Researchers at Brigham and Women's Hospital have identified and assessed underlying mechanisms that may explain the 23 percent reduction in all-cause mortality risk for American women from the Mediterranean diet
The health benefits of the Mediterranean diet have been reported in multiple studies, but there is limited long-term data on its effects in American women and little understanding of why the diet may reduce the risk of death. In a new study that followed more than 25,000 initially healthy American women for 25 years, researchers at Brigham and Women's Hospital, a founding member of the Mass General Brigham health care system, found that participants who followed a greater Mediterranean diet intake had up to a 23% lower risk of all-cause mortality, with benefits for both cancer mortality and cardiovascular mortality. The researchers found evidence of biological changes that may help explain why: They discovered changes in biomarkers of metabolism, inflammation, insulin resistance and more. Results are published in JAMA.
“For women who want to live longer, our study says: watch your diet! The good news is that following a Mediterranean diet could result in a reduction in the risk of death by around a quarter over a period of more than 25 years, with benefits for both cancer and cardiovascular mortality, the leading causes of death in women (and men) in the US and worldwide,” said senior author Samia Mora, MD, cardiologist and director of the Center for Lipid Metabolomics at the Brigham.
The Mediterranean diet is a plant-based varied diet rich in plants (nuts, seeds, fruits, vegetables, whole grains, legumes). The main fat is olive oil (usually extra virgin), and the diet additionally includes a moderate intake of fish, poultry, dairy, eggs and alcohol, and an infrequent consumption of meat, sweets and processed foods.
The current study examined the long-term benefit of following a Mediterranean diet in a US population recruited as part of the Women's Health Study, and examined the biological mechanisms that may explain the diet's health benefits. The study investigators evaluated a panel of approximately 40 biomarkers representing different biological pathways and clinical risk factors.
Biomarkers of metabolism and inflammation made the largest contributions, followed by triglyceride-rich lipoproteins, adipose tissue and insulin resistance. Other biological pathways involve branched chain amino acids, high density lipoproteins, low density lipoproteins, glycemic measures and hypertension have a smaller contribution.
“Our research provides significant public health insight: Even modest changes in established risk factors for metabolic diseases – especially those related to small molecule metabolites, inflammation, triglyceride-rich lipoproteins, obesity and insulin resistance – can yield significant long-term benefits. This finding underlines the potential of encouraging healthier dietary habits to reduce overall risk of mortality,” says lead author Shafqat Ahmad, PhD, associate professor of Epidemiology at Uppsala University, Sweden and researcher at the Center for Lipid Metabolomics and the Department of Preventive Medicine the Brigham.
The current study identifies key biological pathways that may help explain all-cause mortality risk. However, the authors note some important limitations, including that the study was limited to well-educated, middle-aged and older female health care workers, who were predominantly non-Hispanic and white. The study was based on food frequency questionnaires and other self-reported measurements, such as height, weight and blood pressure. But the strengths of the study include its large-scale and long follow-up period.
The authors also note that as the concept of the Mediterranean diet has gained popularity, the diet has been adapted in different countries and cultures.
“The health benefits of the Mediterranean diet are recognized by medical professionals, and our study provides insight into why the diet may be so beneficial. Public health policies should promote the healthy nutritional characteristics of the Mediterranean diet and discourage unhealthy modifications,” said Mora. .
