Healthy plant-based diets cut mortality risks for Spain's seniors

By Hugo Francisco de SouzaApr 23 2024Reviewed by Susha Cheriyedath, M.Sc.

Despite the rising global popularity of healthy pro-vegetarian diets (PVG), including the Mediterranean diet and its derivative DASH (Dietary Approaches to Stop Hypertension), long-term evidence for the benefits of these dietary patterns remains lacking, especially in older populations. In a recent study published in the journal Nutrition, Health, and Aging, researchers investigated the 12-year-long effects of three pre-defined PVG diets on both all-cause and specific-cause (cardiovascular disease [CVD] or cancer) mortality.

Study: Pro-vegetarian dietary patterns and mortality by all-cause and specific causes in an older Mediterranean population. Image Credit: Tatjana Baibakova / Shutterstock

The study cohort comprised 597 Spanish adults over the age of 65. Data collection was predominantly questionnaire-based, with diet adherence representing this study's variable of highest interest. Study findings revealed that participants moderately adhering to the healthy PVG diet depicted lower mortality risk (all-cause and CVD), while those with a higher unhealthy PVG diet adherence displayed higher risk from these conditions.

Why does the public care about healthy diets?

Despite clinical advances substantially extending human life expectancy, the past decades have laid witness to unprecedented surges in chronic ailments, particularly those related to cardiovascular diseases (CVDs), cancers, and mental health. A growing body of research attributes these observations to 'health behaviors' – actions or habits that directly impact an individual's long-term health and clinical well-being. Sleep disruptions, poor health choices (smoking and excessive drinking), physical exercise, and dietary adherence have been singled out as the most critical determinants of long-term health in today's aging global population.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has only served to exacerbate the situation, with novel work schedules, social-distancing enactments, and work-from-home (WFH) policies resulting in greater sleep- and mental health disruptions, and increased adherence to sedentary lifestyles, in turn potentially resulting in present and future surges in chronic disease prevalence and all-cause mortality.

Unfortunately, despite intensive research investigating the current merits of pro-vegetarian diets (PVGs), the gold standard in healthy eating, long-term data elucidating these benefits remains lacking. This demerit is especially relevant to older adults, the primary focal group of chronic diseases.

About the study

The present study aims to elucidate the impacts of three pre-determined PVG dietary regimes (general, healthful, and unhealthful) on the long-term all-cause mortality of elderly Mediterranean citizens. It further attempts to elucidate the contributions of these dietary patterns to specific chronic mortality causes, including CVD and cancers. The study cohort was derived from the European Eye Study (EUREYE), a long-term age-related macular degeneration study based in Spain.

The study population comprised 597 individuals (54.3% female) above the age of 65 from the Spanish province of Alicante. Data collection was predominantly questionnaire-based and included demographic, medical, and lifestyle details. Additionally, periodic health, weight, and height examinations were conducted.

Adherence to the primary variable of interest (dietary adherence) was measured using a Spanish-validated food frequency questionnaire (FFQ) comprising 131 food items and their standard (recommended) portion sizes. The nutritional interventions used herein consisted of the a priori gPVG pattern (general; developed by Martínez-González) and the hPVG and uPVG patterns ('healthful' and 'unhealthful,' respectively; developed by Satija et al.).

"…dietary patterns were constructed using information from 18 food groups, including vegetables, fruits, legumes, whole grains, refined grains, boiled potatoes, fries or chips, nuts, olive oil, tea and coffee, fruit juices, sugar-sweetened beverages, sweets and desserts, meat and meat products, animal fats, eggs, fish and seafood, and dairy."

The study follow-up period was 12 years, during which participant mortality information was obtained from the Mortality Registry in the Valencian Region or the Spanish Statistical Office's National Death Index. Cause of death was recorded as per the 10th version of the International Classification of Diseases (ICD-10) and classified as either CVD, cancer, or all-cause (CVD + cancer + any other cause).

Study findings and conclusions

Analyses of dietary pattern adherence revealed that the hPVG was primarily followed by younger participants and those with a history of diabetes or hypercholesterolemia. In contrast, the uPVG diet was followed predominantly by male participants and those with smoking and alcohol habits.

"After 12 years of follow-up, compared to participants with lowest adherence (T1), those with moderate adherence (T2) to a hPVG dietary pattern showed a 41% (HR: 0.59; 95% CI: 0.43−0.82) and 53% (HR: 0.47; 95% CI: 0.28−0.78) lower risk of all-cause and CVD mortality in the adjusted model, respectively."

The study highlights that the healthful PVG (hPVG) dietary pattern was associated with reduced risk of CVD and all-cause-related mortality. The unhealthful PVG (uPVG) diet was instead found to be associated with a higher risk of these conditions. This suggests that consuming fresh fruits and vegetables, legumes, nuts, and olive oil may provide lasting benefits in today's aging world. Unfortunately, this study fails to elucidate the mechanisms by which these foods confer protection, a requirement of future prospective studies.