Bioavailability of Hydroxytyrosol From Olive Watery Extract Supplements


The aim of this cross-over study is to assess the bioavailability of hydroxytyrosol in healthy males after the intake of two olive watery extract supplements and one olive oil. Blood and urine samples will be collected before and after intake of the investigational products. Sample will be analysed regarding the level of hydroxytyrosol and preventing lipid peroxidation.

Full Title of Study: “Bioavailability of Hydroxytyrosol From Two Olive Watery Extract Supplements and Their Effects on Lipid Peroxidation”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Basic Science
    • Masking: Double (Participant, Outcomes Assessor)
  • Study Primary Completion Date: July 2, 2021

Detailed Description

Background: Hydroxytyrosol is a phenolic phytochemical naturally occurring in olives with potential antioxidant, anti-inflammatory, and health benefits mainly related with cardiovascular diseases [for review see Covas et al., 2015]. OliPhenolia® bitter and OliPhenolia® are two food supplements resulting from the liquid by-product generated during olive oil production, that are rich in olive polyphenols, mainly hydroxytyrosol. Hydroxytyrosol and its derivatives (tyrosol and oleuropein) are present in higher levels in the watery extracts from olives when compared with the oil fraction. Most studies on hydroxytyrosol bioavailability have been performed by consuming it with olive oil or as a highly purified molecule. In a study by D'Angelo and collaborators [D'Angelo et al, 2001] it was shown that hydroxytyrosol can be rapidly absorbed from the blood and distributed in the human body, metabolized and eliminated rapidly in urine mainly as a glucuronide. It has been estimated that the absorption process depends on the composition of the food matrix through which hydroxytyrosol is administered [Visioli et al, 2003], when consumed together with fats (e.g. olive oil) it is absorbed in a greater extent. By being a water-soluble molecule, hydroxytyrosol is only slightly soluble in fats, therefore naturally present in significantly higher concentrations in the olive fruit aqueous fractions than in the olive oil. Overall, the human studies support the need to evaluate the bioavailability of hydroxytyrosol following its administration as a major component of the two aqueous food supplements, OliPhenolia® and OliPhenolia® bitter. Study Procedure: After detailed information and signed informed consent all males meeting the inclusion and exclusion criteria will be included into the study. During their study participation, participants are not allowed to consume any products with or made from olives or olive oil as well as alcohol and supplements with hydroxytyrosol, vitamins, minerals and antioxidants. Products high in polyphenols and antioxidants may only be consumed in moderate amounts. Three days prior to and at each intervention day, volunteers will be requested to avoid moderate or intense physical activity. After a run-in period, participants will return in a fasted state to the site for the first intervention visit. Volunteers will be asked to empty their bladder at home 2h before IP intake. After arriving at the site, a baseline blood and urine sample (-5 min) will be collected and the participants receive according to the individual allocation determining the sequence of the IP intake either one of the olive watery extract supplements (OliPhenolia® bitter or OliPhenolia®) or the olive oil first. Further blood and urine samples will follow (+30 min, +60 min, +90 min, +120 min, +240 min, +12 h). Vital signs and AEs will be checked throughout the intervention visit. Participants will receive several snacks and water during their visit. After a one-week washout phase each, participants will return to their second and third intervention visit. The same procedures as on intervention visit 1 will take place except the IP intake will vary according to the individual allocation. At the end of the third intervention visit, participants will receive a study compensation.


  • Dietary Supplement: Oliphenolia® bitter
    • ingredients: concentrated watery extract of olives 94%, lemon juice 6% 35 mg hydroxytyrosol, 0,24 mg Oleuropein
  • Dietary Supplement: Oliphenolia®
    • ingredients: grape juice concentrate 70%, concentrated watery extract of olives 30% 38 mg hydroxytyrosol, 0,28 mg Oleuropein
  • Dietary Supplement: La Vialla Extra Virgin Olive Oil containing 5 mg hydroxytyrosol
    • extra virgin olive oil 5 mg hydroxytyrosol

Arms, Groups and Cohorts

  • Active Comparator: Group A
    • Group A will receive Oliphenolia® bitter on intervention visit 1 followed by Oliphenolia® on intervention visit 2 and followed by La Vialla Extra Virgin Olive Oil with 5 mg hydroxytyrosol on the third and final intervention visit
  • Active Comparator: Group B
    • Group B will receive Oliphenolia® on intervention visit 1 followed by La Vialla Extra Virgin Olive Oil with 5 mg hydroxytyrosol on intervention visit 2 and followed by Oliphenolia® bitter on the third and final intervention visit
  • Active Comparator: Group C
    • Group C will receive La Vialla Extra Virgin Olive Oil with 5 mg hydroxytyrosol on intervention visit 1 followed by Oliphenolia® bitter on intervention visit 2 and followed by Oliphenolia® on the third and final intervention visit

Clinical Trial Outcome Measures

Primary Measures

  • Bioavailability of hydroxytyrosol in urine
    • Time Frame: -2 hrs to IP intake, 0 to 30 min, 30 to 60 min, 60 to 90 min, 90 to 120 min, 120 to 240 min and +4h to +12h
    • The primary objective is the bioavailability of hydroxytyrosol and its derivatives from both food supplements (OliPhenolia® bitter and OliPhenolia®) in urine when compared to extra virgin olive oil.
  • Bioavailability of hydroxytyrosol in blood
    • Time Frame: 5 min. before IP intake, 30, 60, 90, 120, 240 min and 12 h
    • The primary objective is the bioavailability of hydroxytyrosol and its derivatives from both food supplements (OliPhenolia® bitter and OliPhenolia®) in urine when compared to extra virgin olive oil.

Secondary Measures

  • Oxidative damages to lipids in blood
    • Time Frame: 5 min. before IP intake, 30, 60, 90, 120, 240 min and 12 h
    • The secondary outcome is the measurement of the oxidized LDL(low-density lipoprotein) in blood
  • changes in F2alpha-isoprostanes in urine
    • Time Frame: -2 hrs to IP intake, 0 to 30 min, 30 to 60 min, 60 to 90 min, 90 to 120 min, 120 to 240 min and +4h to +12h
    • The secondary outcome is the measurement of changes in F2alpha-isoprostanes in urine.

Participating in This Clinical Trial

Inclusion Criteria

  • Self-reported healthy men aged 21-50, – subject has an adequate understanding of the study and signs the informed consent to participate in the study, – willingness to follow dietary and physical activity restrictions during study participation, – body mass index range: >18.5 and <29.9 kg/m2. Exclusion Criteria:

  • Any known allergies to IPs (olives and their derivates), – any acute and chronic diseases (e.g. diagnosis of diabetes mellitus, hypertension, dyslipidemia or other cardiometabolic disorders, diagnosed hepatic, renal, or cardiovascular disease), – any kind of eating disorders, – not fluent in German, – any previous (last 14 days prior to screening) and any ongoing pharmacological therapy (e.g. any medication, vaccination, infusion), – any intake of nutritional supplements, – any known addiction to drugs and/or alcohol, – smoker, – Investigator or physician doubts truthfulness of self-reported health information.

Gender Eligibility: Male

Minimum Age: 21 Years

Maximum Age: 50 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • Daacro
  • Collaborator
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Juliane Hellhammer, PhD, Principal Investigator, Daacro


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