Previous research has already shown that being obese increases blood pressure and cholesterol, both of which are risk factors for heart disease.

This new study, funded by the British Heart Foundation and led by a team from Queen Mary University of London (QMUL), has now also found that obesity could increase the risk of a heart attack by triggering an immune response in the body.

For the research, the team took blood samples from 1,172 lean, overweight or obese people.

They found that obese people had higher levels of a certain type of white blood cell, also known as a T-cell, in their blood.

Essential for immune response, T-cells protect the body from infections. However, they also cause inflammation, making certain cardiovascular diseases worse, as well as contributing to conditions such as atherosclerosis a build-up of fatty plaques in arteries, which can lead to a heart attack or stroke.

In addition, the results also showed that those participants who carried more fat around the middle had higher levels of these cells than those carrying fat on their thighs and bottom.

The team also found the same results in mice, with those fed a high-fat diet also showing higher levels of T-cells, leading the researchers to conclude that it is a high-fat diet—which can lead to obesity—that seems to be causing the harmful inflammation.

The team agreed that more research into the findings is now needed, with Dr. Claudio Mauro commenting, “Our next step is to find out how long these harmful T-cells remain in our blood at high levels. As yet we don’t know whether dieting will bring the levels of these T-cells down and reduce the risk of heart disease or whether once raised, these T-cell levels remain high for life.”

The team added that further research could lead to new treatments that target and prevent this inflammation, lowering a person’s risk of heart disease.

The results can be found published online in the journal Cell Metabolism. JB