CurraNZ leads the evidence base for enhancing metabolic flexibility - and women are the biggest winners

A major new paper has just landed – and it’s a landmark moment for CurraNZ.

A systematic review and meta-analysis (1) in the Journal of Dietary Supplements has pooled all the human exercise studies using CurraNZ New Zealand blackcurrant extract - the trusted global science leader - and confirms what athletes have been feeling for years: CurraNZ helps the body burn more fat and less carbohydrate during exercise.

Why This Paper Matters: Top-Tier Evidence

In nutrition science, not all evidence carries the same weight. This new publication by Cook, Bateman and Willems is a systematic review and meta-analysis, which sits at the top of the evidence hierarchy.

A systematic review uses a pre‑registered, comprehensive search strategy to find and screen every eligible study on a topic, minimising bias and cherry‑picking.

A meta-analysis then statistically combines the data from those trials to calculate an overall effect size, giving the clearest picture yet of how reliable and meaningful the results are.

Crucially, every single study included used CurraNZ, so the conclusions speak directly to our product and its effects on exercise metabolism.

How the Research Was Done

The authors searched major scientific databases (PubMed, Web of Science, SPORTDiscus), working from a pre‑registered protocol  and following PRISMA/PERSiST reporting guidelines.

 To make the cut, studies had to:

·      Test blackcurrant supplementation in healthy, physically active adults aged 18–65

·      Measure absolute rates of fat and carbohydrate oxidation during exercise (in g·min⁻¹).

·      Include a placebo or control condition for comparison. 

What they found: 

·      15 studies, 226 participants (192 men, 34 women).

·      All used New Zealand blackcurrant extract CurraNZ™, with the final dose taken 2 hours before the exercise test.

·      Exercise modes: 6 cycling studies, 9 treadmill walking/running studies.

·      Dosing: Most used 210 mg/day anthocyanins for 7 days, with some studies testing 105–315 mg/day and intake from a single acute dose up to 14 days.

The team used a random‑effects meta-analysis, which accounts for differences between study designs and populations, to calculate the overall effect of CurraNZ on fat and carbohydrate use during exercise.

The Headline Results: More Fat, Less Carbs

Across all 15 trials, CurraNZ produced a clear and statistically significant shift in exercise fuel use.

·      CurraNZ Increases Fat Oxidation

·      Average increase in fat oxidation: +0.042 g·min⁻¹ (95% CI 0.017–0.068; p < 0.001).

Heterogeneity (variation between studies) was ~39.5%, which is considered low–moderate, indicating a fairly consistent effect despite different exercise modes and protocols.

Translating that into something more tangible: over a 2‑hour steady‑state session, this average effect equates to roughly an extra ~5 grams of fat oxidised, consistent with individual trials showing higher total fat use across 120 minutes of cycling at 65% VO2max 

CurraNZ Reduces Carbohydrate Oxidation

Average reduction in carbohydrate oxidation: −0.099 g·min⁻¹ (95% CI −0.176 to −0.022; p = 0.012).

Heterogeneity was ~50.1%, meaning the size of this effect varied more between studies, but the overall direction remained clear.

 Together, these findings confirm a meaningful metabolic rebalancing during exercise with CurraNZ on board: greater reliance on fat, lower reliance on carbohydrate.

Not Everyone Responds the Same Way

The meta-analysis also underlines something we see on the ground with athletes: individual responses vary.

Of the 15 studies, eight showed statistically significant changes in substrate oxidation; seven reported no meaningful group‑level effect, even though the pooled result was positive.

Other work cited in the paper shows that in women, the magnitude of the fat‑oxidation increase appears to correlate with body fat percentage – those with higher body fat tended to show larger shifts.

Individuals who are more carbohydrate‑dependent at baseline (higher respiratory exchange ratio, or RER, under placebo) seem to be bigger responders when they supplement with CurraNZ.

In practical terms, the CurraNZ “sweet spot” appears to be active people who naturally lean on carbs heavily during steady aerobic work and those targeting improved metabolic efficiency and body composition.

What This Means for Everyday Athletes and Health‑Conscious Consumers

For runners, cyclists, gym‑goers and weekend warriors, this meta-analysis provides strong, top‑tier evidence that CurraNZ is a credible tool to support better metabolic flexibility – your body’s ability to tap into fat more effectively during exercise.

Why that matters:

Higher fat oxidation is associated with improved endurance and better preservation of limited carbohydrate stores in long events.

Independent research cited in the paper shows that training at intensities that maximise fat oxidation can reduce body mass, fat mass and abdominal fat over a 10‑week period, highlighting the value of a more fat‑reliant engine.

How CurraNZ Was Used in the Studies

The research protocols look very much like how many customers already use CurraNZ:

·      Dose: Typically 210 mg/day - two capsules of CurraNZ.

·      Duration: 7 days of daily intake, with some studies extending to 14 days or exploring 105–315 mg/day.

·      Timing: Last dose taken 2 hours before the key exercise bout.

·      Exercise: 30–120 minutes of walking, running or cycling at moderate intensity (often 50–65%˙VO2max or at lactate threshold).

An Honest Look at the Limitations

The authors are careful – and we agree – not to over‑claim.

·      All included studies used the same standardised CurraNZ extract. We can’t assume identical effects from generic blackcurrant or berry products, juices or non‑standardised powders with different anthocyanin profiles.

·      Participants were healthy, physically active adults; we still need more data in sedentary individuals, older adults and clinical populations, although separate work has already shown increased resting fat oxidation after 14 days of CurraNZ in healthy men.

·      This meta-analysis focuses on substrate use, not race results. Other CurraNZ performance trials and case studies are highly encouraging, but direct performance outcomes were not the primary target here.

·      Some methodological details (such as randomisation procedures and pre‑registered analysis plans) were not consistently reported across all trials, even though the core measurements (gas exchange, oxidation rates) are objective.

The Take-Home

This new meta-analysis marks a key milestone in the CurraNZ story. Across 15 controlled trials in active adults, our New Zealand blackcurrant extract consistently shifted exercise metabolism towards greater fat use and lower carbohydrate use – and did so strongly enough to stand up at the highest level of scientific scrutiny.

Used alongside smart training, good nutrition and proper recovery, CurraNZ now has stronger backing than ever as a daily tool for athletes and health‑conscious consumers who want to get more from every session.

Reference

Cook, M. D., Bateman, J. J., & Willems, M. E. T. (2026). Blackcurrant Anthocyanin Supplementation Alters Exercise-Induced Substrate Utilization - A Systematic Review and Meta-Analysis. Journal of Dietary Supplements, 1–16. https://doi.org/10.1080/19390211.2026.2624114