Causes of sarcopenia
Muscle loss in the elderly leads to a decline in mobility and independence. 
Sarcopenia is multifactorial in cause. These differing factors are inter-related and could contribute differently to the loss of muscle mass, muscle strength or muscle function. 
Of the contributory factors relating to the development of sarcopenia inadequate protein intake, increased splanchnic extraction of amino acids, decreased muscular response to postprandial anabolic stimuli and vitamin D deficiency are directly related to nutrition. 
Evidence suggests that most etiologic factors for sarcopenia are preventable and manageable with resistance training and adequate protein intake as key elements. 
The Society on Sarcopenia, Cachexia and Wasting Disorders (SCWD) recommend leucine-enriched balanced amino acid supplementation to enhance muscle strength. 
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- Paddon-Jones, D. et al., Curr Opin Clin Nutr Metab Care, 2009. 12(1): p. 86-90.
- Morley, J.E., et al., JAMDA, 2010. 11: p. 391-396.