The early use of breast milk could help prevent heart disease in people who are born prematurely, according to a new Irish-led review.

Being born prematurely can lead to long-term health complications, including heart issues. Young adults who were born prematurely often display unique heart characteristics, such as smaller heart chambers, higher blood pressure and a disproportionate increase in heart muscle mass.

Researchers at the Royal College of Surgeons in Ireland (RCSI) and the Rotunda Hospital carried out a review in this area, with colleagues from the UK, the US and Canada.

They pointed to one study involving 46 adults who had been born prematurely. Thirty of the adults had received only breast milk while in hospital after their birth, while 16 received only formula milk.

All underwent extensive cardiovascular assessments between the ages of 23 and 28. As expected, the heart chambers of those born prematurely were smaller than the chambers found in people who were born full-term.

However, the study found that the smaller heart chambers were less profound in those who had received breast milk exclusively compared to those who received formula milk.

This, the researchers said, suggests that breast milk offers a potentially protective effect within the structure of the heart.

They also identified possible reasons why breast milk is linked with a reduced risk of heart disease. They believe that it could help prevent heart disease by better regulating the body's hormones and growth factors, strengthening the immune system, reducing inflammation and possibly improving metabolism.

According to Prof Afif EL-Khuffash, of the RCSI and Rotunda Hospital, "it is becoming increasingly clear that premature birth results in long-term adverse cardiovascular effects with important clinical consequences".

However despite this, there is a lack of preventative and therapeutic interventions available to alleviate those effects.

"The current evidence comes from observational studies and highlights the strong link between early breast milk administrations and improvement in long-term heart health, but it lacks concrete mechanistic explanations.

"More studies on the composition of breast milk could make clear exactly what causes these health benefits, which could in turn lead to better treatment options," he said.

The review article is published in the journal, Pediatric Research. In the meantime, the researchers are continuing to study the effects of breast milk exposure on the heart function of those born prematurely by using novel scans to measure heart function.