A compound produced by gut microbes after consuming foods such as pomegranates improved measures of heart function by up to 80% in early tests, giving researchers a potential new target for a difficult-to-treat form of heart failure.
The compound urolithin A is produced when gut microbes break down ellagitannins, natural compounds found in pomegranates, walnuts, and some berries. Researchers at King's College London found that urolithin A improved the heart's ability to relax in experimental models of heart failure with preserved ejection fraction, or HFpEF.
HFpEF occurs when the heart can still pump blood normally but becomes stiff and has difficulty relaxing between beats. The condition accounts for about half of all heart failure cases and can cause breathlessness, fatigue, and reduced ability to exercise. Treatment options remain limited.
But there is an important caveat: the study does not show that eating pomegranates treats heart failure. The reported 80% improvement was observed in experimental models treated with urolithin A.
What Happens to The Heart in HFpEF?
Heart failure does not always mean the heart has stopped pumping effectively.
In HFpEF, the heart's squeezing function can remain relatively normal while the muscle becomes stiff. This makes it harder for the chambers to relax and fill with blood between contractions.
The condition can develop alongside factors such as aging, high blood pressure, and diabetes. Because the underlying disease involves several different processes, finding treatments that directly improve the heart's ability to relax remains a challenge.
That is where the new research into urolithin A comes in.
A Pomegranate-Linked Compound Targeted Heart Relaxation
The researchers investigated how natural compounds might affect PKG1α, a protein involved in blood vessel function and heart muscle relaxation.
They found that urolithin A targets a specific amino acid on the protein, activating a pathway involved in cardiovascular function.
In animal models of HFpEF, treatment with urolithin A improved measures of heart function by up to 80% compared with untreated models.
The researchers also observed improved relaxation of heart tissue, reduced fibrosis (harmful scarring), and reduced enlargement of heart muscle cells. These changes are important because stiffening, scarring, and abnormal enlargement can all contribute to worsening heart dysfunction.
The findings suggest that urolithin A may influence several of the changes associated with HFpEF rather than addressing just one symptom.
Researchers Tested the Compound on Human Heart Tissue
The study went beyond animal experiments.
Researchers tested urolithin A on engineered human heart tissue made from human stem cells. The laboratory model was designed to reproduce important features of human cardiac muscle.
When the tissue was treated with urolithin A, its ability to relax improved significantly. This provided additional evidence that the biological effect observed in animal models could potentially be relevant to human heart tissue.
However, engineered heart tissue is still a laboratory model. It cannot replicate all the biological processes that occur in a living person.
That means the results are encouraging, but they are not yet evidence that urolithin A improves heart function in people with HFpEF.
What Does the 80% Improvement Actually Mean?
The 80% figure is likely to attract attention, but it needs context.
Researchers measured improvements in heart function in experimental models that received urolithin A. They did not give pomegranates to people with heart failure and observe an 80% improvement in their heart function.
The distinction matters because eating a food containing ellagitannins does not guarantee that the body will produce a particular amount of urolithin A.
The process depends partly on the gut microbiome, which differs from person to person.
Urolithin A has previously been investigated in human studies and has shown a favorable safety profile, according to King's College London. But those findings do not establish that it is an effective treatment for HFpEF.
Clinical trials involving people with HFpEF will still be needed to determine whether the compound can produce meaningful improvements in patients.
Another Study Offers Clues About Urolithin A
The new findings add to the growing body of research on urolithin A and cardiovascular health.
A separate 2026 study published in Experimental & Molecular Medicine examined the compound in a mouse model of HFpEF. Researchers reported improvements in diastolic dysfunction, cardiac enlargement, and fibrosis, and linked these effects to changes in mitophagy, the process cells use to remove damaged mitochondria.
Together, the research suggests that urolithin A may affect several biological pathways involved in heart remodeling and dysfunction.
However, findings from animal studies cannot establish whether the same benefits will occur in humans.
Could Eating Pomegranates Protect the Heart?
The research does not provide enough evidence to say that eating pomegranates can prevent or treat heart failure.
Pomegranates contain ellagitannins, which can be converted by certain gut microbes into urolithin A. But consuming the fruit is not the same as receiving a standardized dose of the compound used in laboratory experiments.
Even the researchers behind the study emphasized that there is insufficient evidence to support eating pomegranates specifically as a treatment for heart failure.
That does not make the food connection irrelevant. Instead, it highlights an emerging area of research on how substances produced by interactions between diet and the gut microbiome might affect human health.
A New Lead for a Difficult-to-Treat Heart Condition
For now, urolithin A remains a research candidate rather than a treatment for heart failure.
The King's College London study provides evidence that the compound can activate a previously identified cardiovascular pathway and improve heart relaxation in animal models and engineered human heart tissue. Researchers now need to determine whether those effects translate into real benefits for patients with HFpEF.
The discovery also offers an intriguing reminder that the health effects of food can extend beyond the nutrients it contains. In this case, scientists are investigating what happens when compounds in a familiar fruit interact with the microbes living in the gut.
The pomegranate itself is not the treatment. The compound it can help the body produce may be the more important discovery.
