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Plasma antioxidant capacity among middle-aged men: the contribution of uric acid
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition Research.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition Research.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Clinical Nutrition Research.
2006 (English)In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 66, no 3, 239-248 p.Article in journal (Refereed) Published
Abstract [en]

Objective. Although assays of plasma antioxidant capacity encompass interactions between various antioxidants, uric acid concentration can exert a predominant effect on results. Therefore, individual differences in uric acid concentration may explain a many of the differences in antioxidant capacity. The objective of this study was to measure the antioxidant capacity of plasma samples with and without uric acid in order to provide more information about how the concept of antioxidant capacity could be applied. Material and methods. Antioxidant capacity was measured using an enhanced chemiluminescence assay, and uric acid was removed from the samples using uricase. Results. Antioxidant capacity was positively correlated with uric acid concentration, body mass index, waist circumference, abdominal sagittal diameter and the concentrations of insulin and triglycerides. These correlations were not evident when uric acid was eliminated from the sample, but antioxidant capacity was correlated with lipid concentration; this may partly reflect tocopherols that are transported by lipid molecules. Conclusions. The significance of the contribution of uric acid to the antioxidant capacity could differ according to the type of study. Antioxidant capacity measurements in cross‐sectional studies may be presented both with and without the contribution of uric acid, because the absence of such data complicates interpretation of results when different populations are compared.

Place, publisher, year, edition, pages
2006. Vol. 66, no 3, 239-248 p.
Keyword [en]
Adult, Aged, Antioxidants/*metabolism, Blood Chemical Analysis, Chemiluminescent Measurements, Humans, Male, Middle Aged, Research Support; Non-U.S. Gov't, Urate Oxidase, Uric Acid/*blood/isolation & purification
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-94249DOI: 10.1080/00365510600590423PubMedID: 16714252OAI: oai:DiVA.org:uu-94249DiVA: diva2:168036
Available from: 2006-04-05 Created: 2006-04-05 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Measurement and Evaluation of Antioxidant Status and Relation to Oxidative Stress in Humans
Open this publication in new window or tab >>Measurement and Evaluation of Antioxidant Status and Relation to Oxidative Stress in Humans
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Numerous diseases are associated with reduced antioxidant defence and oxidative stress. The antioxidant defence includes dietary and endogenous antioxidants and involves complex interactions between them. The effects of dietary factors on antioxidant status and oxidative stress of healthy humans were investigated in the studies described in this thesis. Assays of plasma antioxidant capacity encompass interactions between various antioxidants. Although uric acid has an unclear function as an antioxidant, it is a major determinant of antioxidant capacity. We measured antioxidant capacity in the presence and absence of uric acid to provide more information on the application of measures of antioxidant capacity. Individuals with high dietary intakes of various antioxidants and antioxidant rich foods, especially when combined, had higher plasma antioxidant capacities than those with lower antioxidant intakes. However, there were no associations between dietary intake of antioxidants or antioxidant rich foods and the plasma concentration of F2-isoprostanes, which is considered a reliable biomarker for oxidative stress. Intakes of various doses of a mixture of bilberry juice and black tea, rich in flavonoids for four weeks, increased antioxidant capacity in some groups, but urine levels of F2-isoprostanes were not affected. There were substantial individual variations in responses to the drinks related to baseline antioxidant capacity. Supplementation with eicosapentaenoic acid and docosahexaenoic acid decreased the plasma levels of F2-isoprostanes, but not prostaglandin F formation or antioxidant capacity.

It was concluded that a high intake of foods rich in antioxidants is related to improved antioxidant status. After intake of foods rich in antioxidants, the antioxidant status may increase, but with considerable individual variation in the responses, which warrants further investigation. Lipid peroxidation in vivo is not easily affected by dietary antioxidants in healthy humans. Although n-3 fatty acids are highly unsaturated, they reduce nonenzymatic free radical-catalyzed lipid peroxidation, but not enzymatic lipid peroxidation.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 71 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 131
Keyword
Nutrition, antioxidant, antioxidant status, antioxidant capacity, oxidative stress, lipid peroxidation, F2-isoprostanes, dietary factors, vitamin E, n-3 fatty acids, human, Näringslära
Identifiers
urn:nbn:se:uu:diva-6742 (URN)91-554-6519-6 (ISBN)
Public defence
2006-04-26, Sal IX, Universitetshuset, Uppsala, 13:15
Opponent
Supervisors
Available from: 2006-04-05 Created: 2006-04-05Bibliographically approved

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