CurraNZ study shows 'high impact and exciting' results for reducing GI stress in the heat

    on July 17, 2023


    Ninety percent of athletes suffer from gut issues in the heat, which can derail your competitive chances and months of preparation when racing in soaring summer temperatures.

    A UK study1 has shown high-impact findings for runners, with the discovery that it can effectively support GI integrity in the heat.

    The peer-reviewed, independent study, found that two capsules of CurraNZ experienced a large reduction in small intestinal permeability and heat-induced cell damage of up to 40%.

    Twelve healthy recreationally active, unacclimatised men took 600mg of CurraNZ for seven days before performing 60 minutes of moderate-intensity treadmill running in hot ambient conditions (34°C, 40% humidity).

    Measurements were taken of intestinal fatty acid binding protein, a marker of enterocyte damage, at rest and 20, 60 and 240 minutes post-exercise.

    The findings showed the intake of blackcurrant led to:

    • 40% reduction in intestinal fatty acid binding protein (which indicates intestinal cell damage)
    • 12% reduction in lactulose and rhamnose excretion (biomarkers that indicate intestinal permeability)
    • No adverse effects on thermoregulation, with a slight reduction in deep body temperature
    • Improvements to GI function and integrity, compared to placebo, in all participants

    'We were impressed that 100% of participants responded to blackcurrant'

    Exercise in the heat is one of the most severe demands athletes can place on the gastro-intestinal system.

    Up to 90% of endurance athletes are affected by symptoms of gastrointestinal distress during exercise in the heat, which are in part caused by a redistribution in blood flow away from the gut, leading to a host of symptoms. If left uncontrolled, they can impair exercise performance and may even lead to more severe outcomes such as heat illness.

    Dr Ben Lee, a thermal physiologist at Coventry University in the UK who performed the study, says: “We saw a 50% reduction in upper and lower GI symptoms in athletes using blackcurrant, plus a 33% reduction in other related symptoms, such as nausea, stitch and dizziness.

    “If you were due to compete in the heat, you should consider the use of blackcurrant in the week tapering before the event if you suffer from GI distress.”


    'These are high impact findings for a highly stressful condition'


    Mark Willems, Professor of Exercise Physiology at the University of Chichester (left), describes these findings as “high impact”.

    The experienced researcher, who has authored >30 peer-review published papers on blackcurrant for sports performance, says: “This is a very exciting finding to see an effect in exercising in the heat, which is a really stressful situation for the body. 

    “We were impressed that everyone responded to blackcurrant in this project, which is very unusual in supplementation studies. Usually we either see no effect or about 80% of the subjects responding.”

    Importantly, the study showed that blackcurrant had no adverse effect on the body’s core temperature or thermoregulatory processes, showing the supplement is safe to use in hot conditions.

    “We are realising that it maybe the specific blackcurrant anthocyanin composition that is making this berry stand out from the others.”



    1. Lee et al. Anthocyanin-rich blackcurrant extract preserves gastrointestinal barrier 1 permeability and reduces enterocyte damage but has no effect on microbial translocation and inflammation after exertional heat stress, IJSNEM (in press) doi: 10.1123/ijsnem.2021-0330.