Researchers in Iran and the United States recruited 20 participants to test whether seven days of low and high-dose NZBC improved resistance exercise performance, anaerobic capacity and cognitive function compared with placebo and control.
“Short-term NZBC supplementation improved selected resistance-exercise and cognitive outcomes, with the strongest evidence observed for outcomes that exceeded both CON (control) and PL (placebo),” they concluded.
Anthocyanins and exercise performance
Anthocyanins can improve exercise performance by enhancing nitric oxide availability, improving endothelial function, reducing oxidative stress, and supporting blood flow and oxygen delivery.
NZBC contains four main anthocyanins that likely act together to improve vascular function, energy use and fatigue resistance. However, previous findings are inconsistent, and benefits seen in endurance or cycling do not reliably extend to all exercise types, the authors of the new study noted. Some studies show no effect on cycling performance, force output, muscle activation, or isometric strength, suggesting that responses vary by exercise mode, dose and individual.
Because resistance exercise involves different demands—such as maximal force production, repeated lifting, and neuromuscular fatigue—it remains unclear whether NZBC improves strength, power, or training volume in this context, the researchers noted.
Mixed performance and cognitive benefits of new zealand blackcurrant
The researchers ran a randomized, double-blind, placebo-controlled crossover study in a university exercise lab. Each participant completed four 7-day conditions: no supplement, placebo, low-dose NZBC (250 mg per day), and high-dose NZBC (600 mg per day). The order of the capsule conditions was randomized, while the no-supplement condition always came first, and a seven-day washout separated each treatment.
During each test visit, participants took the assigned capsule, waited two hours, completed a cognitive test (Stroop test), performed strength tests, and completed a 30 second all-out cycling sprint, with heart rate and blood pressure measured throughout.
The researchers compared all four conditions using repeated-measures statistics, focusing on within-person differences.
Results showed that short-term blackcurrant supplementation improved some, but not all, aspects of performance in resistance-trained adults.
Both low- and high-dose blackcurrant increased bench press and leg press strength compared with placebo and no supplement, with the strongest and most consistent gains seen in lower-body performance. The low dose produced the largest improvements in total lifting volume, while the high dose showed smaller but still meaningful benefits and also improved muscle power output.
The researchers suggest that these performance changes may come from improved vascular function, which may help participants maintain force output across repeated sets and delay the onset of fatigue.
They also suggest that blackcurrant may improve fatigue resistance and recovery between sets, possibly by enhancing the clearance of metabolic by-products and supporting more efficient muscle function during repeated high-intensity efforts.
Furthermore, reduced oxidative stress may have played a role, as anthocyanins can help limit exercise-induced cellular stress and support antioxidant defences, allowing muscles to sustain performance for longer.
However, cycling sprint performance did not change under either dose, showing that the supplement did not enhance all forms of high-intensity exercise.
Cognitive performance also improved, with both doses increasing Stroop test scores, although the low dose again showed the most consistent effects. The researchers suggested that NZBC could improve blood flow to the brain, which could support faster and more efficient cognitive processing during demanding tasks.
Furthermore, some placebo-related improvements occurred, especially in lower-body strength and repeated cognitive testing, but blackcurrant generally outperformed placebo in key outcomes.
Overall, they concluded that NZBC may offer small, targeted ergogenic and cognitive benefits in resistance-trained individuals, but it does not enhance all forms of high-intensity performance.
“Independent replication in larger samples, with randomized capsule-free control conditions and mechanistic endpoints built into the design from the outset, is the logical next step before the observed effects can be considered established,” they noted.
Journal: Nutrients; doi: 10.3390/nu18121929; “Effects of Short-Term Low- and High-Dose New Zealand Blackcurrant Supplementation on Exercise and Cognitive Performance in Resistance-Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Crossover Study.” Authors: Koozehchian, M. S. Et al.