The health benefits of a Mediterranean-style eating plan have been well documented. The diet is rich in plant foods (nuts, seeds, fruits, vegetables, whole grains, legumes) and olive oil (its primary source of fat), with only a moderate intake of fish, poultry, dairy, eggs, and alcohol, and rare consumption of meats, sweets, and processed foods. It has been shown in studies to reduce risk of coronary heart disease, ischemic stroke, and total cardiovascular disease, as well as type 2 diabetes and cancer.
As if those benefits weren’t enough, a new study suggests that the popular style of eating could even reduce the risk of death, at least among women. It was published in the May issue of JAMA Network Open.
To assess the diet’s long-term impact on American women, investigators from Brigham and Women’s Hospital analyzed data collected from more than 25,000 initially healthy participants in the Women’s Health Study over a period of 25 years. Participants provided blood samples and dietary information (via a food-frequence questionnaire) at the outset of the study and completed an annual health questionnaire throughout the course of the study.
The blood samples were analyzed for “thirty-three blood biomarkers, including traditional and novel lipid, lipoprotein, apolipoprotein, inflammation, insulin resistance, and metabolism measurements,” at baseline. Mortality was tracked over the course of the study mostly by reports from family members, and the researchers obtained death certificates to determine cause of death.
Analysis of the data found that women who adhered most closely to the Mediterranean diet had up to a 23% lower risk of all-cause mortality over the course of the study. Furthermore, analysis of the blood biomarker data gave at least some evidence of the mechanism behind the diet’s effectiveness. Biomarkers of metabolism and inflammation made the largest contribution, followed by triglyceride-rich lipoproteins, adiposity, and insulin resistance. Other biological pathways related to branched-chain amino acids, high-density lipoproteins, low-density lipoproteins, glycemic measures, and hypertension made smaller contributions.
“Our research provides significant public health insight: even modest changes in established risk factors for metabolic diseases…can yield substantial long-term benefits from following a Mediterranean diet. This finding underscores the potential of encouraging healthier dietary habits to reduce the overall risk of mortality,” said lead author Shafqat Ahmad, PhD.
Conclusions
While the study identifies important biological pathways that may help explain all-cause mortality risk, the authors note some key limitations. For one thing, the study was limited to middle-aged and older well-educated female health professionals who were predominantly non-Hispanic and white. The study also relied on food-frequency questionnaires and other self-reported measures, such as height, weight, and blood pressure.
With that said, the results are consistent with numerous other studies detailing the benefits of a Mediterranean style of eating, and they offer at least some insight into the physiological underpinnings of those benefits. “The health benefits of the Mediterranean diet are recognized by medical professionals, and our study offers insights into why the diet may be so beneficial,” said senior author Samia Mora, MD. “For women who want to live longer, our study says watch your diet…following a Mediterranean dietary pattern could result in about one-quarter reduction in risk of death over more than 25 years with benefit for both cancer and cardiovascular mortality, the top causes of death in women.”
