British Journal of Nutrition

Full Papers

Use of conventional and -omics based methods for health claims of dietary antioxidants: a critical overview

Siegfried Knasmüllera1 c1, Armen Nersesyana1, Miroslav Mišíka1, Christopher Gernera1, Wolfgang Mikulitsa1, Veronika Ehrlicha1, Christine Hoelzla1, Akos Szakmarya1 and Karl-Heinz Wagnera2

a1 Institute of Cancer Research, Inner Medicine I, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna, Austria

a2 Department of Nutritional Sciences, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria

Abstract

This article describes the principles and limitations of methods used to investigate reactive oxygen species (ROS) protective properties of dietary constituents and is aimed at providing a better understanding of the requirements for science based health claims of antioxidant (AO) effects of foods. A number of currently used biochemical measurements aimed of determining the total antioxidant capacity and oxidised lipids and proteins are carried out under unphysiologcial conditions and are prone to artefact formation. Probably the most reliable approaches are measurements of isoprostanes as a parameter of lipid peroxidation and determination of oxidative DNA damage. Also the design of the experimental models has a strong impact on the reliability of AO studies: the common strategy is the identification of AO by in vitro screening with cell lines. This approach is based on the assumption that protection towards ROS is due to scavenging, but recent findings indicate that activation of transcription factors which regulate genes involved in antioxidant defence plays a key role in the mode of action of AO. These processes are not adequately represented in cell lines. Another shortcoming of in vitro experiments is that AO are metabolised in vivo and that most cell lines are lacking enzymes which catalyse these reactions. Compounds with large molecular configurations (chlorophylls, anthocyans and polyphenolics) are potent AO in vitro, but weak or no effects were observed in animal/human studies with realistic doses as they are poorly absorbed. The development of -omics approaches will improve the scientific basis for health claims. The evaluation of results from microarray and proteomics studies shows that it is not possible to establish a general signature of alterations of transcription and protein patterns by AO. However, it was shown that alterations of gene expression and protein levels caused by experimentally induced oxidative stress and ROS related diseases can be normalised by dietary AO.

Correspondence:

c1 Corresponding author: Professor Siegfried Knasmüller, fax +431 4277 9651, email siegfried.knasmueller@mediuniwien.ac.at

Footnotes

† Contributed equally

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