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Israeli Study Focuses on Three Diets: Want to Eat Healthy? Go Mediterranean

Israeli Study Focuses on Three Diets: Want to Eat Healthy? Go Mediterranean

April 16, 2010

Medical Research

For many dieters, it’s easy to list the benefits of staying with a weight-loss program over time: Clothes fit better. Energy increases. Self-esteem goes up.

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Dr. Assaf Rudich (left) and Dr. Yaakov Henkin discuss findings from their two-year study of diets. photo/amanda pazornik

Now medical researchers in Israel are reporting another major benefit. Healthy, long-term weight-loss diets can reverse atherosclerosis, or hardening of the arteries — a direct risk factor for strokes and heart attacks.

According to a recent article published in Circulation, the leading journal of the American Heart Association, participants in a two-year study of weight-loss diets in Dimona, Israel, showed a five percent decrease in average carotid vessel-wall volume and a one percent decrease in carotid artery thickness.

“The best correlation to the changes in volume were changes in blood pressure,” said Dr. Yaakov Henkin, a cardiologist at Soroka University Medical Center in Beer-Sheva. “We know that blood pressure goes down when you lose weight. The more blood pressure went down, the more regression in the wall’s volume.”

Henkin and Dr. Assaf Rudich, speaking to visiting journalists during a recent lunchtime roundtable, discussed their widely reported study on the effectiveness and safety of three weight-loss diets: low-carbohydrate, low-fat and Mediterranean.

The findings were published in the New England Journal of Medicine in July 2008.

The study used 322 moderately obese, mostly male subjects with a body mass index above 27. Researchers also measured the amount of plaque in the carotid arteries of approximately 140 of the participants.

“Weight-loss diets or dietary intervention is first and foremost about promoting health,” said Rudich, a senior lecturer in the department of clinical biochemistry at Ben-Gurion University of the Negev’s Faculty of Health Sciences. “Yes, we link health with weight. But there is more to be gained with what is associated by weight loss.”

The conclusion? All three diets can help people to lose weight (the low-fat diet a little less so), and dieters are advised to choose one of the plans according to personal preference and then stick to it.

“People are still arguing which is more efficient and safe,” said Henkin. “And then there’s the one in the middle we call the Mediterranean diet. We know it’s a very healthy diet and helps prevent cardiovascular disease. [It] puts an emphasis not on what you shouldn’t eat, but what you should eat.” On the list are fruits, vegetables, pasta, olive oil, nuts, fish and very little red meat.

According to the Mayo Clinic Web site, key components of the Mediterranean diet include getting plenty of exercise; eating a generous number of fruits and vegetables; using herbs and spices instead of salt to flavor foods; and for some, drinking red wine in moderation.

“If you reduce the amount of calories in a Mediterranean diet,” Henkin added, “you can also lose weight in a healthy fashion.”

Participants (86 percent of them male), who worked together at a nuclear research center with an on-site medical clinic, were randomly assigned to one of the three diet groups.

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From July 2005 to June 2007, the participants ate lunch — the main meal in Israel — together every day, selecting foods that fit their specific diet. Dietitians visited regularly to check their progress, provide education and work with family members to make sure participants were following through at home.

As a result, “we managed to keep 95 percent adherence in the first year, 85 percent in the second year,” Henkin noted. “That’s unheard of in a dietary study.”

The low-fat, restricted-calorie diet was based on American Heart Association guidelines. Women took in approximately 1,500 calories per day, while men consumed 1,800 calories per day on a diet of low-fat grains, vegetables, fruits and legumes and lean meats. They also limited their intake of additional fats, sweets and high-fat snacks.

The low-carbohydrate, unrestricted-calorie diet aimed to provide 20 grams of carbohydrates per day for the first two months, with a maximum of 120 grams per day to maintain weight loss. Though the intake of calories, protein and fat was not limited, participants were advised to follow a vegetarian diet.

Common attributes in all three diets were less calories; less sweets and junk foods; less trans fat; and more vegetables.

In the end, the restricted-calorie Mediterranean diet group consumed the most dietary fiber and had the highest monounsaturated/saturated fat ratio, while the low-carb group consumed the least carbohydrates and the highest amounts of fat, protein and cholesterol.

During the first six months of the trial, the low-carbohydrate group dropped more pounds than the other two groups, but they all lost weight, according to Henkin. After two years, participants in the Mediterranean and low-carbohydrate groups lost more than those in the low-fat group.

In Israel, where there’s an emphasis on fresh ingredients and an increasing pride in ethnic and cultural cuisine, it’s hard to imagine obesity being the major health issue it is in the United States.

Yet Rudich said the percentage of 17-year-olds considered obese (body mass index of about 30) was around 2.5 percent in the late 1970s, based on figures from Israel Defense Forces recruitment centers; in the last few years, that number has increased to roughly 7.5 percent.

He noted that body mass index at age 17 is a good predictor of the person’s BMI at age 42.

“We do have an obesity problem,” Rudich said. “Just as other nations experience it, in the last two decades it has become a problem [in Israel]. You do not see children playing soccer out on the streets anymore. They’re all watching TV and playing with computers.”

Both Rudich and Henkin acknowledged that it’s not human genetics that have changed in the last 20 years, but the environment in which we live. The challenge in medicine, Rudich said, is to try and understand the “most important change.”

“Diet would be the obvious answer, but it’s only the beginning of many other questions,” he said. “Is there trans fat in the diet? Does the person consume sweetened drinks?

“These are very challenging questions, because so much has changed over the last 20 years.”

 Amanda Pazornik recently participated in the American Associates, Ben-Gurion University of the Negev’s Murray Fromson Media Mission to Israel, where she reported on the latest news, research and community service projects to come out of BGU’s campuses.