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The Mediterranean Diet: Everything You Need to Know

Mediterranean Diet Foods

What is the Mediterranean Diet?

The Mediterranean diet is a way of eating based on traditional foods and drinks of the countries surrounding the Mediterranean Sea.

The Mediterranean diet was first established three decades ago as a cardio-protective diet in the Seven Countries Study.

Keys and co-workers found that residents in Crete in Greece had the lowest mortality from heart disease and this was positively associated with their dietary pattern.

This traditional dietary pattern is characterized by an abundance of plant-based foods such as leafy green vegetables, tomatoes, onions, garlic, herbs, whole grain cereals, legumes, nuts and seeds, olive oil used as the main added dietary fat, moderate amounts of low-fat dairy products, fish and seafood, smaller quantities of red meat and red wine to be consumed in moderation with meals.

Health-Benefits-of-the-Mediterranean-Diet-

Benefits of a Mediterranean Diet

There is an array of benefits associated with consuming this dietary pattern such as reduction or maintenance of weight, primary and secondary prevention of cardiovascular disease (CVD), and it has more recently been linked to reducing non-alcoholic fatty liver disease (NAFLD).

Since the establishment of the Mediterranean diet over three decades ago, there has been increasing scientific evidence regarding the consumption of this dietary pattern.

Researchers of the Seven Countries Study proposed that the high consumption of monounsaturated fats due to increased intake of extra virgin olive oil, and low intakes of saturated fats contributed to the low mortality rate seen within this population group.

The Mediterranean diet differs greatly from the current western diet. Although the most significant difference is the predominant sources of dietary fat. 

Mediterranean Diet & Heart Disease

Wider research has since established the cardio-protective nature of the Mediterranean diet stems from the high consumption of bioactive compounds such as polyphenols in plant-based foods and extra-virgin olive oil, which is also believed to have an anti-inflammatory effect.

The cardioprotective nature of this dietary pattern has been exemplified in two landmark studies: The Lyon Diet Heart Study and Prevención con Dieta Mediterránea (PREDIMED) intervention trial.

PREDIMED is a Spanish primary prevention randomized control trial (n=7447) in high-risk middle-aged people in Spain. The study had three intervention groups:

1) a Mediterranean diet enriched with extra virgin olive oil;

2) a Mediterranean diet enriched with mixed nuts and

3) a control low-fat diet.

In 2013, the final report of the PREDIMED trial indicated a 30% absolute risk reduction in the incidence of a first major cardiovascular event.

The Lyon Diet Heart Study is a randomized secondary prevention trial (n=605), which evaluated whether a Mediterranean-type diet could reduce the rate of secondary cardiovascular events.

The study was published in 1999 and reported a 70% reduction in adverse cardiovascular events after initial myocardial infarction (MI) compared to a control low-fat diet. The findings of this study were so significant; the ethics committee could no longer justify keeping individuals in the control arm and ceased the study.

These two landmark studies exemplify the cardio-protective nature of this dietary pattern. However, there is a range of other benefits associated with this dietary pattern. 

Mediterranean Diet & Weight Loss

The Mediterranean diet is not necessarily a diet aimed at promoting weight loss. In research, this style of eating does not seem to come out superior to other dietary patterns when it comes to short and long-term weight loss.

It is likely that the lower rates of obesity found amongst populations consuming a Mediterranean-style diet were also due to higher rates of physical activity, less time spent being sedentary, and frugality in eating patterns.

Although it would also make sense that a diet high in fibre and low calorie, high volume foods such as fruits, vegetables, and legumes would promote healthy weights amongst a population.

If you are looking to lose weight, the Mediterranean diet could assist with appetite regulation and make maintaining a calorie deficit easier whilst contributing to improved health. However, you would still likely need to take measures to reduce your overall calorie intake to promote significant weight loss.

On the other hand, if you are looking to maintain a healthy weight and reduce the risk of chronic disease later in life, the Mediterranean diet could be a suitable option for you.

Weight loss person on scale

Mediterranean Diet & Type 2 Diabetes Mellitus (T2DM)

Due to the characteristics of the Mediterranean diet, it is often discussed as an anti-inflammatory dietary pattern. Arguably, this could treat diseases that are related to chronic inflammation including type 2 diabetes.

Furthermore, several large epidemiological studies have shown that diets characterized by a low degree of energy density overall such as the Mediterranean diet, prevent weight gain.

Since type 2 diabetes is a condition that is partially mediated through healthy weight control, a Mediterranean diet may also reduce the risk of developing T2DM in that regard.

According to a larger prospective study of 13,380 Spanish university graduate students, a Mediterranean diet was associated with an 83% reduction in the risk of developing T2DM.

Those are some pretty promising statistics!

We also have data for the positive influence of these dietary patterns on existing cases of T2DM. A study in Italy of 901 outpatients with type 2 diabetes found an association between adherence to a Mediterranean-style diet and lower HbA1c levels and 2-hour postmeal glucose levels.

However, in the same study, a paleolithic style diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs, and nuts did come out as superior in improving glucose control to the Mediterranean-style diet.

Mediterranean Diet

Mediterranean Diet & Non-alcoholic Fatty Liver Disease (NAFLD)

Alongside the prevention of heart disease and type 2 diabetes, the Mediterranean-style diet may even reduce the risk of developing fatty liver disease as well as assist in its treatment.

This could be for several reasons including improved weight management, reduction in weight gain around the abdomen, low intake of saturated fats, and a high intake of healthy fats including monounsaturated fats and omega-3.

A recent study published in 2020, compared a “green Mediterranean diet” which was further enriched with specific green polyphenols (Mankai), green tea, and walnuts, and other healthy dietary patterns including the traditional Mediterranean diet.

All groups lost liver fat, but those in the green Mediterranean diet group had the greatest reduction. They dropped an average of 39% of liver fat compared to a 20% reduction with the traditional Mediterranean diet.

So although the traditional Mediterranean diet can be effective in the treatment of fatty liver disease, its effectiveness could be further improved through the addition of more foods rich in polyphenols.

Mediterranean Diet & Inflammatory Bowel Disease (IBD)

For the most part, there are very few dietary recommendations made for all individuals with IBD.

IBD is is an umbrella term used to describe disorders that involve chronic inflammation of your digestive tract such as Crohn’s disease (CD) and ulcerative colitis (UC).

Due to the anti-inflammatory characteristics of a Mediterranean diet, it may actually assist with reducing markers of inflammation in those with IBD.

The role of nutrition in the management of IBD is often overlooked. However, the Western diet characterized by low fiber and a high intake of highly processed foods might worsen intestinal inflammation acting on different pathways.

A study published in May of 2020 took 142 IBD patients with a mix of Crohn’s disease and ulcerative colitis and got them to follow a Mediterranean diet for 6-months.

Clinical disease activity and inflammatory biomarkers (C-reactive protein and fecal calprotectin) were collected at baseline (T0) and compared with those obtained after 6 months (T180) to evaluate the impact of the dietary pattern.

At follow up there was a significant reduction in inflammatory markers in both CD and UC patients. Meaning that the Mediterranean diet may be useful in managing IBD.

Inflammatory Bowel Disease Study
Inflammatory Bowel Disease Study

Summary

The Mediterranean diet has become one of the highest regarded dietary patterns to date.

The consumption of this dietary pattern is associated with a range of health benefits including the risk reduction and potential treatment of many chronic diseases including heart disease, type 2 diabetes, and non-alcoholic fatty liver disease.

This pattern of eating may also assist with weight management, having a flow-on effect again to the risk of many disease states.

Whilst emerging, research on the Mediterranean diet for the management of inflammatory bowel disease appears promising. Which is great news for a condition where treatment options are few and far between.

Unlike many diets, the Mediterranean diet is also known for its palatability and cost-effectiveness. It is truly the gift that keeps on giving.

Pass the olive oil, please?

By Cassandra Bendall

Cassandra completed her Bachelor of Human Nutrition in 2015 at La Trobe University. Upon completion, Cassandra undertook her Honours year at La Trobe University the following year and ended the year with First Class Honours. Cassandra had the opportunity to work on the AusMed Heart Trial, which aims to prevent 12-month cardiac re-event rate using a Mediterranean diet intervention in a multi-ethnic cohort. Her Honours research focussed on the Effect of Mediterranean Diet on Visceral Fat in Australian Patients Post-Cardiac Event. Since cessation of her Honours year, Cassandra has been accepted into the Masters of Dietetic Practice at La Trobe University in 2017, which will allow her to fulfil her goal of becoming a clinical dietitian. At present, Cassandra is in the final stages of preparing to submit her systematic review for publication. Cassandra’s areas of interest include: Mediterranean diet, cardiovascular disease, diabetes and obesity.