Effects of long-term creatine supplementation on liver and kidney functions in American college football players.

The purpose of this study was to determine the effect of long-term Cr supplementation on

blood parameters reflecting liver and kidney function. Twenty-three members of an NCAA

Division II American football team (ages = 19-24 years) with at least 2 years of strength

training experience were divided into a Cr monohydrate group (CrM, n = 10) in which they

voluntarily and spontaneously ingested creatine, and a control group (n = 13) in which they

took no supplements. Individuals in the CrM group averaged regular daily consumption of 5

to 20 g (mean SD = 13.9 5.8 g) for 0.25 to 5.6 years (2.9 1.8 years). Venous blood analysis

for serum albumin, alkaline phosphatase, alanine aminotransferase, aspartate

aminotransferase, bilirubin, urea, and creatinine produced no significant differences

between groups. Creatinine clearance was estimated from serum creatinine and was not

significantly different between groups. Within the CrM group, correlations between all blood

parameters and either daily dosage or duration of supplementation were nonsignificant.

Therefore, it appears that oral supplementation with CrM has no long-term detrimental

effects on kidney or liver functions in highly trained college athletes in the absence of other

nutritional supplements.

Is Creatine Safe ?