Differences in bone health and bone biomarkers between exercising male protein supplement users and non-users

Abstract

Title: Differences in bone health and bone biomarkers between exercising male protein supplement users, and non-users. By R. Warner and L. Doyle, Department of Health, Sport and Exercise Science, Waterford Institute of Technology Background: Increasing protein intake through protein supplements is a growing practice amongst exercising individuals. However there are varying reports in terms of the detrimental(1) and beneficial(2) effects of protein on bone. The effect of high level protein supplementation on bone health in exercising individuals is relatively unexplored. Aim: To investigate the effect of variations in protein intake on bone health and bone biomarkers in exercising males. Subjects and Methods: 50 non-supplement users (25.9 ± 5.1y) and 52 supplement users (25.4 ± 4.9y) were recruited. The average length of time for supplement use was 33 months. All subjects completed a food diary for 3 days which was analyzed using Comp EatTM. Net endogenous acid production (NEAP) was calculated by the method described by Remer et al. (2003). Protein content of supplements consumed was obtained from product labels. Effect of exercise on bone health was calculated using osteogenic index (OI). Bone health (bone mineral density (BMD) and bone mineral content (BMC) and percent lean body mass (LBM) was measured using dual energy xray absorbtiometry (DEXA). Serum samples were analyzed for osetocalcin (S-OC) and crosslaps (S-CTx) using commercially available ELISA kits. Urine was measured for pH using a digital urine analyzer with urinary calcium (U-Ca) and creatinine (U-Cr) levels being measured spectrophotoemetrically. Independent samples t-test or Mann Whitney U test (depending on data normality) were used to test for any differences between supplement users and non-users. Results: There were no significant differences in potential confounders of BMI, OI or percent LBM (P > 0.05) between users and non-users. Protein intake, NEAP and sulphur content of the diet was significantly greater in users than non-users. There were no significant differences in BMD, BMC, urine pH or calcium, serum osteocalcin or crosslaps between users and non-users. This study demonstrates protein supplementation of 33 months duration has no effect on bone health in exercising males. (1)Abelow et al. (1992) (2) Promislow et al. (2002)