Mediterranean Diet and the Rate of Cardiovascular Complications After Myocardial Infarction (Lyon Diet Heart Study)

The Lyon Diet Heart Study was one of the first randomized trials to show that food — not just drugs — could dramatically cut recurrent heart attacks.

Patients who had survived a first myocardial infarction were randomized to a Mediterranean-style diet (rich in plants, fish, and an alpha-linolenic-acid-enriched margarine) or a standard post-MI diet. The result was striking: the Mediterranean group had roughly 70 percent fewer cardiac deaths and nonfatal heart attacks over follow-up — a benefit so large the trial was stopped early. Notably, the effect appeared largely independent of changes in cholesterol, suggesting diet works through multiple pathways.

The finding helped establish dietary pattern as a powerful lever in secondary prevention, foreshadowing the later, larger PREDIMED trial in primary prevention.

We rate the evidence strong, with the caveats its era imposes: the sample was modest, dietary adherence is hard to blind, and the effect size was so large it invites caution. Still, as an early randomized demonstration that diet meaningfully changes hard cardiac outcomes, it remains a landmark.