|
July 2, 1999
 News this month
Mediterranean diet: good and good for your heart?
There may be good news for the millions of Americans at risk
for heart disease. A number of recent studies indicate that a typical Mediterranean diet has beneficial effects on coronary artery disease and may actually reduce the risk of sudden death
from heart disease by as much as 20 percent.
The Lyon Diet Heart Study
The latest study, published in March in Circulation, the journal
of the American Heart Association, is a four-year follow-up of more than 600 men and women in France who had experienced a first heart attack, which put them at high risk for a second
attack. About half the participants were advised to eat a Mediterranean-style diet rich in fruits, vegetables, fish, cereals and beans.
...the benefits of the Mediterranean-type diet were so dramatic that the researchers concluded it would be unethical not to give the comparison group a chance to go on it.
After 46 months of follow-up, the control subjects who ate a western diet and the experimental subjects were examined. Body
fat, blood pressure and blood cholesterol levels were very similar, and about 18 percent of each group smoked cigarettes. The group eating the Mediterranean diet had a 50-70 percent lower
risk of mortality due to a reduction in coronary heart disease.
The control group averaged almost 34 percent of total calories from fat with almost 12 percent from saturated fat compared
with 30 percent fat calories and 8 percent saturated fat calories in the other group's diet. The individuals on the Mediterranean
diet consumed more oleic and alpha-linolenic fatty acids, the omega-3 fatty acids found in high amounts in canola, olive and certain nut oils. The control group consumed more linoleic or
omega-6 fatty acids found in soya and sunflower oils. Dietary fiber intake was about three grams higher in the Mediterranean group than the control group indicating a higher intake of
antioxidants and B vitamins found in fruits and vegetables, all of which may slow the arterial damage that precedes heart disease.
One interesting finding of the Lyon study was that although the project was officially terminated after 27 months, the benefits
of the Mediterranean-type diet were so dramatic the researchers concluded it would be unethical not to give the comparison group a chance to go on it. Michel de Lorgeril, MD, who headed the
research project, says, "By making some simple dietary changes that are easy to understand and easy to follow a person can improve his or her chances of avoiding a second heart attack
and having a better quality of life."
The GISSI Prevention Trial
At the annual meeting of the American College of Cardiology in
New Orleans in April, Dr. Roberto Marchioli of Milan, Italy, said fish oil consumption significantly reduced death. In a study of 11,372 patients who had had heart attacks, fish oil
supplements reduced the risk of dying by 20 percent after a 3.5 year follow-up.
Italian researchers say the patients daily supplemented their diet with either placebo pills or one-gram capsules containing oils
found in sea fish such as salmon, bluefish, tuna, sardines and herring.
The researchers said the death rate in the patients getting placebo was 10.1 percent, while the rate in those taking fish oil was 8.1 percent, representing a risk reduction of 20 percent.
Vitamin E supplements, also administered in the study, did not show as strong a protective effect.
Patients who took the fish oil had a 10 to 15 percent reduction in all clinical events monitored in the trial, but almost all of that
reduction occurred in the reduction of overall mortality. The trend for reduction in mortality among those taking 300 milligrams a day of Vitamin E was about five percent, which is
not statistically significant.
|
Evidence points to Mediterranean diet benefits
Over the past few years, a lot of attention has
been paid to the health benefits of a variety of diets. Some seem to contradict others, and many people are confused about which advice makes sense for them. Low fat, no fat, good fat, bad fat.
...even though Italians have higher cholesterol levels than Americans, they have a lower risk of dying from heart disease.
It's difficult to determine how to change our diets to benefit our health without sacrificing foods we can
enjoy with our families. The Lyon Heart Study is one of two recent studies that highlight the benefits of a Mediterranean-style diet for those at risk for heart disease.
Omega-3 fatty acids: the good fat
This study and another presented at the American College of Cardiology, the GISSI Prevention Trial, corroborate other evidence underscoring the
benefits of omega-3 fatty acids. In the Lyon study, individuals who ate a diet high in these fatty acids, which are found in canola, olive and fish oils, were
50 to 70 percent less likely to suffer a repeat heart attack. In the GISSI Prevention Trial, participants who took a gram of fish oil per day reduced their
risk of a second heart attack by 10 to 15 percent and reduced their risk of dying during the four-year follow-up period by 20 percent.
We don't yet understand the biochemical basis for this benefit, but it is interesting to note that even
though Italians have higher cholesterol levels than Americans, they have a lower risk of dying from heart disease. One possible explanation for this
discordance is that ingestion of omega-3 fatty acids provide anti-arrhythmic benefits. Somehow this substance reduces the incidence of sudden death from disruptions in the heart's rhythm.
Contributing factors
Of course, there are additional differences in the typical Italian diet. Many Italians drink moderate amounts of red wine, which provide both
antioxidant and anticlotting properties. A substance in the skins of red and possibly purple grapes may reduce the risk of arterial clogging by keeping LDL
(bad) cholesterol from attaching to coronary arteries. Most Italians also consume higher percentages of grains, fruits and vegetables as well
. And we can't rule out stress: most Italians take four to five weeks of vacation each year compared to the typical American two-week break.
My recommendations
I consider the fish oil evidence convincing enough to recommend eating fish three times a week to my patients. For patients who have already had a heart
attack, I suggest an additional gram of fish oil by tablet each day. I also suggest what I call "high-color" vegetables: red, green and yellow peppers,
broccoli and tomatoes for their antioxidant properties and red wine in moderation, about two ounces a day.
To avoid weight gain from consuming high-fat fish
such as salmon, sardines, tuna, bluefish or swordfish, which are also high in calories, I strongly recommend moderate exercise. Twenty to 30 minutes a day of exercise, vigorous enough to
result in a light sweat, will not only counteract consuming a few more hundred calories, it also has enormous overall health benefits.
Dr. Mukherjee is a partner with Cardiology Associates of New Haven, 40 Temple Street
, New Haven, CT. He is an attending physician at Yale-New Haven Hospital and an assistant clinical professor of medicine and cardiology at the Yale School of Medicine.
|
