For about 300,000 years homo sapiens has been eating just about everything that seemed edible. Plants, grains, fruits as well as parts of any creature that walks, flies, swims or crawls has travelled down the esophagus. One would think that with all that experience we would have figured out what sort of diet is conducive to health. But here we are, 300,000 years later, talking about low carb diets, ketogenic diets, carnivore diets, low fat diets, vegan diets, flexitarian diets, intermittent fasting diets and a bevy of others. While these all have their devotees, the most enthusiasm being generated by the scientific community is in favour of the “Mediterranean Diet.” There’s a problem here though. There are twenty-one countries around the Mediterranean and they each have their own way of eating. Spaniards don’t eat like the Lebanese, and the French baguette is not like the Greek pita. So, what is that “Mediterranean Diet” the experts are so energetically supporting? And why?
Life expectancy around the Mediterranean is generally a few years longer than in North America, although that mostly applies to the Southern European countries like Spain, Italy and Greece. These countries have a lower rate of heart disease and obesity, and the population is metabolically more healthy which means having optimal levels of five markers, namely waist circumference, fasting glucose, triglycerides, HDL cholesterol, and blood pressure without needing medication. Diet is obviously a factor, but people around the Mediterranean also walk more, have more social connections and generally have access to quality healthcare.
Assuming that diet is a factor, the question then becomes what the Mediterranean people are actually eating. In general, they eat lots of vegetables, fruits, whole grains, legumes, nuts, seeds and fish. They consume little red meat, moderate amounts of dairy (mostly yogurt), poultry and eggs. Their main fat is olive oil. But the secret to their diet may not be what they are eating. It may well be what they are not eating. They don’t eat ultra-processed foods or refined carbs, they stay away from processed meat, and do not drink sugary beverages. This dietary pattern reduces LDL cholesterol and blood pressure, lowers markers of inflammation, and leads to better insulin sensitivity and higher satiety meaning reduced calorie intake.
However, nailing down any benefit the Mediterranean diet may actually have requires more than observational studies. We need proper, randomized interventional studies such as the “Predimed” trial conducted in Spain between 2003 and 2011 that randomized 7500 adults at high risk for heart disease into three groups. One group followed the Mediterranean diet with extra olive oil, another group ate the Mediterranean diet with extra nuts and the third consumed a low-fat control diet. After 5 years the Mediterranean groups had 30% fewer major cardiovascular events meaning heart attacks, strokes or cardiovascular deaths. Impressive!
What about cancer? There is no dramatic difference, but some cancers such as colon and breast have a somewhat lower incidence in the Mediterranean countries than in North America. This may be due to increased fiber and antioxidant intake from vegetables. There is one other type of health that is worth looking into when it comes to the Mediterranean diet, and that is mental health.
We can get a glimpse into this from a study that looked at adherence to the “MIND” diet that is believed to be beneficial for the brain. MIND combines the Mediterranean Diet and the “DASH” (Dietary Approaches to Stop Hypertension) diet. Researchers followed 1600 adults over the age of 60 who had filled out food frequency questionnaires and had MRI scans every four years. Their diet was evaluated on the basis of the “MIND Scoring System” which awards points based on the number of servings of “brain-healthy” foods over a week and deducts points for servings of “brain-unhealthy” foods. The healthy foods are leafy greens, other vegetables, berries, nuts, olive oil, whole grains, fish, poultry, beans, legumes and wine. The unhealthy foods are meat and meat products, butter and margarine, cheese, pastries and sweets, fast and fried foods.
In order to calculate adherence to the MIND diet, add 1 point for intake of brain-healthy foods or unhealthy foods according to the table below. You get 0.5 points for moderate intake of either group and 0 points for low intake of healthy foods or high intake of unhealthy foods according to the table below. For example, if you eat 6 or more servings of green leafy vegetables a week, give yourself 1 point. If you eat only 3 servings, you get half a point. If you eat less than 4 servings of red meat a week you get a point. There are 15 categories so the maximum number of points would be 15.
Participants who adhered to MIND more closely had less brain shrinkage and less loss of grey matter which is vital for memory and cognition. Unfortunately, the researchers did not carry out memory tests to see if less brain shrinkage was associated with better memory. Brain shrinkage and loss of grey matter are also associated with Alzheimer’s disease and even moderate adherence to MIND has been shown to reduce the risk of Alzheimer’s by approximately 35%, while high adherence can reduce it by as much as 50%.
I think this scoring system would also work to evaluate the risk of heart disease, cancer and diabetes. The only quibble I would have is with awarding a point for a glass of wine a day. I don’t believe there is evidence to justify that. I would suggest instead to add one point for no alcohol consumption. In any case make the calculation and if you come up with a score higher than 9, you have a reasonably good diet. However, remember that it is the whole lifestyle package that matters, so anyone who thinks they will live longer by putting olive oil on their salad or eating yogurt instead of ice cream is out to the wrong lunch.