People with a history of heart disease who eat a traditional Southern diet are more likely to die than those who follow a Mediterranean dietary pattern, according to new research.

The large-scale study, published Thursday in the Journal of the American Heart Association(link opens in new window), adds to the growing body of evidence on heart disease and its association with dietary patterns from different parts of the world.

Researchers defined the U.S. Southern diet as high in added fats, fried food, eggs, processed meats and sugar-sweetened beverages. By contrast, the Mediterranean diet was defined as high in vegetables, fruits, fish, whole grains and legumes, and low in meat and dairy.

The study is among the first to zero in on people who already had a history of coronary heart disease, such as a previous heart attack or coronary artery bypass surgery. Researchers examined data from 3,562 white and African-American men and women ages 45 and older living in different parts of the United States. Participants were first given an exam and dietary assessment, and then called every six months to ask about new coronary heart disease events.

Seven years later, 581 people had experienced a second coronary heart disease event, and 1,098 people had died from a variety of causes. After looking closely at an assortment of dietary patterns, researchers found a clear association between death and people who ate a Southern diet.

“The greater someone adheres to the Southern dietary pattern, the higher the risk of all-cause mortality,” said James Shikany, the study’s lead author and a nutritional epidemiologist at the University of Alabama at Birmingham’s Division of Preventive Medicine. “But with the Mediterranean diet, the greater they adhere, the lower the risk of recurrent coronary heart disease and all-cause mortality.”

The study was a follow-up to research published in 2015 that found a higher risk of acute heart attack or heart-related death among participants without a history of heart disease at the start of the study.

Shikany said it’s important to note that the research – both the new study and the 2015 study – looked at dietary patterns, not specific foods. “We do not know which individual components of the Southern pattern confer the most risk,” he said.

Still, he noted, these latest results should be a wake-up call for anyone with heart disease who eats a traditional Southern diet.

“We believe it is prudent to add more fruits and vegetables, and switch to more unsaturated fats, such as olive oil, as opposed to butter,” he said.

Marie-Pierre St-Onge, associate professor of nutritional medicine at Columbia University in New York, called it “a unique study that shows how important it is to consume a healthy diet.” Yet she also called for future studies to examine how people with heart disease fare after they improve their diet.

“A cardiovascular event is a scary thing, and it can be a high motivator for people to eat more healthfully and exercise more,” said St-Onge, who wasn’t involved in the study. “I’d like to know how making lifestyle changes after the first event might prevent secondary events and death.”

Shikany said he hopes the study underscores the importance for doctors to counsel patients on nutrition and offer suggestions for changing their diet. He also recommends patients work with a registered dietitian to plot out concrete ways to eat healthier.

Guidelines from the American College of Cardiology and American Heart Association recommend a diet that emphasizes vegetables, fruits and whole grains; includes low-fat dairy products, poultry, fish, legumes, non-tropical vegetable oils and nuts; and limits saturated fats, sodium, sweets, sugar-sweetened beverages and red meats.

The key for all health care providers, Shikany said, is taking a slow-and-steady approach to get patients to improve their diets for the long-run.

“Instead of eating processed meats every day, perhaps recommend they start out by cutting that down to twice a week,” he said. “If you recommend a radical change, all at once, people … are less likely to make changes.”

If you have questions or comments about this story, please email [email protected].