Nutritional Supplements with Oral Amino Acid Mixtures Increases Whole-Body Lean Mass and Insulin Sensitivity in Elderly Subjects with Sarcopenia

Decreases in whole-body lean mass can cause sarcopenia, a disease frequently found in the elderly. This condition is frequently associated with frailty and disability in aging as well as the onset and progression of several geriatric syndromes. Sarcopenia therefore must be managed with multidimensional approaches that include physical training, nutritional support, and metabolic and anabolic treatment. The purpose of our study was to assess the effect of an orally administered special mixture of amino acids (AAs) in elderly subjects with reduced lean body mass and sarcopenia. A randomized, open-label, crossover study was conducted in 41 elderly subjects (age range: 66–84 years) with sarcopenia, assigned to 2 distinct treatments (AAs and placebo). All subjects had normal body weight (body mass index within 19–23). The AA treatment consisted of 70.6 kcal/day (1 kcal = 4.2 kJ) of 8 g of essential AA snacks, given at 10:00 am and 5:00 pm. Lean mass was measured with dual-energy x-ray absorptiometry in leg, arm, and trunk tissues. Significant increases in whole-body lean mass in all areas were seen after 6 months and more consistently after 18 months of oral nutritional supplementation with AAs. Fasting blood glucose, serum insulin, and homeostatic model assessment of insulin resistance (an index of insulin resistance) significantly decreased during AA treatment. Furthermore, a significant reduction in serum tumor necrosis factor–α (TNF-α) and a significant increase in both insulin-like growth factor–1 (IGF-1) serum concentrations and in the IGF-1/TNF-α ratio were also found. No significant adverse effects were observed during AA treatment. These preliminary data indicate that nutritional supplements with the oral AA mixture significantly increased whole-body lean mass in elderly subjects with sarcopenia. The improvement in the amount of whole-body lean mass could be linked to increased insulin sensitivity and anabolic conditions related to IGF-1 availability.