What exactly is the Mediterranean diet, and why does it help the heart?
The Mediterranean diet isn't a single, rigid meal plan but a traditional eating pattern from countries bordering the Mediterranean Sea. It's high in plant-based foods like fruits, vegetables, whole grains, legumes, and nuts, with olive oil as the main source of fat [5][6]. It includes moderate amounts of fish and poultry, low amounts of red meat, and, traditionally, a low-to-moderate intake of red wine with meals [5]. This combination is rich in antioxidants and healthy fats, which helps reduce inflammation and improve cholesterol levels [6].
The diet's benefits go beyond just one nutrient. A 2021 study found that a "metabolic signature" of 67 different compounds in the blood could reliably reflect how well a person was following a Mediterranean diet, and this signature was linked to a lower future risk of heart disease, even after accounting for other risk factors [8]. This suggests the diet works through a complex network of positive changes throughout the body.
Is it effective for people who already have heart disease?
Yes, the evidence is particularly strong for secondary prevention—that is, preventing further heart problems in people who already have heart disease. The landmark CORDIOPREV trial, which followed over 1,000 patients with established coronary heart disease for 7 years, found that those assigned to a Mediterranean diet had a significantly lower risk of major cardiovascular events (heart attack, stroke, or cardiovascular death) compared to those on a low-fat diet [1]. The rate of these events was 28.1 per 1,000 person-years in the Mediterranean diet group versus 37.7 in the low-fat group, translating to a roughly 25-28% lower risk [1][7].
This finding is supported by earlier, smaller trials. The Lyon Diet Heart Study, for example, found that heart attack survivors advised to follow a Mediterranean-style diet had a 65% lower risk of dying from cardiovascular disease over about 4 years compared to those receiving usual care [4]. An umbrella review of 18 meta-analyses concluded that the preventive effect of the Mediterranean diet was even more significant in studies of people with established heart disease [3].
Does it help prevent heart disease in healthy people?
Yes, the evidence is also strong for primary prevention—preventing the first occurrence of heart disease. A large 2023 meta-analysis that pooled data from 16 studies involving over 720,000 women found that those with the highest adherence to a Mediterranean diet had a 24% lower risk of developing cardiovascular disease and a 23% lower risk of dying from any cause [2]. This is a substantial benefit for a dietary change.
The famous PREDIMED trial, which included over 7,000 people at high risk for heart disease but without a prior event, showed that a Mediterranean diet supplemented with extra-virgin olive oil or nuts reduced the risk of stroke by about 40% compared to a low-fat diet [4]. While the effect on overall heart attacks or cardiovascular death was less clear in that specific trial, the reduction in stroke was a major finding. A 2025 review of multiple meta-analyses confirmed that the Mediterranean diet can reduce the risk of non-fatal heart attacks by 21% to 70% compared to other active diets [3].
About These Sources
This answer is built on 8 peer-reviewed studies — published from 2019 to 2025, 2 from 2024 or later, 3 in Q1 journals, collectively cited 597 times — selected as the most relevant from 11 studies that passed quality screening, drawn from 46 papers retrieved from a database of over 500 million.
Sources used in this answer
Long-term secondary prevention of cardiovascular disease with a Mediterranean diet and a low-fat diet (CORDIOPREV): a randomised controlled trial
In a 7-year randomized controlled trial of 1,002 patients with established heart disease, the Mediterranean diet was superior to a low-fat diet in preventing major cardiovascular events (heart attack, stroke, death), with a 28% lower event rate (28.1 vs 37.7 per 1,000 person-years) [1].
Primary prevention of cardiovascular disease in women with a Mediterranean diet: systematic review and meta-analysis
A meta-analysis of 16 prospective cohort studies in over 720,000 women found that higher adherence to a Mediterranean diet was associated with a 24% lower risk of developing cardiovascular disease and a 23% lower risk of death from any cause [2].
The effectiveness of the Mediterranean Diet for primary and secondary prevention of cardiovascular disease: An umbrella review.
An umbrella review of 18 meta-analyses (covering 238 randomized trials) found that the Mediterranean diet reduced fatal cardiovascular disease risk by 10-67% and non-fatal heart attack risk by 21-70%, with stronger effects in those with existing heart disease [3].
Mediterranean-style diet for the primary and secondary prevention of cardiovascular disease.
A Cochrane review of 30 randomized trials found moderate-quality evidence that a Mediterranean diet reduces stroke risk by about 40% in high-risk individuals (from the PREDIMED trial) and low-quality evidence that it reduces cardiovascular death in heart attack survivors (from the Lyon Diet Heart Study) [6].
The Mediterranean diet and cardiovascular disease
A 2025 review summarizes that large randomized trials (Lyon Diet Heart Study, PREDIMED, CORDIOPREV) consistently support the protective effects of the traditional Mediterranean diet against cardiovascular disease, emphasizing its unique components like extra-virgin olive oil and nuts [7].
What Is the Mediterranean Diet?
A review article explains that the Mediterranean diet is high in bioactive compounds (carotenoids, polyphenols) from fruits, vegetables, and olive oil, which contribute to high antioxidant intake and lower systemic inflammation, a key driver of heart disease [9].
Cardiovascular prevention: Mediterranean or low-fat diet?
A commentary highlights that the CORDIOPREV trial provides convincing evidence from a large, long-term clinical trial that the Mediterranean diet is superior to a low-fat diet for secondary prevention of cardiovascular events [10].
The Mediterranean diet, plasma metabolome, and cardiovascular disease risk.
A study of 1,859 participants from the PREDIMED trial and 6,868 from US cohorts identified a 67-metabolite blood signature that reflects Mediterranean diet adherence and predicts future cardiovascular disease risk, independent of traditional risk factors [11].