Multi-analytical characterization of creatine degradation for dietary supplement safety assessment

Creatine is widely used as a dietary supplement due to its ergogenic and neuroprotective properties. Consumption methods represent an important consideration because of the compound's instability under certain conditions, making it critical to understand how creatine responds to common stress factors during storage, transport, and preparation. Biochemical changes occurring under stress situations could lead to changes in product composition, potentially reducing efficacy, altering nutritional content, or even increasing toxicity. This study presents a comprehensive multi-analytical characterization of creatine degradation under various stress conditions to enhance dietary supplement safety assessment. Commercial creatine samples were subjected to thermal stress (60-200 °C), UV light exposure, pH variations (3, 8 and 13) and common beverage matrices (coffee, orange juice, and energy drink). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and high-resolution mass spectrometry (HRMS) were employed as complementary analytical techniques to identify structural modifications and potential degradation products. FTIR analysis revealed that temperature was the most significant factor affecting creatine stability, furthermore, each stress condition produced distinct spectral patterns, indicating specific degradation pathways affecting different functional groups. HRMS analysis identified several degradation products. Solution-based degradations exhibited matrix-dependent profiles, with distinct m/z patterns for each beverage type, while pH-dependent degradation revealed significant degradation products at alkaline pH but none at acidic pH. This multi-analytical approach provides a more comprehensive understanding of creatine degradation beyond the traditionally studied creatine-to-creatinine conversion, with implications for quality control, stability assessment, and safety of creatine-containing dietary supplements. Future investigations should prioritize comprehensive safety evaluations of identified degradation compounds, development of validated quantitative analytical protocols, and exploration of protective formulation approaches.