Various Types Of Tea Research Articles

Suppression of lipopolysaccharide-induced liver injury by various types of tea and coffee in D-galactosamine-sensitized rats.

Extracts of various types of tea and coffee significantly suppressed lipopolysaccharide (LPS)-induced liver injury, as assessed by the plasma enzyme activities, in D-galactosamine-sensitized rats when administered orally once before injecting the drugs. There was a significant negative correlation between the caffeine levels of these extracts and liver injury. Authentic caffeine also had a hepatoprotective effect. These results suggest that caffeine-containing beverages generally suppress LPS-induced liver injury according to their caffeine content.

Green, oolong and black tea extracts modulate lipid metabolism in hyperlipidemia rats fed high-sucrose diet

The main goal of this study was to compare effects of ethanol-soluble fractions prepared from various types of teas on sucrose-induced hyperlipidemia in 5-week old male Sprague-Dawley rats. Rats (n = 6–8 per group) weighed approximately 200 g were randomly divided into control diet, sucrose-rich diet, green tea, oolong tea and black tea groups. Control-diet group was provided with modified AIN-93 diet while the others consumed sucrose-rich diet. Tea extracts (1% w/v) were supplied in the drink for green tea, oolong tea and black tea groups. Results indicated sucrose-rich diet induced hypertriglyceridemia and hypercholesterolemia. Food intake was reduced by oolong tea extract. Consuming oolong and black tea extracts also significantly decreased body weight gains and food efficiency. Hypertriglyceridemia was normalized by green and black tea drink on day 18 and by oolong tea extract on day 25, respectively. Hypercholesterolemia was normalized by green tea on day 18 and by oolong tea and black tea on day 25, respectively. Plasma HDL-cholesterol concentrations were not affected by any tea extract. The triglyeride content in the liver as well as the cholesterol content in the heart of rats fed sucrose-rich diet were elevated and were normalized by all types of tea drink tested. Although green and oolong tea extracts contained similar composition of catechin, our findings suggest green tea exerted greater antihyperlipidemic effect than oolong tea. Apparent fat absorption may be one of the mechanisms by which green tea reduced hyperlipidemia as well as fat storage in the liver and heart of rats consumed sucrose-rich diet.