The shorter you are- the more your risk of coronary heart disease.

That's the key finding of a new study led by the University of Leicester which discovered that every 2.5 inches change in your height affected your risk of coronary heart disease by 13.5%. For example, compared to a 5ft 6inch tall person, a 5 foot tall person on average has a 32% higher risk of coronary heart disease because of their relatively shorter stature.

The research, led by Professor Sir Nilesh Samani, British Heart Foundation Professor of Cardiology at the University of Leicester, is published online in the New England Journal of Medicine. The research was supported by the British Heart Foundation, The National Institute for Health Research (NIHR) and others.

Professor Samani said: "For more than 60 years it has been known that there is an inverse relationship between height and risk of coronary heart disease.

"It is not clear whether this relationship is due to confounding factors such as poor socioeconomic environment, or nutrition, during childhood that on the one hand determine achieved height and on the other the risk of coronary heart disease, or whether it represents a primary relationship between shorter height and more coronary heart disease.

"Now, using a genetic approach, researchers at the University of Leicester undertaking the study on behalf of an international consortium of scientists (the CADIoGRAM+C4D consortium) have shown that the association between shorter height and higher risk of coronary heart disease is a primary relationship and is not due to confounding factors."

Coronary heart disease is the commonest cause of premature death worldwide. It is the condition where the arteries that supply blood to the heart muscle (coronary arteries) become narrowed due to a deposition of fatty material (plaque) in the walls of the arteries. If a blood clot forms over the plaque then the artery can become completely blocked suddenly giving rise to a heart attack.

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Professor Samani, who is also Head of the Department of Cardiovascular Sciences at the University of Leicester and a Consultant Cardiologist at Leicester's Hospitals, added: "Height has a strong genetic determination and in the last few years a large number of genetic variants have been identified in our DNA that determines one's height.

"The beauty about DNA is that it cannot be modified by one's lifestyle or socio-economic conditions. Therefore if shorter height is directly connected with increased risk of coronary heart disease one would expect that these variants would also be associated with coronary heart disease and this is precisely what we found."

Dr Christopher Nelson, British Heart Foundation-funded lecturer who undertook the analysis said: "We had genetic data through the CARDIoGRAM+C4D consortium on almost 200,000 persons with or without coronary heart disease. We examined whether 180 genetic variants that affect height also associated with coronary heart disease. In aggregate, we found that for every change in height of 6.5 cm (approx. 2.5 inches) caused by these variants the risk of coronary heart disease changed on average by 13.5%.

"The more height increasing genetic variants that you carry the lower your risk of coronary heart disease and conversely if you were genetically shorter the higher your risk."

Dr Nelson added: "We also examined whether the association we found between shorter height and higher risk of coronary heart disease could be explained by an effect of height on known risk factors for coronary heart disease like cholesterol, high blood pressure, diabetes etc. We only observed an association with cholesterol and fat levels which could explain a small proportion (less than a third) of the relationship between shorter height and coronary heart disease. The rest is probably explained by shared biological processes that determine achieved height and the development of coronary heart disease at the same time."

Professor Jeremy Pearson, Associate Medical Director at the BHF, which part-funded the study, said: "By using the power of very large scale genetic studies, this research is the first to show that the known association between increased height and a lower risk of coronary heart disease is at least in part due to genetics, rather than purely down to nutrition or lifestyle factors. The team has identified several ways that naturally occurring gene variations can control both a person's height and their risk of coronary heart disease. Further exploration of these genes may suggest new ways to reduce the risk of heart and circulatory disease."

Professor Samani concluded: "While we know about many lifestyle factors such as smoking that affect risk of coronary heart disease, our findings underscore the fact that the causes of this common disease are very complex and other things that we understand much more poorly have a significant impact.

"While our findings do not have any immediate clinical implications, better and fuller understanding of the biological mechanisms that underlie the relationship between shorter height and higher risk of coronary heart disease may open up new ways for its prevention and treatment."