Mediterranean diet could raise risk of heart attacks

Eating a Mediterranean diet to boost levels of good cholesterol could in fact be bad for some people, research indicates.

It has long been thought that a diet rich in olive oil, nuts and oily fish is good for health because it can reduce bad cholesterol levels.

However, a study suggests that some heart attack patients may have genetic mutations that mean the diet increases their risk of suffering further cardiac problems.

It found that those at most risk of suffering subsequent heart attacks had large amounts of the high-density lipoprotein (HDL), or 'good' cholesterol', in their blood that destroys unhealthy trans fats in foods such as biscuits and cakes.

They also had more of a protein known as CRP which causes inflammation – suggesting this influences whether good cholesterol protects or endangers individuals.

The findings, published in Arteriosclerosis, Thrombosis, and Vascular Biology, could also explain disappointing results from a trial of an experimental drug called torcetrapib designed to increase HDL cholesterol.

Manufacturers Pfizer had to halt it in 2006 due to a surprisingly excessive number of unexplained heart attacks and deaths that were linked with higher levels of good cholesterol.

Pathologist Professor James Corsetti, of the University of Rochester, New York, said: "It seems counter-intuitive that increasing good cholesterol – which we've always thought of as protective – leads to negative consequences in some people.

"We've confirmed high HDL cholesterol is in fact associated with risk in a certain group of patients."

Out of 767 patients followed for two years, about 20 per cent at high risk of another heart attack also had high levels of HDL and CRP – the first study to find supposedly good cholesterol can harm a subgroup of people.

Co-researcher Prof Charles Sparks said: "The ability to identify patients who will not benefit from efforts to increase HDL cholesterol is important because they can be excluded from trials testing medications that aim to raise HDL cholesterol.

"With these patients excluded researchers may find raising HDL cholesterol in the remaining population is effective in reducing cardiovascular disease risk."

The researchers believe genetics and environmental factors – particularly inflammation – decide what effect good cholesterol has on patients.

Given an inflammatory environment a person's unique set of genes determines whether HDL transforms from good to bad in the heart disease process.

In the high-risk subgroup of patients they also identified two genes associated with recurrent heart attacks – CETP which moves cholesterol away from the vascular system and is associated with HDL and p22phox which influences inflammation-related processes and is associated with CRP.

Prof Corsetti said: "Our research is oriented around the ability to better identify patients at high risk.

"Identifying these patients and determining what puts them at high risk may be useful in choosing treatments tailored to the specific needs of particular patient subgroups. This gets us another step closer to achieving the goal of personalised medicine."

Despite the outcome of the torcetrapib trial drug companies are continuing to develop drugs to increase HDL cholesterol.

Merck recently announced plans to launch a major clinical trial in 2011 to test whether anacetrapib – a chemical cousin of torcetrapib designed to raise good cholesterol – reduces the risk of heart attack and death.

Source http://www.telegraph.co.uk/health/healthnews/7769483/Mediterranean-diet-could-raise-risk-of-heart-attacks.html