Mediterranean Diet Better Than Low-Fat Diet for Heart Health, Study Shows

Pouring extra virgin olive oil in a glass bowl


Key Takeaways

  • A new study looked at the effect of the Mediterranean diet vs. a low-fat diet on endothelial function in patients with existing coronary heart disease (CHD).
  • They learned that the Mediterranean diet was better at regulating endothelial function when compared to a low-fat diet.
  • The study results suggest that the Mediterranean diet can be recommended as the best dietary strategy to protect endothelial health in patients with CHD.

The Mediterranean diet, which features a variety of vegetables, fruits, grains, beans, and olive oil, has long been studied for its beneficial effects on heart health.

Endothelial dysfunction has been identified as an important underlying contributor to many kinds of heart problems.

The endothelium is a thin layer of protective cells that line the inner walls of the arteries and heart. It helps ensure efficient blood flow around the entire body. An impaired or dysfunctional endothelium is a significant predictor of cardiovascular disease.

A recent study published in PLOS Medicine measured the effect of the Mediterranean diet on endothelial function, compared to a low-fat diet, assessed byflow-mediated dilation (FMD). The FMD is an ultrasound test, which measures blood vessel health and helps predict cardiovascular disease risk. Higher FMD results are a favorable outcome.

What the Study Found

This study is based on the data set from the Spanish CORDIOPREV study, which is an ongoing prospective, randomized, single-blind, controlled trial including 1,002 coronary heart disease (CHD) patients.

This current study is the result of one secondary outcome of the CORDIOPREV study, and it focuses on 805 participants who completed an endothelial function study at baseline.

For this research, patients were randomized to one of the following diets:

  • Mediterranean diet: 15% protein, a maximum of 50% carbohydrates, and a minimum of 35% of calories from fat, including at least four tablespoons of virgin olive oil daily.
  • Low-fat, high-complex carbohydrate diet: 15% protein, a minimum 55% carbohydrates, and a maximum of 30% of calories from fat, including no more than two tablespoons of oil daily.

Both diets included vegetables, fruit, and fish, recommended whole grains over refined grains, and were limited in red meat and sweets.

The researchers evaluated endothelial function by FMD of the brachial artery at the beginning of the study and again after one year of dietary intervention.

They found that patients who followed the Mediterranean diet had higher FMD compared to those following the low-fat diet, and they concluded that the Mediterranean diet is better for endothelial functioning compared to the low-fat diet.

Brynn McDowell, RD

The Mediterranean diet works because of the focus on variety, real food, and plant-based foods like fruits, vegetables, nuts, seeds, beans, and olive oil.

— Brynn McDowell, RD

What makes this study unique is that it specifically looks at patients with existing CHD and confirms that a long-term Mediterranean diet is a good choice.

It means that the Mediterranean diet is not only useful for heart disease prevention, but it can also be recommended for patients with existing CHD or with severe endothelial dysfunction.

Since there is a high cardiovascular event recurrence rate in CHD patients with endothelial dysfunction, it’s important to find therapeutic approaches that can be beneficial to this population. The right diet is one such intervention.

"There is a strong correlation between the Mediterranean diet and heart health," says Brynn McDowell, dietitian and author of The Mediterranean Diet Made Easy cookbook.

"So, I wasn’t surprised to find that the Mediterranean diet was found more effective than a traditional low-fat diet in terms of modulating endothelial function in this study," says McDowell.

What This Means For You:

If you have CHD or endothelial dysfunction, it’s advised to follow a Mediterranean diet. Made up of vegetables, fruit, grains, beans, lean protein, and olive oil, this diet is high in variety, includes many delicious meal options, and is easy to stick with for the long term.

Olive Oil in the Spotlight

The addition of olive oil was a key differentiator in the two diets used in this study.

It should be noted that the CORDIOPREV study is partially funded by the Olive Community Heritage Foundation, which includes the International Olive Council and the Spanish Federation of Industrial Olive Oil Manufacturers among its members.

While this funding partnership may have been why olive oil was of interest, it didn’t make the findings any different than previous studies, which also support the role of olive oil for heart health.

Elena Paravantes-Hargitt, a registered dietitian and author of The Mediterranean Diet Cookbook for Beginners, says she’s not surprised by the study results nor the important role olive oil plays.

“Extra virgin olive oil contains numerous compounds including polyphenols, sterols, squalene, and tocopherols, which can influence endothelial function positively and are responsible for most of the benefits associated with olive oil.”

She says that extra virgin olive oil also contains monounsaturated fats, antioxidants, and other beneficial nutrients.

The researchers say that saturated fats impair endothelial function, but diets containing foods rich in monounsaturated fats, such as olive oil, have been linked to improved endothelial function in patients with high cholesterol or metabolic syndrome.

The Whole Diet Matters

But it’s not the olive oil alone that’s beneficial. The Mediterranean diet is a whole eating pattern, and benefits are not based on eating only one or two nutrient-dense foods.

“I don’t believe there is one specific food or ingredient that is going to make or break your health," says McDowell. "The Mediterranean diet works because of the focus on variety, real food, and plant-based foods like fruits, vegetables, nuts, seeds, beans, and olive oil.”

It's the pattern that matters most.

“A true Mediterranean diet is based on vegetables, legumes, and olive oil, supplemented with moderate amounts of grains, dairy, (mainly) fatty fish, and smaller amounts of poultry,” says Paravantes-Hargitt. “Fresh fruit is a typical daily dessert, and red meat is consumed a few times per month.”

For Your Long-Term Health

People with heart disease don’t always follow the advice of their doctor or dietitian, especially if the diet regime seems hard to stick to or doesn’t include foods they love.

Paravantes-Hargitt says that one of the most important characteristics of the Mediterranean diet is that it is very palatable and not particularly restrictive, which makes it easy and enjoyable to follow.

“Thanks to generous amounts of olive [oil] and herbs, it is easy to consume large amounts of vegetables, greens, and legumes,” says Paravantes-Hargitt. “Most staple dishes require little time to prepare and use ingredients that most of us have in the kitchen.”

What’s Next?

In the study, the researchers explain that there remains a need to explore the effect of dietary models on endothelial vascular homeostasis for a longer period than just one year.

Also, the study was comprised of a Mediterranean population in Spain, so the results may not be generalizable to other populations. The study needs to be replicated globally with different cultures to see if the results are the same.

6 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Liyanage T, Ninomiya T, Wang A, et al. Effects of the Mediterranean diet on cardiovascular outcomes—a systematic review and meta-analysisPLoS One. 2016;11(8):e0159252. doi:10.1371/journal.pone.0159252

  2.  Vita JA. Endothelial function. Circulation. 2011;124(25):e906-e912. doi:10.1161/CIRCULATIONAHA.111.078824

  3. Yubero-Serrano EM, Fernandez-Gandara C, Garcia-Rios A, et al. Mediterranean diet and endothelial function in patients with coronary heart disease: an analysis of the CORDIOPREV randomized controlled trial. PLoS Med. 2020;17(9):e1003282. doi 10.1371/journal.pmed.1003282

  4. CORDIOPREV. Introduction. 2020.

  5. Hernáez Á, Fernández-Castillejo S, Farràs M, et al. Olive oil polyphenols enhance high-density lipoprotein function in humans: a randomized controlled trial. Arterioscler Thromb Vasc Biol. 2014;34(9):2115-2119. doi:10.1161/ATVBAHA.114.303374

  6. Davis CR, Hodgson JM, Woodman R, Bryan J, Wilson C, Murphy KJ. A Mediterranean diet lowers blood pressure and improves endothelial function: results from the MedLey randomized intervention trialAm J Clin Nutr. 2017;105(6):1305-1313. doi:10.3945/ajcn.116.146803

By Cara Rosenbloom, RD
 Cara Rosenbloom RD is a dietitian, journalist, book author, and the founder of Words to Eat By, a nutrition communications company in Toronto, ON.