Let’s break down what the researchers found.
Reviewed by Dietitian Jane Leverich, M.S., RDN
Key Points
- The Mediterranean diet lowered heart disease risk more than a low-fat diet in this new study.
- A diet rich in vegetables, fish, nuts and whole grains may benefit heart health more than cutting fat alone.
- Sustainable, whole-food eating patterns like the Mediterranean diet are key to long-term heart health.
Heart disease kills more Americans than any other condition, and scientists have done research for decades trying to understand how best to prevent and treat the disease. We know that what we eat can make a significant impact on our cardiovascular health, but there’s still research to be done about what kind of eating pattern has the best benefits for your heart. You may have heard that a low-fat diet is best for cardiovascular health, but the Mediterranean diet has long been celebrated for cardiovascular benefits, with major studies backing that reputation.
But we can always learn more about how the Mediterranean diet stacks up against other healthy or trendy diets out there, including popular choices like a low-fat diet. A landmark Spanish trial called PREDIMED showed real promise for the Mediterranean approach, but researchers still wanted to see how the diet would stack up against a low-fat diet and guidelines set by the American Heart Association (AHA).
A new study took a careful look at exactly that question, and the results were published in the American Journal of Clinical Nutrition.
How Was the Study Conducted?
To dig into this question, researchers turned to two of the longest-running health studies in the country: the Nurses’ Health Study and the Health Professionals Follow-Up Study. Together, these projects have tracked the diets, habits and health of tens of thousands of Americans for years, with participants regularly filling out detailed questionnaires about what they eat and how they live.
Instead of launching a brand-new clinical trial, the team used an approach called “target trial emulation.” What this means is that they used existing data to mimic the structure of a randomized trial. They compared three eating patterns: a Mediterranean diet (rich in olive oil, nuts, fish, vegetables and legumes), the AHA 2020 dietary goals (rich in fruits, vegetables, fish and whole grains) and a low-fat diet (discourages fried snacks, nuts, pastries, fatty fish and fats/oils used for spreading, salad dressings or cooking).7 Then they estimated what each person’s risk of cardiovascular disease might look like over a 20-year span if they had followed one of these patterns closely.
It’s important to be clear: this was not a new randomized trial where people were assigned a diet and followed in real time. It’s a careful modeling study built on observational data, which shapes how we read the results.
What Did the Study Find?
Among adults at high risk for heart disease, the differences were striking. Over 20 years, the estimated risk of cardiovascular disease was:
- 35.9% for those following a low-fat diet
- 28.2% for the Mediterranean diet
- 31.2% for the AHA-2020 dietary goals
Compared with the low-fat diet, both the Mediterranean pattern and the AHA-2020 goals were linked to a lower risk. Though the percentage difference may be small, those numbers are still meaningful.
The benefits showed up across several outcomes, including coronary heart disease, death from cardiovascular causes, and death from any cause. One notable exception: researchers did not find a clear reduction in stroke risk, which may reflect the complex and varied nature of strokes.
The team also looked at the general population, not just high-risk individuals. There, the benefits were smaller but still present. The takeaway suggests these eating patterns may help a broad range of people, with the strongest effects among those who start out at higher risk.
Overall, the study estimated that U.S. adults who more closely stuck with either a Mediterranean-style diet or the AHA’s 2020 dietary goals over time had a lower 20-year risk of cardiovascular disease than those following a low-fat diet.
Limitations
Because this study relied on observational data, it can show associations but can’t prove that diet directly caused the differences in risk. Diet information was self-reported, which always introduces some potential error. The Mediterranean diet studied here was a modified, U.S.-friendly version, not the traditional pattern tested in earlier European research. One example of this is the authors explicitly note they could not quantify what proportion of oil consumed was extra-virgin olive oil versus olive oil.
Population-wise, most participants were white health professionals, so the findings may not apply equally to everyone.
How Does This Apply to Real Life?
What can you take away from this? One thing worth flagging first: the low-fat diet in this study was the baseline for comparison, and both the Mediterranean diet and the AHA-style eating pattern outperformed it. That means the generic “eat less fat” approach might not be the best choice for you. Simply cutting fat from your diet—especially without a clear sense of what replaces it—may not do much for your heart.
Instead, this evidence points toward a specific, well-defined eating pattern, and not a vague directive to eat less fat. Vegetables, legumes, fish, whole grains, nuts and olive oil form the core of what worked best in this study, whether it was the Mediterranean diet or the AHA’s 2020 guidelines. Swapping ultra-processed foods for low-fat alternatives without shifting toward this kind of whole-food pattern is unlikely to deliver the same benefit. The quality and composition of what you eat appear to matter far more than simply trimming fat from your diet.
Our Expert Take
When it comes to eating for your heart health, following American Heart Association guidance or the Mediterranean diet may be more beneficial than a low-fat diet, according to this study. The research published in the American Journal of Clinical Nutrition evaluated 20-year cardiovascular risk among U.S. adults and found that the low-fat diet was less likely to lower your heart disease risk.
The most useful conclusion may be the most practical one: The best diet is one that’s both heart-healthy and sustainable for you. A pattern rich in plants, healthy fats,and whole foods looks like a sensible, evidence-backed choice, especially when you can stick with it for the long haul.
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