Lyon Diet Heart Study


 

What is the Lyon Diet Heart Study?

This is a randomized, controlled trial with free-living subjects. Its goal is to test the effectiveness of a Mediterranean-type diet (which is consistent with the new American Heart Association dietary guidelines) on the rate of coronary events in people who've had a first heart attack. The results suggest that a Mediterranean-style Step I diet may help reduce recurrent events in patients with heart disease.

What were the methods used?

A total of 302 experimental- and 303 control-group subjects were randomized into the study. All were patients who had survived a first heart attack. The two groups had a similar coronary risk factor profile (blood lipids and lipoproteins, systolic and diastolic blood pressure, body mass index and smoking status). Patients in the experimental group were asked to comply with a specific Mediterranean-type diet. Patients in the control group received no dietary advice from the researchers but were asked by their physicians to follow a prudent diet.

An intermediate analysis was performed after a minimum follow-up of one year for each patient. The study was stopped at that point because of significant beneficial effects noted in the original group. All patients were invited to the research unit for a final exam, where they were informed of the results. 204 of the control group and 219 of the experimental group participated in the final visit. This represented 93 percent of the patients still alive at the time.

What is a Mediterranean-style diet?

There's no one, typical "Mediterranean" diet. At least 16 countries border the Mediterranean Sea. Diets vary between these countries and also between regions within a country. Many differences in culture, ethnic background, religion, economy and agricultural production result in different diets. But the common Mediterranean dietary pattern has these characteristics:

• high in fruits, vegetables, bread and other cereals, potatoes, beans, nuts and seeds
• includes olive oil as an important source of monounsaturated fat
• dairy products, fish and poultry consumed in low to moderate amounts, little red meat
• eggs consumed zero to four times weekly
• wine consumed in low to moderate amounts

What are the Step I and Step II diets?

The Step I and Step II diet guidelines were developed by the National Cholesterol Education Program and the American Heart Association to treat patients with high blood cholesterol. These diets were replaced in 2001 by the publication of the Adult Treatment Panel III (ATP III) of the National Cholesterol Education Program (NCEP). The American Heart Association's "Eating Plan for Healthy Americans" is recommended for healthy people. Step II has ben replaced by the Total Lifestyle Change (TLC) diet.  It's for all people who are at high risk of heart disease or who have heart disease.

The NCEP and the AHA recommend the TLC diet for two groups of people:

• those with coronary heart disease, diabetes or high LDL ("bad") cholesterol
• those without CHD and with fewer than two risk factors who have not met the LDL cholesterol treatment goal of less than 160 mg/dL 

What was the diet in the Lyon Diet Heart Study?

The Mediterranean-style diet used in the Lyon Diet Heart Study was quite comparable to the common pattern but different in a significant way. It was high in alpha-linolenic (lin"o-LEN'ik) acid (a type of polyunsaturated omega-3 fatty acid). It included

• more bread, more root vegetables and green vegetables, more fish.
• less beef, lamb and pork (replaced with poultry).
• no day without fruit.
• butter and cream were replaced with margarine high in alpha-linolenic acid.

The diet averaged 30 percent of calories from fat, 8 percent from saturated fat, 13 percent from monounsaturated fat, 5 percent from polyunsaturated fat and 203 mg/day of cholesterol. This is consistent with the American Heart Association Eating Plan for Healthy Americans. Compared to the control group, people in the experimental group consumed less linoleic acid and more oleic acid, alpha-linolenic acid and dietary fiber.

What was the diet in the control group?

People in the control group consumed a diet with about 34 percent of calories from fat, 12 percent from saturated fat, 11 percent from monounsaturated fat, 6 percent polyunsaturated fat and 312 mg/day of cholesterol. This diet is comparable to what is typically consumed in the United States.

The control group's diet did not meet our Eating Plan for Healthy Americans diet guidelines. Nor did it meet the Therapeutic Lifestyle Changes (TLC) diet guidelines, which are recommended for people at high risk of heart disease or who have had a heart attack.

What were the results of the study?

After an average follow-up of 46 months (almost four years), patients following the Mediterranean-style diet had a 50–70 percent lower risk of recurrent heart disease. The risk was measured by three combinations of outcome measures:

• cardiac death and non-fatal heart attacks
• the above two plus major events (unstable angina, stroke, heart failure, and pulmonary or peripheral embolism) 
• all of these measures plus minor events that required hospitalization

What were the problems with the study?

These results are quite impressive. However, limitations in study methods raise questions about the true impact of this diet on risk of recurrent heart disease and related measures. Specifically, the baseline diet was only assessed in the experimental group at the start of the study. The control group's diet was only assessed at the conclusion. This was done to avoid influencing the dietary behavior of these subjects. Thus, it's not clear whether there were any dietary changes made by the control group.

Dietary data at the final visit are reported for only 83 out of 303 subjects (30 percent ) in the control group and 144 out of 302 (less than 50 percent) in the experimental group. The diet of the other subjects who completed the study is unknown. This raises questions about the role of diet in explaining the results reported for recurrent coronary events.

What are the conclusions?

The Lyon Diet Heart Study shows the potential importance of a dietary pattern that emphasizes fruits, vegetables, breads and cereals, and fish as well as alpha-linolenic acid within the context of an Eating Plan for Healthy Americans diet plan. The findings from this study imply risk factors beyond lipids and lipoproteins (cholesterol) that have been our primary focus in secondary prevention. The fact that omega-3 fatty acids exert cardioprotective effects in several ways suggests that they could have accounted for the results that were observed. The reduction in coronary recurrence rates, even though lipid and lipoprotein risk factors were comparable, clearly points to other important risk factor changes as major influences in the development of CVD. There's a pressing need to identify these risk factor(s) and find effective treatment strategies.

Had this dietary pattern been prescribed with a TLC diet, as we recommend for patients with CVD, the beneficial effects could have been even more remarkable. Still, this study shows that a Mediterranean-style Eating Plan for Healthy Americans diet can be followed by free-living people. This diet plan has not yet been evaluated as a long-term strategy for primary prevention.

Related AHA publications:

• An Eating Plan for Healthy Americans
• Easy Food Tips for Heart-Healthy Eating (also in Spanish) 
• "How Can I Cook Healthfully?" and "How Do I Follow a Low-Fat Diet?" in Answers By Heart kit (also in Spanish kit)

Detailed Research

 

AHA Scientific Statement: AHA Dietary Guidelines: Revision 2000, #71-0193 Circulation. 2000;102:2284-2299; Stroke. 2000;31:2751-2766

"Coronary Heart Disease in Seven Countries," Circulation, 1970;41(Suppl I):I-1--I-211

Summary of the Second Report of the NCEP Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel II), NIH Publication No. 93-3095, 1993 (Full Text in Circulation. 1994;89)

de Lorgeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N, "Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: Final report of the Lyon Diet Heart Study," Circulation. 1999;99:779-785

AHA Science Advisory: Lyon Diet Heart Study: Benefits of a Mediterranean-Style, National Cholesterol Education Program/American Heart Association Step I Dietary Pattern on Cardiovascular Disease, #71-0202 Circulation. 2001;103:1823-1825; Editorial: Can a Mediterranean-Style Diet Reduce Heart Disease? #71-0202 Circulation. 2001;103:1821-1822

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