The Lyon Diet Heart Study is a clinical trial that was conducted in the 1990s in Lyon, France. The study aimed to investigate the potential health benefits of a Mediterranean-style diet in individuals who had already suffered a heart attack.

The study included over 600 participants who had previously experienced a heart attack. The participants were randomly assigned to one of two groups: a group that followed a Mediterranean-style diet, or a control group that followed a more traditional Western-style diet. The Mediterranean-style diet included foods such as fruits, vegetables, whole grains, fish, and olive oil, and discouraged consumption of red meat, butter, and cream.

The study found that the group following the Mediterranean-style diet had a significantly lower risk of recurrent heart attacks and overall mortality compared to the control group.

Specifically, the Mediterranean-style diet reduced the risk of recurrent heart attacks by 72% and the risk of death from any cause by 56% over a four-year follow-up period.

The Lyon Diet Heart Study is considered to be one of the most influential studies on the health benefits of the Mediterranean diet. It provided strong evidence that a diet rich in whole, minimally processed foods, and low in saturated fats can significantly reduce the risk of heart disease and mortality in individuals who have already experienced a heart attack.

The study has helped to shape dietary guidelines and recommendations around the world, and has contributed to the growing interest in the Mediterranean diet as a healthy and sustainable eating pattern.