The Mediterranean diet refers to the eating patterns of the people living in countries located around the Mediterranean basin, especially olive-growing countries. Based on the results of research, the American Heart Association1 and the American dietary guidelines2 recommend adhering to the Mediterranean diet to stay healthy. But what are the health benefits of the Mediterranean diet and why has it gained so much interest?
What is the Mediterranean diet?
Although there are differences between individual countries, the common components are plant-based foods, olive oil and moderate amounts of poultry, seafood and dairy products. Red meat is eaten in small amounts and sweets are usually substituted by fruits3 in addition to the occasional consumption of red wine in some countries; however, the American dietary guidelines advise against drinking alcohol to seek potential health benefits2.
In addition to the dietary choices, researchers now stress the importance of a Mediterranean lifestyle which also includes physical activity, adequate hydration, and spending time with friends and family.3
History of research
In the mid 20th century, researchers observed lower incidence rates of coronary artery disease in inhabitants of Mediterranean countries like Italy. These observations spurred an array of studies by researchers exploring the potential benefits of this eating pattern. Ancel Keys, an American physiologist led a large cohort study known as “The seven countries study” to research the effects of diet and lifestyle on cardiac and vascular diseases.4 The first phase of the study involved data collected from 12,225 men aged 45-59 in cohorts from seven countries. The researchers found that coronary heart disease events (heart attacks) occurred 3 times more in Northern European countries compared to Southern European countries that followed a Mediterranean diet.5This in turn led to many more studies to explore the benefits of a Mediterranean diet.
Health benefits of the Mediterranean diet
The health benefits of the Mediterranean diet come from the benefits of its individual foods and the combined benefit of different nutrients together. Following a Mediterranean diet involves eating more fruits and vegetables, whole grains, nuts and seeds. These foods are rich in vitamins, minerals and antioxidants. It is also based on eating healthy fats like olive oil which is rich in monounsaturated fat and fatty fish that are rich in omega-3 fatty acids.
Heart health
The PREDIMED trial was a randomized controlled trial conducted in Spain that examined the effects of adherence to two types of Mediterranean diets (one rich in nuts and the other rich in olive oil) compared to a low fat diet in 7447 participants with a high risk for heart disease (e.g., diabetic, hypertensive, smoker). The participants were followed for 4.8 years and monitored for cardiovascular events. The two groups following a Mediterranean diet had a smaller incidence of cardiovascular events and lower blood pressures. This risk reduction may be caused by the anti-inflammatory effects of the Mediterranean diet and improvement of endothelial function.3
Conversely, a systematic review published in the Cochrane library that included 30 randomized controlled trials examined the effect of a Mediterranean diet on prevention of heart disease. Despite the large number of studies, the researchers concluded that more evidence is needed to support the preventive effects of a Mediterranean diet on heart disease and the evidence available was low or moderate in quality.6
Brain health
Studies have suggested the possible benefit of a Mediterranean diet on mental health, but data were conflicting. In a systematic review of 45 studies on the effects of a Mediterranean diet on cognitive function and mental health, researchers found that a Mediterranean diet had a protective effect on cognitive decline associated with aging. However, the protective effect could not be confirmed for Alzheimer’s disease or dementia and more research is required in this area.7
A large meta-analysis published in the European journal of epidemiology examined the effects of a Mediterranean diet on the risk of stroke. Twenty studies were included (16,000 stroke cases) and the results showed that following a Mediterranean diet lowered the risk for both ischemic and hemorrhagic stroke.7
Diabetes
Researchers studied the effects of the Mediterranean diet on diabetes in a systematic review published in the journal of Diabetes Research and Clinical Practice. The review involved 17 studies, two of which were prospective studies. The researchers found that adherence to a Mediterranean diet lowered the risk of developing type 2 diabetes in healthy participants and in patients who had heart disease. In addition, 5 randomized controlled trials were included that examined the effect of a Mediterranean diet on blood sugar control; it was also found to be improved in followers of a Mediterranean diet. 8
Cancer
A 2017 systematic review and meta-analysis included data from 27 studies on the effect of adherence to the Mediterranean diet in cancer patients. Their results showed that adherence to a Mediterranean diet was inversely related to overall cancer mortality risk. The studies included data on patients with colorectal, breast, gastric, liver, head and neck, gallbladder, and biliary tract cancer. The researchers attribute this protective effect to the high amount of fruits and vegetables in the Mediterranean diet.9
A Mediterranean diet offers a healthy lifestyle pattern that may play a role in reducing the risk of heart disease, diabetes, cognitive decline, and even cancer. Always seek medical advice before following a new diet plan and transition gradually into a healthy diet by eliminating processed foods, decreasing saturated fats, increasing consumption of fruits, vegetables, whole grains and unsaturated fats like olive oil. Spend time with your loved ones and stay active to reap the benefits of a Mediterranean lifestyle.
1. What is the Mediterranean Diet? | American Heart Association. https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/nutrition-basics/mediterranean-diet. Accessed October 28, 2020.
2. 2015-2020 Dietary Guidelines | health.gov. https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/. Accessed October 28, 2020.
3. Tuttolomondo A, Simonetta I, Daidone M, Mogavero A, Ortello A, Pinto A. Metabolic and vascular effect of the mediterranean diet. Int J Mol Sci. 2019;20(19):4716. doi:10.3390/ijms20194716
4. About the Seven Countries Study. https://www.sevencountriesstudy.com/about-the-study/. Accessed October 23, 2020.
5. Keys A, Menotti A, Aravanis C, et al. The seven countries study: 2,289 deaths in 15 years. Prev Med (Baltim). 1984;13(2):141-154. doi:10.1016/0091-7435(84)90047-1
6. Rees K, Takeda A, Martin N, et al. Mediterranean-style diet for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2019;2019(3). doi:10.1002/14651858.CD009825.pub3
7. Gardener SL, Rainey-Smith SR. The Role of Nutrition in Cognitive Function and Brain Ageing in the Elderly. Curr Nutr Rep. 2018;7(3):139-149. doi:10.1007/s13668-018-0229-y
8. Esposito K, Maiorino MI, Ceriello A, Giugliano D. Prevention and control of type 2 diabetes by Mediterranean diet: A systematic review. Diabetes Res Clin Pract. 2010;89(2):97-102. doi:10.1016/j.diabres.2010.04.019
9. Schwingshackl L, Schwedhelm C, Galbete C, Hoffmann G. Adherence to mediterranean diet and risk of cancer: An updated systematic review and meta-analysis. Nutrients. 2017;9(10). doi:10.3390/nu9101063
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