UCLA researchers have shown that black tea alters energy metabolism in the liver and promotes weight loss by changing gut metabolites. Published in the European Journal of Nutrition, the study found that black tea changed the ratio of intestinal bacteria; the percentage of bacteria in the intestinal track associated with obesity decreased, while bacteria associated with lean body mass increased.

Previous studies indicated that chemicals in green tea called polyphenols are absorbed and alter the energy metabolism in the liver. The new findings show that black tea polyphenols, which are too large to be absorbed in the small intestine, stimulate the growth of gut bacterium and the formation of short-chain fatty acids, a type of bacterial metabolites that has been shown to alter the energy metabolism in the liver.

Our new findings suggest that black tea, through a specific mechanism through the gut microbiome, may also contribute to good health and weight loss in humans, Susanne Henning, one of the researchers in the study.