Tea Aids Weight Loss by Altering the Gut Microbiome

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Tea has been drunk for thousands of years and new age gurus have been extolling the health benefits of tea for decades. In recent years, scientific evidence has begun to support some of these health claims - particularly for modest weight loss – however, it is not really known how tea exerts these effects on the body.


Now a team from UCLA has discovered that tea (black tea in this case) may promote weight loss and other health benefits by altering the gut microbiome.


The study, published in the European Journal of Nutrition, shows that in mice, black tea alters energy metabolism in the liver by altering gut metabolites.


Both black and green tea altered the ratios of gut bacteria in the animals. The percentage of obesity-associated bacteria decreased, while bacteria associated with lean body mass increased.


The results suggest that both green and black tea act as prebiotics.


Previous studies have shown that polyphenols found in green tea are absorbed into the blood and affect energy metabolism in the liver. These new findings suggest that black tea polyphenols, which are too large to be absorbed, stimulate the growth of good bacteria and promote the production of short-chain fatty acids (shown to have many health benefits).


How was the study conducted?

Mice in the study were placed on 1 of 4 diets:

  1. Low-fat, high-sugar.
  2. High-fat, high-sugar.
  3. High-fat, high-sugar + green tea extract.
  4. High-fat, high-sugar + black tea extract.


After four weeks researchers were amazed to find that the weights of the mice receiving the green or black tea extracts had dropped to the same levels as the mice on the low-fat diet.


By analyzing the gut bacteria of the mice, the researchers found that mice consuming either tea extract had lower levels of obesity-associated bacteria and higher levels of lean mass-associated bacteria.


However, only mice consuming the black tea extract had increases in a specific type of bacteria called Pseudobutyrivibrio, which could explain the differences in how green and black tea affect energy metabolism.


These new findings suggest the health benefits of tea extend beyond the antioxidant effects to significantly influence the gut microbiome.