Safety assessment of red spinach as a potential sports nutrition supplement: An evidence based comprehensive overview

• A comprehensive search method was used to extract published resources. • Red spinach is a nitrate rich functional food with sports nutrition potential. • Nitric oxide is a versatile molecule involved in endothelial functions. • Evidence based studies revealed its safety as a sports nutrition supplement. • Further studies on safety, efficacy and therapeutic applications are warranted. Red spinach ( Amaranthus tricolor ), a leafy vegetable, is gaining importance as a functional food particularly in the realm of sports nutrition. It contains essential nutrients, dietary fiber, phytochemicals and notably, dietary nitrate—precursor to nitric oxide, a molecule crucial for vascular function, muscle performance, and exercise tolerance. The review presents pre-clinical and clinical safety of red spinach as a potential sports nutrition supplement based on published evidence. Pre-clinical studies revealed that red spinach offered hepatoprotection, gastric and cyto protection in experimental animals. Red spinach extract was found to be safe in sub-chronic studies up to 1000 mg/kg and 180 mg/kg in chronic studies. Clinical evidence demonstrated red spinach’s ergogenic potential and cardio protective nature through improved oxygen utilization, vasodilation and endurance in human studies. Clinical studies revealed that there is a 255 % increase in humoral nitrate at dose of 1 g red spinach extract 65–70 min post ingestion. Despite its potential, current body of clinical evidence is limited by short-duration studies, small sample size and multi-centric trials. Evidence is also lacking on safety studies. The present report underscores the need for including diverse population in clinical studies in addition to addressing above limitations to expand red spinach’s wider acceptance as a sports nutrition supplement. Furthermore, we present the regulatory perspective of inorganic nitrate as outlined by EFSA and WHO. Given several health benefits offered by red spinach as a source of dietary nitrate, further investigations are needed on its safety, therapeutic application and efficacy.