25 years of data links Mediterranean diet to longer life, study finds

Many studies of the Mediterranean diet rely on what people report eating, although dietary questionnaires may be unreliable. But a new study took a different approach: using blood markers that indicate how well a person is following their diet.

Published in the American Journal of Clinical NutritionThe study found that people with higher scores on a 67-metabolite blood signature of adherence to the Mediterranean diet had a 23% lower risk of death. Furthermore, the pattern was replicated in three large US cohorts followed for an average of 25 years. Here’s what you need to know.

How was the study conducted?

Researchers started with PREDIMED, a Spanish trial of adults at high cardiovascular risk who did not have cardiovascular disease at the time of enrollment. Of the 7,447 participants, 1,880 had blood metabolite data at baseline and were followed for a median of 13.2 years. Deaths were tracked using medical records and national death registers.

Using blood samples, researchers calculated each participant’s score on a previously developed signature of 67 metabolites following adherence to the Mediterranean diet. They then repeated the analysis with 12,704 participants from the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study. This group was made up of 83% women, with an average age of approximately 55 years, and was followed for an average of 25 years.

What did the study reveal?

When analyzing PREDIMED data, participants with the highest Mediterranean diet scores had a 23% lower risk of death from any cause than those in the bottom third, with the mortality rate falling from about 24 people per 1,000 to 18 people per 1,000. Each standard deviation increase in score was linked to a 19% lower risk of mortality.

The US cohorts had similar results, with the highest quintile having a 23% lower risk of death than the lowest quintile: the mortality rate fell from 15 people per 1,000 to about 11.5 people per 1,000.

Even so, results for some causes of death were mixed. For example, in PREDIMED, the one-year score was linked to fewer cardiovascular deaths, but participants’ baseline score was not significantly linked. People with higher scores in PREDIMED generally followed a Mediterranean diet more closely and were less likely to smoke or have type 2 diabetes.

Boundaries

These results were observations, so they can’t show that increasing your score or changing your diet has an impact on how long you live. The signature is a marker of adherence to the Mediterranean diet, not the diet itself, and changes in score after one year were not significantly related to prior mortality. The authors also note that the PREDIMED sample was limited to studying specific causes of death and that the profiling method could not measure phenolic compounds or other antioxidants found in Mediterranean foods. The study was funded by the National Institutes of Health and Spanish government agencies, and some authors reported ties to nut and olive oil industry groups.

How does this apply to real life?

We love the Mediterranean diet because it focuses on adding healthy foods to your routine (and it doesn’t have strict rules like some fad diets). To change your eating habits toward the Mediterranean diet, try including olive oil, fruits, vegetables, legumes and fish, and opt for less red and processed meat, butter and sweets. Here are some helpful ways to include more of these foods in your diet:

• Cook with olive oil instead of butter.
• Add beans or lentils to soups, salads or grain bowls.
• Have a handful of nuts and a piece of fruit instead of sugary snacks.
• Try filling half your plate with vegetables.

If you want to dive in head first, we have some meal plans that can help you on your way. All of our meal plans are developed by dietitians, so you’ll know that this beginner-friendly week of work meals (or month of all-inclusive meals) is a balanced choice.

Our expert opinion

A new study published in The American Journal of Clinical Nutrition found that a blood signature of people following the Mediterranean diet was associated with a 23% lower risk of death in a Spanish trial and in three large US cohorts followed for an average of 25 years. However, because the study was observational, researchers cannot prove that the diet extends life. Nevertheless, the results suggest that a Mediterranean diet can help you live longer and that the foods behind it, such as olive oil, vegetables, legumes and nuts, can be gradually added to your diet starting today.