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Sarcopenia is a prevalent neuromuscular condition among older adults, marked by significant reductions in muscle mass and strength, which result in notable impairments in physical performance. Modifications in lifestyle habits have been frequently highlighted as essential approaches to mitigate the progression of sarcopenia, with a particular focus on protein consumption. Over the past few decades, a wealth of knowledge has emerged, driven by both observational and experimental studies exploring various factors related to protein intake, such as amount, timing, and sources. This review provides a pauca verba overview of these findings, presenting a concise yet informative summary of key insights.

Objectives: The present study examined the associations between the dietary intake of polyunsaturated fatty acids (PUFAs), physical function, and the prevalence of sarcopenia in Italian community-dwelling older adults. Design: Cross-sectional study. Setting: Unconventional settings across Italy (e.g., exhibitions, health promotion campaigns). Participants: Older adults (65+ years) who provided a written informed consent. Methods: Physical function was evaluated according to isometric handgrip strength (IHG) and 5-time sit-to-stand (5STS) performances. Muscle power parameters were estimated based on 5STS values. Sarcopenia was operationalized according to the presence of low physical function (IHG or 5STS) plus low appendicular skeletal muscle mass (ASM), estimated according to calf circumference. A 12-item food questionary was used to estimate the dietary intake of PUFAs, which included omega-3 (α-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid) and omega-6 fatty acids. Results: Multiple linear regression results indicate negative and significant associations between the dietary intake of α-linolenic acid and muscle power, and between docosahexaenoic acid consumption and ASM. No significant associations were found between PUFAs-related variables and sarcopenia. Conclusions: Results of the present study indicate that PUFAs-related variables were negatively and significantly associated with physical function and body composition in older adults. Nevertheless, no significant associations were found with sarcopenia. These findings suggest that a more detailed analysis of covariates should be conducted in future investigations that aim to examine the associations between the dietary intake of PUFAs and sarcopenia-related parameters.

Background: An age-dependent normative values of calf circumference (CC) has been recently proposed as an accessible proxy for muscle mass. However, its usefulness to estimate sarcopenia has not been assessed. The objectives of the present study were to determine if the substitution of the classical way to assess muscle mass by these values have enough diagnostic accuracy and prognostic value among older adults living in the community. Methods: Data from the Toledo Study of Healthy Ageing (TSHA) were used. CC was measured using an anthropometric tape. We used two age-groups CC cut-off points: the TSHA CC median and the one proposed in the Longevity Check-up 7+ (Lookup 7+) project. Sarcopenia was defined based on the European Working Group on Sarcopenia in Older People (EWGSOP2), the Foundation for the National Institutes of Health (FNIH), and FNIH criteria standardized for our population (sFNIH). Frailty (according to the Frailty Phenotype and the Frailty Trait Scale-5) and disability (Katz index) were assessed at baseline and follow-up. Mortality and first hospitalization were also recorded. Logistic (incident frailty and worsening disability) and Cox (mortality and hospitalization) regressions were performed. Diagnostic accuracy was assessed through Kappa index, AUCs, positive and negative predictive values. Predictive ability was assessed through AUCs and integrated AUCs (IAUCs). Results: 1531 participants (74.8 ± 5.8 years; 45.6% men) were included in the analysis. Prevalence rates of sarcopenia were 22.7% (sFNIH), 15.0% (FNIH), and 13.9% (EWGSOP2). Using TSHA-based cut-points of CC, the prevalence of sarcopenia was 16.8% (sFNIH), 11.0% (FNIH), and 11.5% (EWGSOP2). According to LC7+-based CC cut-off points, sarcopenia prevalence was 17.6% (sFNIH), 11.9% (FNIH), and 12.4% (EWGSOP2). CC cut-off points showed low-to-moderate agreement (Kappa Index values between 0.49 and 0.69) with appendicular lean mass for the evaluation of sarcopenia. Sarcopenia identified by Lookup 7+ and TSHA CC cut-off points was associated with the adverse events examined, with similar AUCs and IAUCs than original sarcopenia definitions, and were lost after adjustment by baseline frailty, except when the original EWGSOP2 definition was used. Conclusions: Using normalized values of CC as a criteria of muscle mass shows moderate agreement with classical criteria for diagnosing sarcopenia and offer similar predictive value in community-dwelling older adults.

Objectives: Insulin resistance determined by Homeostasis Model of Insulin Resistance (HOMA-IR) has been associated with functional decline in non-diabetic older subjects. However, insulin is not routinely assessed. The study evaluated the predictive value of non-insulin-dependent IR surrogates on functional decline in non-diabetic older men and women. Design and participants: Prospective cohort study over 5 years. The study included 615 older participants from the Toledo Study of Healthy Aging. Methods: Frailty was assessed by the Frailty Trait Scale-5 (FTS-5) at baseline and after 5 years follow-up. 193 subjects experienced functional decline (2.5-point reduction in the FTS-5 score). Multivariate regression models analysed the effect of five described IR surrogates on functional decline considering potential confounders. Results: Among evaluated IR proxies, triglyceride glucose-body mass index (TyG-BMI) and HOMA-IR were significantly associated with an increased risk of functional decline (odd ratio (95% confidence interval) TyG-BMI: 1.16 (1.05, 1.28), p = 0.0035 and HOMA-IR: 1.59 (1.15, 2.21), p = 0.0056) among all participants. When stratified by gender, HOMA-IR was related to functional decline in men [2.02 (1.13, 3.59), p = 0.0173] and TyG-BMI in women [1.19 (1.05, 1.35), p = 0.0057]. Conclusions: Only TyG-BMI index mimics the predictive capacity of insulin-based IR marker. The predictive ability of IR indexes is gender-specific, being TyG-BMI the only index able to predict functional decline in women and HOMA-IR in men.

Background: Supplementation with β-hydroxy β-methyl butyrate (HMB) appears to be effective in preserving muscle in older adults. However, the association between endogenously produced HMB with frailty has not been studied in people with chronic disease. Objectives: The purpose of this study is to explore whether an association exists between endogenous HMB levels and frailty status in older adults with type-2 diabetes mellitus (T2DM). Methods: Data were taken from the Toledo Study of Healthy Ageing, a community-dwelling aged (65 years+) cohort. Frailty was assessed at baseline and at 2.99 median years according to the Frailty Phenotype (FP) standardized to our population and the Frailty Trait Scale 12 (FTS12). The associations between HMB levels and frailty were assessed using three nested multivariate logistic regressions and segmented by sex. Glucose, HMB and glucose interaction, age and body composition were used as covariables. Results: 255 participants (mean age 75.3 years, 52.94% men) were included. HMB levels showed an inverse cross-sectional association with frailty, which was modified when the interaction term HMB*glucose was included, remaining significant only for FTS12 [OR (95% CI): 0.436 (0.253, 0.751), p-value 0.003]. The association between HMB endogenous levels and FTS12 appears to be independent of sex, in which the association was maintained after adjusting for the covariates. However, there appears to be threshold points for glucose levels, above which the protective effect of HMB is lost: 145.4 mg/dl adjusted by gender for the whole sample and 149.6 mg/dl and 138.9 mg/dl for men and women, respectively. Endogenous HMB levels were not found to be associated with incident frailty. Conclusions: Cross-sectional analysis revealed that endogenous HMB levels were inversely associated with frailty as assessed by the FTS12 in older people with T2DM. This association was found to be dependent on circulating fasted glucose levels.