Molecular mechanism and possible nutritional approach for sarcopenia

Sarcopenia, the age-related loss of skeletal muscle mass, is characterized by a deterioration of muscle quantity and quality leading to a gradual slowing of movement, a decline in strength and power, increased risk of fall-related injury, and often frailty. Muscle loss has been linked with several proteolytic systems, including the ubiquitin-proteasome or lysosome-autophagy systems. Although many factors are considered to regulate age-dependent muscle loss, this gentle atrophy is not affected by factors known to enhance rapid atrophy (denervation, hindlimb suspension etc). Intriguingly, recent studies indicated an apparent functional defect in autophagy-dependent signaling in sarcopenic muscle. The combination of resistance training with supplements containing amino acids is the gold standard for preventing sarcopenia. Amino acid (HMB) supplementation alone has no significant effect on muscle strength or muscle mass in sarcopenia, but the combination of HMB and exercise (whole body vibration stimulation) is likely to be effective. Tea catechins, soy isoflavones, and ursolic acid are interesting candidates for reducing sarcopenia, but both more detailed basic research on this treatment and clinical studies in humans are needed. In this symposium, I summarized molecular mechanism and nutritional approach for sarcopenia.