Blackcurrant Extract Enhances Elite Athlete Blood Flow & Fuel Use

The Cardiovascular Engine: A Case Study on Fuel Use and Blood Flow

Training for a marathon places extraordinary demands on the cardiovascular system, which must efficiently deliver oxygen and fuel to working muscles for hours. Recent research provides a detailed look at how a specific dietary supplement, anthocyanin-rich blackcurrant extract, influenced these processes in an elite endurance athlete. A 2026 case study from researchers at Mahidol University and the University of Chichester monitored an athlete’s cardiovascular and metabolic responses during Zone 2 running, offering insights into the complex interplay between fuel selection, cardiac output, and vascular function.

Blackcurrant Extract Alters Fuel Selection and Heart Function

In the study led by MET Willems and A. Nana, a 48-year-old elite female marathoner consumed 420 mg of anthocyanins from blackcurrant extract daily for one week. Two hours after her final dose, she performed a one-hour treadmill run at 50% of her VO2max—a classic Zone 2 intensity. Using precise beat-to-beat hemodynamic and gas analysis technology, the team captured clear differences from a placebo condition.

During the run, the athlete’s stroke volume—the amount of blood ejected per heartbeat—was 9% higher with the extract. Combined with a stable heart rate, this led to a 10% greater cardiac output, meaning more blood was circulated each minute. Simultaneously, systemic vascular resistance, a measure of how hard the heart must work to push blood through the vessels, dropped by 24%. This combination suggests the extract may promote vasodilation, improving blood flow efficiency to muscles. This mechanism shares a conceptual link with the vascular benefits explored in research on yogic breathing for cardiovascular health.

A Shift Towards Carbohydrates and a Drastic Lactate Drop

The most pronounced metabolic change was a 43% increase in carbohydrate oxidation during the run with the blackcurrant extract. Correspondingly, fat oxidation decreased by 7%, and the respiratory exchange ratio rose, confirming a shift toward using more carbs for fuel. This shift occurred despite the exercise intensity remaining constant, indicating a change in the muscle’s intrinsic fuel preference.

Perhaps the most striking result was the post-exercise blood lactate measurement. Lactate concentration was 1.7 mMol/L after the placebo run but only 0.7 mMol/L after the run with the extract—a 59% reduction. In Zone 2 training, lower lactate at a given pace is often associated with better aerobic efficiency and endurance capacity. This finding connects to a broader body of work on lactate and brain health in Zone 2 training and lactate clearance mechanisms.

Interpreting the Cardiovascular and Metabolic Trade-Off

The observed effects present a fascinating physiological puzzle. Improved cardiac output and lower vascular resistance are typically beneficial for endurance, reducing the cardiac strain of prolonged exercise. The dramatic drop in post-run lactate is also a positive signal, potentially linked to better lactate clearance or a different metabolic handling of glucose.

However, the strong shift toward carbohydrate oxidation could be a double-edged sword. For marathoners relying on finite glycogen stores, burning carbs 43% faster could risk “hitting the wall” sooner if not managed with nutrition. The authors caution that the mechanisms are unclear and note the critical limitation: this is a case study of one athlete. The responses of this 48-year-old, heat-acclimatized, elite female may not generalize to other populations. The exploratory design means we should view these as preliminary observations, not established facts.

Practical Considerations for Endurance Athletes

For athletes interested in the potential of blackcurrant extract, this study suggests a protocol of 420 mg of anthocyanins daily for at least seven days. The cardiovascular changes indicate its primary action may be vascular, improving blood flow to enhance oxygen and nutrient delivery. The lactate-lowering effect could be valuable for sustaining pace in long training sessions or improving recovery between workouts.

It is vital to contextualize this with other nutritional strategies. For instance, the shift in fuel use differs from the effects of ketone esters, which aim to spare glycogen. Athletes should consider their individual training goals—whether maximizing fat adaptation or optimizing high-intensity carbohydrate utilization—before adopting any supplement. As always, evidence from a single subject cannot replace personalized experimentation and professional guidance.

Frequently Asked Questions

Does this mean blackcurrant extract will improve my marathon time?

Not necessarily. This case study showed altered physiology in one elite athlete, but it did not measure race performance. The observed changes, like higher cardiac output and lower lactate, could be beneficial, but the increased reliance on carbohydrates might require careful fuel management during a race.

Why did lactate drop if carbohydrate use went up?

This is the central question from the research. The authors propose that the extract may improve the efficiency of carbohydrate metabolism or enhance lactate clearance from the blood, but the exact mechanism remains unknown and requires further investigation.

Should I take blackcurrant extract for my Zone 2 training?

It may be an option to experiment with, understanding it’s not a guaranteed “boost.” Given it’s a single-case study, the effects for the average trainee are unpredictable. Focus first on consistent training, as methods like remote concurrent training can reliably build metabolic fitness.

Sources:
https://pubmed.ncbi.nlm.nih.gov/42460269/
https://pubmed.ncbi.nlm.nih.gov/41936375/
https://pubmed.ncbi.nlm.nih.gov/41843336/