Comparison of the effects of black and green tea on in vitro lipoprotein oxidation in human serum

Lipoprotein oxidation is a process thought to be involved in atherogenesis. Dietary antioxidants that prevent or inhibit oxidative damage to lipoprote ins may help to prevent atherosclerosis. Both black and green teas can be m ajor dietary sources of flavonoids and other phenolics with antioxidant act ivity. Results of previous studies suggest that green tea may have a greate r antioxidant potential than black tea. The aim of this study was to assess and compare the effects of black and green tea on in vitro lipoprotein oxi dation. The tea extracts were prepared using a method similar to that used to prepare infusions of tea for drinking. Antioxidant activities of seven b lack teas and four green teas were assessed using an in vitro assay that me asures Cu2+-induced oxidation of lipoproteins in human serum. All tea extra cts inhibited in vitro lipoprotein oxidation in human serum to a similar ex tent. No significant difference in antioxidant activity was found between b lack and green tea. Caffeine prepared to a comparable concentration to that found in tea had no effect on lipoprotein oxidation. Further studies are r equired to determine the importance of these findings in relation to possib le protective effects of black and green tea consumption against atherogene sis and cardiovascular disease. (C) 1999 Society of Chemical Industry.