Mediterranean diet cuts heart disease risk by nearly half

Adults who closely followed the Mediterranean diet were 47 percent less likely to develop heart disease over a 10-year period compared to similar adults who did not closely follow the diet, according to a study to be presented at the American College of Cardiology's 64th Annual Scientific Session in San Diego.

Among the study's participants, adherence to the Mediterranean diet was more protective than physical activity. The study, conducted in Greece, bolsters evidence from earlier studies pointing to the diet's health benefits and is the first to track 10-year heart disease risk in a general population. Most previous studies have focused on middle-aged people.

"Our study shows that the Mediterranean diet is a beneficial intervention for all types of people--in both genders, in all age groups, and in both healthy people and those with health conditions," said Ekavi Georgousopoulou, a Ph.D. candidate at Harokopio University in Athens, Greece, who conducted the study along with Demosthenes B. Panagiotakos, Ph.D., professor at Harokopio University. "It also reveals that the Mediterranean diet has direct benefits for heart health, in addition to its indirect benefits in managing diabetes, hypertension and inflammation."

The study is based on data from a representative sample of more than 2,500 Greek adults, ages 18 to 89, who provided researchers with their health information each year from 2001 to 2012. Participants also completed in-depth surveys about their medical records, lifestyle and dietary habits at the start of the study, after five years and after 10 years.

Overall, nearly 20 percent of the men and 12 percent of the women who participated in the study developed or died from heart disease, a suite of conditions that includes stroke, coronary heart disease caused by the buildup of plaque in the heart's arteries, acute coronary syndromes such as heart attack, and other diseases. Other studies have shown Greeks and Americans have similar rates of heart disease and its risk factors.

The researchers scored participants' diets on a scale from 1 to 55 based on their self-reported frequency and level of intake for 11 food groups. Those who scored in the top-third in terms of adherence to the Mediterranean diet, indicating they closely followed the diet, were 47 percent less likely to develop heart disease over the 10-year follow-up period as compared to participants who scored in the bottom-third, indicating they did not closely follow the diet. Each one-point increase in the dietary score was associated with a 3 percent drop in heart disease risk.

This difference was independent of other heart disease risk factors including age, gender, family history, education level, body mass index, smoking habits, hypertension, diabetes and high cholesterol, all of which the researchers adjusted for in their analysis.

The analysis also confirmed results of previous studies indicating that male gender, older age, diabetes and high C-reactive protein levels, a measure of inflammation, are associated with an increased risk for heart disease.

While there is no set Mediterranean diet, it commonly emphasizes fresh fruits and vegetables, whole grains, beans, nuts, fish, olive oil and even a glass of red wine. Earlier research has shown that following the traditional Mediterranean diet is linked to weight loss, reduced risk of diabetes, lower blood pressure and lower blood cholesterol levels, in addition to reduced risk of heart disease.

"Because the Mediterranean diet is based on food groups that are quite common or easy to find, people around the world could easily adopt this dietary pattern and help protect themselves against heart disease with very little cost," Georgousopoulou said.

Among study participants, women tended to follow the Mediterranean diet more closely than did men. Despite the fact that Greece is the cradle of the Mediterranean diet, urbanization has led many Greeks to adopt a more Western diet over the past four decades, he said.

The study was limited to participants living in and around Athens, Greece, so the sample does not necessarily reflect the health conditions or dietary patterns of people in more rural areas or the rest of the world. However, previous studies have also linked the Mediterranean diet with reduced cardiovascular risks, including the Nurses' Health Study, which included nearly 75,000 American nurses who were tracked over a 30-year period. Additional studies in other adult populations would further advance understanding of the diet's influence on heart disease risk.

 “Prudent” diet (higher intake of fruits and vegetables; associated with a lower heart attack risk

The typical Western diet — fried foods, salty snacks and meat — accounts for about 30 percent of heart attack risk across the world, according to a study of dietary patterns in 52 countries reported in Circulation: Journal of the American Heart Association.

Researchers identified three dietary patterns in the world:

• Oriental: higher intake of tofu, soy and other sauces;

• Prudent: higher intake of fruits and vegetables; and

• Western: higher intake of fried foods, salty snacks, eggs and meat.

The Prudent diet was associated with a lower heart attack risk than the Oriental, researchers said.

“The objective of this study was to understand the modifiable risk factors of heart attacks at a global level,” said Salim Yusuf, D.Phil., the study’s senior author.

Previous studies have reached similar conclusions about the Prudent and Western diet in the United States and Europe. This study broadens those findings and identifies a unique dietary pattern that researchers labeled “Oriental” (because of a higher content of food items typical of an Oriental diet.) The dietary pattern recommended by the American Heart Association is similar to the Prudent diet described in this study.

“This study indicates that the same relationships that are observed in Western countries exist in different regions of the world,” said Yusuf, professor of medicine at McMaster University and director of the Population Health Research Institute at Hamilton Health Sciences in Ontario, Canada.

Researchers analyzed the INTERHEART study, which documents the association of various risk factors and the risk of heart attack in about 16,000 participants in 52 countries. Here, they analyzed 5,761 heart attack cases and compared them to 10,646 people without known heart disease (controls).

The researchers created a dietary risk score questionnaire for heart attacks patients, based on 19 food groups and adjusted it for dietary preferences for each country. Trained medical personnel interviewed the heart attack patients and the control group. The questionnaires included healthy food items (such as fruits and vegetables) and unhealthy food items (such as fried foods and salty snacks).

“A simple dietary score, which included both good and bad foods with the higher score indicating a worse diet, showed that 30 percent of the risk of heart disease in a population could be related to poor diet,” said Romania Iqbal, Ph.D., lead author of the study.

After adjusting for known risk factors, researchers found:

• People who consumed the Prudent diet of more fruits and vegetables had a 30 percent lower risk of heart attack compared to people who ate little or no fruits and vegetables.

• People who consumed the Western diet had a 35 percent greater risk of having a heart attack compared to people who consumed little or no fried foods and meat.

• The Oriental pattern showed no relationship with heart attack risk.

Researchers said that while some components of the Oriental pattern may be protective, others such as the higher sodium content of soy sauces, may increase cardiovascular risk, neutralizing any relationship.

It’s expensive and time-consuming to establish a large and long-term study examining the relationship of diet and heart attack in every region of the world. So the approach of this study is the only feasible way to examine the relationship to diet and heart disease from multiple populations in a relatively short time at an affordable cost, Yusuf said.

Data from this study helped confirm that changes in dietary intake, including the consumption of more fruits and vegetables, can help reduce the risk of having a heart attack in populations worldwide, he said.

“At the same time, an unhealthy dietary intake, assessed by a simple dietary risk score, accounts for nearly one-third of the world population’s attributable risk,” Yusuf said.