By Kathleen Doheny
Eating a diet rich in olive oil, nuts, fresh fruits and vegetables, along with red wine, helped those at high risk for cardiovascular problems avoid heart trouble better than those eating a low-fat diet, a new Spanish study has found.
During a follow-up period of about five years, study participants on a Mediterranean diet that emphasized either olive oil or nuts had a 30 percent greater reduction in relative risk of a heart attack, stroke or death from cardiovascular disease, said study lead author Dr. Miguel Angel Martinez-Gonzalez. He is chairman of preventive medicine and public health at the Universidad de Navarra in Spain.
"This is a moderate-to-high benefit," he said. "The low-fat diet also helped, but to a lesser degree."
The new findings are published online Feb. 25 in the New England Journal of Medicine. They will also be presented Monday at the International Congress on Vegetarian Nutrition in Loma Linda, Calif.
The findings echo those from previous research.
Martinez-Gonzalez's team evaluated nearly 7,500 men and women. They ranged in age from 55 to 80 when they enrolled in the study, which began in Spain in 2003. Fifty-seven percent of the participants were women.
While the men and women had no history of heart attack or stroke or other cardiovascular problems at enrollment, they did have risk factors such as type 2 diabetes, smoking, high blood pressure or high cholesterol.
The researchers assigned the men and women to one of three groups -- a low-fat diet, a Mediterranean diet that focused on nuts or a Mediterranean diet that focused on olive oil.
The olive oil group consumed about four tablespoons a day or more. The nuts group ate about three servings a week or more, including walnuts, hazelnuts and almonds. Members of both groups also ate plenty of fruits and vegetables, as well as fish, and drank wine with meals. They could have white meat but were told to avoid red and processed meats.
The low-fat group ate low-fat dairy, breads, potatoes, fruits and vegetables, and lean fish. They were told to avoid oils, baked goods, nuts, red and processed meat, and fatty fish.
At the end of the study, 288 cardiovascular events had occurred. While 109 of those events occurred in the low-fat group, 96 were in the group that ate a Mediterranean diet with olive oil, and 83 were in the Mediterranean diet-with-nuts group.
When the researchers looked separately at stroke, heart attack and death, only the link between the Mediterranean diet and stroke was statistically significant. The researchers found a link between the diets and heart protection, but it did not prove cause and effect, they said.
So why does the Mediterranean diet seem to boost heart health? Martinez-Gonzalez said it's probably the combination of good-quality fats -- both monounsaturated like olive oil and polyunsaturated like vegetable oils -- and the wide range of other nutrients.
The findings came as no surprise to two U.S. experts.
"I think this is demonstrating again, conclusively, that this is the diet to go on to prevent heart disease," said Dr. Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York City, and a spokeswoman for the American Heart Association's Go Red for Women campaign.
The 30 percent reduction in relative risk, she said, is ''significant."
Alice Lichtenstein, the Stanley Gershoff Professor of Nutrition Science and Policy at Tufts University in Boston, said the new findings are "confirming what we have been saying all along." The findings are strong, she said, due to the number of people studied and the length of the follow-up.
"Essentially, they confirmed what the current recommendations from the American Heart Association and the U.S. Dietary Guidelines are saying," added Lichtenstein, who's also a spokeswoman for the American Heart Association.
However, she said, ''the results of this study do not provide a license to start snacking on nuts or adding nuts to salads and yogurt without taking something out of the diet that has an equivalent number of calories. The same goes for olive oil."
Steinbaum added: "Every time you use butter, just use olive oil instead. Instead of snacking on popcorn, have some nuts."
The California Walnut Commission is a sponsor of the Congress. One study researcher is on the commission's board. Another has received grants from the International Nut and Dried Fruit Council. The Spanish government funded the research.
To learn more about the Mediterranean diet, visit the American Heart Association.