Current Opinion in Clinical Nutrition and Metabolic Care最新文献

Purpose of review: Nutrition remains a key focus in the preoptimization of patients undergoing cancer surgery. Given the catabolic nature of cancer, coupled with the physiological insult of surgery, malnutrition (when assessed) is prevalent in a significant proportion of patients. Therefore, robust research on interventions to attenuate the detrimental impact of this is crucial.

Recent findings: As a unimodal prehabilitation intervention, assessment for malnutrition is the first step, as universal supplementation has not been shown to have a significant impact on outcomes. However, targeted nutritional therapy, whether that is enteral or parenteral, has been shown to improve the nutritional state of patients' presurgery, potentially reducing the rate of postoperative complications such as nosocomial infections. As part of multimodal prehabilitation, the situation is more nuanced given the difficulty in attribution of effects to the differing components, and vast heterogeneity in intervention and patient profiles.

Summary: Multimodal prehabilitation is proven to improve length of hospital stay and postoperative outcomes, with nutrition forming a significant part of the therapy given. Further work is required to look at not only the interplay between the optimization of nutritional status and other prehabilitation interventions, but also how to best select which patients will achieve significant benefit.

Purpose of review: Highlight the controversies and challenges associated with a sarcopenia diagnosis in infants and children and the potential physiological mechanisms contributing to this disorder.

Recent findings: Sarcopenia has been recently identified in infants and children with chronic diseases such as liver, cardiac, gastrointestinal, cancer and organ transplant recipients. However, there is no consensus regarding the definition of pediatric sarcopenia. Different sarcopenic phenotypes (sarcopenia and sarcopenic obesity) have been identified in healthy children and children with chronic disease. Both conditions have been associated with adverse clinical outcomes (e.g. delayed growth, increased hospitalization) in children and youth with chronic disease. The etiology of pediatric sarcopenia is likely multifactorial associated with malnutrition, physical inactivity and altered metabolic environments influencing skeletal muscle mass accumulation and function. Gaps in the literature include the lack of standard tools that should be used for the evaluation of skeletal muscular fitness and body composition in sarcopenia, particularly in infants and young children (<4years).

Summary: Longitudinal evaluation of sarcopenia expression and the underlying physiological and lifestyle factors contributing to pediatric sarcopenia are important to understand to ensure effective rehabilitation strategies can be developed and to avoid the adverse clinical consequences in children.

Purpose of review: This review will highlight recent studies that have examined the endothelial glycocalyx in a variety of health conditions, as well as potential glycocalyx-targeted therapies.

Recent findings: A degraded glycocalyx is present in individuals that consume high sodium diet or have kidney disease, diabetes, preeclampsia, coronavirus disease 2019 (COVID-19), or sepsis. Specifically, these conditions are accompanied by elevated glycocalyx components in the blood, such as syndecan-1, syndecans-4, heparin sulfate, and enhanced heparinase activity. Impaired glycocalyx barrier function is accompanied by decreased nitric oxide bioavailability, increased leukocyte adhesion to endothelial cells, and vascular permeability. Glycocalyx degradation appears to play a key role in the progression of cardiovascular complications. However, studies that have used glycocalyx-targeted therapies to treat these conditions are scarce. Various therapeutics can restore the glycocalyx in kidney disease, diabetes, COVID-19, and sepsis. Exposing endothelial cells to glycocalyx components, such as heparin sulfate and hyaluronan protects the glycocalyx.

Summary: We conclude that the glycocalyx is degraded in a variety of health conditions, although it remains to be determined whether glycocalyx degradation plays a causal role in disease progression and severity, and whether glycocalyx-targeted therapies improve patient health outcomes. Future studies are warranted to investigate therapeutic strategies that target the endothelial glycocalyx.

Purpose of review: Nutritional interventions using protein and amino acids in obesity are popular therapeutical strategies to limit obesity development. However, the effects of dietary protein intake and amino acid metabolic alterations involved in obesity pathophysiology have not been completely unravelled. Significant recent studies have brought to light new findings in these areas, which are the primary focus of this review.

Recent findings: We describe the effects of protein intake on weight regain prevention, the influence on gut microbiota, the response to low-protein highly processed foods, and the contrasting impacts of a high-protein diet on adults and children. We also explore newly discovered correlations between amino acids, liver fat accumulation, and the dysregulation of the liver-pancreas axis due to alterations in amino acid levels in the context of obesity. Lastly, we consider branched-chain amino acids, along with glycine and tryptophan, as significant biomarkers during periods of positive or negative energy balance.

Summary: Interventions using dietary protein in obesity may be useful, especially during energy restriction but also in sarcopenic obesity. Furthermore, metabolic profiles that encompass alterations in certain amino acids can provide valuable insights into the metabolic condition of patients with obesity, particularly in relation to insulin resistance and the risk of developing type 2 diabetes.

Purpose of review: Improved survival from critical illness has enhanced the focus on ways to augment functional outcomes following discharge from the Intensive Care Unit. An area that is gaining increased attention is the effect of critical illness on bone health and fragility fractures following the episode. This review discusses the micronutrients that may play a role in bone metabolism and the potential benefits of their supplementation to prevent osteoporosis. These include calcium, phosphorous, magnesium, vitamin D, vitamin C, vitamin K, and certain trace elements.

Findings: Although there is sound physiological basis for the involvement of these micronutrients in bone health and fracture prevention, there are few clinically relevant publications in this area with calcium and vitamin D being the best studied to date.

Summary: In the absence of high-quality evidence in critically ill populations, attention to measurement and supplementation of these micronutrients as per current guidelines outlining micronutrient requirements in enteral and parenteral nutrition might mitigate bone loss and its sequelae in the recovery phase from critical illness.

Purpose of review: Very low-calorie diets (VLCD) are used as a weight loss intervention, but concerns have been raised about their potential negative impact on lean mass. Here, we review the available evidence regarding the effects of VLCD on lean mass and explore their utility and strategies to mitigate reductions in skeletal muscle.

Recent findings: We observed that VLCD, despite their effects on lean mass, may be suitable in certain populations but have a risk in reducing lean mass. The extent of the reduction in lean mass may depend on various factors, such as the duration and degree of energy deficit of the diet, as well as the individual's starting weight and overall health.

Summary: VLCD may be a viable option in certain populations; however, priority needs to be given to resistance exercise training, and secondarily to adequate protein intake should be part of this dietary regime to mitigate losing muscle mass.

Purpose of review: Physical activity impacts energy balance because of its contribution to total energy expenditure. Measuring physical activity energy expenditure (PAEE) is often performed by subtracting the estimated 24 h expenditure on basal metabolism (called basal energy expenditure or BEE) from the total energy expenditure (TEE) measured by doubly labelled water minus an estimate of the thermic effect of food (TEF). Alternatively it can be measured as the ratio of TEE/BEE, which is commonly called the physical activity level (PAL).

Recent findings: PAEE and PAL are widely used in the literature but their shortcomings are seldom addressed. In this review, we outline some of the issues with their use.

Summary: TEE and BEE are both measured with error. The estimate of PAEE by difference magnifies these errors and consequently the precision of estimated PAEE is about 3× worse than TEE and 25-35× worse than BEE. A second problem is that the component called PAEE is actually any component of TEE that is not BEE. We highlight how the diurnal variation of BEE, thermoregulatory expenditure and elevations of RMR because of stress will all be part of what is called PAEE and will contribute to a disconnect between what is measured and what energy expenditure is a consequence of physical activity. We emphasize caution should be exerted when interpreting these measurements of PAEE and PAL.