'23% lower death risk': A diet tracked for 25 years

The traditional Mediterranean diet, long regarded as one of the healthiest ways to eat, is drawing fresh attention for its link to longevity. A new study has found that people whose blood chemistry reflects close adherence to the diet face a significantly lower long-term risk of death than those whose blood chemistry does not. Unlike earlier research that relied mainly on self-reported dietary questionnaires, the study used blood-based biomarkers to capture the biological effects of eating habits.

The paper, published in the latest issue of The American Journal of Clinical Nutrition, is a joint effort by the University of Navarra in Spain and the Harvard T.H. Chan School of Public Health. It examined how patterns of diet-related metabolites in the blood relate to mortality risk.

The researchers analyzed 67 metabolites in blood samples and used them to generate a score reflecting how closely a person's diet matched the Mediterranean pattern — the higher the score, the more the blood's composition resembled that of a confirmed Mediterranean diet follower. The team then tracked 1,880 participants in Spain over 13 years, and applied the same index to 12,704 participants in the United States over 25 years.

In Spain, participants whose blood metabolite scores placed them in the top third had a 23 percent lower risk of death from all causes than those in the bottom third.

The United States cohort produced a nearly identical finding: participants in the top 20 percent of scores had a 23 percent lower all-cause mortality risk than those in the bottom 20 percent.

Most of the blood metabolites the study analyzed were fat-related compounds, reflecting the diet's emphasis on foods rich in unsaturated fats — olive oil, nuts and fish. When a person follows the diet closely, that pattern shows up in the fat-related substances circulating in the blood.

The Mediterranean diet's credentials extend well beyond this study. It has topped the annual diet rankings published by US News & World Report for nine consecutive years through this year — a list compiled each year by panels of physicians, dietitians and other specialists who evaluate eating plans for nutritional balance and health benefits, and which is widely used as a reference guide for consumers seeking healthier food choices.

The Mediterranean diet centers on olive oil, vegetables and fruit, whole grains, legumes and nuts. Fish and seafood are the preferred protein sources, while poultry, eggs and dairy are consumed in moderate amounts. Red meat, processed meats, and heavily processed or sugary foods are kept to a minimum.