Which diet would you rather follow to protect against heart disease and stroke - the Mediterranean diet, which stresses fish, nuts, olive oil, beans, fresh veggies and wine, or a low-fat diet, which basically makes you cranky and miserable?
We all know the answer to this one, and now science backs us up.
A major study in Spain of nearly 7,450 adults ages 55 to 80 who were at high risk for heart disease found that those who followed a Mediterranean diet had a 30 percent lower overall risk of heart disease, particularly strokes. The control group, which followed a low-fat diet, not only had more heart problems; they also dropped out of the study at higher rates, suggesting the diet was harder to stick with.
The study, published online today in the New England Journal of Medicine, was the first major clinical trial to test the benefits of a Mediterranean diet on heart disease. Health and nutrition experts quickly praised the new research, saying the study's size and focus on patients who were already at risk of heart disease offered powerful proof of the diet's protective effects.
"Really impressive," Rachel Johnson, Ph.D., professor of nutrition at the University of Vermont and spokeswoman for the American Heart Association, told the New York Times. What was most impressive, she said, was that the researchers didn't look at whether the diet affected risk factors but whether it actually reduced "heart attacks and strokes and death. At the end of the day, that is what really matters."
Lead researcher Ramon Estruch, M.D., senior consultant at the Hospital Clinic of Barcelona, said the findings should encourage physicians to urge their patients who are overweight or have diabetes or other risk factors for heart disease to follow a Mediterranean approach. "As a doctor it is easier to say take a pill," Estruch said in the Boston Globe. "But diet is a very powerful effect in protecting against cardiovascular disease."
The study's subjects had no cardiovascular disease when they began the study, though they did have either type 2 diabetes or least three major risk factors for heart disease, including smoking, high blood pressure, high cholesterol, obesity or a family history of heart problems.
Estruch and his researchers randomly assigned subjects to one of three groups: one that ate a Mediterranean diet that included extra olive oil (at least four tablespoons a day); another that also followed the Mediterranean diet but were told to eat one additional ounce daily of walnuts, hazelnuts and almonds; and the control group, which was told to eat a low-fat diet that did not include olive oil or nuts.
In addition, the Mediterranean-diet groups were instructed to eat at least three servings of fruits and at least two of vegetables daily. They had to include both fish and legumes - such as beans, peas or lentils - at least three times a week and avoid red meat. They could have a daily glass of wine with meals, but they were cautioned to avoid commercially made sweets and to limit their consumption of dairy products and processed meats.
Participants filled out annual questionnaires about their health and diet. Plus, those in the Mediterranean groups were given urine tests to measure whether they were eating the required amount of olive oil or nuts.
Although a 30 percent reduction is nothing to sneeze at, the actual numbers of people in the study who developed heart disease or died were relatively small. After a follow-up of nearly five years, there were 109 heart attacks, strokes or deaths from heart disease in the low-fat diet (control) group - or about 4.4 percent of the 2,450 participants. By comparison, there were only 83 in the Mediterranean group that ate extra nuts (3.3 percent of those participants), and 96 in the Mediterranean group that consumed extra olive oil, or 3.7 percent.
That means that for every 1,000 people who followed the Mediterranean diet, three each year would avoid a heart attack or stroke because of the diet, the scientists said.
Still, that's equivalent to or slightly better than taking drugs, said Walter Willett, M.D., chairman of the departments of nutrition and epidemiology at the Harvard School of Public Health. "Even the best available drugs, like statins, reduce heart disease by about 25 percent, which is in the same ballpark as the Mediterranean diet," Willett told the Boston Globe. "But the statins increase the risk of diabetes, whereas this diet can help reduce the risk."
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