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Uric Acid Metabolism, Endothelial Function and Oxidative Stress in Vegans and Omnivores.

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ClinicalTrials.gov Identifier: NCT03849677
Recruitment Status : Recruiting
First Posted : February 21, 2019
Last Update Posted : May 30, 2019
Sponsor:
Collaborators:
Fonds National de la Recherche Scientifique
Fonds Erasme
Fonds pour la chirurgie cardiaque
Information provided by (Responsible Party):
Erasme University Hospital

Brief Summary:

50 vegans and 50 omnivores will be recruited at the Erasme Hospital, Brussels.

Hypothesis

  • Relative induced-hyperuricemia by the vegan diet is not associated with impaired endothelial function if vitamin B12 and folic acid levels are normal.
  • Quantification of xanthine oxidoreductase (XOR) isoforms varies according to the diet. Omnivores present more xanthine oxidase (XO) than vegans in which the xanthine dehydrogenase (XD) isoform is more prevalent.
  • The vegan group has more favorable oxidant, metabolic and inflammatory profiles than the omnivore group.

Condition or disease Intervention/treatment
Healthy Diet Modification Other: Endothelial function and inflammation

Detailed Description:

Non-meat eaters rise widely worldwide. This choice answers ideological, ecological or health concerns. Several vegetarian diets exist and the vegan diet is the most restricted one as it excludes all animal products, eggs and dairy.

Beside benefits on health and particularly on the cardiovascular system (blood pressure, weight, lipid profile), some authors described less favorable lipid and oxidative profiles and others described an impairment in endothelial function markers in 'vegans'. These effects were attributed to low vitamin B12 and folate levels and high homocystein levels. However, vitamin B12 supplementation improved these parameters. Epidemiological studies also showed that 'vegans' disclose higher uric acid levels than other vegetarians or omnivores. Uric acid acts as an antioxidant in the plasma but can be deleterious for vascular cells leading to endothelial dysfunction. The main enzyme involved in uric acid metabolism is xanthine oxidoreductase which exists under two interconvertible isoforms. Xanthine dehydrogenase is the main form and uses nicotinamide adenine dinucleotide (NAD+) as electron acceptor and does not produce reactive oxygen species (ROS). In contrast, the other isoform xanthine oxidase uses oxygen as an electron acceptor and produces reactive oxygen species (ROS). The investigators wish to test the hypothesis that it is not uric acid per se, but which isoform of xanthine oxidoreductase which alters endothelial function. This is why the investigators wish to determine if regular 'vegans' (with normal vitamin B12 and folate levels) disclose increased uric acid levels in the presence of a reduced inflammation, oxidative stress and improved endothelial function, as compared to matched 'omnivores'.

50 vegans and 50 omnivores will be recruited at the Erasme Hospital, Brussels.

Hypothesis

  • Relative induced-hyperuricemia by the vegan diet is not associated with impaired endothelial function if vitamin B12 and folic acid levels are normal.
  • Quantification of oxidoreductase (XOR) isoforms varies according to the diet. Omnivores present more xanthine oxidase (XO) than vegans in which the xanthine dehydrogenase (XD) isoform is more prevalent.
  • The vegan group has more favorable oxidant, metabolic and inflammatory profiles than the omnivore group.

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Study Type : Observational
Estimated Enrollment : 100 participants
Observational Model: Case-Control
Time Perspective: Prospective
Official Title: Differential Analysis of Uric Acid Metabolism, Endothelial Function, Oxidative Stress and Cardiovascular Parameters in Vegans and Omnivores.
Actual Study Start Date : March 10, 2019
Estimated Primary Completion Date : December 2019
Estimated Study Completion Date : June 2020

Resource links provided by the National Library of Medicine

Drug Information available for: Uric Acid

Group/Cohort Intervention/treatment
Omnivore Other: Endothelial function and inflammation
Analysis of endothelial function, oxidative stress

Vegan Other: Endothelial function and inflammation
Analysis of endothelial function, oxidative stress




Primary Outcome Measures :
  1. Measure of the perfusion of the microcirculation of the skin [ Time Frame: 2 hours ]

    Endothelial function assessment will be performed through analyse of the perfusion of the microcirculation of the skin in the forearm will be assessed by means of a laser Doppler imager and iontophoresis of acetylcholine and sodium nipride. Heating-induced hyperemia will be assessed after iontophoresis of inhibitor of NO synthase and saline. Units are perfusion unit.

    Iontophoresis is a non-invasive tool which permits to infuse molecules in the first micrometers of the skin. The used molecules are vasodilative, saline or NO synthase inhibitor.



Secondary Outcome Measures :
  1. Concentration of Uric acid [ Time Frame: 2 hours ]
    Uric acid (mg/dL or SI)

  2. Concentration of xanthine oxidase and xanthine dehydrogenase in blood [ Time Frame: 2 hours ]
    western blot

  3. Measure of hemoglobin [ Time Frame: 2 hours ]
    g/l

  4. Measure of white blood cells, red blood cells and platelets [ Time Frame: 2 hours ]
    cells/µl of blood

  5. Measure of urea, creatinine, bilirubin, albumine, prealbumin, LDL, HDL, lp(a), total cholesterol, triglyceride, apolipoprotein A and B [ Time Frame: 2 hours ]
    mg/dl

  6. Measure of glycemia, vitamine and iron status (B3, B6, B12, C, D, E, B9, Zn, Cu, Selenium, iron, ferritin), c-reactive protein, homocystein [ Time Frame: 2 hours ]
    mg/dl

  7. Measure of sodium, potassium, chlore, phosphor, calcium, magnesium, HbA1c, omega 3 et 6 [ Time Frame: 2 hours ]
    mmol/l

  8. Measure of glomerular filtration rate [ Time Frame: 2 hours ]
    ml/min

  9. Measure of gamma-glutamyltransferase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, creatin phosphokinase, insulin, TSH [ Time Frame: 2 hours ]
    u/l

  10. Measure of allantoin, homocitrulline/lysine, chloro-tyrosine/tyrosine, Il-8, myeloperoxidase [ Time Frame: 2 hours ]
    Mass spectrometry and Elisa Kits

  11. Measure of renin, aldosterone, angiotensin 2, angiotensin converting enzyme [ Time Frame: 2 hours ]
  12. Measure of main proteomes and metabolomes in cells incubated with sera from participants [ Time Frame: 2 hours ]
    Sera will be used for cell cultures. Theses cells will be lysed and used to analyse and compare the different proteomes / metabolomes according to the groups. We will be able to understand which protein groups are reduced or enhanced according to the diet.

  13. Measure of blood pressure [ Time Frame: 2 hours ]
    Systolic and diastolic blood pressure

  14. Measure of baroreflex sensitivity [ Time Frame: 2 hours ]
    finometer

  15. Measure of heart rate [ Time Frame: 2 hours ]
    finometer

  16. Measure of augmentation index [ Time Frame: 2 hours ]
    Assessment of the arterial stiffness

  17. Measure of pulse wave velocity [ Time Frame: 2 hours ]
    Assessment of the arterial stiffness

  18. Diet questionary [ Time Frame: 2 hours ]
    Diet History Questionnaire third version provides estimation of one year consumption of proteins, carbohydrates, lipids, micronutrient and vitamines



Information from the National Library of Medicine

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Ages Eligible for Study:   20 Years to 50 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
Participants will be recruited upon invitation on social network mainly.
Criteria

Inclusion Criteria:

  • Vegan or omnivore diet for at least one year (matched for age, gender, BMI, socio-economic status and weight)
  • Healthy

Exclusion Criteria:

  • Smoking
  • Chronic treatment
  • No allowed drugs taking
  • Excessive alcohol consumption

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03849677


Contacts
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Contact: Benjamin De Becker, MD 025555919 ext +32 benjamin.de.becker@erasme.ulb.ac.be

Locations
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Belgium
Erasme Hospital Recruiting
Brussels, Belgique, Belgium, 1070
Contact: Benjamin De Becker    +32474328542    Benjamin.De.Becker@erasme.ulb.ac.be   
Principal Investigator: Benjamin De Becker         
Sponsors and Collaborators
Erasme University Hospital
Fonds National de la Recherche Scientifique
Fonds Erasme
Fonds pour la chirurgie cardiaque

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Responsible Party: Erasme University Hospital
ClinicalTrials.gov Identifier: NCT03849677     History of Changes
Other Study ID Numbers: 34735921
First Posted: February 21, 2019    Key Record Dates
Last Update Posted: May 30, 2019
Last Verified: May 2019
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No

Keywords provided by Erasme University Hospital:
uric acid
hemodynamic parameters
endothelial function
oxidative stress and inflammation
vegan
omnivore

Additional relevant MeSH terms:
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Uric Acid
Antioxidants
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs