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

Free University of Brussels (ULB)

Status

Completed

Conditions

Healthy

Diet Modification

Treatments

Other: Endothelial function and inflammation

Study type

Observational

Funder types

Other

Identifiers

NCT03849677

34735921

Details and patient eligibility

About

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.

Full 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.

Enrollment

103 patients

Sex

All

Ages

20 to 50 years old

Volunteers

Accepts Healthy Volunteers

Inclusion criteria