Diabetes mellitus (DM) is a major public health problem and its incidence is rising dramatically. The brain, particularly the cerebral cortex, is very susceptible to glucose fluctuations and hyperglycaemia-induced oxidative stress. Tea (Camellia sinensis (L.)) is widely consumed; however, the antidiabetic properties of white tea remain largely unexplored. In the present study, we investigated the effects of daily consumption of white tea on the cerebral cortex of prediabetic rats. The cerebral cortex metabolic profile was evaluated, and the expression levels of GLUT, phosphofructokinase-1, lactate dehydrogenase (LDH) and monocarboxylate transporter 4 were assessed. LDH activity was also determined. The cerebral cortex oxidative profile was determined by evaluating its antioxidant power, lipid peroxidation and protein oxidation levels. Catalase, glutathione, glutamate, N-acetylaspartate, aspartate, choline, γ-aminobutyric acid, taurine and valine contents were determined. Daily consumption of white tea ameliorated glucose tolerance and insulin sensitivity. Moreover, white tea altered the cortex glycolytic profile, modulating GLUT expression and lactate and alanine contents. Finally, white tea consumption restored protein oxidation and lipid peroxidation levels and catalase expression, and improved antioxidant capacity. In conclusion, daily consumption of white tea improved the cerebral cortex metabolic and oxidative profile in prediabetic rats, suggesting it as a good, safe and inexpensive strategy to prevent DM-related effects in the cerebral cortex.

Free radicals are continuously generated during an organism's lifetime. In order to understand the involvement in the oxidative status of fish, methionine and white tea were assayed as antioxidant supplements in diets for gilthead sea bream (Sparus aurata). For the purpose of this study, four isonitrogenous and isolipidic diets were formulated to contain 45 % of protein and 18 % lipid and 0·3 % methionine (Met diet), 2·9 % white tea dry leaves (Tea diet) and 2·9 % of white tea dry leaves+0·3 % methionine (Tea+Met diet). An unsupplemented diet was used as the control. Key enzymatic antioxidant defences, superoxide dismutase (SOD) isoenzyme profile, total, reduced and oxidised glutathione and oxidative damage markers were determined. The results showed that dietary methionine supplementation increased liver SOD activity, while white tea induced higher hepatic catalase activity. Dietary white tea induced a notable increase in Mn-SOD isoenzyme. This is the first study to provide evidence that dietary tea inclusion in fish feeding could be an important source of Mn with metabolic repercussions on antioxidant mechanisms.