Clinicians should integrate nutritional assessment with sarcopenia screening for Moreover, it is a major contributing factor of physical disability, frailty and loss of assessment and disease and its relationship with nutritional requirements, in the complex aetiology of sarcopenia, and it may be amenable to intervention. Clinical and pathophysiological relationships in sarcopenia and frailty. with multiple causes, inter-relationships and complex pathways proposed. W.J. EvansExercise training and nutritional supplementation for physical frailty in very . The nutrients that have been most consistently linked to sarcopenia and frailty in older adults are vitamin D, protein, and a number of muscle function are complex and include both genomic and nongenomic roles [20, 22]. . been studied most extensively in relation to protein/amino acid supplementation.
In a recent study [ 20 ], both entities have been studied in a post-acute care geriatric unit, applying the new ESPEN definition of malnutrition and EWGSOP criteria, assessing the potential clinical relationship between them. The prevalence of malnutrition in this population was On the other hand, in the study of Senior et al. According to these criteria, The prevalence of malnutrition was higher in subjects with low handgrip strength Moreover, research has shown that reductions in handgrip strength are common in individuals who have sarcopenia as well as in individuals who are malnourished [ 522 ].
Screening tools for malnutrition are intended for the quick identification of patients at risk of malnutrition, for more in-depth nutritional assessment, or for identifying patients at risk of developing complications or even increased risk of mortality. Based on the evidence presented, the combination of screening and assessing for malnutrition and sarcopenia is recommended to screen for the presence of malnutrition-sarcopenia syndrome in at-risk patient populations, particularly older adults in clinical settings [ 4 ].
Clinicians are urged to screen, assess and treat these conditions currently. Nutritional interventions to prevent sarcopenia The relationship between muscle mass, strength, physical function and nutritional status has significant clinical implications regarding the therapeutic approaches [ 26 ]. Early identification of sarcopenia would be of great clinical relevance because the loss of muscle mass and strength with ageing can be largely reversed by proper exercise programs and nutritional intervention [ 27 ].
Of all the therapeutic options available, lifelong improvements in physical activity and diet are probably the most effective public health intervention and the most important treatment option in nursing home residents for this condition, ongoing independence and autonomy in older people.
The Society for Sarcopenia, Cachexia and Wasting Disease developed nutritional recommendations for the prevention and management of sarcopenia, which combined exercise with adequate protein and energy intake [ 28 ]. On the other hand, adequate caloric intake has to be considered as an essential requisite for any successful therapeutic approach in the institutionalised elderly participants, in terms of prevention and treatment of sarcopenia. Nutrient intake, especially adequate amounts of high-quality protein and amino acids, is the most important anabolic stimulus of skeletal muscle protein synthesis.
Epidemiological studies suggest that a low protein intake is associated with sarcopenia. To prevent it, as optimal dietary protein intake, daily 1. Specifically, the amino acid leucine and meal-induced insulin, both independently stimulate muscle protein synthesis.
It has been demonstrated that exercise and amino acid supplementation 3 g of a leucine-enriched balanced essential amino acid mixture twice a day together may actually be effective in enhancing muscle strength, variables of muscle mass and walking speed in sarcopenic women [ 29 ]. Low hydroxyvitamin D 25 OH D serum level in adults is also a potentially modifiable risk factor for sarcopenia [ 30 ].
In fact, nutritional interventions combining adequate amounts of vitamin D and proteins are promising strategies to attenuate sarcopenia development [ 31 ]. The exact estimates of the prevalence of poor nutrition may differ according to the definitions used, but studies of community-dwelling adults consistently suggest that it is common in older age.
Nutrition and Sarcopenia: A Review of the Evidence and Implications for Preventive Strategies
These figures are clearly substantial and indicate that there are significant numbers of older adults living in developed settings who currently have less than optimal nutrition. Is Diet a Modifiable Influence on Sarcopenia? There are two consequences of declining food intakes in older age that could be important for muscle mass and strength.
Firstly, lower energy intakes, if not matched by lower levels of energy expenditure, lead to weight loss, including a loss of muscle mass [ 4 ].
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Secondly, as older people consume smaller amounts of food, it may become more challenging for them to meet their nutrient needs—particularly for micronutrients. For older people with low food intakes, this highlights the importance of having diets of adequate quality.
Although the importance of adequate nutrition has been recognised for a long time, its contribution to muscle mass and strength has not been studied extensively and much of the research in this area is relatively new [ 10 ]. A number of interventions have been studied, ranging from provision of nutritional support [ 11 ], to supplementation with specific nutrients [ 1213 ]. The nutrients that have been most consistently linked to sarcopenia and frailty in older adults are vitamin D, protein, and a number of antioxidant nutrients, that include carotenoids, selenium, and vitamins E and C [ 10 ].
However, there is also some evidence that variations in long-chain polyunsaturated fatty acid status may have important effects on muscle strength in older people [ 13 ].
Sarcopenia and Malnutrition in the Elderly
Protein Protein is considered a key nutrient in older age [ 14 ]. Dietary protein provides amino acids that are needed for the synthesis of muscle protein, and importantly, absorbed amino acids have a stimulatory effect on muscle protein synthesis after feeding [ 15 ].
There is some evidence that the synthetic response to amino acid intake may be blunted in older people, particularly at low intakes [ 14 ], and when protein is consumed together with carbohydrate [ 16 ]. Recommended protein intakes may, therefore, need to be raised in older people in order to maintain nitrogen balance and to protect them from sarcopenic muscle loss [ 14 ].
Whilst there is currently no consensus on the degree to which dietary protein requirements change in older age, there is important observational evidence that an insufficient protein intake may be an important contributor to impaired physical function.
Sarcopenia and frailty in chronic respiratory disease
For example, in the US Health, Aging and Body Composition Study, a greater loss of lean mass over 3 years, assessed using dual-energy X-ray absorptiometry, was found among older community-dwelling men and women who had low energy-adjusted protein intakes at baseline [ 17 ].
However, whilst amino acid supplementation has been shown to increase lean mass and improve physical function [ 18 ], other trials have not been successful [ 1619 ]. Further work, including longer-term trials, is needed to define optimal protein intakes in older age [ 16 ].
Vitamin D An association between vitamin-D-deficient osteomalacia and myopathy has been recognised for many years [ 20 ], but the role of vitamin D, and the extent to which it has direct effects on normal muscle strength and physical function remains controversial [ 21 ]. The potential mechanisms that link vitamin D status to muscle function are complex and include both genomic and nongenomic roles [ 2022 ]. The vitamin D receptor VDR has been isolated from skeletal muscle, indicating that it is a target organ [ 20 ], and polymorphisms of the VDR have been shown to be related to differences in muscle strength [ 23 ].
At the genomic level, binding of the biologically active form of the vitamin 1,dihydroxyvitamin D results in enhanced transcription of a range of proteins, including those involved in calcium metabolism [ 20 ].
The nongenomic actions of vitamin D are currently less well understood [ 22 ]. Much of the epidemiological literature is consistent with the possibility that there are direct effects of vitamin D on muscle strength. However, the evidence is not always consistent as some observational studies find no association between vitamin D status and physical function, and supplementation studies have not always resulted in measurable improvements in function [ 21 ].
In a review of published studies, Annweiler and colleagues [ 21 ] discuss the reasons for the divergence in study findings, some of which may be due to methodological differences, including a lack of consideration of confounding influences in some studies.
It is without a doubt a common and complex medical condition, with multiple causative factors, and the potential for huge personal and financial cost. Frailty also develops as a result of multisystem age-related decline, which results in a gradual reduction in physiological reserve and increased vulnerability to sudden changes in health status which can be triggered by minor stressor events, for example, a minor infection.
Like sarcopenia, frailty can be considered a clinical geriatric syndrome; it is common and complex, has multiple causative factors and spans multiple disease states. From a landmark study in older people, Fried et al. Here, frailty can also be quantified, and the accumulated vulnerability measured, rather than dichotomized into the presence or absence of frailty as with the phenotypic models.
Contextualizing sarcopenia and frailty as syndromes has helped to develop practical ways to screen, identify and assess those at high risk of adverse outcomes. By assessing contributing factors, clinicians are also able to identify appropriate strategies to reduce risk in a personalized manner, aiming to prevent or delay the occurrence of disability, falls, dependency and even death.
Assessment of sarcopenia and frailty Sarcopenia Numerous national and international groups have reached consensus on the definition, assessment and diagnosis of sarcopenia. There is now widespread agreement that sarcopenia should be defined as a combination of low muscle mass and loss of function, indeed a new ICD code ICDM