Landmark study reveals the 'rare' effect of CurraNZ in trained athletes

    on June 18, 2024

    A new CurraNZ case study (1) is exciting researchers after revealing startling enhancements to performance factors in an unacclimatised, amateur peak-trained male ultra-marathoner in the heat.

    The ergogenic aid led to large changes in the male’s energy metabolism with the highest-ever value for reducing carbohydrate expenditure (31%).

    The landmark case study tested the effects of CurraNZ blackcurrant extract in a male and female who were due to race in the 2023 Marathon Des Sables, a six-stage, 250km ultra-marathon across the Sahara Desert.

    This study allowed rare access to ultra-endurance athletes at the end of their training programme, ahead of one of the world’s toughest multi-day stage races in hot desert conditions.

    The male’s results showed short-term intake of CurraNZ:

    • reduced carbohydrate use 31% - the highest-ever recorded value in blackcurrant research
    • increased fat oxidation by 21%
    • lowered core temperature 0.4C 

    Mark Willems, Professor of Exercise Physiology at the University of Chichester, says: “It is quite amazing to see that blackcurrant could change fat and carbohydrate oxidation positively to this degree in someone due to compete in the Marathon Des Sables, where we’d expect them to have an already high degree of fat-burning adaptations for fuelling.”

    Remarkable fuelling observation in hot conditions

    The findings reinforce our extract’s well researched applications for influencing energy metabolism, which can lead to enhanced endurance, and potentially lowering an individual’s reliance on carbohydrate for energy.

    Unlike carbohydrate, fat is an unlimited valuable fuel source for muscles during low and moderate-intensity endurance exercise, so becoming ‘fat adapted’ is highly desirable for endurance athletes. 

    Muscles also depend upon glycogen from carbohydrate for energy, so reducing carbohydrate use and increasing fat oxidation during exercise is beneficial for endurance performance.

    CurraNZ has been validated to improve running endurance, cycling and climbing performance by 2.6% - 11% - improvements normally seen after months and years of structured training.

    The data validates a dozen previously-published cohort studies (2-13) that show short-term intake of CurraNZ influences energy metabolism to a large degree at rest and during exercise, in both genders, across multiple exercise durations and intensities, and in hot and ambient temperatures.

    Prior to starting heat acclimation training four weeks before the Marathon Des Sables, the two novice endurance athletes were tested in an hour’s treadmill running in 34C heat, having dosed on two capsules (600mg) of CurraNZ for 7 days. They had a light breakfast before the session. 

    The female was a non-responder to blackcurrant, which is not uncommon in sports nutrition studies, however her data has provided new insights on potential energy metabolism thresholds for blackcurrant.

     'It is rare to see an ergogenic aid can change the metabolism of highly trained endurance athletes like this'

    Professor Willems adds: “Running in hot conditions usually leads to a decline in fat oxidation, which leads to greater fatigue, so to see blackcurrant once again enhancing access to fat as fuel and sparing carbohydrate in the heat is really meaningful.”

    Reflecting on the volume of research to date, Professor Willems says: “We have convincing evidence that blackcurrant extract can effectively change an individual’s energy metabolism after just 7 days, without manipulating the diet and irrespective of someone’s training status, which is really amazing – and rare to see.”

    Conversely, the female had an existing high degree of fat burning which may be the reason she did not respond to blackcurrant.

    Professor Willems says: “It is likely there wasn’t much improvement that could be achieved because of her intrinsically high rate of fat oxidation – 77% of the existing contribution to her energy requirements were from fat. Therefore, there was less room to play with in enhancing her fat burning capabilities. In saying that, it would’ve been interesting to have tested a higher dose.


    Thermoregulation – is blackcurrant a supplemental aid for athletes in the heat?

    Previous work (15) has shown that blackcurrant can reduce the exertional heat stress response in runners and protect the gut, with a pilot study in runners revealing a small trend towards reducing deep core temperature (16).

    In this Marathon Des Sable case study, blackcurrant led to a reduction of 0.4C in the male’s core temperature, an indicator of enhanced thermoregulation. This is indicative of the athlete experiencing lower heat stress than in the long term may lower fatigue and benefit exercise performance.

    Professor Willems says: “Clearly, it’s advantageous if an individual can exercise for longer at intensity in the heat without their core temperature rising.

    “It is not uncommon to see such lower core temperatures during exercise after heat acclimation training in preparation for competition in hot environments.”

    “This could be linked to blackcurrant’s ability to enhance blood flow, meaning more blood supply to the skin could be helping the body dissipate heat more quickly.

    “This is an encouraging observation of enhanced thermoregulation, but is only a case study, suggesting this warrants more investigation in cohort studies.”



    1. Effects of CurraNZ, a New Zealand Blackcurrant Extract, during 1 Hour of Treadmill Running in Female and Male Marathon des Sables Athletes in Hot Conditions: Two Case Studies, Journal of Functional Morphology and Kinesiology, May 2024, Willems et al,
    2. New Zealand blackcurrant extract enhances fat oxidation during prolonged cycling in endurance-trained females. Strauss, JA, Willems, MET and Shepherd, SO (2018) European Journal of Applied Physiology. ISSN 1439-6327
    3. Daily and Not Every-Other-Day Intake of Anthocyanin-Rich New Zealand Blackcurrant Extract Alters Substrate Oxidation during Moderate-Intensity Walking in Adult Males, Journal of Dietary Supplements, October 2020,
    4. Intake Duration of Anthocyanin-Rich New Zealand Blackcurrant Extract Affects Metabolic Responses during Moderate Intensity Walking Exercise in Males, June 2020 in the Journal of Dietary Supplements,
    5. New Zealand Blackcurrant Improves Performance and Fat Oxidation in Cyclists, European Journal of Applied Physiology, 2015 DOI 10.1007/s00421-015-3215-8.
    6. Dose Effects of New Zealand Blackcurrant on Substrate Oxidation and Physiological Responses During Prolonged Cycling, Matthew David Cook, Stephen David Myers · Mandy Lucinda Gault · Victoria Charlotte Edwards · Mark Elisabeth Theodorus Willems, Eur J Appl Physiol ,2017 117:1207–1216 DOI 10.1007/s00421-017-3607-z
    7. Enhanced Walking-Induced Fat Oxidation by New Zealand Blackcurrant Extract Is Body Composition-Dependent in Recreationally Active Adult Females Willems, M.E.T.; Banic, M.; Cadden, R.; Barnett, L Nutrients 2022, 14, 1475.
    8. New Zealand Blackcurrant Improves Performance and Fat Oxidation in Cyclists, Willems ME1, Myers SD, Blacker S, Cook MD. European Journal of Applied Physiology, 2015 DOI 10.1007/s00421-015-3215-8
    9. Effect of New Zealand Blackcurrant Extract on Physiological Responses at Rest and during Brisk Walking in Southeast Asian Men: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study. M Willems, N Parktin, W Widjaja, An Ajjimaporn. Nutrients 2018, 10(11), 1732;
    10. Dietary supplementation with New Zealand blackcurrant extract enhances fat oxidation during submaximal exercise in the heat, Ania M. Hiles, Tessa R. Flood, Ben J. Lee,∗, Lucy E.V. Wheeler, Rianne Costello,Ella F. Walker, Kimberly M. Ashdowna, Matthew R. Kuennenc, Mark E.T. Willems, Journal of Science and Medicine in Sports, March 2020 DOI: 10.1016/j.jsams.2020.02.017
    11. Enhanced walking-induced fat oxidation by New Zealand blackcurrant extract is body composition-dependent in recreationally active adult females Mark ET Willems et al, Nutrients, 2022
    12. New Zealand Blackcurrant Increases Post-Exercise Hypotension Following Sustained Moderate Intensity Exercise, International Journal of Sport Nutrition and Exercise Metabolism,
    13. Two weeks daily intake of anthocyanin-rich New Zealand blackcurrant extract enhances whole-body fat oxidation during supine rest in healthy males, M Willems, Journal Dietary Supplements, August 2023 Dietary Supplements and Nutraceuticals 2023; 2(8): 30-40. DOI:
    14. Running-induced metabolic and physiological responses by New Zealand blackcurrant extract in a male ultra-endurance runner: A case study J. Funct. Morphol. Kinesiol. 2022, 7, 104.
    15. New Zealand blackcurrant extract modulates the heat shock response in men during exercise in hot ambient conditions, Lee et al, Eu J Applied Physiology April 2024, B Lee, M Kuennen, M Willems et al,
    16. Anthocyanin-rich blackcurrant extract preserves gastrointestinal barrier permeability and reduces enterocyte damage but has no effect on microbial translocation and inflammation after exertional heat stress, Ben J Lee, Tessa R Flood, Ania M Hiles, Ella F Walker, Lucy EV Wheeler, Kimberly M Ashdown, Mark ET Willems, Rianne Costello, Luke D Greisler, Phebe Romano , Garrett W Hill , Matthew R Kuennen