An open-label, single-center pilot study to test the effects of an amino acid mixture in older patients admitted to internal medicine wards

Objective: Older patients are frequently subjected to prolonged hospitalization and extended bed rest, with a negative effect on physical activity and caloric intake. This results in a consistent loss of muscle mass and function, which is associated with functional decline and high mortality. The aim of this study was to investigate the effect of 1 wk of oral amino acid (AA) supplementation in older patients subjected to low mobility during hospitalization. Methods: Hospitalized older patients (69-87) were included in the control group (n = 50) or were administered 25 g of AA mixture (n = 44) twice daily throughout 7 d of low mobility. We collected data related to length of stay as primary outcome measure. In-hospital mortality, 90-d postdischarge mortality, 90-d postdischarge rehospitalization, and falls also were considered. Moreover, variations of anthropometric measures, body composition and muscle architecture/strength, circulating interleukins, and oxidative stress markers between the beginning and the end of the supplementation period were analyzed as secondary outcomes. Results: Similar values were reported between the two groups regarding age (76.6 ± 6.8 versus 79 ± 7.2 y old), body weight (61.5 ± 14.3 versus 62.1 ± 16.1 kg), and body mass index (28.7 ± 4.15 versus 28.1 ± 3.62 kg/m2). Although no difference in terms of in-hospital, 90-d postdischarge, or overall mortality rate was observed between the two groups, a reduction in length of stay, 90-d postdischarge hospitalization, and falls was observed in the AA supplementation group rather than in controls. Furthermore, the AA mixture limited muscle architecture/strength impairment and circulating oxidative stress, which occurred during hospitalization-related bed rest. The latter data was associated with increased circulating levels of anti-inflammatory cytokines interleukin-4 and -10. Conclusions: These results suggest that the AA mixture limits several alterations associated with low mobility in older hospitalized patients, such as length of stay, 90-d postdischarge hospitalization, and falls, preventing the loss of muscle function, as well as the increase of circulating interleukins and oxidative stress markers.