Safety of 12-month creatine supplementation combined with resistance training in older adults

Abstract

Introduction: Creatine is a nitrogen-containing compound that is found in many supplements that claim to increase muscle mass and there is increasing evidence that creatine supplementation can increase muscle mass in older individuals. Purpose: To evaluate the safety of 12-months creatine supplementation and resistance exercise in older adults by monitoring measures of kidney and liver function, complete blood count, and reports of adverse events. Methods: Older adults (n=70, males 50 years of age or older (39), and post-menopausal females (31) who were not performing resistance exercise were recruited for the study and randomized by computer to creatine (32; 18 males, 14 females) or placebo (38; 21 males, 17 females) groups. Other exclusionary criteria were: presence/history or kidney impairments, consumption of creatine supplement/bone altering drugs, and the presence of fragility fractures. Participants were given creatine or placebo (0.1g/kg/day) consumed before and after resistance training on exercise days and with a meal on non-exercise days. The study used a double-blind, placebo-controlled design. Blood and urine were collected to assess complete blood cell count, liver function indicators (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and Bilirubin), and creatinine clearance (kidney function) at baseline, 4 months, 8 months, and 12 months. A mixed ANOVA was used to determine differences in the kidney and liver measures within and between groups, and chi-square analysis was used to determine if the frequency counts for liver, kidney, and other adverse events were different between groups.