White tea has more antioxidative, antidiabetic and antiobesogenic properties than green and black tea 

Rebecca Ready and Md. Shahidul Islam 
Biomedical Research Laboratory, Department of Biochemistry, School of Life Sciences, University of KwaZulu-Natal, Durban 4000, South Africa

Background: Tea consumption has been extensively studied in relation to various diseases when several studies have been accomplished to investigate the association of tea consumption with type 2 diabetes. The chemical components of tea primarily include polyphenols, caffeine and flavonoids. These compounds were reported to have anti-oxidant properties having many beneficial effects. However, comparative effects of the different types of teas in terms of their antioxidative, antidiabetic and antiobesogenic activities are still not clear.
Aim: This study was aimed at investigating the comparative anti-oxidative, anti-diabetic, and anti-obesogenic potentials of the aqueous extract of black, green and white tea by using several experimental models. 
Materials and methods: Aqueous extracts of the black, green and white teas were prepared and subsequently analyzed for their total phenolic contents; antioxidant activity vis-à-vis 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and ferric reducing ability  (FRAP); inhibition of 𝛼-amylase and 𝛼-glucosidase enzymes activity in vitro. The extracts were also investigated for their role in the inhibition of intestinal glucose absorption in isolated rat jejunum. 
Results: The white tea had the highest total polyphenol content and antioxidant properties. Furthermore, all the teas inhibited alpha-amylase and alpha-glucosidase, with white tea showing the highest inhibitory activity. White and green tea showed significantly higher (p<0.05) inhibition of pancreatic lipase, when black tea showed little or no inhibition. All tea extracts significantly (p<0.05) inhibited intestinal glucose absorption, when green and white tea showed the better activities compared to black tea. Phytochemical compositions of different tea extracts were also different with higher caffeine in black tea compared to green and white tea.
Conclusion: Data of this study suggest that white has more potent antioxidative, antidiabetic and antiobesogenic properties compared to green and black tea, which may be attributed to its different phytochemical compositions. Further studies are needed in experimental animals and humans to confirm the results of this study.