A compound produced in the body after eating foods such as pomegranates, walnuts and some berries improved measures of heart function by up to 80% in animal models of heart failure, according to a new study from researchers at King's College London.

Published in Science Advances, the study found that urolithin A helped stiff heart tissue relax, reduced scarring and limited harmful enlargement of heart muscle.

The findings, published September 28, 2026, could be important for people with heart failure with preserved ejection fraction (HFpEF), a condition in which the heart can still pump blood but has difficulty relaxing and filling properly. Researchers also tested the compound in engineered human heart tissue, where it improved the tissue's ability to relax.

HFpEF accounts for about half of heart failure cases in the UK and affects nearly half a million people there, according to the study material. The condition can cause shortness of breath, tiredness, reduced ability to exercise, and a lower quality of life.

Unlike some forms of heart failure where the heart struggles to pump blood, people with HFpEF can have a heart that pumps normally but has become too stiff. This means the heart cannot relax enough between beats to fill properly.

The condition can develop alongside aging, high blood pressure, and diabetes. Because of its complex causes, treatment options remain limited, with doctors often focusing on controlling the conditions that contribute to it and recommending lifestyle changes.

Dr. Joseph Burgoyne, senior author of the study at King's College London, said the problem is becoming more common as populations age and rates of obesity and diabetes increase.

"This type of heart failure is becoming increasingly common as populations age and rates of obesity and diabetes rise. Despite its growing burden, treatment options remain limited because the disease is complex and varies considerably between patients," Burgoyne said.

The researchers investigated how urolithin A works inside heart tissue. They found that the compound activates a protein called PKG1α, which has an important role in blood vessel function and the relaxation of heart muscle.

Representational image showing a girl holding the pomegranate. AI Generated/IBT SG

In animal models, treatment with urolithin A improved measures of heart function by as much as 80% compared with untreated models. The researchers also found less fibrosis, or harmful scarring, in the heart tissue.

The compound also reduced abnormal enlargement of heart muscle cells. These changes are important because excessive stiffness, scarring, and enlargement can interfere with the heart's ability to work normally.

The study did not stop with animal experiments. Researchers also tested urolithin A using engineered human heart tissue made from human stem cells.

The laboratory tissue model is designed to closely reproduce important features of human heart muscle. In these experiments, urolithin A significantly improved the tissue's ability to relax, suggesting that the biological effect seen in animals may also be relevant to human heart function.

However, this does not mean the compound has been proven to treat heart failure in people. The researchers said additional studies and clinical trials are still needed before urolithin A could become a treatment for patients.

This is where the study needs to be understood carefully.

Although urolithin A is produced in the body after consuming foods including pomegranates, walnuts, and some berries, the research does not show that eating those foods can treat or reverse heart failure.

Burgoyne specifically warned against interpreting the findings as evidence that people should eat pomegranates as a treatment.

"While there isn't enough evidence to suggest that people should eat pomegranates to treat heart failure, these findings raise the possibility that dietary approaches that enhance urolithin A production may help alleviate this condition," Burgoyne said.

Urolithin A has already been studied in humans and has shown a favorable safety profile, according to the study material. But safety evidence is different from evidence that the compound can successfully treat HFpEF.

Professor James Leiper, director of research at the British Heart Foundation, said the findings are encouraging but remain at an early stage.

"While these findings are promising, the benefits have so far been seen in animals and engineered human tissue, so clinical trials involving people are needed to test if this approach is effective for patients," Leiper said.

He also stressed that no single food should be viewed as a treatment for heart disease.

"In the meantime, a healthy, balanced diet remains one of the best ways to look after your heart. Eating plenty of fruit and vegetables is linked to better heart health, but it's important to remember that no single food can prevent or treat heart disease on its own," Leiper said.

The study was funded by the British Heart Foundation. The next step is to determine whether the improvements seen in animals and engineered human tissue can be reproduced safely and effectively in people with HFpEF.