The effect of royal jelly in oxidative stress, athletic performance, and mitochondrial biogenesis-related gene expression in endurance athletes: study protocol for a double-blind crossover trial

Abstract

Background: In the field of global health, meeting the energy requirements of athletes has surfaced as an essential concern. This study seeks to evaluate the effectiveness of royal jelly (RJ) in improving exercise performance in endurance-trained men. Methods: In this randomized, crossover, double-blind, placebo-controlled study, we will enroll 18 male endurance athletes. Participants will be randomly assigned to one of two conditions: the intervention condition, which will receive royal jelly (RJ) in 500 mg capsules taken orally twice daily for 2 weeks, or the control condition, which will receive a placebo consisting of 500 mg starch capsules taken orally twice daily for the same duration. The study will utilize a 2 × 2 crossover design with a 2-week washout period between treatments. To evaluate aerobic performance, we will determine each participant’s maximal aerobic speed (MAS), followed by a test conducted at 80% of the MAS to measure time to exhaustion. Blood samples (5 cc) will be collected from all participants before and after the treadmill tests to analyze mRNA expressions of Nrf2 and PGC-1α, as well as oxidative stress parameters. Additionally, participants’ dietary intake will be assessed using 3-day food records, and their blood pressure will be monitored before exercise, immediately after, and half an hour post-exercise. Discussion: This trial aims to evaluate the effectiveness of RJ as a nutraceutical agent for enhancing endurance athletic performance. We anticipate that the results will provide new insights into the clinical and molecular benefits of RJ. Additionally, these findings will offer valuable data to guide the design and execution of future clinical research involving RJ. Trial registration: This study was registered in the Iranian Registry of Clinical Trials (registration No. IRCT20231209060310N1, date: December 21, 2023).