Wednesday, September 19, 2007

Mediterranean diet helps....but not much

Repeatedly the media tells us that we should be eating a "Mediterranean diet" because of a range of health benefits that it will bring. For example

The Mediterranean diet - rich in grains, vegetables, pulses, fruit and nuts, with little meat, plenty of fish, and olive oil as the main fat - has long been adopted as a model of healthy eating. And not only is it healthy but it has a strong sensual appeal full of rich flavours, aromas and colours which can be adopted for everyday cooking and entertaining.

Leaving aside for a second the true definition of the Mediterranean diet, which we will get to, it there any evidence for all this hype?

This new study seems to indicate that the benefits may be a bit overstated, at least for overweight people:

Mediterranean diet and insulin sensitivity, lipid profile and blood pressure levels, in overweight and obese people; The Attica studyBackground

We aimed to investigate if overweight and obese adults "close" to Mediterranean diet present better insulin, lipids profile and better pressure levels, compared to individuals close to a more Westernized diet. Methods: The ATTICA study is a population -based cohort that has randomly enrolled 3042 adult men and women, stratified by age - gender, from the greater area of Athens, during 2001-2002. Of them, in this work were have studied 1762 participants with excess body weight, meaning overweight (BMI: 25-29.9 kg/m2) and obese (BMI>30 kg/m2). 1064 were men and 698 women (20-89 years old). Adherence to Mediterranean diet was assessed through a diet-score that was based on a validated food-frequency questionnaire. Blood pressure was measured and also fasting glucose, insulin and blood lipids. Insulin sensitivity was also assessed by the homeostasis model assessment (HOMA) approach (glucose x insulin / 22.5).
Results: Individuals with excess bodyweight in the highest tertile of diet score, were more insulin sensitive than those in the lowest tertile (11.4% lower HOMA, p=0.06), had 13% lower levels of total cholesterol (p=0.001) and 3 mmHg decrease of systolic blood pressure levels (p<0.001), when adjusted for age, sex and BMI. Multivariate analysis after taking into account several confounders demonstrated that insulin sensitivity, total cholesterol and systolic blood pressure were independently but only modestly correlated with Mediterranean diet in people with excess bodyweight.
Conclusions: Adherence to Mediterranean diet is modestly associated with a better insulin sensitivity, lower levels of total cholesterol and lower levels of systolic blood pressure in overweight and obese subjects. This may suggest that compared to general population, the beneficial effect of this diet in cardiovascular system of excess body weight people is limited.

So there is some effect....but not much

What do we do with this? Well one thing is to re-examine the true nature of a Mediterranean diet. We are told that it is all olive oil, lean meat and tomatoes but it seems that such a menu is not at all typical. We have been sold an inaccurate caricature.

Barry Groves has an interesting article which mentions the true nature of the Mediterranean diet:

The Mediterranean diet

The 'Mediterranean' diet is healthier than ours, we are told. We should eat what the French, Italians and Spanish eat. That could be right - but not for the reasons usually given. The Mediterranean diet is what the health fanatics advocate because, they say, it is low in fat. This is nonsense! Obviously, they have never been there. They don't seem to know that northern Italians love butter, that bowls of pork dripping are sold on Spanish markets or that the Spanish spread it thickly on their toast for breakfast. They don't know that goose fat is used to make cassoulet in the south of France, or that throughout the Mediterranean the sausages, salamis and pâtés all all contain up to fifty percent fat.

The Mediterranean diet may be healthier than the British but, contrary to popular belief, it is very far from being a low-fat diet!

However, there are a number of major differences between the Mediterranean countries and Britain that may play a significant part in their effects on health. Not only is the food eaten by the average working family in southern Europe very different from that eaten by a typical family in Britain, more importantly, the way it is bought, presented and eaten is also different.

For example:

The average Mediterranean diet comprises natural, unprocessed meat, vegetables and fruit that are usually bought fresh daily / The average British diet is composed of packaged, highly processed foods with chemical additives

Meat plays an important part in the Med diet / in the UK we are told to eat less meat

Fats eaten in teh Med are butter, olive oil and unprocessed animal fats / Fats eaten here are highly processed margarines, low-fat fat substitutes, and vegetable oils.

In the Med, meals are taken slowly, without hurrying. Lunch usually takes up to two hours - and is followed by a siesta / Here, food is rushed. Lunches are eaten on the run or combined with work. Often, they are junk-food snacks.

To illustrate this true med diet, have a look at the post by Dr Eades recently where he gives a mouth watering description, with photos, of a feast he had recently in Tuscany. Lots of animal fat is on display....


Chris said...

just noticed that I've messed up some of the quote from Barry Groves where there s a contract between British and Med diets - I'll put it right tonight.

Check out the whoel articlr on his site.

G said...

I really enjoy reading this space. Keep up the good work.

Chris said...

Thanks for the comment g, glad you find it helpful.