Dietary Supplementation on Physical Performance and Recovery in Active-Duty Military Personnel: A Systematic Review of Randomized and Quasi-Experimental Controlled Trials

Background: Warfighters, often called tactical athletes, seek dietary supplementation to enhance training and recovery. Roughly 69% of active-duty US military personnel have reported consuming dietary supplements. The objective of this systematic review was to examine the impact of dietary supplements on muscle-related physical performance and recovery in active-duty military personnel. Methods: Randomized controlled trials and quasi-experimental controlled trials of oral dietary supplementation in active-duty military members were examined. A protocol was registered (PROSPERO CRD42023401472), and a systematic search of MEDLINE and CINAHL was undertaken. Inclusion criteria consisted of studies published between 1990-2023 with outcomes of muscle performance and recovery among active-duty military populations. The risk of bias was assessed with the McMaster University Guidelines and Critical Review Form for Quantitative Studies. Results: Sixteen studies were included. Four were conducted on protein or carbohydrate; four on beta-alanine alone, creatine alone, or in combination; two on mixed nutritional supplements; two on probiotics alone or in combination with beta hydroxy-beta methylbutyrate calcium; and four on phytonutrient extracts including oregano, beetroot juice, quercetin, and resveratrol. Ten examined outcomes related to physical performance, and six on outcomes of injury or recovery. Overall, protein, carbohydrate, beta-alanine, creatine, and beetroot juice modestly improved performance, while quercetin did not. Protein, carbohydrates, beta-alanine, probiotics, and oregano reduced markers of inflammation, while resveratrol did not. Conclusions: Nutrition supplementation may have small benefits on muscle performance and recovery in warfighters. However, there are significant limitations in interpretation due to the largely inconsistent evidence of ingredients and comparable outcomes. Thus, there is inadequate practical evidence to suggest how dietary supplementation may affect field performance.