CurraNZ: Helping Your Heart Pump More With Less Effort

If you’re an endurance athlete, you already know that a strong heart and efficient circulation are non‑negotiable. This study asked a very specific question:

Can New Zealand blackcurrant extract (CurraNZ) change cardiovascular function in well‑trained endurance cyclists at rest – and does a higher dose create a bigger effect?

Who Was Studied?

• 15 male cyclists, averaging 6-10 hours of riding per week
• Highly trained, with a VO₂max of about 57 mL·kg⁻¹·min⁻¹ - typical of serious club riders and amateur racers

These were not sedentary volunteers - their cardiovascular systems were already adapted by years of training.

What They Took

Each cyclist completed four 7‑day blocks in random order:

• No CurraNZ (control)
• 300 mg/day CurraNZ (1 capsule - 105 mg anthocyanins)
• 600 mg/day CurraNZ (2 capsules - 210 mg anthocyanins)
• 900 mg/day CurraNZ (3 capsules - 315 mg anthocyanins)

On the final day of each block, they came into the lab two hours after a standard breakfast, lay down on their backs, and rested while scientists recorded beat‑to‑beat blood pressure and haemodynamic data for 20 minutes.

The Headline: More Blood Flow, Less Resistance

The deeper cardiovascular variables - the ones that matter for how efficiently your heart and blood vessels are working - changed clearly and consistently.

Cardiac Output: Bigger “Engine” At Rest

Cardiac output is the total volume of blood your heart pumps per minute. After 7 days of CurraNZ:

• 600 mg/day increased cardiac output by ~15% versus control
• 900 mg/day increased cardiac output by ~28% versus control
• Most cyclists showed an increase; effect sizes were moderate to large.
  

For an athlete, that means your heart is moving more blood per minute at rest - without pounding harder - giving your muscles and organs better perfusion even in recovery mode.

Stroke Volume: More Blood Per Beat

Stroke volume is how much blood you eject with each heartbeat. With CurraNZ:

• At 600 mg/day, stroke volume was about 7% higher than control
• At 900 mg/day, it was about 18% higher than control

In simple terms: every beat does more work. For endurance athletes, higher stroke volume is a hallmark adaptation you usually earn through years of training. Here, a week of CurraNZ shifted that baseline further.

Total Peripheral Resistance: Easier Blood Flow

Total peripheral resistance reflects how “tight” or constricted your vascular system is. Lower resistance means easier blood flow, better delivery of oxygen and nutrients, and improved removal of metabolic waste.

With CurraNZ:

• 600 and 900 mg/day both reduced total peripheral resistance by around 20% compared with no supplement

That’s a substantial loosening of the system - your blood vessels allowing flow more freely, without a drop into hypotension or a compensatory increase in heart rate.

Mean Arterial Pressure: A Gentle Drop

The study also saw a dose effect and clear trends for mean arterial pressure (the average pressure in your arteries over a cardiac cycle): some dose comparisons showed reductions of 6-8%, with moderate to large effect sizes.

Taken together, this pattern - more blood pumped, less resistance, slightly lower mean arterial pressure, same heart rate and “headline” blood pressure - points to a cardiovascular system running more efficiently.

What Does This Mean For Athletes?

The researchers highlight several practical implications that matter if you race, train hard, or simply want better health and recovery.

1. Primed For Better Recovery

Post‑exercise recovery depends on how effectively you can:

• Clear lactate and metabolic by‑products
• Deliver oxygen and nutrients to muscles
• Support repair processes

A higher resting cardiac output and stroke volume, combined with lower peripheral resistance, creates a kind of “circulatory tailwind” for these processes.

While this particular study measured rest rather than post‑exercise recovery directly, the authors note that such haemodynamic changes may enhance recovery in athletes by improving blood flow and volume pumped when you’re off the bike or out of your running shoes.

2. Support For Circulation‑Limited Populations

Although the study was done in healthy endurance‑trained men, the pattern of increased cardiac output and reduced vascular resistance has obvious implications for people with compromised circulation – for example, those with cardiovascular risk factors or conditions affecting blood flow.

The authors specifically suggest that New Zealand blackcurrant extract may be beneficial in clinical populations affected by reduced circulation, building on wider epidemiological data linking flavonoid intake to lower cardiovascular disease risk.

3. Dose Matters – Up To A Point

Because this was a dose‑response study, it answers a key practical question for athletes considering CurraNZ:

Benefits grew from 300 to 600 mg/day, but tended to plateau between 600 and 900 mg/day for many cardiovascular variables.

That suggests there may be a “sweet spot” around 600 mg/day (2 capsules ≈210 mg anthocyanins) for resting cardiovascular improvements, at least in the context of this 7‑day protocol and supine rest.

For athletes, that supports the idea that chasing ever‑higher doses isn’t necessarily better: intelligent dosing within a proven effective range is likely optimal.

How CurraNZ Might Be Driving These Changes

CurraNZ is rich in specific anthocyanins, at concentrations and combinations not present in other berries, that have known vascular effects:

In vitro and animal work shows they can induce vasodilation, protect endothelial function, and modulate endothelial nitric oxide synthase (eNOS).

Anthocyanins are absorbed and reach peak blood levels within about 2 hours, and their metabolites can remain in circulation for up to 48 hours.

Where This Fits In The Bigger CurraNZ Picture

This work adds another piece to a growing body of evidence showing that New Zealand blackcurrant extract:

• Alters cardiovascular function at rest in trained athletes
• Improves blood flow and vascular efficiency
• Does so in a dose‑dependent way up to a mid‑range plateau, supporting practical dosing guidelines rather than “megadosing”

Combined with data on CurraNZ’s effects on endurance performance, lactate handling, fat burning and GI heat stress from other studies, it reinforces a central message:

CurraNZ isn’t just about marginal gains when you’re working hard - it reshapes your underlying physiology in ways that can support better performance, recovery and long‑term cardiovascular health.

Reference

Cardiovascular function during supine rest in endurance‑trained males with New Zealand blackcurrant: a dose–response study, 2016, Eur J Appl Physiol DOI 10.1007/s00421-016-3512-x