Date:

October 4, 2017

Source:

University of California
– Los Angeles Health Sciences

Summary:

Black tea may promote weight loss and other
health benefits by changing bacteria in the gut, research indicates for the
first time.

UCLA researchers have
demonstrated for the first time that black tea may promote weight loss and
other health benefits by changing bacteria in the gut. In a study of mice, the
scientists showed that black tea alters energy metabolism in the liver by
changing gut metabolites.

The research is published
in the European Journal of Nutrition.

The study found that both
black and green tea changed the ratio of intestinal bacteria in the animals:
The percentage of bacteria 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.

“It was known that
green tea polyphenols are more effective and offer more health benefits than
black tea polyphenols since green tea chemicals are absorbed into the blood and
tissue,” said Susanne Henning, the study’s lead author and an adjunct
professor at the UCLA Center for Human Nutrition, which is part of the David
Geffen School of Medicine at UCLA. “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.”

“The results suggest
that both green and black teas are prebiotics, substances that induce the
growth of good microorganisms that contribute to a person’s well-being,”
she said.

In the study, four groups
of mice received different diets — two of which were supplemented with green
tea or black tea extracts:

Low-fat, high-sugar

High-fat, high-sugar

High-fat, high-sugar and green tea extract

High-fat, high-sugar and black tea extract

After four weeks, the
weights of the mice that were given green or black tea extracts dropped to the
same levels as those of the mice that received the low-fat diet throughout the
study.

The researchers also
collected samples from the mice’s large intestines (to measure bacteria
content) and liver tissues (to measure fat deposits). In the mice that consumed
either type of tea extract, there was less of the type of bacteria associated
with obesity and more of the bacteria associated with lean body mass.

However, only the mice
that consumed black tea extract had an increase in a type of bacteria called
Pseudobutyrivibrio, which could help explain the difference between how black
tea and green tea change energy metabolism.

Dr. Zhaoping Li, director
of the UCLA Center for Human Nutrition, chief of the UCLA Division of Clinical
Nutrition and the study’s senior author, said the findings suggest that the
health benefits of both green tea and black tea go beyond their antioxidant
benefits, and that both teas have a strong impact on the gut microbiome.

“For black tea
lovers, there may be a new reason to keep drinking it,” she said.

The findings build on a
2015 UCLA study that demonstrated that both green tea and black tea helped
prevent obesity in mice that consumed a high-fat, high-sugar diet.

Story Source:

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Journal Reference:

1.    Susanne M. Henning,
Jieping Yang, Mark Hsu, Ru-Po Lee, Emma M. Grojean, Austin Ly, Chi-Hong Tseng,
David Heber, Zhaoping Li. Decaffeinated green and black tea polyphenols
decrease weight gain and alter microbiome populations and function in
diet-induced obese mice. European Journal of Nutrition, 2017; DOI: 10.1007/s00394-017-1542-8