New study shows CurraNZ® blackcurrant extract increases muscle glycogen and fat burning in trained athletes

A pioneering study¹ has shown that New Zealand blackcurrant extract, CurraNZ®, can significantly increase muscle fuel stores, effectively supercharging the body’s "petrol tank" and offering everyday athletes a real advantage when it matters most.

After just seven days of supplementing with two capsules per day (600 mg CurraNZ), athletes started exercise with significantly higher levels of muscle glycogen, the body’s critical and limiting fuel source during exercise.

For trained athletes and weekend warriors alike, that means beginning a session with a much bigger "petrol tank", more energy in reserve, and greater potential to perform, without negative side effects.

Published in leading sports science journal

This new research, conducted in trained male athletes, has been published in the European Journal of Applied Physiology. Its findings are highly relevant for endurance athletes and active individuals looking for a genuine, science-backed performance edge.

Muscle glycogen is widely recognised as a key limiting factor in endurance and high-intensity performance. Athletes who can store more glycogen have the capacity to go harder for longer and finish stronger.

Having greater glycogen reserves is like holding an insurance policy for the unknown. It gives athletes and fitness enthusiasts the extra "fuel in the tank" when it counts, whether that is the final climb, last kilometre, or closing sprint.

More glycogen, more fat burning, stronger finish

The study showed that CurraNZ did more than increase starting glycogen levels. It also enhanced fat burning during prolonged exercise:

• Participants experienced a 24% increase in fat utilisation compared to placebo.
• 9 out of 10 athletes improved their performance at the end of the test, meaning they were not only able to go for longer, but were more likely to produce a decisive finishing effort.

Dr Sam Shepherd, the study’s lead author, explains:

"These results show that CurraNZ offers a science-backed advantage to enhance fuelling, by boosting the body’s ability to refill muscle energy stores, recover more quickly and burn more fat during training.

"The performance measure was not the main aim of the study, so it was not powered specifically to test performance outcomes, but the data are very interesting. We saw that 9 out of 10 people performed better with CurraNZ. The test itself mimicked a 3 to 4 minute effort at the end of endurance exercise, such as trying to break away from a group over the final 1 to 2 km of a bike race or triathlon."

As a co-nutrient alongside carbohydrate intake after hard efforts, CurraNZ can support athletes to restore glycogen more rapidly.

Dr Shepherd adds:

"Anecdotally, it seems many athletes struggle to meet carbohydrate intake recommendations day to day, particularly females and larger men.

"Even professionals get this wrong more often than you might think. It is a common basic error that athletes simply do not eat enough carbohydrate to recover fully from their training.

"CurraNZ offers a practical advantage when used alongside moderate carbohydrate intake after intense, prolonged or exhaustive exercise. The result is faster and greater recovery of muscle glycogen stores.

"There is clear application for endurance athletes and those doing high-intensity performance, especially for people who train twice a day or compete in multi-day events with short recovery windows between sessions."

Expert reaction from the field

Dr Stefanie Flippin, Board Certified surgeon, professional ultra runner and respected endurance coach, reviewed the study and commented:

"This study is extremely promising. The authors found that CurraNZ increased fat oxidation during prolonged exercise while also boosting pre-exercise muscle glycogen, which is a perfect scenario for endurance athletes searching for optimal fuel.

"What is most unique is seeing increased fat burning without sacrificing muscle glycogen. In simple terms, you get the best of both worlds. Endurance athletes have tried to optimise fat oxidation for years, yet rarely achieve this balance.

"As a physician and professional athlete, I am excited by these results, especially for their potential impact on female athletes, who naturally tend to have higher rates of fat oxidation and greater glycogen sparing."

Dr Flippin highlighted that the study used the gold standard muscle biopsy technique to confirm the 24% increase in fat burning, making the findings particularly robust.

She adds:

"New Zealand blackcurrant extract, via CurraNZ supplementation, positively intervenes in the processes that endurance athletes have always tried to improve through training, nutrition and even heat acclimation.

"Having more energy stored and ready, without the usual trade offs, is a real game changer for those of us who demand sustainable performance across long events."

A powerful co-nutrient for fuelling

The latest study is the first mechanistic analysis to show exactly how CurraNZ works at the muscle level. It helps explain and deepen the findings of 34 previous clinical trials and case studies that have demonstrated CurraNZ’s effects on performance²⁻¹⁷, recovery¹⁸⁻²² and metabolism²³⁻³⁴ across a wide range of individuals, from less fit participants to elite athletes.

Taken together, these data show that CurraNZ delivers a unique and repeatable profile of benefits:

A powerful co-nutrient for fuelling

• Bigger fuel tank: Seven days of supplementation measurably increases muscle glycogen and starting energy reserves.
• Faster recovery: Glycogen restoration after hard sessions is accelerated, helping to reduce recovery time between intense workouts.
• Greater fat burning: Enhanced fat breakdown during endurance exercise supports metabolic health and weight management goals, from recreational athletes to professionals, as demonstrated in multiple previous studies.
• Stronger race finish: A clear trend for improved sprint ability after prolonged exercise suggests real world competitive advantage.
• Trusted track record: Prior studies show benefits in both highly trained and less fit individuals, particularly in relation to fat metabolism and exercise performance.

In September, CurraNZ was awarded the NutraIngredients Asia Sports Nutrition Product of the Year 2025, recognising its growing reputation as a natural metabolic enhancer with an unmatched body of evidence among polyphenol-based supplements.

About the study

Following seven days of CurraNZ intake (600 mg per day, providing 210 mg anthocyanins), ten trained men completed two hours of steady state, submaximal cycling, followed immediately by an exercise test to exhaustion.

Muscle samples were taken immediately before, during and after the submaximal cycling bout and were analysed to measure muscle glycogen and intramuscular fat (triglyceride) stores.

Two days before this trial, participants visited the lab and performed cycling designed to deplete muscle glycogen stores. They were then provided with a carbohydrate rich diet for the next 48 hours, while taking their final CurraNZ or placebo capsules, to attempt to replenish glycogen equally between conditions.

The key difference observed was that CurraNZ increased the amount of glycogen stored in the muscle and enhanced the breakdown of intramuscular fat during prolonged exercise.

Unique quality and science: the Enzans® factor

The health and performance benefits of CurraNZ are underpinned by Enzans®, the key identifiers of the high potency New Zealand blackcurrant bioactives that deliver the supplement’s unique, broad spectrum effects.

Only CurraNZ Enzans have been used in an international programme of peer reviewed research in both health and sports settings, making this proprietary extract the most researched and trusted blackcurrant supplement in the world.

With adulterated and lower quality blackcurrant products on the rise, and many brands claiming equivalence to CurraNZ without evidence, consumers should always look for the CurraNZ and Enzans trademarks to be sure they are choosing an authentic, science backed product.

References

1.  Jones, L.A., Leung, L., Barrett, J.S. et al. New Zealand blackcurrant extract augments muscle glycogen storage at rest and enhances intramuscular triglyceride degradation during prolonged exercise. Eur J Appl Physiol (2025). https://doi.org/10.1007/s00421-025-05995-9
2. Perkins, I.C., Vine, S.A., Blacker, S.D., & Willems, M.E.T. (2015). New Zealand blackcurrant extract improves high-intensity intermittent running. International Journal of Sports Nutrition and Exercise Metabolism, 2015 Oct;25(5):487-93. doi: 10.1123/ijsnem.2015-0020. Epub 2015 Mar 26. PMID: 25812064.
3. Perkins, I.C., Bradley, M., Blacker, S.D., Willems, M.E.T. Effect Of New Zealand Blackcurrant Extract On Muscle Fibre-Specif     ic Fatigue, Sports 2020 doi:10.3390/sports8100135
4. Potter, J.A., Hodgson, C.I., Broadhurst, M., Howell, L., Gilbert, J., Willems, M.E. and Perkins, I.C., 2019. Effects of New Zealand blackcurrant extract on sport climbing performance. European Journal of Applied Physiology, https://doi.org/10.1007/s00421-019-04226-2
5. Godwin C, Cook MD, Willems MET. Effect of New Zealand blackcurrant extract on performance during the running based anaerobic sprint test in trained youth and recreationally active male football players. Sports 5, 69, 2017. doi:10.3390/sports5030069.
6. Willems, M.E.T., Cousins, L., Williams, D., & Blacker, S.D. (2016). Beneficial effects of New Zealand blackcurrant extract on maximal sprint speed during the Loughborough Intermittent Shuttle Test. Sports, 4(3), 42.
7. Murphy C, Cook MD, Willems MET. Effect of New Zealand blackcurrant extract on repeated cycling time trial performance. Sports 5(2), 25, 2017. doi: 10.3390/sports5020025.
8. Cook, M.D., Myers, S.D., Blacker, S.D. and Willems, M.E.T., 2015. New Zealand blackcurrant extract improves cycling performance and fat oxidation in cyclists. European Journal of Applied Physiology, 2015 DOI 10.1007/s00421-015-3215-8
9. Fryer S, Paterson C, Perkins IC, Gloster C, Willems ME, Potter JA. New Zealand Blackcurrant Extract Enhances Muscle Oxygenation During Forearm Exercise in Intermediate-Level Rock Climbers. International Journal of Sport Nutrition and Exercise Metabolism. 2020 May 26;1(aop):1-6.
10. Fryer S, Giles D, Bird E, Stone K, Paterson C, Baláš J, Willems MET, Potter J, Perkins I.  New Zealand blackcurrant extract enhances muscle oxygenation during repeated intermittent forearm muscle contractions in advanced and elite rock climbers. 2020. European Journal of Sport Science, DOI: 10.1080/17461391.2020.1827048
11. Burnett, P.J.M.; Willems, M.E.T. Effects of New Zealand Blackcurrant Extract on Sequential Performance Testing in Male Rugby Union Players. Sports 2022, 10, 152. https://doi.org/10.3390/ sports10100152. *Data from personal communication with Professor Willems.
12. Willems et al Effect of New Zealand Blackcurrant Extract on Force Steadiness of the Quadriceps Femoris Muscle during Sustained Submaximal Isometric Contraction.  J. Funct. Morphol. Kinesiol. 2022, doi: 10.3390/jfmk7020044
13. M Willems, S Montenari et al Acute Effects of NZBC on Cycling Time-Trial Are Performance Dependent in Endurance-Trained Cylists: A Home-Based Study, Sports 2023, 11, 93. https://doi.org/10.3390/sports11050093
14. Moss, Brindley, Enright et al The effects of an acute dose of New Zealand blackcurrant extract on 5 km running performance,  Int J Sport Nutr Exerc Metab Samantha L. Moss, Edward Brindley, Kevin Enright, Jamie Highton & Richard Bott 2023 https://doi.org/10.1123/ijsnem.2023-0029
15. Şahin M, Bilgiç P, Montanari S, Willems M. Intake Duration of Anthocyanin-Rich New Zealand Blackcurrant Extract Affects Metabolic Responses during Moderate Intensity Walking Exercise in Adult Males, Journal of Dietary Supplements. doi: 10.1080/19390211.2020.1783421
16. Beneficial physiological and metabolic effects with acute intake of New Zealand blackcurrant extract during 4h of indoor cycling in a male Ironman athlete: A case study, M Willems, T Spurr, J Lacey, A Briggs, Journal of Functional Morphology and Kinesiology, August 2024  https://doi.org/10.3390/jfmk9030141
17. I Perkins, S Blacker, M Willems et al, Individual responses to Repeated Dosing with anthocyanin-Rich New Zealand Blackcurrant Extract During High-Intensity, Intermittent Treadmill Running in Active Males, Nutrients, 2024, 16(24), 4253; https://doi.org/10.3390/nu16244253
18. Hunt, J.E.A.; Coelho, M.O.C.; Buxton, S.; Butcher, R.; Foran, D.; Rowland, D.; Gurton, W.; Macrae, H.; Jones, L.; Gapper, K.S.;et al. Consumption of New Zealand Blackcurrant Extract Improves Recovery from Exercise-Induced Muscle Damage in Non-Resistance Trained Men and Women: A Double-Blind Randomised Trial. Nutrients 2021, 13, 2875. https:// doi.org/10.3390/nu13082875
19. Fryer S, Paterson C, Perkins IC, Gloster C, Willems ME, Potter JA. New Zealand Blackcurrant Extract Enhances Muscle Oxygenation During Forearm Exercise in Intermediate-Level Rock Climbers. International Journal of Sport Nutrition and Exercise Metabolism. 2020 May 26;1(aop):1-6.
20. Fryer S, Giles D, Bird E, Stone K, Paterson C, Baláš J, Willems MET, Potter J, Perkins I.  New Zealand blackcurrant extract enhances muscle oxygenation during repeated intermittent forearm muscle contractions in advanced and elite rock climbers. 2020. European Journal of Sport Science, DOI: 10.1080/17461391.2020.1827048
21. Hurst R, Lyall K, Roberts J et al.  Consumption of an Anthocyanin-Rich Extract Made From New Zealand Blackcurrants Prior to Exercise may Assist Recovery from Oxidative Stress and Maintains Circulating Neutrophil Function: A Pilot Study, Frontiers In Nutrition doi: 10.3389/fnut.2019.00073
22. Hurst R, Lyall K, Roberts J et al. Daily consumption of NZBCE for five weeks supports recovery through management of Oxidative Stress and inflammation: A Randomized Placebo Controlled Pilot Study. Frontiers in Nutrition doi: 10.3389/fnut.2020.00016
23. Cook, M.D., Myers, S.D., Blacker, S.D. and Willems, M.E.T., 2015. New Zealand Blackcurrant Extract Improves Cycling Performance and Fat Oxidation in Cyclists. European Journal of Applied Physiology, 2015 DOI 10.1007/s00421-015-3215-8
24. Şahin MA, Bilgiç  P, Montanari S, Willems MET. Effects of Daily and Intermittent Intake of New Zealand Blackcurrant Extract on Whole-Body Fat Oxidation During Moderate Intensity Exercise in Males  IJSNEM Vol. 29, Suppl 1, 2019 s1-4
25. Lee BJ, Flood TR , Hiles AM, Wheeler LEV, Costello R, Walker EF, Ashdown K, Kuennen MR, Willems MET. New Zealand Blackcurrant Extract Enhances Fat Oxidation During Submaximal Exercise in the Heat IJSNEM https://doi.org/10.1016/j.jsams.2020.02.017
26. Strauss JA, Willems MET, Shepherd SO. New Zealand blackcurrant extract enhances fat oxidation during prolonged cycling in endurance-trained females. European Journal of Applied Physiology 118(6), 1265-1272, 2018. doi: 10.1007/s00421-018-3858-3.
27. Cook MD, Myers SD, Gault ML, Edwards VC, Willems ME. Dose effects of New Zealand blackcurrant on substrate oxidation and physiological responses during prolonged cycling. European Journal of Applied Physiology. 2017 Jun 1;117(6):1207-16.
28. Şahin M, Bilgiç P, Montanari S, Willems M. Intake Duration of Anthocyanin-Rich New Zealand Blackcurrant Extract Affects Metabolic Responses during Moderate Intensity Walking Exercise in Adult Males, Journal of Dietary Supplements. doi: 10.1080/19390211.2020.1783421
29. Willems M, Briggs A. Running-Induced Metabolic and Physiological Responses Using New Zealand Blackcurrant Extract in a Male Ultra-Endurance Runner: A Case Study. Journal of Functional Morphology and Kinesiology, 2022 https://doi.org/10.3390/jfmk7040104
30. Willems, M.E.T.; Banic, M.; Cadden, R.; Barnett, L. Enhanced Walking-Induced Fat Oxidation by New Zealand Blackcurrant Extract Is Body Composition-Dependent in Recreationally Active Adult Females. Nutrients 2022, 14, 1475. https:// doi.org/10.3390/nu14071475
31. Willems M.E.T Anthocyanin-rich New Zealand blackcurrant extract enhances whole-body resting fat oxidation in physically active males, Dietary Supplements and Nutraceuticals, August 2023 2(8): 30-40. DOI: https://www.doi.org/10.31989/dsn.v2i8.1124.
32. Willems M.ET et al Effects of CurraNZ, a New Zealand Blackcurrant Extract during Sables Athletes in Hot Conditions: Two Case Studies, J Func Morph Kinesiology https://doi.org/10.3390/jfmk9020076
33. Beneficial Physiological and Metabolic Effects with Acute Intake of New Zealand Blackcurrant Extract during 4 h of Indoor Cycling in a Male Ironman Athlete: A Case Study, J. Funct. Morphol. Kinesiol. 2024, 9, 141. https://doi.org/10.3390/jfmk9030141
34. Cook et al. Effects of New Zealand Black Currant Extract on Exercising Substrate Utilization and Postexercise Blood Pressure in Men and Women. International Journal of Sport Nutrition and Exercise Metabolism. Advance online publication. https://doi.org/10.1123/ijsnem.2024-0108..