The Lyon Diet Heart Study investigated how a specific eating pattern influences cardiovascular health following a heart attack. Its objective was to determine if adopting a Mediterranean-type diet could reduce the likelihood of experiencing further heart-related problems after an initial myocardial infarction. This study was one of the first to show the direct impact of dietary intervention on preventing recurrent cardiovascular events.
The Study’s Approach
The Lyon Diet Heart Study was a randomized, single-blind secondary prevention trial, aiming to prevent future events in individuals who had already experienced a medical condition. Its purpose was to observe the effects of dietary changes on patients who had recently survived a myocardial infarction. The study recruited 605 participants, all under 70, who had experienced their first heart attack within six months. They were enrolled at the University Hospital of Lyon in France between 1988 and 1992.
Participants were divided into two dietary groups. One followed a Mediterranean-type diet, emphasizing fruits, vegetables, grains, legumes, fish, and poultry, with olive oil as the primary fat source. This diet also limited red meat and dairy. The control group followed a prudent Western-type diet, reflecting conventional dietary advice prevalent at the time.
Randomized assignment helped ensure observed differences were due to the diets. It was single-blind, meaning participants were not fully aware of specific dietary comparisons. Dietary habits were primarily assessed in the experimental group to avoid influencing control participants. The study followed participants for an average of 46 months, with regular medical interviews, blood samples, and blood pressure measurements to monitor for cardiovascular events.
Key Outcomes and Findings
The Lyon Diet Heart Study revealed a protective effect of the Mediterranean dietary pattern on cardiovascular health. The main finding was a substantial reduction in cardiac death and nonfatal myocardial infarction among Mediterranean diet participants compared to the Western-type diet group.
After an average follow-up of 46 months, the Mediterranean diet group experienced 14 cardiac deaths and nonfatal infarctions, compared to 44 in the control group. This reduction was statistically significant.
The study also tracked broader cardiovascular outcomes. It found reductions in major secondary endpoints like unstable angina, stroke, heart failure, and pulmonary or peripheral embolism. Minor events requiring hospital admission were also reduced in the Mediterranean diet group.
The adjusted risk ratios for these composite outcomes ranged from 0.28 to 0.53. These beneficial effects were observed even when traditional cardiovascular risk factors, such as high cholesterol and blood pressure, were considered. This suggested the overall dietary pattern provided a protective effect independent of its influence on individual risk factors. The consistency of these findings over an extended follow-up reinforced the protective effect of the Mediterranean diet.
Shaping Modern Heart Health Advice
The Lyon Diet Heart Study influenced the understanding of diet’s role in preventing recurrent cardiovascular events and shaped modern heart health advice. The evidence it provided for the Mediterranean diet’s effectiveness in secondary prevention helped solidify its position in dietary recommendations, showing that dietary changes could be as effective as some pharmaceutical interventions in reducing cardiac mortality.
This research also contributed to a shift in public health focus, moving beyond individual nutrients to recognize the importance of entire dietary patterns. The study highlighted that the synergy of various foods within a Mediterranean diet, rather than isolated components, conferred its benefits.
This holistic view of nutrition became influential in dietary guidelines for chronic disease prevention. The study’s findings paved the way for subsequent research into the Mediterranean diet’s broader health benefits and its role in preventing various chronic diseases.
Its relevance is evident in current public health advice, which promotes the Mediterranean dietary pattern as a foundation of heart-healthy living. The Lyon Diet Heart Study continues to serve as evidence supporting the impact of diet on long-term cardiovascular well-being.