The Mediterranean diet unfolded

Mediterranean diet with plenty of vegetables (Photo: Maria Pontiki)

Mediterranean diet with plenty of vegetables (Photo: Maria Pontiki)

Time to put some nuts in your salad or why not a dollop of olive oil. This is now supposed to be the secret combination explaining the beneficial effects of the Mediterranean diet. This diet, recognised as an “Intangible Cultural Heritage” by UNESCO in December 2013, was originally inspired by the traditional dietary patterns of Spain, Morocco, Italy, Greece, Portugal, Cyprus and Croatia. Well, Portugal might be a bit of a stretch and most of Morocco, but the rest of the countries are situated around the Mediterranean Sea, thus the name.

The Mediterranean diet is based on the paradox that, although the people living in Mediterranean countries tend to consume relatively high amounts of fat, they have far lower rates of cardiovascular disease than in countries like the United States with similar levels of fat consumption. The important components of this diet include proportionally high consumption of olive oil, legumes, unrefined cereals, fruits, and vegetables, moderate to high consumption of fish, moderate consumption of cheese and yoghurt, moderate wine consumption, and low consumption of meat and meat products.

What about olive oil and red wine?

The Mediterranean diet has often been cited as beneficial for being low in saturated fat and high in monounsaturated fat and dietary fibre. One of the main explanations is thought to be the health effects of olive oil included in the Mediterranean diet. It contains a very high level of monounsaturated fats, most notably oleic acid, which epidemiological studies suggest may be linked to a reduction in coronary heart disease risk. The inclusion of red wine has also been considered a factor contributing to health as it contains flavonoids with powerful antioxidant properties.

Studies have shown that a Mediterranean diet appears to be more effective than a low-fat diet in lowering cardiovascular risk factors, such as cholesterol and blood pressure, thereby lowering the rate of early deaths by more than 50 per cent.  One study reported that the Mediterranean diet reduced the risk of heart disease in people at high risk by about 30 per cent when compared with individuals on just a low fat diet. Sounds marvellous, doesn’t it?

Now before we go overboard here, let’s make it clear that not all people around the Mediterranean adhere to this diet. In Northern Italy, lard and butter are commonly used in cooking, and olive oil is reserved for dressing salads and cooked vegetables. In both North Africa and the Middle East, sheep’s tail fat and rendered butter are the traditional staple fats. In Egypt, Malta, and Israel, olive oil consumption is negligible. And on top of that, the most popular dietary candidate, olive oil, has been undermined by findings that diets enriched in monounsaturated fats such as olive oil are not atheroprotective when compared to diets enriched in either polyunsaturated or even saturated fats. So what’s going on here?

Nitro fatty acids lower blood pressure (Photo: Illuminati Owl)

Nitro fatty acids lower blood pressure (Photo: Illuminati Owl)

Nitro fatty acids explains the benefits

The answer now seems to be the formation of nitro fatty acids. A diet that combines unsaturated fats found in olive oil, nuts and avocados, along with vegetables like lettuce, spinach, celery and carrots that are rich in nitrates and indirectly nitrites can reduce blood pressure, suggests a new study led by King’s College London. When these two food groups are combined, the reaction of unsaturated fatty acids with nitrogen compounds in the vegetables results in the formation of nitro fatty acids. Studies in two types of mice showed that nitro fatty acids lower blood pressure by inhibiting an enzyme known as soluble Epoxide Hydrolase which regulates blood pressure.

So now you know why a diet supplemented with extra-virgin olive oil or nuts can reduce the incidence of cardiovascular problems like stroke, heart failure and heart attacks.

Time to indulge!

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4 thoughts on “The Mediterranean diet unfolded

    • A very balanced summary Gerry. However, to be honest I am still very suspicious of broad brush epi studies blocking together so many products in the meat area. A good thing of this study is that they actually repeated the consumption survey but without looking at the publication itself I suspect that they only used the dreaded food frequency questionnaire method for data capturing. I was very happy to see that they compared absolute mortality rates rather than only relative differences. Happy to see more of this.

  1. Even a prestigious institution such as the Harvard School of Public Health does not have the resources to conduct 2 non-consecutive day 24-hr recall studies for 121,000 people over 24 years. Nor does it seem feasible since the ‘investment’ would be in the hundreds of millions of dollars. However, while a good scientist should always be ‘suspicious’, should we build dietary advice on the best available epi studies or on anecdotal reports and laboratory studies as in the past?

    Besides, low meat and meat product consumption is consistent with the Mediterranean Diet as you point out. Furthermore, being only one-tenth as efficient as plants as a protein source, mass production of food animals contributes to food insecurity. It also adversely impacts on the environment and is a growing ethical concern among many consumers.

  2. Let me declare an interest here. I worked for 14 years for the Australian red meat industry in funding research. One of my project areas was actually nutrition. So I am biased and will need very convincing evidence to change my mind. I am also conscious about a recent EPIC study that only managed to find statistic significance between processed meat and mortality but not red meat and mortality. But I accept your argument about the environmental pressure. Animal welfare is a concern. I always buy free range eggs with not more than 1500 animals per hectare. We also have free range pork available in Melbourne and grass fed beef is no problem. But of course such production is limited and the supply will not be sufficient for everyone.

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