In a recent study published in the European Journal of Clinical Nutrition, researchers assessed the long-term impact of adherence to the Mediterranean diet on the incidence of hypertension (HTN) over a 20-year period in a cohort of non-hypertensive adults.

Study: Adherence to the Mediterranean diet and 20-year incidence of hypertension: the ATTICA prospective epidemiological study (2002–2022). Image Credit: Luigi Giordano

Background 

HTN significantly impacts global health, leading to severe complications like heart disease and stroke, especially prevalent in low and middle-income countries. Despite effective antihypertensive medications stabilizing global blood pressure levels, HTN affects about 30% of adults, driving up cardiovascular disease(CVD)-related costs and mortality. Lifestyle modifications, such as balanced diets, exercise, and quitting smoking, are essential in managing and preventing HTN. Health guidelines advocate diets high in plant-based foods, healthy fats, lean proteins and low in sodium and alcohol. The Mediterranean diet, known since the 1960s for preventing chronic diseases and reducing cardiovascular mortality, lacks long-term definitive evidence on its effectiveness in blood pressure management, necessitating further research.

About the study 

The ATTICA study, adhering to the Declaration of Helsinki, is a long-term, population-based health study investigating CVD incidence among Greek adults. Initiated with 4056 invitees from Attica, 3,042 consented and have been followed for 20 years. The initial phase of the ATTICA study, conducted in 2001-2002, involved face-to-face interviews at participants’ homes or workplaces. These interviews were carried out by trained health professionals who collected comprehensive sociodemographic, clinical, and biochemical data using a standardized protocol. Key measures included fasting blood samples to assess glucose, insulin, total cholesterol (TC) levels, and high sensitivity C-reactive protein (hsCRP), among others. Participants also underwent physical examinations to confirm the absence of CVD and to record their blood pressure. Lifestyle factors such as diet, physical activity, and smoking habits were carefully recorded, with dietary patterns assessed using a validated food frequency questionnaire and adherence to the Mediterranean diet evaluated through the MedDietScore.

Over the 20 years, the study maintained engagement with participants through scheduled follow-ups, the most recent of which occurred in 2022. This latest follow-up re-evaluated 2169 of the original participants, gathering data on their health outcomes, including the development of HTN, diabetes, and CVD. Information was verified through family reports and medical records for those who had passed away.

The study used statistical software to analyze data, comparing baseline and 10-year dietary patterns and identifying four distinct trajectories of adherence to the Mediterranean diet. Statistical analyses included correlation coefficients, chi-squared tests, and logistic regression models to explore the association between dietary adherence and HTN risk, adjusting for multiple confounders such as age, sex, body mass index (BMI), lifestyle habits, and baseline health status. 

Study results 

The study, tracking 1,415 participants, examined the relationship between Mediterranean diet adherence and health over 20 years. At baseline, the average participant age was 41 years, with a roughly equal distribution across gender (44% men). The population showed moderate adherence to the Mediterranean diet, with an average MedDietScore of 27.1. Physically, 63.1% of the subjects were minimally active, and about half were overweight or obese. Medical evaluations revealed a prevalence of hypercholesterolemia in 35.3% and diabetes in 3.9% of participants.

The analysis of baseline data indicated a clear negative correlation between Mediterranean diet adherence and systolic and diastolic blood pressures, suggesting that higher adherence was associated with lower blood pressure levels. During the two-decade follow-up, 314 individuals developed hypertension, marking a 22.2% incidence rate. Those who developed hypertension were generally older, predominantly male, and had higher rates of obesity, worse cardiometabolic profiles, and greater tobacco use compared to those who remained HTN-free.

In-depth analysis showed that a lower baseline MedDietScore was linked to a higher incidence of hypertension. Specifically, participants with low diet adherence had significantly higher rates of developing HTN compared to those with medium or high adherence. Statistical analysis confirmed that each point increase in MedDietScore at baseline was associated with a 7% reduction in the risk of developing HTN over 20 years. Even after adjusting for factors like age, gender, BMI, lifestyle habits, and baseline health status, the inverse relationship between diet adherence and HTN risk remained significant.

Further examination of diet adherence trajectories from baseline to the 10-year mark revealed diverse patterns. A significant finding was that participants consistently adherent to the Mediterranean diet (always close trajectory) exhibited a substantially lower incidence of HTN compared to those whose adherence waned over time. This group had a 46.5% lower risk in the fully adjusted model, highlighting the protective effect of sustained adherence to the Mediterranean diet against HTN.