The Mediterranean diet: what it is, and what the trial showed
The Mediterranean diet is a pattern of eating built on olive oil as the main fat, vegetables and fruit every day, legumes, whole grains, nuts and fish several times a week, with little red or processed meat and few sweets. It is the dietary pattern with the strongest trial evidence for the heart. In the PREDIMED trial, which followed about 7,400 Spanish adults at high cardiovascular risk for nearly five years, those assigned to a Mediterranean diet supplemented with extra-virgin olive oil or with nuts had roughly 30% fewer major cardiovascular events than those advised to follow a low-fat diet. It is not a weight-loss diet and has no forbidden foods. For someone who eats in restaurants most days, it is also the easiest sound pattern to follow: grilled fish, vegetables, pulses and olive oil are on almost every menu.
How Mediterranean is your week?
Eight habits taken from the research questionnaires. Answer for a normal week.
- Points
- 0 out of 8
- Reading
- Far from the pattern: start with olive oil, vegetables and fish
A simplified self-check, not a validated score.
A pattern, not a list of rules
The term describes the traditional eating habits of olive-growing regions around the Mediterranean in the mid-twentieth century. It is defined by proportions and frequencies rather than by quantities.
- Daily: vegetables, fruit, whole grains, olive oil as the principal fat.
- Several times a week: legumes, nuts, fish and seafood.
- In moderation: poultry, eggs, cheese and yoghurt.
- Rarely: red meat, processed meat, sweets, sugary drinks.
Wine with meals is part of the traditional pattern. It is not a reason to start drinking, and current guidance does not recommend alcohol for health. See alcohol and training.
The World Health Organization's general advice on healthy diet points in the same direction: at least 400 grams of fruit and vegetables a day, unsaturated fats in place of saturated ones, less than 5 grams of salt, and free sugars below 10% of energy.
What the PREDIMED trial found
Most evidence on diet comes from observation: people who eat in a certain way are compared with people who do not, and the differences between them can never be fully separated from the diet. PREDIMED was a randomised trial, which is rare in nutrition.
About 7,400 adults in Spain, aged 55 to 80, with type 2 diabetes or several cardiovascular risk factors but no cardiovascular disease, were assigned to one of three diets: a Mediterranean diet with extra-virgin olive oil provided free, a Mediterranean diet with mixed nuts provided free, or advice to reduce dietary fat. After a median follow-up of 4.8 years, the rate of heart attack, stroke or cardiovascular death was about 30% lower in each of the two Mediterranean groups.
The trial was first published in 2013 and republished in 2018 after irregularities in randomisation at some sites were identified and corrected. The conclusions were unchanged.
Two limits should be kept in mind. The participants were older and at high risk, so the size of the benefit in a healthy 40-year-old is not known. And the comparison group was given advice on a low-fat diet, which it followed imperfectly.
The foods that carry the effect
- Extra-virgin olive oil. In the trial, participants were given a litre a week for the household and encouraged to use it generously, about four tablespoons a day per person. It replaces butter, cream and refined oils rather than being added to them.
- Nuts. Thirty grams a day of walnuts, almonds and hazelnuts in the trial: a small handful.
- Legumes. Lentils, chickpeas and beans three times a week or more, as a main dish and not only a garnish.
- Fish. Three or more servings a week, with oily fish among them.
- Vegetables. Two or more servings a day, one of them raw.
The calculator above is a short self-check built on these habits. It is a simplified version of the questionnaires used in research, intended to show which habits are missing rather than to produce a diagnosis.
How it fits with training
The pattern supplies ample carbohydrate from grains, fruit and legumes for people who train, and good fats. Its one weakness for someone lifting weights is protein, which can fall short if meals lean heavily on vegetables and grains.
The correction is simple: a clear protein source at each meal. Fish, eggs, yoghurt, poultry and legumes all belong to the pattern. See protein needs.
Energy needs still apply. Olive oil and nuts are dense in calories, and the diet does not cause weight loss by itself. See calorie needs.
Eating this way in restaurants
This is where the pattern suits people with full diaries.
- Start with vegetables. A salad, grilled vegetables or a soup.
- Choose fish or a legume dish as the main course. Grilled rather than fried.
- Ask for olive oil in place of butter and cream sauces.
- Bread, if you eat it, with oil rather than butter.
- Fruit for dessert, most days.
The cuisines of the Levant, widely available across the Gulf, fit naturally: hummus, tabbouleh, grilled fish, lentil soup, fattoush, moutabal. The same applies to Greek, southern Italian and Spanish menus.
At home, in ten minutes
- Tinned sardines or mackerel, tomatoes, bread and olive oil.
- Lentils from a jar, warmed with onion, spinach and a fried egg.
- Greek yoghurt, walnuts and fruit.
- Chickpeas, cucumber, feta, parsley, lemon and oil.
None of these requires cooking skill, which is the point for people who arrive home at nine.
What it does not promise
The Mediterranean diet does not treat disease, replace medication or guarantee a result for an individual. People with diabetes, kidney disease or food allergies need individual advice from a physician or registered dietitian.
The trial's finding applies to people at high cardiovascular risk. The pattern is nonetheless the one most consistently recommended by health authorities for adults in general.
Questions
What do you eat on a Mediterranean diet?
Vegetables, fruit and whole grains every day, with olive oil as the main fat. Legumes, nuts and fish several times a week. Poultry, eggs, cheese and yoghurt in moderate amounts. Red meat, processed meat, sweets and sugary drinks rarely. It is a pattern of proportions and frequencies, without forbidden foods or fixed quantities.
Is the Mediterranean diet good for losing weight?
It is not designed for weight loss. Olive oil and nuts are high in energy, and people can gain weight on it if they eat more than they use. It makes weight loss easier to sustain, because meals based on vegetables, legumes and fish are filling. The energy balance still decides. See the article on calorie needs.
How much olive oil per day on a Mediterranean diet?
In the PREDIMED trial, participants in the olive oil group were encouraged to consume about four tablespoons of extra-virgin olive oil a day, used for cooking and for dressing food. It replaced other fats such as butter and refined oils rather than being added on top of them, which matters for the total energy of the diet.