# A Narrative Review of Metabolomic Insights into Olive Oil's Nutritional Value
## 4 Case Studies and Applications
The same analysis method, UHPLC-ESI-QqQ-MS/MS, was applied in a distinct study whose purpose was to evaluate whether different food matrices influenced the pharmacokinetics and bioavailability of HT and its metabolites HTA and DOPAC. In fact, a blind study involved 20 volunteers who were administered \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Technique** & **Aim** & **Compounds Analyzed** & **Results** & **Reference** \\ \hline nanoLC-ESI-TOF-MS & Evaluate the effects of olive oil components on colon cancer cells & HT, elenolic acid, luteolin, vanillin, OLE aglycone, HT acetate, 4-OH-benzoic acid, vanillin acid, 10-H-OLE aglycone, syringarenol, acetoxy-pinoresinol, pinoresinol, npigenin, methyl-DOA, and DOA & Phenolic compounds have antiproliferative and & [PERSON] et al. [93] \\  & & & & \\ HPLC with diode array detection (DAD) & Assess the beneficial health effects of isolated polyphenols & HT, tyrosol, oleocanthal, and oleacein & Oleocanthal and oleacein & \\  & & & & have not only antioxidant \\  & & & & properties but also healthy & [PERSON] et al. [94] \\ \hline \hline \end{tabular}
\begin{tabular}{c c} \hline \hline  & CE-MS = capillary electrophoresis mass spectrometry; DOA = decarboxymethyl oleurogenic aglycone; DOPAC = 2,3-dihydroxyproxyphenylacetic acid; H NMR = hydrogen nuclear magnetic resonance; HPLC with diode array detection (DAD) = high-performance liquid chromatography with diode array detection; HPLC = high-performance liquid chromatography; HPLC/MS = high-performance liquid chromatography tandem mass spectrometry; HT = hydroxy tyrosol; LC-ESI-QqQ-MS /MS = liquid chromatography electrospray ionization lifetime quadrupole mass spectrometry; nanoLC-ESI-TOF-MS = nano-liquid chromatography electrospray ionization time-of-flight mass spectrometry; OLE = oleurogenic; UHPLC-ESI-QqQ-MS/MS = ultra-high-performance liquid chromatography electrospray ionization triple quadrupole mass spectrometry; UPLC-ESI-HRMS = ultra-performance liquid chromatography electronography electrongyrozioration high-resolution mass spectrometry; UPLC-MS = ultra-performance liquid chromatography mass spectrometry; UPLC-MS/MS = ultra-performance liquid chromatography mass spectrometry. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._5 mg of HT through various food matrices. Plasma and urine samples were analyzed, and the results showed that the food matrix and nature of the oil influenced both factors being studied. According to the authors, the best matrix for delivering HT and its derivatives is EVOO [86]. Furthermore, in a distinct study, the use of an in vitro dialysis system that mimics the metabolism of the human gastrointestinal system, the gastrointestinal dialysis-colon model, allowed for the study of the metabolism and bioavailability of both HT and tyrosol. Samples were collected and analyzed by UPLC-ESI-high-resolution MS (HRMS) as the compounds went through the system, allowing the authors to uncover aspects of the pathways in which these compounds are involved [87]. Moreover, the analytical technique LC-ESI-QqQ-MS/MS and a novel strategy of solid-phase extraction allowed the determination of the levels of phenols excreted in urine, contributing to the knowledge regarding their bioavailability [88]. Nevertheless, while the health benefits of olive oil appear to be clear, one study used UPLC-MS to demonstrate the low bioavailability of phenolic compounds and, consequently, their decreased concentration as free phenolic compounds in biological fluids. Polyphenols, particularly HT, are present as conjugated metabolites in urine and plasma. Contrary to previous studies, the authors demonstrated that these conjugated metabolites have non-significant antioxidant activities, suggesting that they are not the main contributors to the numerous health benefits associated with olive oil consumption [89].