madman
Super Moderator
Purpose of review
Sarcopenia is a wasting disease, mostly age-related in which muscle strength and mass decline, such as physical performance. With aging, both lower dietary protein intake and anabolic resistance lead to sarcopenia. Moreover, aging and sarcopenia display low-grade inflammation, which also worsens muscle condition. In this review, we focused on these two main targets to study dietary strategies.
Recent findings
A better understanding of mechanisms involved in sarcopenia helps build combined dietary approaches including physical activity that would slow the disease progression. New approaches include a better understanding of the choice of quality proteins, their amount and schedule, and their association with antioxidative nutrients.
Summary
First, anabolic resistance can be countered by increasing significantly protein intake. If increasing amounts remain insufficient, the evenly delivered protein schedule provides interesting results on muscle strength. Quality of protein is also to consider for decreasing the risk for sarcopenia because varying sources of proteins appear relevant with increasing plant-based protein ratio. Although new techniques have been developed, as plant-based proteins display a lower availability, we need to ensure an adapted overall amount of proteins. Finally, specific enrichment with leucine from whey protein remains the dietary combined approach most studied and studies on citrulline provide interesting results. As a cofactor at the edge between anabolic and antioxidative properties, vitamin D supplementation is recommended. Antioxidative dietary strategies include fibers, vitamins, micronutrients, and polyphenols from various sources for positive effects on physical performance. The v3-polyunsaturated fatty acids also display positive modifications to body composition. Gut microbiota modifiers, such as prebiotics, are promising pathways to improve muscle mass and function and body composition in sarcopenic patients. Nutritional interventions could be enhanced by combination with physical activity on sarcopenia. In healthy older adults, promoting change in lifestyle to get near a Mediterranean diet could be one of the best options. In sarcopenia adults in which lifestyle changes appear unprobable, specific enrichment potentialized with physical activity will help in the struggle against sarcopenia. Longitudinal data are lacking, which makes it hard to draw strong conclusions. However, the effects of physical activity combined with a set of nutrition interventions on sarcopenia seem promising.
INTRODUCTION
Musculoskeletal aging appears as one of the main systems to target in the global understanding of the aging processes. Sarcopenia is defined as a global skeletal muscle decline in both mass, strength, and physical function. This wasting condition exposes to various noxious effects, such as falls, disability, and death. The current ESGWOP2 definition seems the most operational at this state of the art [1]. In the elderly, sarcopenia overlaps with malnutrition and frailty, highlighting the therapeutical role of both physical activity and adapted nutritional support.
Several studies focused on the pathophysiology of age-related sarcopenia and highlighted the biological mechanisms underlying the decline in muscle strength and mass with aging.
The first mechanism to report is the impairment of protein metabolism (whole body and muscle) with aging. Anabolic resistance includes a loss of efficiency in muscle protein synthesis in response to protein intake, as well as the loss of proteolysis inhibition. Thus, targeting anabolic resistance is a priority in muscle loss. In addition, an increase in splanchnic extraction of amino acids in elderly subjects has also been reported, limiting amino acid bioavailability for muscle. Inactivity, hormonal, and growth factors changes also affect negatively protein synthesis. Physical activity remains the first line of therapy for muscle protein synthesis enhancement, with specific guidelines in sarcopenia [2]. Nonetheless, modification of dietary habits also optimizes muscle protein synthesis in sarcopenia. In the elderly with sarcopenia, increasing the protein intake to 1–1.2 g/kg/day, by food or supplements, is recommended [3]. Many other parameters should be taken into account, such as the quality of these proteins, their distribution throughout the day, and their animal or plant-based source [4].
Redox signaling and oxidative damage are among the other accepted mechanisms underlying the decline of muscle mass and strength with aging. At the cellular scale, neural plaque changes, mitochondrial dysfunction, and cellular loss (motoneuron and satellite cell) also contribute to the increase in oxidative stress, inflammation, protein catabolism, and apoptosis. In sarcopenia, ESPEN micronutrient guidelines [5] reported that deficiency in vitamins B1, B12, and D, carnitine, and zinc are in favor of disease development [6].
Dietary fibers, micronutrients, omega-3 polyunsaturated fatty acids, such as plant-based proteins all display antioxidant properties that could limit this inflammation circle. Vitamin D is the last main factor to be cited with positive effects on the musculoskeletal system through several pathways including inflammation.
The current global approach to limit sarcopeniatries is to combine all the previous elements. Hence, both industrial combinations of high amounts of proteins, specific enrichment [essential amino acids (EAAs), vitamin D, micronutrients, and so on], and lifestyle modification approaches (Mediterranean diet for instance) have been tested to define the best strategy to manage sarcopenia. Multimodal approaches combining nutritional approaches with physical activity are also promising but will not be discussed in this review.
In the present review, we will develop the positive effects of dietary approaches to reduce aged-related sarcopenia without focusing on the effect of physical activity, developed elsewhere.
TARGETING ANABOLIC RESISTANCE
-Amount of proteins
-Distribution schedule
-Protein quality and sources
-Specific protein and amino acids enrichment
OTHER TARGETS
-Antioxidant and anti-inflammatory nutrients
-Vitamins and minerals
-Fibers and prebiotics
INTEGRATIVE APPROACHES
-Dietary patterns
-Multimodal approach
CONCLUSION
In the primary prevention of sarcopenia, lifestyle modifications such as adopting the Mediterranean diet could be key to successful aging. Inspired by this strategy in already sarcopenic patients, multiple approaches including long-term and multimodal interventions seem the best strategy (Fig. 1). Dietary intervention should focus on upgrading the amount, schedule and variety of proteins, adequate levels of vitamin D, and dietary antioxidative nutrients.
Sarcopenia is a wasting disease, mostly age-related in which muscle strength and mass decline, such as physical performance. With aging, both lower dietary protein intake and anabolic resistance lead to sarcopenia. Moreover, aging and sarcopenia display low-grade inflammation, which also worsens muscle condition. In this review, we focused on these two main targets to study dietary strategies.
Recent findings
A better understanding of mechanisms involved in sarcopenia helps build combined dietary approaches including physical activity that would slow the disease progression. New approaches include a better understanding of the choice of quality proteins, their amount and schedule, and their association with antioxidative nutrients.
Summary
First, anabolic resistance can be countered by increasing significantly protein intake. If increasing amounts remain insufficient, the evenly delivered protein schedule provides interesting results on muscle strength. Quality of protein is also to consider for decreasing the risk for sarcopenia because varying sources of proteins appear relevant with increasing plant-based protein ratio. Although new techniques have been developed, as plant-based proteins display a lower availability, we need to ensure an adapted overall amount of proteins. Finally, specific enrichment with leucine from whey protein remains the dietary combined approach most studied and studies on citrulline provide interesting results. As a cofactor at the edge between anabolic and antioxidative properties, vitamin D supplementation is recommended. Antioxidative dietary strategies include fibers, vitamins, micronutrients, and polyphenols from various sources for positive effects on physical performance. The v3-polyunsaturated fatty acids also display positive modifications to body composition. Gut microbiota modifiers, such as prebiotics, are promising pathways to improve muscle mass and function and body composition in sarcopenic patients. Nutritional interventions could be enhanced by combination with physical activity on sarcopenia. In healthy older adults, promoting change in lifestyle to get near a Mediterranean diet could be one of the best options. In sarcopenia adults in which lifestyle changes appear unprobable, specific enrichment potentialized with physical activity will help in the struggle against sarcopenia. Longitudinal data are lacking, which makes it hard to draw strong conclusions. However, the effects of physical activity combined with a set of nutrition interventions on sarcopenia seem promising.
INTRODUCTION
Musculoskeletal aging appears as one of the main systems to target in the global understanding of the aging processes. Sarcopenia is defined as a global skeletal muscle decline in both mass, strength, and physical function. This wasting condition exposes to various noxious effects, such as falls, disability, and death. The current ESGWOP2 definition seems the most operational at this state of the art [1]. In the elderly, sarcopenia overlaps with malnutrition and frailty, highlighting the therapeutical role of both physical activity and adapted nutritional support.
Several studies focused on the pathophysiology of age-related sarcopenia and highlighted the biological mechanisms underlying the decline in muscle strength and mass with aging.
The first mechanism to report is the impairment of protein metabolism (whole body and muscle) with aging. Anabolic resistance includes a loss of efficiency in muscle protein synthesis in response to protein intake, as well as the loss of proteolysis inhibition. Thus, targeting anabolic resistance is a priority in muscle loss. In addition, an increase in splanchnic extraction of amino acids in elderly subjects has also been reported, limiting amino acid bioavailability for muscle. Inactivity, hormonal, and growth factors changes also affect negatively protein synthesis. Physical activity remains the first line of therapy for muscle protein synthesis enhancement, with specific guidelines in sarcopenia [2]. Nonetheless, modification of dietary habits also optimizes muscle protein synthesis in sarcopenia. In the elderly with sarcopenia, increasing the protein intake to 1–1.2 g/kg/day, by food or supplements, is recommended [3]. Many other parameters should be taken into account, such as the quality of these proteins, their distribution throughout the day, and their animal or plant-based source [4].
Redox signaling and oxidative damage are among the other accepted mechanisms underlying the decline of muscle mass and strength with aging. At the cellular scale, neural plaque changes, mitochondrial dysfunction, and cellular loss (motoneuron and satellite cell) also contribute to the increase in oxidative stress, inflammation, protein catabolism, and apoptosis. In sarcopenia, ESPEN micronutrient guidelines [5] reported that deficiency in vitamins B1, B12, and D, carnitine, and zinc are in favor of disease development [6].
Dietary fibers, micronutrients, omega-3 polyunsaturated fatty acids, such as plant-based proteins all display antioxidant properties that could limit this inflammation circle. Vitamin D is the last main factor to be cited with positive effects on the musculoskeletal system through several pathways including inflammation.
The current global approach to limit sarcopeniatries is to combine all the previous elements. Hence, both industrial combinations of high amounts of proteins, specific enrichment [essential amino acids (EAAs), vitamin D, micronutrients, and so on], and lifestyle modification approaches (Mediterranean diet for instance) have been tested to define the best strategy to manage sarcopenia. Multimodal approaches combining nutritional approaches with physical activity are also promising but will not be discussed in this review.
In the present review, we will develop the positive effects of dietary approaches to reduce aged-related sarcopenia without focusing on the effect of physical activity, developed elsewhere.
TARGETING ANABOLIC RESISTANCE
-Amount of proteins
-Distribution schedule
-Protein quality and sources
-Specific protein and amino acids enrichment
OTHER TARGETS
-Antioxidant and anti-inflammatory nutrients
-Vitamins and minerals
-Fibers and prebiotics
INTEGRATIVE APPROACHES
-Dietary patterns
-Multimodal approach
CONCLUSION
In the primary prevention of sarcopenia, lifestyle modifications such as adopting the Mediterranean diet could be key to successful aging. Inspired by this strategy in already sarcopenic patients, multiple approaches including long-term and multimodal interventions seem the best strategy (Fig. 1). Dietary intervention should focus on upgrading the amount, schedule and variety of proteins, adequate levels of vitamin D, and dietary antioxidative nutrients.
