Dietary implications on mechanisms of sarcopenia: roles of protein, amino acids and antioxidants

Sarcopenia, the age-related loss of muscle mass and strength, is a fundamental cause of frailty, functional decline and disability. In the year 2000, $18.5 billion in health care costs were directly attributable to sarcopenia. This economic burden will increase dramatically as the elderly population grows over the next decade. The primary causes of sarcopenia include a sedentary lifestyle and malnutrition. While resistance training appears to be a promising intervention, older individuals exhibit a blunted hypertrophic response to exercise stimuli. It has been posited that this decrement in regenerative capacity may be due to the loss of postprandial anabolism as well as an increase in reactive oxygen species. As such, a combination of resistance training and nutritional interventions may be a promising candidate in combating sarcopenia. Nevertheless, the mechanisms by which the manipulation of dietary variables may improve the sarcopenic condition are not well understood. To address this gap in extant knowledge, this review will examine the effects of protein, amino acid and/or antioxidant intake on sarcopenia both at rest and following resistance training exercise.