CurraNZ Study: Bigger Fuel Tank for Muscles – New Findings Reveal Enhanced Carbohydrate Reserves, Fat Burning and a Stronger Finish

A pioneering study¹ has shown that New Zealand blackcurrant extract, CurraNZ®, supercharges the “petrol tank”, by increasing muscle fuel supplies, potentially offering everyday athletes a significant advantage when it matters most.

In practical terms, taking two capsules (600mg) of CurraNZ for just seven days enables muscles to start with significantly greater reserves of glycogen, which is the body’s critical and limiting fuel source during exercise.

For trained athletes or weekend warriors, this means starting a session with a far bigger “petrol tank” and significantly boosting performance potential, without any negative side effects.

This new research utilizing trained male athletes was published in the European Journal of Applied Physiology. These results are extremely relevant for athletes and highly active populations seeking a genuine performance edge.

Muscle glycogen is widely acknowledged as a limiting factor for endurance and high-intensity performance; athletes who store more muscle glycogen have the capacity to go harder for longer - and finish stronger.

Having greater stores of glycogen is like holding an insurance policy for the unknown - ensuring fitness lovers have the extra “fuel in the tank” when it matters most.

The study found that, alongside boosting starting glycogen levels, CurraNZ promoted fat burning, with users experiencing a 24% increase in fat utilisation compared to placebo.

Also interesting was that 9 out of 10 participants in the study improved their performance at the end of the test - meaning they not only “went for longer” but were more likely to have that crucial finishing kick at the end of a race.

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 wasn’t the main aim of the study – and so the study wasn’t powered sufficiently to truly test this - but the data is interesting and shows that 9 out of 10 people had better performance with CurraNZ. The performance test itself mimicked a 3-4 minute effort at the end of endurance exercise, for example, trying to break away from a group over the final 1-2 km of a bike race or triathlon.”

As a co-nutrient for carbohydrate re-feeding after hard efforts, CurraNZ can support athletes to recover their glycogen stores more quickly.

Dr Shepherd says:

“Anecdotally, it seems many athletes struggle to meet the recommendations for carbohydrate intake on a day-to-day basis – particularly females and larger men." 

“Even professionals get this surprisingly wrong – it’s a common basic error that athletes often do not eat enough carbs to recover sufficiently from their training.”

“CurraNZ offers a practical advantage for athletes, to supplement in conjunction with moderate consumption levels of carbohydrate after intense, prolonged or exhaustive exercise bouts, which will lead to faster and higher recovery of muscle glycogen stores."

“There’s a real application for endurance athletes and high-intensity performance, particularly for people who train twice a day or do multi-day races, where there’s short recovery periods between sessions.”

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 CurraNZ increased fat oxidation during prolonged exercise, while also boosting pre-exercise muscle glycogen - a perfect scenario for endurance athletes searching for optimal fuel. What's most unique is seeing increased fat burning without sacrificing muscle glycogen: In layman's terms, you get the best of both worlds. Endurance athletes have tried to optimize 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 gold-standard muscle biopsy method was used to confirm 24% higher fat burning, making the findings exceptionally robust. She adds:

"NZBC extract, via CurraNZ supplementation, positively intervenes with processes that endurance athletes have always sought to improve, be it through special training, nutrition, or 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."

This latest study is also the first mechanistic analysis showing exactly how CurraNZ works on optimising muscle machinery, deepening and explaining the findings of 34 earlier clinical trials and case studies demonstrating the supplement’s performance^2-17, recovery^18-22 and metabolic^23-34 effects. Those studies covered a range of individuals, from less fit people to elites, and consistently demonstrated CurraNZ’s powerful fat burning, exercise performance and muscle recovery properties.

Awarded the Nutra Ingredients Asia Sports Nutrition Product 2025 Award in September, no other polyphenol matches this proprietary extract’s unique versatility as a natural metabolic enhancer, nor the repeatability of these results across so many different groups.

A Powerful Co-Nutrient for Fuelling:

Bigger “Fuel Tank”: Seven days’ use measurably increases muscle glycogen and starting energy reserves.

Faster Recovery: Glycogen restoration after hard sessions is accelerated, reducing recovery time between intense workouts.

Greater Fat Burning: Enhanced fat breakdown during endurance activity supports metabolic health and weight goals for everyone - from recreational athletes to pros – and demonstrated in previous studies.

Stronger Race Finish: A trend for improved sprint ability post-endurance exercise highlights real-world competition advantage.

Trusted Track Record: Prior studies confirm benefits not only in the highly trained, but also less fit individuals seeking improved fat metabolism.

About The Study

Following seven days’ intake of CurraNZ, ten trained men completed two hours of steady-state submaximal cycling, followed immediately by an exercise test to exhaustion. Muscle samples were taken from participants immediately before, during and after the submaximal cycling bout. Muscle samples were analysed to measure muscle glycogen and fat stores.

Two days before this test, participants had been to the lab and performed cycling exercise designed to deplete muscle glycogen stores. They were then provided with a carbohydrate-rich diet for the next 48 hours, while consuming their final CurraNZ (600mg – 210mg anthocyanin) or placebo capsules In an attempt to replenish their glycogen stores equally between the two conditions.

Unique Quality and Science – The Enzans® Factor

The health and sports benefits of CurraNZ® are characterized by Enzans®, key identifiers of the high-potency New Zealand blackcurrant bioactives that deliver the unique, proven, broad-spectrum properties of the supplement.

Only the CurraNZ® Enzans® have been proven in an international program of peer-reviewed health and sports research, making our proprietary formulation the most researched and trusted blackcurrant extract supplement in the world.

With adulterated blackcurrant products on the rise and many claiming false equivalence with CurraNZ, consumers must look for the CurraNZ and Enzans® trademarks to ensure they are choosing the authentic, science-backed supplements.

References

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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. 
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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 
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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 
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