Effects of New Zealand blackcurrant extract supplementation on muscle damage, oxidative stress, and inflammatory markers following high-intensity training in elite taekwondo athletes: a randomized, double-blind trial

Exercise-induced muscle damage, oxidative stress, and inflammation can impair recovery and performance in elite athletes. Anthocyanin-rich New Zealand blackcurrant (NZBC) has been proposed as a nutritional strategy to counteract these effects. In a randomized, double-blind, placebo-controlled trial, 29 male elite taekwondo athletes received either NZBC extract (210 mg anthocyanins/day) or placebo for 7 days. Blood samples and muscle soreness ratings were collected at baseline, immediately post-exercise, 24 h, and 7 d after repeated high-intensity training sessions. Primary outcomes included creatine kinase (CK) and reactive oxygen species (ROS); secondary outcomes were total antioxidant capacity (TOAC) and inflammatory cytokines. Compared with placebo, NZBC significantly attenuated the 24-h increase in CK (mean difference − 356 U/L; 95% CI − 510 to − 202) and ROS (− 1.8 units; 95% CI − 2.5 to − 1.0), while enhancing TOAC (+ 0.21 mmol Trolox equivalents; 95% CI + 0.09 to + 0.33). At 7 days, cytokine levels (IL-6, TNF-α) were lower in NZBC than placebo (IL-6: −1.2 pg/mL; 95% CI − 2.1 to − 0.3). Effect sizes were moderate to large. No adverse events were reported. Short-term supplementation with NZBC extract reduced exercise-induced muscle damage, oxidative stress, and inflammation in elite taekwondo athletes. These findings support the role of anthocyanin-rich NZBC as a personalized recovery aid in combat sports.