Supplementation with a combination of antioxidants does not affect glycaemic control, oxidative stress or inflammation in type 2 diabetes subjects

Abstract

The present clinical trial examined the influence of a supplement, containing a combination of antioxidants extracted from fruit, berries and vegetables, on levels of plasma antioxidants (tocopherols, carotenoids and ascorbate), glycaemic control (blood glucose, HbA1c, insulin), oxidative stress biomarkers (F₂-isoprostane, malondialdehyd, nitrotyrosine, 8-oxo-7, 8-dihydro-2′-deoxyguanosine, formamidopyrimidine glycosylase sites, frequency of micronucleated erythrocytes) and inflammatory markers (interleukin-6, C-reactive protein, prostaglandin F_2α-metabolite) in type 2 diabetes. Forty subjects were randomly assigned to control, single or double dose group and completed the study. In summary, 12 weeks of antioxidant supplementation did neither affect glycaemic control nor the levels of biomarkers of oxidative stress or inflammation, despite substantially increased plasma concentrations of antioxidants. The absence of an effect may be explained by the selected study subjects with relatively well-controlled diabetes, a high intake of fruit and vegetable and levels of plasma antioxidants, biomarkers of oxidative stress and inflammatory markers comparable to those found in healthy subjects.

Keywords::

• Antioxidants
• supplementation
• glycaemic control
• oxidative stress
• inflammation
• diabetes mellitus type 2

Acknowledgements

We are grateful to Lars-Börje Sjöberg, the staff at KPL (Centre for Human Studies of Foodstuffs), Siv Tengblad, Eva Sejby, Barbro Simu and Anders Kallner for good co-operation and excellent technical assistance. Rawya Mohsen and Lars Berglund are acknowledged for statistical analyses. Vinnova (the Swedish Governmental Agency for Innovation System), Semper AB and Procordia AB are acknowledged for financial support. The data has been presented as an abstract at the 23th International symposium on Diabetes and Nutrition, Ebeltoft, Denmark, 2005.

Declaration of interest: Elisabet Rytter was employed by the financial supporter Semper AB during the study (employment terminated 2005-01-01). Elisabet Rytter has no other conflicts of interest. All other authors declare no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

This paper was first published online on early online on 22 September 2010.