Thousands of deaths from heart disease and stroke could be prevented if everybody ate a Mediterranean diet, a major study of the UK’s eating habits has shown.

The health benefits of the Mediterranean diet, rich in olive oil and fruits and vegetables, are well-known, but the study is the first to look at it in the real world of the UK. Gathering data about eating habits among nearly 24,000 people in Norfolk over an average of 12 to 17 years, the researchers found that 12.5% of heart attack and stroke deaths that occurred could have been prevented. In the context of the UK as a whole, that would be 19,000 deaths averted out of the 155,000 that occur as a result of heart disease every year.

Dr Nita Forouhi, lead author from the Medical Research Council epidemiology unit at the University of Cambridge, said: “We estimate that 3.9% of all new cardiovascular disease cases or 12.5% of cardiovascular deaths in our UK-based study population could potentially be avoided if this population increased their adherence to the Mediterranean diet.”

In spite of the name, the Mediterranean diet does not have to feature squid, anchovies, hummus and pitta bread. It is descriptive, not prescriptive – taken to mean a diet that includes a lot of fruit and vegetables, olive oil, nuts, legumes, some fish and dairy and little red and processed meat. It usually includes a small amount of red wine.

The difficulty for the researchers was in pinning down how much of the diet of the participants in the study, which began in the 1990s, qualified as “Mediterranean”. After a considerable amount of work searching the literature, and with reference to the Mediterranean diet pyramid produced by the Mediterranean Diet Foundation, they worked out a way to score the food families consumed. The top possible score would be a diet with 15 Mediterranean elements. They found the maximum score among their participants was 13.1 and the lowest score was 3.

They found that those with higher scores – more elements of the Mediterranean diet in their daily meals – were less likely to get heart disease and to die as a result of it after taking into account other problematic factors such as smoking, weight and physical activity.

Forouhi said one of the messages from their work was that the “superfoods” approach often promoted by society, advocating kale or certain types of berry for greater health, was not the answer. Nor was a focus on reducing single dietary elements like sugar or fat. “It is very much more a balance across the range of foods available to us,” she said.

People who have have heart disease are already recommended to follow a Mediterranean diet in the UK. The new study shows it is helpful for everyone else as well, said Forouhi.

Dr Louis Levy, head of nutrition science at Public Health England, said: “The Mediterranean-style diet in this study is in fact similar to official UK advice, as shown in the Eatwell Guide. We also recommend cutting back on sugary, fatty and salty food and drinks and being mindful of calories to help protect your heart and general health.”

Sarah Boseley/the Guardian