Dr. Kumar’s Take:
A major randomized trial supports what nutrition experts have long suspected: eating a Mediterranean diet rich in olive oil or nuts can lower the risk of heart disease. This study, which followed over 7,400 people at high cardiovascular risk, found that those who ate a Mediterranean diet had up to a 31% lower risk of heart attack, stroke, or cardiovascular death.
Actionable Tip: If you’re looking to protect your heart, start by switching to a Mediterranean diet with plenty of extra-virgin olive oil or a daily handful of nuts. In this trial that cut the absolute risk of a major cardiovascular event by about 1 percentage point over a median 4.8 years.
Brief Summary:
The PREDIMED study was a large, multi-center trial conducted in Spain that tested the impact of a Mediterranean diet supplemented with either extra-virgin olive oil or nuts compared to a low-fat diet on heart disease prevention.
Over 4.8 years, researchers found that participants who followed the Mediterranean diet had a significantly lower risk of cardiovascular events than those who were advised to eat a low-fat diet.
Key Takeaways:
✔ Mediterranean diet with extra-virgin olive oil: 31% lower relative risk (hazard ratio 0.69), an absolute risk reduction of 0.6 percentage points.
✔ Mediterranean diet with nuts: 28% lower relative risk (hazard ratio 0.72), an absolute risk reduction of 1.0 percentage point.
✔ Both diets outperformed a traditional low-fat diet for heart disease prevention.
✔ Neither Mediterranean arm was assigned a calorie target, participants simply followed the diet’s principles.
Study Design:
- Participants: 7,447 adults aged 55 to 80 (57% women) at high cardiovascular risk but with no cardiovascular disease at enrollment.
- Intervention Groups:
- Mediterranean diet + extra-virgin olive oil (EVOO) (1 liter per week)
- Mediterranean diet + mixed nuts (30g/day: walnuts, hazelnuts, almonds)
- Control diet (low-fat diet recommendations)
- Follow-up Period: median 4.8 years, at which point the trial was stopped on a prespecified interim analysis
- Primary Outcome: Major cardiovascular event (heart attack, stroke, or cardiovascular death).
Results:
✔ Heart attacks, strokes, and cardiovascular deaths were significantly lower in both Mediterranean diet groups compared to the low-fat diet group.
✔ A primary end-point event occurred in 288 of the 7,447 participants.
✔ The Mediterranean diet with olive oil group had a 31% lower risk (HR: 0.69, 95% CI 0.53 to 0.91).
✔ The Mediterranean diet with nuts group had a 28% lower risk (HR: 0.72, 95% CI 0.54 to 0.95).
✔ Event rates and absolute risk reductions:
- Mediterranean diet with extra-virgin olive oil: 96 events, 3.8% vs 4.4% in controls, an ARR of 0.6 percentage points
- Mediterranean diet with nuts: 83 events, 3.4% vs 4.4% in controls, an ARR of 1.0 percentage point
✔ Neither Mediterranean arm was given a calorie target.
A note on this citation: the results above come from the 2018 corrected and republished version of PREDIMED in the New England Journal of Medicine. The investigators identified protocol deviations in the original 2013 report, including enrollment of household members without randomization and non-random assignment at one of eleven sites, and reanalyzed the data adjusting for baseline characteristics and propensity scores. The hazard ratios held up.
How the Mediterranean Diet Protects Your Heart:
The Mediterranean diet is known for its anti-inflammatory and heart-protective effects. Key factors include:
- Healthy fats from olive oil and nuts help lower LDL and increase HDL.
- Rich in antioxidants that reduce oxidative stress and inflammation in the arteries.
- High fiber intake from vegetables, legumes, and whole grains supports heart health.
- Moderate fish and poultry intake provides lean protein.
Related Studies and Research
Frequently Asked Questions:
Who benefits most from the Mediterranean diet?
The study focused on people at high risk of heart disease (e.g. those with diabetes, high blood pressure, or obesity). Whether people at lower risk would see the same benefit was not tested here.
Do I need to count calories on this diet?
The Mediterranean arms of this trial were not assigned a calorie target. The emphasis was on quality of food rather than quantity, with quarterly education sessions and free olive oil or nuts.
What’s the best way to start a Mediterranean diet?
✔ Swap vegetable oils for extra-virgin olive oil in cooking.
✔ Eat a handful of nuts daily (walnuts, almonds, hazelnuts).
✔ Increase vegetables, fruits, and whole grains in your meals.
✔ Reduce processed foods and sugar.
Can the Mediterranean diet help with weight loss?
This study focused on heart disease prevention, not weight loss, so it does not answer that question.
Conclusion:
The Mediterranean diet is one of the best diets for heart health. This study provides strong clinical evidence that eating more olive oil and nuts can significantly reduce your risk of heart disease.
Keep the size of the effect in view. By crude event counts over a median 4.8 years, the difference was 0.6 to 1.0 percentage points. Using the trial’s estimated five-year absolute risks (3.6% with olive oil, 4.0% with nuts, 5.7% with the control diet), the difference was 1.7 to 2.1 percentage points, which means that for every 100 high-risk people following this diet, roughly 2 fewer will experience a major heart event compared to those on a low-fat diet. The relative reduction of 28% to 31% sounds larger because the underlying event rate was low to begin with.
If you’re looking for a long-term, sustainable way to eat for your heart, this pattern has some of the strongest trial evidence behind it.
