Physician's view: 'Optimising both major energy systems for active people is a remarkable and rare discovery'

By Dr. Stefanie Flippin, Professional Athlete & Physician

Imagine starting your workout with a bigger fuel tank and ending with more power. That’s the exciting promise of CurraNZ New Zealand blackcurrant extract, as revealed by a groundbreaking new study (1) published in the European Journal of Applied Physiology in October. 

As an ultra-runner and physician, this reveals how CurraNZ appears to optimise both major energy systems for active people - a remarkable and rare discovery in sports nutrition.

The findings

To recap, (full study report HERE), researchers observed that taking two CurraNZ capsules (600mg) daily for just seven days enables your muscles to start exercise with significantly more glycogen. This is the essential “petrol” for endurance and intensity. 

The study also found a 24% increase in fat burning compared to placebo, especially from intramuscular triglyceride (IMTG) stores - the fats your muscles use when pushing hard. 

Additionally, CurraNZ boosted athletes’ exercise capacity by 39%. 

The Discovery

During exercise, our bodies tap into carbohydrates and fats as fuel. Carbohydrates (glycogen) are preferred at higher intensities, while fat oxidation ramps up as exercise grows more prolonged. 

However, once exercise intensity exceeds about 60% of your maximal oxygen capacity (VO2max) – which covers most race scenarios or hard training – fat burning drops off considerably, and the fats used must come from within the muscle itself: intramuscular triglyceride (IMTG) stores.

CurraNZ not only increases the body’s ability to burn fat (in ranges of 24%-29% for trained males and females (2-5)), but does so by specifically accelerating the use of those crucial IMTG stores in Type I muscle fibres (1) – the gold-standard source of endurance energy. 

Even more surprisingly, athletes supplementing with CurraNZ had significantly higher muscle glycogen levels before exercise, a response typically only seen after carbohydrate loading, yet they didn’t observe the usual trade-off of glycogen depletion or reduced fat burning. 

Instead, CurraNZ supports both high starting glycogen and robust fat utilisation, a combination that I’m not aware has been documented or observed before in one single supplement in sports nutrition science.

Why It Matters

For athletes, these findings mean potential advantages in races or training blocks where sustaining high intensity and prolonging endurance are both essential. 

The observed increase in pre-exercise glycogen means more fuel for big efforts; meanwhile, enhanced IMTG mobilisation means more fat burned when you need it most. 

For everyday exercisers, better fat burning is linked to improved metabolic flexibility, insulin sensitivity, and lower risks of weight gain and chronic disease. 

The study shows how CurraNZ is intervening with a process that endurance athletes have long since aimed to influence via training, nutrition (high fat diets) and heat training (by improving mitochondrial function, which indirectly improves the body’s ability to convert fat to fuel). 

The streamlined pathway between increased IMTG breakdown and elevated fat oxidation is utterly unique.

As a professional athlete and physician, I am extremely excited about these results and look forward to further investigation by the authors, particularly in females, as women tend to have higher rates of fat oxidation (and thus glycogen sparing) namely due to the presence of estrogen and higher levels of enzymes that are critical to the fat oxidation process. 

So far, the fat-burning studies (2,3,4,5) have shown that females respond more highly than men to CurraNZ intake – so the early signs are promising. 

About Dr. Stefanie Flippin

Colorado-based Dr. Stefanie Flippin (left) is an ultramarathon champion, physician, and coach. She brings clinical expertise and a first-hand perspective on how cutting-edge science translates into real athletic performance. 

Her double role as a Board-Certified Physician and elite athlete means she reviews research with an eye for both rigorous evidence and practical impact.

CurraNZ 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. 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, 35(2), 150–161. https://doi.org/10.1123/ijsnem.2024-0108 nu14071475
3. S Shepherd, J Strauss et al, New Zealand blackcurrant extract enhances fat oxidation during prolonged cycling in endurance-trained females. European Journal of Applied Physiology. https://doi.org/10.1007/s00421-018-3858-3
4. Cook MD, Myers SD, Gault ML, Edwards VC, Willems MET (2017) Dose effects of New Zealand blackcurrant on substrate oxidation and physiological responses during prolonged cycling. Eur J Appl Physiol 117:1207–1216. https ://doi.org/10.1007/s00421-017-3607-z
5. M. Willems et al, Enhanced walking-induced fat oxidation by New Zealand blackcurrant extract is body composition-dependent in recreationally active adult females, Nutrients, April 2022 https://doi.org/10.3390/

Choose Trusted Supplements 

As this study shows, supplement quality is critical. Only products carrying the CurraNZ® trademark guarantee research-backed New Zealand Blackcurrant extract, standardised to the proven research specification.

With growing adulteration and product variability in the market, athletes and active individuals should look for the CurraNZ® brand on labels to ensure they’re getting authentic science-backed performance benefits.