Discussion
cardiovascular disease
VASODILATION, CARDIOVASCULAR DISEASE, ENDOTHELIAL DYSFUNCTION, INFLAMMATION, MINOR, EVENT, CVD, PAT, BLOOD, ATHEROSCLEROSIS, ENDOTHELIAL DYSFUNCTION
Most of the evidence on the potential health beneficial effects of olive minor components come from in vitro studies in different cell models or from preclinical animal studies [reviewed in 6]. However, clinical studies in humans on the cardiometabolic effects of these compounds are scarce, limited to the use of pure components such as squalene or triterpenic acids as drug therapy or dietary supplements [Some of the most notable results observed were the decreased serum concentrations of LDL-C (Squalene is another characteristic component of olive oils with potential cardioprotective effects. Of the three trials developed in hypercholesterolemic patients, only one reported reduced TC and LDL-C, and increased HDL-C concentrations when participants were supplemented with 869 mg/d of squalene for 20 weeks [Aliphatic alcohols are present in OPO (978 mg/g) in much higher concentrations than in HOSO (32 mg/kg). A review by Hargrove et al. [Indeed, after HOSO intervention, there was an increase in TC, LDL-C, LDL/HDL and TC/HDL in both NC and HC volunteers, contrary to that observed with OPO (Table It is important to highlight the effects observed after OPO intake on coronary event predictors such as LDL/HDL ratio and Apo B concentrations. Apo B is considered a better predictor of cardiovascular risk than LDL-C [Blood pressure showed no changes throughout the study, and SBP and DBP values remained within a normal range (Table Endothelial dysfunction is another key risk factor for atherosclerosis. None of the soluble molecules analysed as biomarkers of endothelial function showed significant changes, although circulating concentrations of eNOS increased after OPO and HOSO in both groups of volunteers (Table Flow mediated dilatation (FMD) is a non-invasive measurement of vasodilation and it is considered an index of NO bioavailability [Another underlying mechanism of endothelial dysfunction is inflammation. As shown in Table Overall, consumption of OPO during four weeks resulted in an improved blood lipid profile, decreasing LDL-C, Apo B and LDL/HDL both in healthy and at-risk volunteers, in contrast to the opposite effect observed with HOSO, with no significant changes in other CVD risk factors. It is important to highlight that this study intended to reproduce normal consumption patterns in which OPO was used as culinary oil, without further supplementing or enriching this oil with bioactive compounds, either phenolics, triterpenes, squalene, etc. This resulted in relatively low intakes of the minor components of olive unsaponifiable fraction, which might have compromised observing more clear responses on the different biomarkers studied.This study has several strengths and limitations. The study was well-powered, and its randomized, controlled, crossover design can be considered as another strength. The dietary intervention had a realistic approach, since participants consumed a moderate amount of oil in accordance to Spanish recommendations. OPO was a non-supplemented oil as consumers can find in supermarkets. As for limitations, SO intake in the run-in and wash-out periods resulted in a different lipid profile (MUFA, PUFA, and SFA) intake in comparison with the test and control oils. However, the crossover design ensured that all subjects started with the same dietary conditions at the beginning of each intervention. NO could not be determined in blood samples. Volunteers were instructed to maintain their lifestyle unchanged; however, physical activity was not surveyed during the study. To assess endothelial function, PAT, a non-invasive technique similar to FMD, was used to measure the hyperemic response. This had certain limitations considering that the data generated by endoPAT have more variability in their results compared to the FMD technique [In conclusion, OPO could have hypolipidemic actions in healthy consumers and in subjects with high blood cholesterol, contributing to cardiovascular disease prevention. This is the first chronic clinical intervention carried out with OPO and its results corroborate previous findings with some of the characteristic minor components of this oil. Therefore, this study contributes to consider OPO as a relevant source of fat in the diet.