MEDLINE and Embase (January 2013 to April 2026), supplemented by manual reference screening and Web of Science citation searches through May 2026, and an updated PubMed search covering January to October 2026. Risk ratios (RRs) with 95
Companion dogs are a valuable source of translational discovery about the basic biology of aging because of their well-characterized genome, phenotypic variation in lifespan, aging, and disease profiles, and diverse environmental exposures shared with their human owners. The Dog Aging Project (DAP)’s prospective, longitudinal open cohort study was begun in 2019 to investigate the biological and environmental determinants of healthy aging in companion dogs. As of December 31, 2024, the study has enrolled 50,188 companion dogs across all 50 US states and the District of Columbia, including over half with follow-up data, spanning up to five years, and 14,978 documented deaths. The DAP is a community science research program in which owners volunteer to provide detailed longitudinal information about their dogs. This manuscript describes the recruitment and retention of this study population, known as the DAP Pack, including the data collection processes, and the means by which DAP Open Data are shared with the research community. The goals of this manuscript are to present the detailed methodology of the DAP as a resource to support authors and readers of DAP publications, to provide the scientific community with a framework to support the design of similar future studies, and to facilitate use of DAP data by investigators with Open Data access.
Handgrip strength (HGS) declines with age and is associated with morbidity and mortality. This study aimed to investigate sex-specific associations between absolute and allometric HGS and all-cause mortality in Mexican adults aged 50 years and older. We analyzed data from the Mexican Health and Aging Study, including 1917 adults aged ≥ 50 years with HGS assessed at wave 3. Absolute HGS (kg) and allometric HGS (HGS/height2) were examined using sex-specific quartiles and standardized z-scores. Participants were followed through 2021. Sex-stratified Cox proportional hazards models and interaction analyses were performed, and survey-weighted mortality rates were calculated per 1000 person-years. During follow-up, 371 deaths occurred. Associations between lower HGS and higher mortality were stronger in men. For absolute HGS, men in the lowest quartile had higher mortality than those in the highest quartile (HR 5.56, 95
