Blackcurrants – valuable prebiotics to support gut function.

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Berry polyphenols have garnered interest in recent times for their potential benefits to gut health, flora balance and improving intestinal barrier function, writes Fleur Cushman.

Of all the berries, blackcurrants possess some of the richest densities and concentrations of phenolics, with a combination and concentration of anthocyanins not found in other berries.

Blackcurrants grown in New Zealand have one of the highest anthocyanin densities of any fruit grown globally and confer the deep purple colouring to the berry. New Zealand’s strong ultra-violet sunlight and long sunlight hours stimulate the berry into high levels of pigments – anthocyanins - as a natural defence against the environment.

CurraNZ has become a science leader in the blackcurrant polyphenol space globally, with over 50 product-specific published exercise and health studies on its proprietary 35% anthocyanin extract, made exclusively from New Zealand blackcurrants.

Here are the science-led benefits supporting intake of blackcurrants for gut health.

1. Gut Microbiota Modulation: Blackcurrants polyphenols can positively influence the gut microbiota, which plays a crucial role in maintaining gut health. A 2009 Massey University study1 found that blackcurrant increased the abundance of beneficial gut bacteria like Lactobacillus and Bifidobacterium, and decreased potentially harmful bacteria associated with colon cancer.  

A later study, in 20212, exploring the anti-obesity potential of blackcurrant anthocyanins and its correlation between gut microbiota in mice, showed that 12 weeks’ intake significantly changed the overall structure and composition of gut microbiota. The mice fed a high-fat diet experienced reduced obesity-related markers, with the study concluding that blackcurrant supplementation could be a beneficial treatment for preventing high fat diet-induced obesity by targeting microbiota.

2. Enhancement of Gut Barrier Function: A trial in athletes3,4,5 has shown the fast-acting effects of CurraNZ for reducing symptoms of exertional heat stress and its deleterious effects on the gut, which occurs when blood is redistributed away from the digestive system to help with thermoregulation, resulting in symptoms of ‘leaky gut’.

One week’s intake of 600mg CurraNZ (2 capsules) in unacclimatised runners during 60 minutes running in a heat chamber led to a 40% reduction in heat-induced cell damage and a 12% reduction in intestinal permeability.
Blackcurrant also abolished GI stress symptoms in 73% of the study cohort, reinforcing the role the berry can play in helping the body cope with stress and aiding gut barrier function, which affects 90% of endurance athletes.

3. Gut-bone axis for reducing post-menopausal bone loss: Microbiome plays a vital role in bone turnover and density via effects on host metabolism, immune function, hormone secretion and the gut-brain axis.

A pilot trial6 in 51 peri- and post-menopausal women showed highly promising, protective effects of New Zealand blackcurrant extract for reducing bone loss in postmenopausal women.

The proposed mechanism of actions of blackcurrant were via the gut-microbiota-immune-bone-axis, with the high intake cohort in the study (784mg anthocyanin) showing significant changes to Ruminococcus 2, believed to be a genus of bacteria responsible for driving bone protective effects.

The high blackcurrant group also observed an abundance in six microbial species, which are known to contribute to a healthy gut ecosystem.

4. Antioxidant Effects: The antioxidant properties of berry polyphenols also contribute to gut health. Polyphenols help neutralize free radicals and reduce oxidative stress, which can otherwise damage gut cells and disrupt barrier function. A 2019 study7 demonstrated that the antioxidant activity of berry polyphenols helps protect gut cells from oxidative damage and supports overall gut health.

Overall, berry polyphenols contribute to gut health by modulating the gut microbiota, reducing inflammation, enhancing barrier function, and providing antioxidant protection. These mechanisms collectively support a healthy and functional gastrointestinal system.

Fleur Cushman is the founder of Health Currancy / CurraNZ Ltd, a New Zealand blackcurrant nutraceutical supplement company, based in the UK and NZ.

References

1. The ability of blackcurrant extracts to positively modulate key markers of gastrointestinal function in rats. World J. Microbiol. Biotechnol. 2010;26:1735–1743. doi: 10.1007/s11274-010-0352-4. https://doi.org/10.1002/mnfr.202001090

   BC anthocyanins improve lipid metabolism and modulate gut microbiota in high-fat diet-induced obese mice, 2021  

2. 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 et al https://www.tandfonline.com/doi/full/10.1080/15502783.2023.2187955 [In review]

3. New Zealand blackcurrant extract modulates the heat shock response in men during exercise in hot ambient conditions. European Journal of Applied Physiology https://doi.org/10.1007/s00421-024-05439-w, February 2024 Nathan J. Conrad et al

4.  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

5. Blackcurrants shape gut microbiota profile and reduce risk of postmenopausal osteoporosis via the gut-bone axis: Evidence from a pilot randomized controlled trial, 2024, Nutritional Biochemistry https://doi.org/10.1016/j.jnutbio.2024.109701

6. Berry polyphenols and human health: evidence of antioxidant, anti-inflammatory, microbiota modulation, and cell-protecting effects, https://doi.org/10.1016/j.cofs.2021.06.003