One of the best diets for health keeps getting better.
A new study that followed more than 25,000 women for a quarter of a century found that the more their diet matched the Mediterranean diet, the less likely they were to die during that period. The relationship held even when researchers took into account other factors that influence lifespan, such as age, exercise habits and smoking history.
The findings were published Friday in the journal JAMA Network Open.
The Mediterranean diet is heavy on fruits, vegetables and whole grains. Extra virgin olive oil, rich in antioxidants, is the main source of fat. Protein comes from lean sources such as beans, legumes and nuts, as well as fish, poultry, eggs and low-fat or fat-free dairy products. Wine is welcome in small to moderate amounts, while red and processed meats, butter and sweets are eaten sparingly or not at all.
The diet takes a long time favorite by doctors, nutritionists And weight loss programs. Studies consistently show that it helps people to fall off, lower cholesterol and bring them down blood pressure, all of which reduce the risk of cardiovascular disease. It also helps people control their blood sugar levels and prevent type 2 diabetes.
How exactly can the Mediterranean diet achieve this? That is what Shafqat Ahmadwho studies the development of cardiovascular disease at Sweden's Uppsala University and Harvard Medical School, and his colleagues wanted to find out.
They turned to the Women's Health Study, which included tens of thousands of female healthcare workers who were at least 45 years old. When the women took part in the study in the mid-1990s, they answered 131 questions about the food they ate.
The researchers used those answers to give each woman a score between 0 and 9 that reflected the extent to which they followed the Mediterranean diet. When they were upstairs the median when it came to consumption of vegetables, fruits, nuts, whole grains, legumes or fish, they received one point. The same if they were above the median in terms of their monounsaturated ratio (which are good) to saturated (that are bad) fatty acids.
If the women were below the median for red and processed meat consumption, they earned another point. And if they consumed between 5 and 15 grams of alcohol per day – the equivalent of a typical glass of wine or a can of beer – they also received a point.
Those with a total score between 0 and 3 were categorized as having “low” adherence to the Mediterranean diet. A total of 4 or 5 was classified as 'medium' and an amount between 6 and 9 was considered 'high'.
The Women's Health Study ended in 2004, but researchers continued to contact participants once a year. Ahmad and his colleagues focused on the 25,315 women who had both dietary data and a host of biomedical measurements from the time they entered the study.
By November 2023, 3,879 women had died. But the risk of interfering was not the same for everyone.
Compared to the women in the low adherence group, those in the intermediate group were 16% less likely to die during the study period, while the risk of death for those most adherent to the Mediterranean diet was 23% lower, according to the study. study.
When the researchers controlled for smoking status, physical activity, alcohol consumption and menopausal factors, women in the intermediate group had an 8% lower risk of death, and those in the high group had an 11% lower risk of death.
In addition to a reduced risk of death from any cause, following the Mediterranean diet was associated with a lower risk of death from cancer or cardiovascular disease. Dr. Samia Moraa cardiologist at Brigham and Women's Hospital in Boston and senior author of the study.
As for why the Mediterranean diet appeared to protect against premature death, the most influential factor – of the approximately 40 biomarkers the researchers were able to test – was a group of metabolites that appeared to explain 14.8% of the benefit. Ahmad and his colleagues drew particular attention to higher levels of a useful amino acid Alanine as well as lower levels of another amino acid called homocysteine that is increased in people with heart disease.
Inflammation accounting for 13% of the mortality benefits enjoyed by people strongly adhering to the Mediterranean diet. Chronic inflammation is linked to a variety of health problems, including cardiovascular disease, diabetes and some cancers.
From a woman body mass index and a measure of how well her body processes triglycerides each accounted for 10.2% of the reduced risk of death, and insulin resistance accounted for 7.4%.
The study suggests that making even modest improvements in these factors could help people get longer life from the Mediterranean diet, Ahmad said.
But he and Mora added that there must be other biological mechanisms at work that their research could not measure. The gut microbiome may be one of them, they said.
Dr. Frank HuProfessor of Nutrition and Epidemiology at Harvard TH Chan School of Public Health said the study offers “new insights” into why people who embrace the Mediterranean diet tend to live longer.
“It suggests that the health benefits in reducing mortality are explained by the effects on harmful blood metabolites, inflammation, insulin resistance and body weight, rather than by lowering total and LDL cholesterol,” said Hu, who was not involved in the study was involved.
The study has several caveats, including the fact that 96% of participants were white women. This means that the results may not generalize to the population as a whole.
In addition, the women were only asked once about their eating habits, so it is not possible to know whether their diets changed as they got older.
However, Mercedes Sotos Pietroa nutritional epidemiologist at the Autonomous University of Madrid, said the findings on the reduced risk of death are consistent with research she has lead using data from the Health Study of Nurses and the Follow-up study for health professionals who assessed the diet several times.
Sotos Pietro, who did not participate in the new research, said the Mediterranean diet is “golden” because it includes a variety of tasty foods and doesn't forbid anything. That makes it easy for people to stick with it for a long time, she said.
Hu added that the diet's flexibility makes it adaptable to many cuisines.
“For example, an Asian individual could use tofu as a protein source and replace white rice with brown rice,” he said. “Individuals can integrate traditional recipes from other cultures and locally available foods while maintaining the core principles of MedDiet.”
