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Struggle with runner's tummy? Finally, a supplement that provides 'impressive' gut-protective effects

on May 22, 2024


Scientists are hailing a new study showing the ‘impressive’ gut-protecting effects of CurraNZ, as a new go-to for relief against the dreaded ‘Runner’s Trots’, which affects runners when exercising in the heat.

Runners and scientists alike say the discovery is "an extremely valuable" prevention strategy for those of us who run in the heat and a new means to gain an “extra few percent” in performance too.

The supplement reduced symptoms in over two-thirds of the recreationally active male runners tested, all of whom were unaccustomed to running in the heat.

Until now, there has been limited supplement options for runners.

CurraNZ provided ‘impressive’ protection against exertional heat stress by:

- reducing total gastric distress symptoms in 73% of runners, compared to a placebo (1)
- enhancing barrier function (3)
- suppressing heat-induced cell damage (3)
- reducing ‘leaky gut’ by up to 40% (3)
- reducing the body’s stress response (2)

Runner's Trots explained

Runner's Trots is a symptom of exertional heat stress, caused by exercising in high temperatures, when blood is redistributed away from the digestive system to help with thermal regulation.

As a result, lack of blood supply stresses the gut, resulting in symptoms commonly referred to as ‘Runner’s Trots’. These affect both upper and lower gastro-intestinal tracts, which can lead to diarrhoea, vomiting, nausea, stitch and dizziness.

Heat-induced gastric stress affects 90% of endurance athletes, whether professional or recreational, and is one of the biggest issues for people running in the heat. It also prevents runners from taking on nutrition and fuelling, and a common cause of 'DNF'.

Current prevention strategies are limited to multiple weeks of complex heat acclimation training, which is impractical and inaccessible for those enjoy running recreationally.

'Blackcurrant could resolve GI issues in runners who customarily experience these symptoms'

The University of Chichester’s Mark Willems, (left) a Professor in Exercise Physiology, who collaborated on the joint project, says: “It is impressive that the 92% of participants who displayed total GI symptoms were reduced to 25% with blackcurrant. This is really meaningful.

“The take-out message is that if you are a customarily experience mild GI symptoms from running in the heat, they are likely to be resolved by supplementing with New Zealand blackcurrant extract.”

US scientist: 'This is a meaningful supplement for when heat acclimation is not an option'

Additionally, the US Exercise Physiologist and co-author on the study, Dr Matthew Kuennen (right), an Associate Professor at High Point University in North Carolina, said, “I am impressed with blackcurrant’s ability to reduce markers of gut leak and gastro-intestinal barrier function during prolonged endurance exercise under hot/dry conditions.

“Based on these findings, I would recommend blackcurrant supplementation as a potentially meaningful alternative when heat acclimation is not an option.”

The all male cohort underwent moderate-intensity treadmill running in hot ambient conditions (34C/93.2F) after taking 600mg (two capsules) of CurraNZ Original for seven days.

As well as demonstrating various gut-protecting effects, the study showed that blackcurrant is safe to use in hot conditions, with no adverse effects on the body’s core temperature or thermoregulatory processes.

Dr Kuennen adds, “It’s important to stress that exercising in the heat still provides the best adaptations, however just on the basis of improvements in gut barrier function that blackcurrant provides, it has merit in this cohort.”

Pro ultra-runner Ruth Croft recorded the third-fastest women’s time at the Western States Endurance Run in Auburn, California, in 2022 using CurraNZ, lowering her previous best time in the race by 12 minutes.

CurraNZ is used by leading endurance athletes with great success across triathlon and ultra-endurance running, including Dr David Haunschmidt, Simon Cochrane, Scotty Hawker, Caitlin Fielder, Hayden Hawks and Dr Stefanie Flippin.


1. CurraNZ, an anthocyanin-rich New Zealand blackcurrant extract reduces treadmill running-induced gastro-intestinal symptoms in the heat: A pilot study. Proceedings of the Nineteenth International Society of Sports Nutrition (ISSN) Conference and Expo, 2023, Mark ET Willems 1, *, Tess R Flood 1,2, Matthew R Kuennen 3 and Ben J Lee, [In review]

2. New Zealand blackcurrant extract modulates the heat shock response in men during exercise in hot ambient conditions. European Journal of Applied Physiology, February 2024 Nathan J. Conrad, Emerson P. Heckler, Ben J. Lee, Garrett W. Hill, Tessa R. Flood, Lucy E. V. Wheeler, Rianne Costello,  Ella F. Walker,  Trevor L. Gillum, Mark E. T. Willems, Matthew R. Kuennen
3. 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, International Journal of Sports Nutrition and Exercise Metabolism, July 2022. DOI: 10.1123/ijsnem.2021-0330 Ben J. Lee, Tessa R. Flood, Ania M Hiles, Ella F. Walker, Lucy E. V. Wheeler, Kimberley M Ashdown, Mark E. T. Willems, Rianne Costello, Luke Griesler, Phebe A Romano, Garrett W Hill, Matthew R. Kuennen.