Oral creatine supplementation in humans does not elevate urinary excretion of the carcinogen N-nitrososarcosine

Objective Creatine is a popular oral supplement in athletes and may have therapeutical potential in neuromuscular diseases. It has been hypothesized that creatine ingestion can lead to increased formation of the carcinogen N-nitrososarcosine. Methods We investigated in a double-blind, placebo-controlled study the urinary excretion of N-nitrososarcosine after 1-wk high-dose (20 g/d) and 20-wk low-dose (5 g/d) creatine supplementation in healthy humans. Results and conclusion Creatine ingestion does not systematically increase urinary N-nitrososarcosine excretion.