Benefits
Endurance and repeated-sprint exercise performance
A meta-analysis of 9 small placebo-controlled trials found a small average performance gain of about 0.45% with 105 to 210 mg of anthocyanins taken before exercise. A newer review of 21 crossover trials rated the certainty as low: effects were clearest in repeated sprints and smaller and variable in endurance cycling, and one trial in 16 trained cyclists found no effect.
Fat use during moderate exercise
Pooling 15 controlled studies in 226 active adults, blackcurrant extract raised fat burning during exercise by about 0.04 g per minute on average and lowered carbohydrate use. The reviewers noted that responses differed by person, sex, training status, dose and length of use. This is a shift in fuel use during exercise, not evidence of weight or fat loss.
Muscle soreness and recovery after hard exercise
In a trial of 27 adults not used to resistance training, 3 g a day of extract for 8 days before and 4 days after a hard arm workout gave faster return of strength, about half the soreness at 24 and 48 hours, and lower creatine kinase (a muscle damage marker) at 96 hours. In 20 recreational runners, 600 mg a day made no difference to recovery after a half-marathon.
Blood sugar and insulin response after meals
In a crossover trial in 23 adults, a drink with extract supplying 600 mg of anthocyanins lowered the early rise in blood sugar and insulin after a high-carbohydrate meal, while 150 and 300 mg did not. In 13 adults with overweight or obesity, 600 mg a day of extract for 8 days improved insulin sensitivity and trimmed post-meal glucose, but a single dose did not. Both studies were small and short.
Blood flow and artery stiffness
In 14 adults in their early 70s, 600 mg a day of extract for 7 days lowered pulse-wave velocity (a measure of artery stiffness) and central blood pressure more than placebo. A blackcurrant drink taken with a high-fat meal improved blood vessel dilation in 23 healthy adults. These were short studies of markers, not of heart health outcomes.
Eye fatigue after screen work
In one small crossover study in healthy adults, the shift in eye focus after a screen task was smaller with 50 mg of blackcurrant anthocyanins than with placebo, but only borderline and not statistically significant; eye-strain symptom scores did improve. Dark adaptation improved after 50 mg in 12 people versus their own pre-dose values. It is a single, older study.
Mechanism of action
Delphinidin and cyanidin anthocyanins and their breakdown products
Delphinidin-3-rutinoside, cyanidin-3-rutinoside and their glucoside forms typically make up about 97 to 98% of the berry's anthocyanins. In a human beverage trial, blood levels of breakdown products such as hippuric acid and isovanillic acid predicted the change in blood vessel dilation, which suggests these metabolites, not only the intact pigments, may be active.
Relaxation of blood vessel walls
In a rat hind-limb model, blackcurrant concentrate lowered resistance to blood flow through the vessel lining, using nitric oxide, hydrogen peroxide and potassium channels, with two delphinidin anthocyanins doing most of the work. In a small human study, a single dose kept forearm blood flow up during prolonged sitting, with no difference from placebo in blood nitrite, nitrate or endothelin-1, so the pathway in people is unclear.
Shift in fuel use during exercise
Pooled exercise studies show more fat and less carbohydrate burned at moderate intensity after several days of extract. One proposed explanation is that better blood flow to working muscle changes the delivery of fuel, but this has not been confirmed in people.
Blunted early sugar and gut hormone response
With a high-carbohydrate meal, the 600 mg anthocyanin drink lowered early blood sugar and insulin along with GIP, a gut hormone released as sugar is absorbed. This pattern fits slower sugar uptake from the gut, but the trial did not measure absorption directly.
Clinical trials
Systematic review of 16 randomized placebo-controlled trials of New Zealand blackcurrant products, 9 of which were pooled in a meta-analysis of sport performance; searches ran to August 2019 (Braakhuis et al. 2020, J Int Soc Sports Nutr).
Healthy human participants in small randomized placebo-controlled trials, mostly exercise performance tests.
Performance improved by a pooled 0.45% (95% CI 0.09 to 0.81, p = 0.01), with an apparent effective dose of 105 to 210 mg of anthocyanins before exercise. Too few studies reported oxidative markers, cognition or side effects to draw conclusions. A published correction disclosed that one author holds roles with organizations that could benefit from blackcurrant sports products, and that adding an excluded low-oxygen trial gives 0.41%.
Randomized, double-blind, placebo-controlled crossover trial of New Zealand blackcurrant extract (CurraNZ, 300 mg/day providing 105 mg anthocyanins) for 7 days with a 14-day washout (Cook et al. 2015, Eur J Appl Physiol).
14 trained male cyclists, mean age 38.
The 16.1 km time trial was 2.4% faster with extract (1678 vs 1722 seconds, P < 0.05), and fat oxidation at 65% of VO2max was 27% higher. Blood lactate was higher right after the time trial. One small study in men only.
Placebo-controlled, double-blind, randomized crossover trial testing a single dose and 7 days of blackcurrant extract at 4.3 mg anthocyanins per kg body weight a day (about 315 mg on average), registered as ACTRN12622001277730 (Morton et al. 2025, Eur J Sport Sci).
16 trained cyclists (10 men, 6 women), mean age 37, each completing a maximal incremental test and a 4 km time trial.
Neither the single dose nor 7 days of extract changed cycling performance or the measured physiological and metabolic responses (p > 0.05); any differences were trivial to small. This null result came from a group that included the lead author of the earlier positive meta-analysis.
Double-blind, randomized, placebo-controlled parallel trial of New Zealand blackcurrant extract 3 g/day for 8 days before and 4 days after exercise; the manufacturer supplied the capsules but, per the authors, had no role in design, analysis or writing (Hunt et al. 2021, Nutrients).
27 healthy men and women not used to resistance training (14 extract, 13 placebo), doing 60 strenuous biceps contractions.
Strength returned to baseline faster (p = 0.04), soreness was lower at 24 hours (21 vs 40 mm) and 48 hours (22 vs 44 mm), and creatine kinase was lower at 96 hours (p = 0.04). A small trial with a wide spread in the creatine kinase values.
Randomized, double-blind, placebo-controlled independent-groups trial of New Zealand blackcurrant extract (CurraNZ) 600 mg/day for 7 days before and 2 days after a half-marathon (Costello et al. 2020, Int J Sport Nutr Exerc Metab).
20 recreational runners (8 women), mean age 30.
No effect on recovery of jump performance or on perceived muscle soreness and fatigue over 48 hours. Urine interleukin-6, an inflammation marker, rose at 48 hours in the extract group only.
Two double-blind randomized placebo-controlled trials of New Zealand blackcurrant extract 600 mg: a single dose before a high-carbohydrate, high-fat liquid meal, and 8 days of daily intake with continuous glucose monitoring (Nolan et al. 2021, Eur J Nutr).
25 sedentary adults with overweight or obesity (12 in the single-dose trial, 13 in the 8-day trial).
A single dose had no effect on 3-hour glucose, insulin or triglyceride responses. After 8 days, insulin sensitivity was 22% better than with placebo (P = 0.011), C-reactive protein was lower, and free-living glucose rises after breakfast and lunch were 9% and 8% smaller. Very small groups over about a week.
Randomized, double-blind crossover trial of low-sugar fruit drinks with blackcurrant extract providing 150, 300 or 600 mg anthocyanins, or no extract, taken just before a high-carbohydrate meal; three co-authors worked for GlaxoSmithKline (one) and Suntory Beverage and Food (two) (Castro-Acosta et al. 2016, J Nutr Biochem).
23 men and postmenopausal women, mean age 46.
Only the 600 mg drink lowered the early (first 30 minutes) rise in blood glucose and insulin and reduced GIP; the 150 and 300 mg drinks did not differ from control. No effect on an oxidative stress marker or on vascular function. This tested a drink with extract, roughly equal to 100 g of blackcurrants, not capsules.
Randomized, double-blind, placebo-controlled crossover trial with a 28-day washout; two 300 mg capsules a day of New Zealand blackcurrant extract for 7 days (Okamoto et al. 2020, Clin Exp Hypertens).
14 older adults, mean age 73.
Carotid-femoral pulse-wave velocity (central artery stiffness) and central blood pressure fell more with extract than with placebo (P = .04 and P = .001). Blood lipids did not change. One small, one-week study of markers.