What is the Mediterranean diet? Is it good for our bodies and our brains? 

• What is the Mediterranean diet?
• Can it reduce the risk of cardiovascular disease?
• Can it reduce the risk of obesity?
• Can it help manage type 2 diabetes?
• What about cancer and liver disease?
• Can a Mediterranean diet slow cognitive decline and reduce the risk of Alzheimer’s? 

What is the Mediterranean diet?

The Mediterranean diet describes a combination of foods traditionally eaten in countries around the Mediterranean.  

Typically, these foods:

• are high in plant-based ingredients, including fruits, vegetables, legumes and pulses
• are often prepared with olive oil as the main source of fat
• include moderate amounts of fish, poultry, dairy products, often eaten with red wine
• are low in sugar, red meat and processed meat.

In practice, the actual ingredients, quantities and proportions can vary from country to country. This is one of the challenges for researchers, as it makes it difficult to make an exact like-for-like comparison between Mediterranean diets of different countries. Another challenge is how to ensure that it is the Mediterranean diet, rather than other factors of the Mediterranean lifestyle, which is making the difference to people’s health and wellbeing. This helps explain why different researchers sometimes report different health results. 

Can it reduce the risk of cardiovascular disease?

Greater adherence to the Mediterranean diet is associated with a lower risk of developing cardiovascular disease (CVD) and a lower mortality from CVD.

In 1999, The Lyon Diet Heart Study established that there was an approximately 70% lower risk of suffering recurrent myocardial infarction (heart attack) in participants on a Mediterranean diet compared with those who followed recommendations close to the low calorie Step 1 diet of the US Heart, Lung and Blood Institute. 

A trial conducted in Spain with 7,447 people aged 55–80yrs, and published in 2018 in one of the world’s most highly rated medical journals, found that among participants with high cardiovascular risk, a Mediterranean diet that was supplemented with extra-virgin olive oil or nuts reduced the incidence of major cardiovascular events.  This meant fewer heart attacks and strokes and fewer deaths from heart attacks and strokes.

Another study, of 23,902 people in East Anglia in the UK, published in 2016, reported that the more closely people followed a Mediterranean diet the lower the rate of cardiovascular disease and death appeared to be. 

Can a Mediterranean diet reduce the risk of obesity?

An analysis of published research in 2015 concluded that the Mediterranean diet appeared to be effective in reducing obesity, and that the effects were greater the longer the Mediterranean diet was followed. 

The Mediterranean diet has beneficial effects on levels of body fat despite being a high-fat diet. A 2016 review considered trials which compared the effectiveness of the Mediterranean diet with a low fat diet, a low carbohydrate diet and the American Diabetes Association diet. It found that the Mediterranean diet appeared to produce greater weight loss than a low fat diet and similar weight loss to the other two diets.

One possible explanation for these findings is that a large amount of dietary fibre is found in the plant foods that make up a high proportion of the Mediterranean diet. This makes us feel full and therefore stops us eating more. The diet also contains higher levels of unsaturated fats, found in olive oil, avocados, nuts and seeds, which are associated with better lipid profiles (blood tests that screen for specific fats) than the saturated fats from animals. 

Can it help manage Type 2 Diabetes?

The Mediterranean diet has been shown to be beneficial in controlling blood sugar levels in people with diabetes, even without calorie restriction. 

The evidence for the effectiveness of the Mediterranean diet in managing type 2 diabetes was explored in reviews of the evidence in 2014, 2015 and 2016. The 2014 analysis concluded that following a Mediterranean diet closely was associated with a 23% reduced risk of developing type 2 diabetes. 

A 2015 review in BMJ Open concluded that the evidence suggested a Mediterranean diet is suitable for the overall management of type 2 diabetes. 

And a 2016 review noted that the American Diabetes Association and the American Heart Association both recommend the Mediterranean diet for reducing risks associated with type 2 diabetes.  

What about cancer and liver disease?

A 2017 updated systematic review and meta-analysis found that the highest adherence to the Mediterranean diet was associated with lower risk of certain types of cancer and a lower risk of cancer mortality. 

Research has also found potential in the Mediterranean diet to prevent and treatment of non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disease. This is largely based on evidence from cross-sectional and longitudinal studies, meaning that longer term trials are necessary to establish more definitively the effects of the diet on the disease. 

Can a Mediterranean diet slow cognitive decline and reduce the risk of Alzheimer’s?

There is some evidence to show that the Mediterranean diet can reduce the risk of dementia.

A 2016 systematic review found that in a majority of studies, the Mediterranean diet was associated with improved cognitive function, a decreased risk of cognitive impairment or a decreased risk of dementia, or Alzheimer’s.  However, with many studies being observational, more research is needed to confirm this association. 

So, can a Mediterranean diet reduce the risk of death from cardiovascular disease and cancer and reduce the risk of getting dementia?

A review of the evidence published in 2010 found studies which indicated that following a Mediterranean diet more fully is associated with a reduced risk of cardiovascular disease (such as heart attack and stroke), cancer and neurodegenerative diseases (such as dementia). 

Conclusions

Most studies so far suggest a positive association between following a Mediterranean diet and the following health benefits:

• A reduced risk of cardiovascular disease
• Weight management and a reduced risk of obesity
• Management of type 2 diabetes
• A possible reduced risk of certain types of cancer
• Slower cognitive decline and a reduced risk of dementia. 

It is difficult to conclude exactly which elements of the Mediterranean diet contribute to the health benefits observed. Further research is required, in particular more scientifically controlled trials which compare the health of people who follow a Mediterranean diet with the health of a comparable group of people who don’t. These trials also need to be carried out with more consistent ingredients and quantities.

The evidence from trials so far suggests that, overall, people should be encouraged to follow a balanced diet similar to a Mediterranean diet, with plenty of fruit and vegetables, nuts, legumes, unrefined grains, use olive oil as the main oil, and reduce intake of red and processed meats. 

Reviewed and updated by Nicole Musuwo, December 2020. Next review date, November 2024.

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Other relevant articles on the Age Watch website:

• Diet: Diet 
• Diet: Good fats and bad fats? 
• Diet: Healthy foods 
• Diet: Regional diets 
• Diet: Vegetarian diet 
• Tackling obesity: Are carbs really bad for your diet? 
• Living longer: Looking after your body