Guanidinoacetic acid (GAA) is a direct precursor of creatine, an essential compound for cellular energy metabolism, particularly in muscle tissue. Muscle wasting—also known as cachexia or sarcopenia—often involves reduced muscle mass and impaired energy metabolism. Scientific interest in GAA for wasting conditions stems from its role in enhancing creatine stores, which may help improve muscle energy availability and potentially slow or reverse muscle atrophy.

Several small-scale clinical studies and preclinical trials have investigated GAA supplementation in wasting conditions. For example, research in patients with chronic illnesses (such as multiple sclerosis, heart failure, or muscle dystrophies) has shown that GAA supplementation can increase creatine levels in muscle and improve some markers of muscle function. A 2013 pilot study (Ostojic et al., Clin Nutr) reported that GAA supplementation improved muscle strength and body composition in patients with muscle wasting. Animal studies have also suggested protective effects against muscle loss.

However, the evidence base is still limited. Most studies are preliminary, with small sample sizes and short durations. Large-scale, long-term randomized controlled trials are lacking. While the mechanism of action is biologically plausible, and early results are promising, the clinical efficacy and safety profile of GAA supplementation for muscle wasting remain to be firmly established.