Although the polyphenols in black tea are less well absorbed than those in green tea, they also seem able to influence weight, but through an effect on the intestinal microbiota, according to new work carried out in mice.
Green tea and black tea may come from the same plant (Camellia Sinensis), but they differ in particular by the nature of their phenolic compounds. Those of green tea are shorter, and therefore better absorbed in the small intestine. They are found in greater quantities in circulation than those of black tea, which has led to green tea being considered more “active”. But this work carried out by researchers from UCLA (University of California at Los Angeles) leads us to consider black tea from a new angle, which would give it properties just as worthy of interest as those of green tea, but with a another key mechanism.
Green tea and black tea act on weight
The researchers subjected rodents to different diets for 4 weeks:
- low in fat and high in sugar,
- high in fat and high in sugar,
- rich in fat and sugar with green tea extracts,
- high in fat and sugar with black tea extracts.
After 4 weeks, the weight of the mice given the green or black tea extracts was at the same level as that of the animals given the low-fat diet. Previous work conducted by UCLA had already shown this for green tea, but this is the first time that researchers have observed it for black tea as well.
Effects that pass through the microbiota
Stool analyzes reveal that for both green tea and black tea, there are fewer bacteria associated with obesity and more bacteria associated with thinness. However, only the animals having received the black tea extract show a significant increase in the bacterium Pseudobutyrivibrio.
It is therefore clear that the beneficial effects of both green tea and black tea go beyond the antioxidant properties, and also involve changes in the microbiota. The fact that the polyphenols in black tea are larger in size, they are less absorbed in the intestine, but then exert prebiotic properties in the colon.
Susanne M. Henning: Decaffeinated green and black tea polyphenols decrease weight gain and alter microbiome populations and function in diet-induced obese mice. European Journal of Nutrition