London: The Mediterranean diet, believed to
be the healthiest in the world, may not be that good for
certain people as it may raise their risk of heart attacks, a
new study has claimed.
It has long been thought that a diet rich in olive oil,
nuts and oily fish is good for health because it can reduce
the levels of bad cholesterol, which is blamed for clogging
arteries and increasing the risk of heart attacks.
But researchers at University of Rochester, New York,
found that some heart attack patients may have genetic
mutations that mean the diet increases their risk of suffering
further cardiac problems, the Telegraph reported.
They 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
They also had more of a protein known as CRP which causes
inflammation -- suggesting this influences whether good
cholesterol protects or endangers individuals.
For their study, the first to find supposedly good
cholesterol can harm a subgroup of people; the researchers
followed 767 heart patients for two years. They found that
about 20 per cent of the patients at high risk of another
heart attack also had high levels of HDL and CRP.
Lead researcher Prof James Corsetti 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."
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.
In 2006, pharma company Pfizer had to halt the trial due
to a surprisingly excessive number of unexplained heart
attacks and deaths that were linked with higher levels of good
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
"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, they said.
In the high-risk subgroup of patients they also identified
two genes associated with recurrent heart attacks -- CETP that
moves cholesterol away from the vascular system and is liked
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."