A recent study published by Italian researchers shows that adhering to a Mediterranean-style diet can offer protection against type 2 diabetes. The paper is just the latest in a long line of research pointing out the wonders of this diet – so what are we to take from these latest findings?
Despite its name, the Mediterranean diet is more a way of life based on the dietary traditions of Greece and southern Italy in the 1950s and 1960s. At the time, rates of chronic disease in these areas were among the lowest in the world, and adult life expectancy among the highest.
Food and life
In simple terms, the Mediterranean diet is a healthy diet (not a low-fat diet) low in omega-6 fatty acids and rich in omega-3 fatty acids (from olive oil).
In the 1950s, people in Greece and southern Italy were poorer and consequently ate red meat only about once a week. Herbs and spices were frequently used instead of salt to flavour foods.
They usually ate about nine servings of fruit and vegetables every day, and fish such as mackerel, herring, sardines and anchovies at least twice a week. Eggs, dairy and poultry were eaten regularly but in smaller portions than in current western diets.
Desserts, such as ice cream, were eaten only during family outings and at home on feast days. People ate processed and cured meats but only in small servings. Curing was a way to extend the consumption of local food as importing food was uncommon.
There are many lifestyle factors associated with the Mediterranean diet. Meals were (and still are) centred around a social atmosphere, with friends and family gathering to enjoy each others company as much as the food. Alcohol (mainly red wine) was consumed in moderation.
People also did a lot of manual work in a warm climate, such as growing vegetables, fishing or tending to animals. The salt from cured meats replaced what was lost during the working day.
Overall, dietary calorie intake was balanced with daily exercise. Nowadays, people don't have the same kind of physically active jobs and so can't eat cured and processed foods with such frequency.
How do we know
The relationship between the traditional Mediterranean diet and lower rates of sickness, disease and death was first written about in 1995.
Since then, there have been many studies investigating the link between this diet and reduced risk of chronic diseases such as cardiovascular and Alzheimer's disease.
These studies have been conducted in different countries and in different ethnic groups, suggesting that the beneficial effects of the Mediterranean diet are transferable to different populations.
There are several ways of collecting dietary data, including weighed food records (weighing all the food and drink you have for three or four days), 24-hour diet recall (telling a researcher everything you have eaten and drunk in the last 24 hours in an interview) and food frequency questionnaires (a list of food and drink consumed with the quantity and frequency of each).
All of these are prone to errors in reporting food intake, estimating serving sizes, and determining nutrient content. Despite these shortcomings, data can still provide sufficient information about adherence to dietary patterns for analysis.
A disappearing lifestyle
Like other countries in the developed world, Greece and Italy have now entered an era of supermarkets and aggressive convenience-food marketing, and much of the highly-praised Mediterranean diet no longer exists.
As people move away from villages to live in cities, they work longer hours in more sedentary jobs, resulting in less time to prepare meals and decreased calorie expenditure.
Meat is also more accessible and consumed more often. So it's unsurprising that countries such as Greece and Italy have increasing obesity rates.
What's more, the traditionally home or locally-grown fruit and vegetables consumed as part of the Mediterranean diet are today subject to long delays between field and supermarket. Add this to the time fresh food spends on shelves in the market or at home, and you've got a serious reduction in the level of the beneficial components of fruits and vegetables.
Most people don't realise the crucial importance of freshness. As soon as fruit and vegetables are harvested, they begin to deteriorate, either via bacteria, mould and fungi, or through their own internal enzymes.
One way to overcome this is to use frozen fruit and vegetables, which are usually frozen very soon after harvest, thereby preserving vitamin and mineral levels.
But the best option is to buy fruit and vegetables at local farmers' markets, which provide fresh produce and support the local farming community.
We still need to determine which aspects of the Mediterranean diet and associated lifestyle are most beneficial. But it's clear we should all be trying to emulate it to help reduce our risk of chronic diseases.