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The effect of dose, frequency, and timing of protein supplementation on muscle mass in older adults

Protein supplementation has shown to improve muscle mass in older adults. However, its effect may be influenced by supplementation dose, frequency and timing. This systematic review aimed to assess the effect of dose, frequency and timing of protein supplementation on muscle mass in older adults. Five databases were systematically searched from inception to 14 March 2023, for randomised controlled trials investigating the effect of protein supplementation on muscle mass in adults aged ≥65 years. Random effects meta-analyses were performed, stratified by population. Subgroups were created for dose (≥30 g, <30 g/day), frequency (once, twice, three times/day) and timing of supplementation (at breakfast, breakfast and lunch, breakfast and dinner, all meals, between meals). Heterogeneity within and between subgroups was assessed using I 2 and Cochran Q statistics respectively. Thirty-eight articles were included describing community-dwelling (28 articles, n=3204, 74.6±3.4 years, 62.8 % female), hospitalised (8 articles, n=590, 77.0±3.7 years, 50.3 % female) and institutionalised populations (2 articles, n=156, 85.7±1.2 years, 71.2 % female). Protein supplementation showed a positive effect on muscle mass in community-dwelling older adults (standardised mean difference 0.116; 95 % confidence interval 0.032–0.200 kg, p=0.007, I 2=15.3 %) but the effect did not differ between subgroups of dose, frequency and timing (Q=0.056, 0.569 and 3.084 respectively, p>0.05). Data including hospitalised and institutionalised populations were limited. Protein supplementation improves muscle mass in community-dwelling older adults, but its dose, frequency or timing does not significantly influence the effect.

The intensive care medicine research agenda in nutrition and metabolism

PURPOSE: The objectives of this review are to summarize the current practices and major recent advances in critical care nutrition and metabolism, review common beliefs that have been contradicted by recent trials, highlight key remaining areas of uncertainty, and suggest recommendations for the top 10 studies/trials to be done in the next 10 years.METHODS: Recent literature was reviewed and developments and knowledge gaps were summarized. The panel identified candidate topics for future trials in critical care nutrition and metabolism. Then, members of the panel rated each one of the topics using a grading system (0-4). Potential studies were ranked on the basis of average score.RESULTS: Recent randomized controlled trials (RCTs) have challenged several concepts, including the notion that energy expenditure must be met universally in all critically ill patients during the acute phase of critical illness, the routine monitoring of gastric residual volume, and the value of immune-modulating nutrition. The optimal protein dose combined with standardized active and passive mobilization during the acute phase and post-acute phase of critical illness were the top ranked studies for the next 10 years. Nutritional assessment, nutritional strategies in critically obese patients, and the effects of continuous versus intermittent enteral nutrition were also among the highest-ranking studies.CONCLUSIONS: Priorities for clinical research in the field of nutritional management of critically ill patients were suggested, with the prospect that different nutritional interventions targeted to the appropriate patient population will be examined for their effect on facilitating recovery and improving survival in adequately powered and properly designed studies, probably in conjunction with physical activity.

Aerobic exercise increases post-exercise exogenous protein oxidation in healthy young males

The capacity to utilize ingested protein for optimal support of protein synthesis and lean body mass is described within the paradigm of anabolic competence. Protein synthesis can be stimulated by physical exercise, however, it is not known if physical exercise affects post-exercise protein oxidation. Characterization of the driving forces behind protein oxidation, such as exercise, can contribute to improved understanding of whole body protein metabolism. The purpose of this study is to determine the effect of two levels of aerobic exercise intensity on immediate post-exercise exogenous protein oxidation. Sixteen healthy males with a mean (SD) age of 24 (4) years participated. The subjects' VO2-max was estimated with the Åstrand cycling test. Habitual dietary intake was assessed with a three-day food diary. Exogenous protein oxidation was measured by isotope ratio mass spectrometry. These measurements were initiated after the ingestion of a 30 g 13C-milk protein test drink that was followed by 330 minutes breath sample collection. On three different days with at least one week in between, exogenous protein oxidation was measured: 1) during rest, 2) after 15 minutes of aerobic exercise at 30% of VO2-max (moderate intensity), and 3) after 15 minutes of aerobic exercise at 60% of VO2-max (vigorous intensity). After vigorous intensity aerobic exercise, 31.8%±8.0 of the 30 g 13C-milk protein was oxidized compared to 26.2%±7.1 during resting condition (p = 0.012), and 25.4%±7.6 after moderate intensity aerobic exercise compared to resting (p = 0.711). In conclusion, exogenous protein oxidation is increased after vigorous intensity aerobic exercise which could be the result of an increased protein turnover rate.

Assessing nutritional status in cancer: role of the patient-generated subjective global assessment

PURPOSE OF REVIEW:The Scored Patient-Generated Subjective Global Assessment (PG-SGA) is used internationally as the reference method for proactive risk assessment (screening), assessment, monitoring and triaging for interventions in patients with cancer. This review aims to explain the rationale behind and data supporting the PG-SGA, and to provide an overview of recent developments in the utilization of the PG-SGA and the PG-SGA Short Form.RECENT FINDINGS:The PG-SGA was designed in the context of a paradigm known as 'anabolic competence'. Uniquely, the PG -SGA evaluates the patient's status as a dynamic rather than static process. The PG-SGA has received new attention, particularly as a screening instrument for nutritional risk or deficit, identifying treatable impediments and guiding patients and professionals in triaging for interdisciplinary interventions. The international use of the PG-SGA indicates a critical need for high-quality and linguistically validated translations of the PG-SGA.SUMMARY:As a 4-in-1 instrument, the PG-SGA can streamline clinic work flow and improve the quality of interaction between the clinician and the patient. The availability of multiple high-quality language versions of the PG-SGA enables the inclusion of the PG-SGA in international multicenter studies, facilitating meta-analysis and benchmarking across countries.

Proteins and amino acids are fundamental to optimal nutrition support in critically ill patients

In this review, we present the growing scientific evidence showing the importance of protein and amino acid provision in nutritional support and their impact on preservation of muscle mass and patient outcomes.

Anabolic competence: assessment and integration of the multimodality interventional approach in disease-related malnutrition