The purpose of this study was to investigate the effects of supplementation with amino acids and vitamins on health conditions in unhealthy older people. One bedridden inpatient group (n = 10; mean age, 79.8 ± 8.5 y) and one outpatient group (n = 9; mean age, 72.9 ± 12.2 y) participated in this study. A mixture supplementation with amino acids containing arginine (500 mg/day), glutamine (600 mg/day), and leucine (1200 mg/day), and 11 kinds of vitamins was daily administrated for 8 weeks. In both groups, general blood biomarkers such as white blood cell count, natural killer cell activity, and C-reactive protein levels were measured. All measurements were taken before (baseline), at 4 weeks (mid-point), and after each trial (post-point). At mid-point, natural killer cell activity in the outpatient group increased significantly compared to baseline. At post-point, natural killer cell activity in the outpatient and inpatient groups increased significantly compared to baseline. The other blood biomarkers did not show any significant change throughout the trial. This pilot study suggested that a mixture of arginine, glutamine, leucine, and vitamins is useful to support innate immunity in unhealthy older people, even if their diseases, symptoms, and prescribed medicines are different.
Keywords: amino acids; bedridden older inpatients; immune function; natural killer cell activity; older outpatients.