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, Greece had the lowest mortality from heart disease and this was positively associated with their dietary pattern.
This traditional dietary pattern is characterised 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.
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 the Prevención con Dieta Mediterránea (PREDIMED) intervention trial.
PREDIMED is a Spanish primary prevention randomised 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 randomised secondary prevention trial (n=605), which evaluated whether a Mediterranean-type diet could reduce the rate of secondary cardiovascular events.
The study, published in 1999, reported a 70% reduction in adverse cardiovascular events after an initial heart attack (MI) compared to those on a low-fat diet. The results were so remarkable that the ethics committee decided to stop the study early, as they could no longer justify keeping people in the control group.
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.
Likely, 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’re trying to lose weight, the Mediterranean diet can help control your appetite and make it easier to stick to a calorie deficit, while also improving your health. However, you’ll still need to reduce your overall calorie intake for 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.
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 characterised 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 on 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 & 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, 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 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 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 characterised by low fibre and a high intake of highly processed foods might worsen intestinal inflammation acting on different pathways.
A study published in May 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.
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. This 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?
