Table 4: Effect of nutrients or dietary supplementations on metabolic correlates of sarcopenia.

Nutrients or dietary supplementationsRecommendationsSpecific effect

Proteins: average daily intakeIt is recommended that the total protein intake should be 1–1.2 g/kg/day [16]

Proteins: timing of intakeIt is recommended to have 30 grams of protein of high biological value for each meal [25]The elderly, compared with younger subjects, would require a larger amount of protein to obtain the same maximization of protein synthesis

Proteins: fast and slowIt is recommended to have whey protein ingestion because whey protein ingestion results in greater postprandial protein retention than does casein ingestion [31]The greater anabolic properties of whey than of casein are mainly attributed to the faster digestion and absorption kinetics of whey, which results in a greater increase in postprandial plasma amino acid availability and thereby further stimulates muscle protein synthesis. Moreover, whey has a considerably higher leucine content

Proteins: animal and vegetal sourcesWhen the total protein intake is adequate, the source of protein consumed (vegetal or animal) does not influence muscle strength and size [36]Increases in muscle strength and size were not influenced by the predominant source of protein consumed by older men with adequate total protein intake

Branched chain amino acids (BCAAs),It is recommended to have an adequate daily leucine supplementation (3 g/day)A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly

Beta-hydroxy-methylbutyrate (HMB)It is recommended to have a daily intake of beta-hydroxy butyrate (HMB-b, 2 g/day) because it can attenuate the loss of muscle mass and increase muscle mass and strength [50]Beta-hydroxy-beta-methylbutyrate is a product of leucine metabolism that has been shown to slow protein breakdown in muscle tissue

CreatineIt is recommended to have an adequate creatine supplementation because it could represent an intriguing intervention to counteract sarcopenia and in particular fatigue associated with sarcopenia; the timing of creatine ingestion (i.e., 0.03–0.5 g/kg before and after the sessions of resistance training) can be more relevant than the amount of creatine [73, 76]The ingestion of an adequate creatine supplementation determines the increase in muscle phosphocreatine (PCr) and the energy provided for the phosphorylation of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) during and after intense exercise largely depends on the amount of PCr stored in the muscle

Vitamin DIt is recommended to have a dietary vitamin D supplementation (800–1000 UI ergo-calciferol/day) in vitamin D deficient sarcopenic subjects [127]Dietary vitamin D supplementation determines an increase of the expression of the receptors VDR (vitamin D receptor) in skeletal muscle

Antioxidants. vitamin E, vitamin C, carotenoids, and resveratrolIt is recommended to have a diet with high intake of fruits, vegetables whole grains, which is rich in antioxidant, and lower consumption of red meat and saturated fats, because it is associated with a reduced risk of inflammation correlated to oxidative damage [83]Adherence to the diet rich in antioxidants is associated with lower circulating IL-6

Long-chain omega-3 polyunsaturated fatty acids (LC-3PUFA)It is recommended to have dietary long-chain omega-3 polyunsaturated fatty acids (1.86 g eicosapentaenoic acid and 1.50 g docosahexaenoic acid/day) supplementation [131]Long-chain omega-3 polyunsaturated fatty acids (LC-3PUFA) supplementation improves insulin-mediated glucose metabolism in insulin-resistant states and increases the activation (phosphorylation) of anabolic signaling proteins in muscle during administration of insulin and amino acids and increases the nonoxidative whole-body disposal of amino acids, an index of increased whole-body protein synthesis