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-alpha (
TNF-alpha) and a significant increase in both
insulin-like growth factor-1 (IGF-1) serum concentrations and in the IGF-1/
TNF-alpha 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.