Proof of Principle: Short-Term Sulforaphane Precursor Intake Alters Selected Circulating Oxidative Stress and Muscle Damage Biomarkers Following Maximal Exercise: A Double-Blind Crossover Trial

Background: Endurance exercise is known to induce the excessive production of reactive oxygen metabolites due to enhanced metabolic activity and inflammation, leading to oxidative stress and related injuries. Sulforaphane (SFN), an isothiocyanate, is broadly acknowledged for its potential antioxidant and anti-inflammatory properties, along with other protective functions. Objective: The purpose of this study was to investigate the effects of short-term SFN precursor supplementation on maximal exercise-induced muscle damage, oxidative stress and endurance capacity in healthy adults. Methods: In a double-blind placebo-controlled crossover design, 14 healthy participants (7 males, 7 females; age, 25.07 ± 1.04 years; weight, 65.28 ± 4.13 kg; height, 170.07 ± 3.46 cm; BMI, 22.48 ± 0.91) received SFN glucosinolate capsules (200 µmol/day) or placebo for 2 weeks during the first trial. Following a three-week washout period, the participants crossed over to the alternate treatment. Maximal exercise tests were performed following each supplementation (SFN or placebo) period. Blood samples were collected at baseline (before treatment), pre-exercise, post-exercise and 2 h after each exercise session. Results: SFN supplementation did not alter endurance capacity or blood cell counts; however, it significantly attenuated serum creatine kinase (CK) activity (p = 0.034; SFN, 121.52 ± 16.89; placebo, 291.84 ± 133.07) and the myoglobin (Mb) concentration (p = 0.011; SFN, 15.82 ± 1.95; placebo; 27.31 ± 5.71) following exercise. Analysis of oxidative stress markers showed no significant changes in the absolute values; however, in the d-ROMs (p = 0.038; SFN, 107.42 ± 2.39; placebo; 112.32 ± 2.11) and OXY-adsorbent tests (p = 0.032; SFN, 115.97 ± 4.15; placebo; 107.73 ± 3.88), the percent changes from the baseline showed a significant interaction with the supplement. These findings suggest that short-term SFN supplementation may mitigate exercise-induced muscle damage and oxidative stress, suggesting a modest influence on the circulating biomarkers associated with muscle damage without altering the endurance capacity of healthy people. Conclusion: SFN intake may be a beneficial, non-invasive strategy to modulate acute biochemical responses to exercise via the antioxidant defense system in physically active individuals.