The Mediterranean diet is a healthy dietary pattern whose main characteristic is olive oil consumption. The potential health benefits of olive oil have been extensively investigated and the present review provides the more recent clinical evidence supporting the positive impact of olive oil intake on human health. PubMed (n = 227) and Scopus (n = 308) databases were searched for published clinical studies in English over the past six years (October 2016 to December 2022), following key word searches of “olive oil” and “health”. Major findings associated olive oil with antioxidant and anti-inflammatory effects, improvement in endothelial function and lipid profile, prevention of obesity, diabetes, cardiovascular and neurodegenerative diseases, and modulation of the gut microbiota. These benefits are attributed to the nutritional composition of olive oil, which has a high content of monounsaturated fatty acids (MUFA) (oleic acid in particular) and minor compounds such as polyphenols (oleuropein and hydroxytyrosol). Although additional research continues to be required, the more recently generated evidence supports the potential of olive oil to contribute beneficially to health and to the prevention and management of a variety of non-communicable diseases, as a consequence of the synergism between its components’ complexity.

Extra virgin olive oil (EVOO) with a high content of polyphenols has attracted attention due to its proved beneficial effects in decreasing the risk of cardiovascular disease, modulating cholesterol levels (HDL and LDL), modulating inflammatory markers, and decreasing the levels of haemoglobin1Ac, suggesting that EVOO can have an impact in glycemia regulation. This study assessed the impact of the consumption of a northern Portuguese polyphenol-rich EVOO with a high profile of bioactive molecules on several parameters, such as saliva and serum inflammatory biomarkers, and explored EVOO impact on gut and oral microbiota regarding Bacillota and Bacteroidota content. Thus, the impact on glycated haemoglobin (HbA1c), low-density lipoprotein cholesterol (LDL-C), C-reactive protein (CRP), inflammatory biomarkers, and faecal and salivary microbiomes were evaluated before and after the exposure to EVOO. The results showed that EVOO promotes a decrease in the levels of HbA1C and in the pro-inflammatory interleukin IL-1β, associated with inflammatory processes. Moreover, EVOO intake modulated gut and oral microbiota, increasing Bacteroidota in both ecological niches and Bacillota in the oral microbiota, both phyla being associated with health, demonstrating a prebiotic effect.

(1) Background: Extra virgin olive oil (EVOO) is studied mostly for its health benefits in preventing non-communicable chronic diseases, particularly within a Mediterranean dietary pattern. However, few studies have addressed the effect of EVOO in healthy individuals, prior to an established disease. This study aims to evaluate the impact of Northern Portuguese polyphenol-rich EVOO (NPPR-EVOO) consumption on various important clinical parameters in healthy adult volunteers. (2) Methods: This quasi-experimental intervention study assessed the impact of NPPR-EVOO for a period of 100 days. Serum total cholesterol, HbA1c, HDL-c, LDL-c, and CRP, and anthropometric measures—waist and hip perimeters, hand grip strength, and body fat—were assessed and food logs were analyzed. (3) Results: Serum HbA1c (5.12 ± 0.32%; 4.93 ± 0.24, p = 0.000) and LDL-c (96.50 ± 28.57 mg/dL; 87.41 ± 31.38 mg/dL, p = 0.017) significantly decreased following NPPR-EVOO. Also, daily energy significantly increased, but no changes in other dietary parameters, or anthropometry, were seen. Adherence to the Mediterranean diet did not explain the differences found in individuals regarding serum lipid profile and HbA1c, reinforcing the role of EVOO’s effect. (4) Conclusions: NPPR-EVOO lowered the serum levels of LDL cholesterol and HbA1c, providing clues on the effect of EVOO-putative health benefits. These results pave the way for a deeper exploration of EVOO as a functional food.