Mechanism-based Nutritional Strategies for Performance and Recovery in Soccer Players: a Qualitative Research Synthesis

BACKGROUND AND OBJECTIVES:Modern soccer, characterized by its intermittent high-intensity nature, requires a combination of explosive power and aerobic endurance. This physiological demand results in substantial metabolic load, oxidative stress, and disruption of recovery processes in players. Multi-target nutritional supplements may therefore provide critical support in maintaining performance and accelerating recovery. This qualitative review synthesizes current evidence regarding the efficacy of melatonin, gut-axis interventions (prebiotics, probiotics, and synbiotics), magnesium, sodium pyruvate, and purple grape-derived products on performance and recovery outcomes in soccer players. METHODS:Twenty-two interventional studies conducted on soccer players were systematically extracted and qualitatively synthesized following PRISMA 2020 reporting guidelines. Methodological quality and risk of bias were assessed using design-specific tools, including the Cochrane Risk of Bias 2 (RoB 2) tool for randomized controlled trials and the ROBINS-I framework for non-randomized intervention studies. Overall certainty of evidence was evaluated using an adapted GRADE framework. Particular attention was directed to study design, dosage and timing protocols, performance and biochemical outcomes, and methodological limitations, with emphasis placed on linking mechanistic evidence with applied performance and recovery outcomes. RESULTS:Melatonin, administered either nocturnally or prior to exercise, was associated with reductions in oxidative stress markers and upregulation of antioxidant enzymes, contributing to attenuation of short-term performance decline; however, its effects on maximal performance indices were inconsistent. Prebiotic, probiotic, and synbiotic interventions enhanced mucosal immunity and reduced the incidence and duration of upper respiratory tract infections (URTI) as well as delayed onset muscle soreness (DOMS). Certain combined formulations-particularly those co-administered with protein or spirulina-also demonstrated improvements in body composition and muscular strength. Magnesium supplementation alone showed limited and inconsistent benefits in athletes without deficiency, although combined formulations indicated potential improvements in buffering capacity and anaerobic performance. Short-term sodium pyruvate supplementation supported ATP-PCr system resynthesis and enhanced repeated sprint performance. Purple grape-derived products increased serum antioxidant capacity and, in some participants, improved endurance performance. LIMITATIONS AND CONCLUSIONS:Key limitations across studies included small sample sizes, protocol heterogeneity, and a lack of standardized mechanistic biomarkers. Overall, these supplements may support performance and recovery in soccer players; however, larger-scale, field-based randomized controlled trials are required to establish precise, evidence-based operational strategies.