Clinical trial NCT03849677: Uric Acid Metabolism, Endothelial Function and Oxidative Stress in Vegans and Omnivores.
Official title: Differential Analysis of Uric Acid Metabolism, Endothelial Function, Oxidative Stress and Cardiovascular Parameters in Vegans and Omnivores.
Study type: OBSERVATIONAL
Overall status: COMPLETED
Conditions: Healthy
Diet Modification
Keywords: uric acid
hemodynamic parameters
endothelial function
oxidative stress and inflammation
vegan
omnivore
Lead sponsor: Erasme University Hospital
Sponsor class: OTHER
Collaborators: name: Fonds National de la Recherche Scientifique
name: Fonds Erasme
name: Fonds pour la chirurgie cardiaque
First posted: 2019-02-21
Enrollment: 103
Sex: ALL
Minimum age (years): 20
Maximum age (years): 50
Standard ages: ADULT
Accepts healthy volunteers: yes
Observational model: CASE_CONTROL
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Participants will be recruited upon invitation on social network mainly.

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.

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.

Eligibility 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

Primary outcomes:
measure: Measure of the perfusion of the microcirculation of the skin
timeFrame: 2 hours
Secondary outcomes:
measure: Concentration of Uric acid
timeFrame: 2 hours
measure: Concentration of xanthine oxidase and xanthine dehydrogenase in blood
timeFrame: 2 hours
measure: Measure of hemoglobin
timeFrame: 2 hours
measure: Measure of white blood cells, red blood cells and platelets
timeFrame: 2 hours
measure: Measure of urea, creatinine, bilirubin, albumine, prealbumin, LDL, HDL, lp(a), total cholesterol, triglyceride, apolipoprotein A and B
timeFrame: 2 hours
measure: Measure of glycemia, vitamine and iron status (B3, B6, B12, C, D, E, B9, Zn, Cu, Selenium, iron, ferritin), c-reactive protein, homocystein
timeFrame: 2 hours
measure: Measure of sodium, potassium, chlore, phosphor, calcium, magnesium, HbA1c, omega 3 et 6
timeFrame: 2 hours
measure: Measure of glomerular filtration rate
timeFrame: 2 hours
measure: Measure of gamma-glutamyltransferase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, creatin phosphokinase, insulin, TSH
timeFrame: 2 hours
measure: Measure of allantoin, homocitrulline/lysine, chloro-tyrosine/tyrosine, Il-8, myeloperoxidase
timeFrame: 2 hours
measure: Measure of renin, aldosterone, angiotensin 2, angiotensin converting enzyme
timeFrame: 2 hours
measure: Measure of main proteomes and metabolomes in cells incubated with sera from participants
timeFrame: 2 hours
measure: Measure of blood pressure
timeFrame: 2 hours
measure: Measure of baroreflex sensitivity
timeFrame: 2 hours
measure: Measure of heart rate
timeFrame: 2 hours
measure: Measure of augmentation index
timeFrame: 2 hours
measure: Measure of pulse wave velocity
timeFrame: 2 hours
measure: Diet questionary
timeFrame: 2 hours
Other outcomes:
Locations:
city: Brussels
country: Belgium
facility: Erasme Hospital
state: Belgique
Study officials:
References: