Like green tea, extracts from black tea may also help reduce weight gain by Stephen Daniells
Like green tea, extracts from black tea may also
help reduce weight gain and cut body fat levels, says a new study
from Japan with rats and mice.
Supplementing the diet of lab animals fed a high-fat diet with
black tea extracts suppressed body weight gain and body fat levels,
with the benefits linked to reduced fat absorption, according to
findings published in Nutrition.
Interest in tea and its constituents has bloomed in recent
years, with the greatest focus on the leaf's polyphenol content.
Green tea contains between 30 and 40 per cent of water-extractable
polyphenols, while black tea (green tea that has been oxidized by
fermentation) contains between 3 and 10 per cent. Oolong tea is
semi-fermented tea and is somewhere between green and black tea.
The four primary polyphenols found in fresh tealeaves are
epigallocatechin gallate (EGCG), epigallocatechin (EGC),
epicatechin gallate (ECG), and epicatechin (EC).
Most of the studies have focussed on green tea and its
constituents, most notably EGCG. To date green tea has been linked
to a reduced risk of Alzheimer's and certain cancers, improved
cardiovascular and oral health, as well as benefits in weight
"Although black tea extract contains only small amounts of
these components, significant physiologic effects of administering
black tea extracts were observed," wrote researchers from the
Functional Food Business Project at Kirin Holdings Company.
"It has been reported that the primary polyphenols in black
tea are theaflavins and thearubigins. However, it has not yet been
clarified whether thearubigins also have a preventive effect on
obesity. Our results are consistent with the possibility that black
tea-derived polyphenols are responsible for the observed
physiologic effects of the black tea extracts," they
The Japanese scientists fed male rats a fat emulsion containing
the black tea extract at a level of 500 or 1,000 mg per kg of body
weight. Fat levels in the blood were subsequently evaluated and
showed that the black tea extract "suppressed increases in rat
plasma triglyceride levels in a dose-dependent manner", said
In a separate study with female mice, the researcher
supplemented their high-fat diets with either 1 or 5 per cent of
the tea extract for eight weeks.
"Administration of the 5 per cent black tea extract
suppressed increases in body weight, adipose tissue mass, and liver
lipid content (reduced to 56.9 and 81.7 per cent of control mice,
respectively) in mice fed a high-fat diet," they stated.
While more research is needed, the researchers concluded that
the polymerized polyphenol fraction of the black tea was
responsible for the apparent weight management benefits.
Back to Health
Published online ahead of print, doi:
"Prevention of diet-induced obesity by dietary black tea
polyphenols extract in vitro and in vivo"
Authors: S. Uchiyama, Y. Taniguchi, A. Saka, A. Yoshida, H.