Only virgin type of olive oil consumption reduces the risk of mortality. Results from a Mediterranean population-based cohort

The Mediterranean diet (MedDiet), characterized by high olive oil (OO), fruit, vegetable, and nut consumption, is linked to reduced mortality and chronic disease risk. OO, particularly virgin OO (rich in phenolic compounds), possesses anti-inflammatory and antioxidant properties beneficial for cardiovascular health. While previous studies showed an association between OO consumption and reduced mortality, few distinguished between common and virgin varieties. This study aimed to assess the association between common and virgin OO consumption and long-term mortality (all-cause, cardiovascular, and cancer) in a large, representative sample of Spanish adults, addressing the gap in research on OO variety's impact.

Observational evidence suggests OO plays a crucial role in the health benefits of the MedDiet, especially concerning cardiovascular disease (CVD). Virgin OO, with its high phenolic compound content, shows anti-inflammatory, antioxidant, and anti-atherosclerotic properties. The PREDIMED trial demonstrated reduced cardiovascular and total mortality in individuals consuming a MedDiet supplemented with virgin OO. However, results from other European cohorts regarding OO consumption and mortality have been inconclusive, mainly due to the lack of differentiation between common and virgin OO varieties. This distinction is crucial as refined OO lacks the bioactive compounds present in virgin OO.

The Study on Nutrition and Cardiovascular Risk in Spain (ENRICA) recruited 12,948 individuals aged 18+ through random stratified cluster sampling. 12,161 participants with complete data were included in the analysis. Baseline data included sociodemographics, lifestyle factors, and comorbidities. Dietary assessment used a validated computerized dietary history (DH-ENRICA), providing detailed information on OO consumption (common and virgin). Mortality data was obtained from the Spanish National Death Index. Cox proportional hazard models, adjusted for potential confounders (sex, age, energy intake, educational level, smoking, BMI, physical activity, TV viewing, alcohol consumption, fiber intake, Mediterranean Diet Score, medications, hypertriglyceridemia, hypercholesterolemia, hypertension, diabetes, and number of chronic conditions), were used to analyze the association between OO consumption and mortality. Subgroup analyses were performed stratifying by age, sex, BMI, physical activity, and MedDiet adherence. Sensitivity analyses excluded the first two years of follow-up.

Over a mean follow-up of 10.7 years, 739 all-cause, 143 cardiovascular, and 146 cancer deaths occurred. After adjusting for confounders, high virgin OO consumption (highest vs. lowest tertile) was significantly associated with a 34% reduction in all-cause mortality (HR 0.66; 95% CI 0.49–0.90; P-trend 0.040) and a 57% reduction in cardiovascular mortality (HR 0.43; 95% CI 0.20–0.91; P-trend 0.017). For every 10 g/day increase in virgin OO consumption, there was a 9% reduction in all-cause mortality (HR 0.91; 95% CI 0.83–1.00) and an 11% reduction in cardiovascular mortality (HR 0.78; 95% CI 0.59–1.03). In contrast, common OO consumption showed no significant association with all-cause or cardiovascular mortality. No significant association was found between either OO type and cancer mortality. Subgroup analyses revealed a stronger protective effect of virgin OO among participants with prevalent CVD or diabetes. A significant interaction was found between virgin OO consumption and physical activity on all-cause mortality, with a greater risk reduction among more physically active individuals. The protective effect of virgin OO on mortality appeared even greater in those with lower adherence to the MedDiet.

This study provides strong evidence that moderate daily consumption of virgin OO is significantly associated with reduced all-cause and cardiovascular mortality in a large representative sample of the Spanish population. The lack of association with common OO highlights the importance of the bioactive compounds present in virgin OO, which are lost during the refining process. These findings contrast with some previous studies, possibly due to differences in population characteristics, study periods, and dietary habits. The study's large sample size and rigorous methodology enhance the reliability of the findings. The interaction between virgin OO consumption and physical activity underscores the importance of a combined healthy lifestyle approach.

This study demonstrates a significant inverse association between virgin OO consumption and all-cause and cardiovascular mortality, but not with cancer mortality, in a representative Spanish cohort. The absence of a similar effect with common OO emphasizes the role of bioactive compounds in virgin OO. These findings support the inclusion of virgin OO in dietary guidelines and warrant further research exploring the mechanisms underlying its cardioprotective effects and potential interactions with other lifestyle factors.

While this study used a large representative sample and sophisticated statistical methods, some limitations exist. Reliance on self-reported dietary data might introduce recall bias. Residual confounding, despite adjusting for several factors, cannot be entirely excluded. Furthermore, the study's focus on a Spanish population limits the generalizability of the findings to other populations with different dietary habits and genetic backgrounds.