GROWTH HORMONE RESPONSE TO ORAL ARGININE SUPPLEMENTATION

Abstract

98 The specific aim of this study was to determine the effect of oral arginine(ARG) supplementation on plasma growth hormone (hGH) levels. The hypothesis was that the increase in plasma levels of hGH would be directly related to the dosage of ARG supplementation. Eight healthy male subjects, between the ages of 20-42 years, were admitted to the laboratory at 0700 h after an overnight fast. After baseline hGH measurements (RIA kits; DPC, Los Angeles, CA), subjects were given oral ARG dosages of 0, 3, 6, or 9 g, in random order. Growth hormone responses were measured at 30 min intervals for the next 4 h. The hGH responses to ARG were variable, with three types being characterized. The non-responders (n = 2) showed no elevation of hGH to any of the ARG doses. The high responders (n = 2) had a 200-1000% increase of hGH secretion to ARG supplementation. The low responders (n = 4) showed only a slight increase of plasma hGH (70-120%) in response to ARG. In the high and low responders, hGH secretion did not appear to be related to dose, order of dose, age, body weight, or percent body fat. However, in the overall group, body mass index(BMI) was inversely related to the hGH response (Spearman r=-0.81). Within this small sample it appears that the effects of oral ARG is variable. Thus, some large athletes (BMI > 28) who use arginine as an ergogenic aid may not find it to be a beneficial supplement at dosages of ≤ 9 g.