Summary: Following a Mediterranean diet reduces the risk of all-cause mortality by 23% among American women over the age of 25. Benefits of the diet include decreased cancer and cardiovascular mortality, linked to positive changes in metabolism, inflammation, and insulin resistance. Researchers analyzed biomarkers to understand these health improvements. The study highlights the diet’s potential for long-term health benefits.
Key fact:
- The Mediterranean diet reduces the risk of all-cause mortality by 23% in American women.
- Benefits include reduced cancer and cardiovascular mortality.
- Positive changes in metabolism, inflammation and insulin resistance explain health improvements.
Source: Brigham and Women’s Hospital
The health benefits of the Mediterranean diet have been reported in numerous studies, but there is little long-term data on its effects in American women and little knowledge about why the diet may reduce the risk of death.
In a new study that followed more than 25,000 initially healthy American women for up to 25 years, researchers at Brigham and Women’s Hospital, a founding member of the Mass General Brigham Health System, found that participants who consumed more of the Mediterranean diet had up to 23% lower risk of all-cause mortality, with benefits in terms of cancer mortality and cardiovascular mortality.
The researchers found evidence of biological changes that could help explain why: They detected changes in biomarkers of metabolism, inflammation, insulin resistance and more.
The results are published in JAMA.
“For women who want to live longer, our study advises monitoring their diet! The good news is that following a Mediterranean diet could lead to a reduction in the risk of death by around a quarter over 25 years, with a benefit on both cancer and cardiovascular mortality, the leading causes of death among women (and men) in the United States and globally,” said lead author Samia Mora, MD, a cardiologist and director of the Center for Lipid Metabolomics at Brigham.
The Mediterranean diet is a diverse 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 moderate consumption of fish, poultry, dairy products, eggs and alcohol, as well as rare consumption meats, sweets and processed foods.
The present study investigated the long-term benefits of adhering to a Mediterranean diet in a US population recruited from the Women’s Health Study and explored the biological mechanisms that may explain the health benefits of the diet. . Study investigators evaluated a panel of approximately 40 biomarkers representing various biological pathways and clinical risk factors.
Biomarkers of metabolism and inflammation made the greatest contribution, followed by triglyceride-rich lipoproteins, adiposity, and insulin resistance. Other biological pathways involve branched chain amino acids, high density lipoproteins, low density lipoproteins, glycemic measurements and hypertension have a lesser contribution.
“Our research provides significant public health information: even modest changes in established risk factors for metabolic diseases, particularly those related to small molecule metabolites, inflammation, triglyceride-rich lipoproteins, obesity and insulin resistance, can generate substantial long-term benefits from following a Mediterranean diet.
“This finding highlights the potential for encouraging healthier dietary habits to reduce overall mortality risk,” said lead author Shafqat Ahmad, PhD, associate professor of epidemiology at Uppsala University in Sweden and researcher in the Center for Lipid Metabolomics and the Division of Preventive Medicine at the Brigham.
The current study identifies important biological pathways that may help explain all-cause mortality risk. However, the authors note some key limitations, including that the study was limited to well-educated, middle-aged and older female healthcare professionals, who were predominantly non-Hispanic and white.
The study used questionnaires on meal frequency and other self-reported measurements, such as height, weight and blood pressure. But the study’s strengths lie in 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 health professionals, and our study provides insight into why the diet may be so beneficial. Public health policies should promote the healthy dietary attributes of the Mediterranean diet and discourage unhealthy adaptations,” Mora said.
Paternity: In addition to Ahmad and Mora, Brigham authors include M. Vinayaga Moorthy, I-Min Lee, Paul M. Ridker, JoAnn E. Manson, Julie E. Buring, and Olga V. Demler.
Disclosures: Mora said he is co-inventor of a patent to examine glycoprotein acetylation in relation to colorectal cancer risk licensed to LabCorp and a patent application for a method of predicting future cardiovascular disease risk via Glycome IgG analysis, attributed to GENOS doo and Brigham and Women’s Hospital. , Inc. Additional information can be found in the document.
Funding: The Women’s Health Study is supported by the NIH (grant nos. CA047988, HL043851, HL080467, HL099355, and UM1 CA182913). Dr. Ahmad was supported by career-starting research grants from the Swedish Research Council (2022-01460) and FORMAS (2020-00989), as well as a research grant from EpiHealth, Sweden. Dr. Demler received an NHLBI K award from the NIH under award number K01HL135342-02.
Dr. Mora was supported by research grants from the National Institute of Diabetes and Digestive and Kidney Diseases (Grant No. DK112940); NHLBI (grant numbers R01HL160799, R01HL134811, R01HL117861, and K24 HL136852); American Heart Association (grant no. 0670007N); and the Molino Family Trust.
Additionally, LabCorp provided the results of the LipoProfile IV under study at no additional cost.
About this research news on diet and mortality
Author: Cassandra Falone
Source: Brigham and Women’s Hospital
Contact: Cassandra Falone – Brigham and Women’s Hospital
Picture: Image is credited to Neuroscience News
Original research: Free access.
“Adherence to the Mediterranean diet and risk of all-cause mortality in women” by Samia Mora et al. JAMA Open network
Abstract
Adherence to the Mediterranean diet and risk of all-cause mortality in women
Importance
Greater adherence to the Mediterranean diet has been associated with a reduced risk of all-cause mortality, but data on the underlying molecular mechanisms over long follow-up are limited.
Goals
To study adherence to the Mediterranean diet and risk of all-cause mortality and examine the relative contribution of cardiometabolic factors to this risk reduction.
Design, setting and participants
This cohort study initially included healthy women from the Women’s Health Study, who provided blood samples, biomarker measurements, and dietary information. Baseline data included self-reported demographic data and a validated meal frequency questionnaire. The data collection period extended from April 1993 to January 1996 and data analysis took place from June 2018 to November 2023.
Exhibitions
The Mediterranean diet score (range 0–9) was calculated based on 9 dietary components.
Main results and measures
Thirty-three blood biomarkers, including traditional and novel measures of lipids, lipoproteins, apolipoproteins, inflammation, insulin resistance, and metabolism, were assessed at baseline using standard assays and nuclear magnetic resonance spectroscopy.
Mortality and cause of death were determined from medical and death records. Cox proportional hazards regression was used to calculate hazard ratios (HRs) for Mediterranean diet adherence and mortality risk, and mediation analyzes were used to calculate the mediating effect of different biomarkers in understanding this association.
Results
Among the 25,315 participants, the baseline mean (SD) age was 54.6 (7.1) years, with 329 (1.3%) Asian women, 406 (1.6%) Black women, 240 ( 0.9%) Hispanic women, 24,036 (94.9%). White women and 95 (0.4%) women of other races and ethnicities; the median (IQR) Mediterranean diet adherence score was 4.0 (3.0-5.0).
Over a mean (SD) of 24.7 (4.8) years of follow-up, 3,879 deaths occurred. Compared to low adherence to the Mediterranean diet (score 0-3), adjusted risk reductions were observed for the middle (score 4-5) and high (score 6-9) groups, with HRs of 0.84 (95% CI, 0.78-0.90) and 0.77 (95% CI, 0.70-0.84), respectively (P. for trend < 0.001).
Further adjustment for lifestyle factors attenuated the risk reductions, but they remained statistically significant (mean adherence group: HR, 0.92 (95% CI, 0.85-0.99); higher adherence group: HR, 0.89 (95% CI, 0.82-0.98); P. for trend = 0.001). Among the biomarkers examined, small molecule metabolites and inflammatory biomarkers contributed the most to the lower mortality risk (explaining 14.8% and 13.0% of the association, respectively), followed by triglyceride-rich lipoproteins ( 10.2%), body mass index (10.2%) and insulin resistance (7.4%).
Other pathways, including branched-chain amino acids, high-density lipoproteins, low-density lipoproteins, glycemic measures, and hypertension, had lower contributions (<3%).
Conclusions and relevance
In this cohort study, greater adherence to the Mediterranean diet was associated with a 23% lower risk of all-cause mortality. This inverse association was partly explained by multiple cardiometabolic factors.