Antioxidants called polyphenols, which are found in both
green and black tea, can block bacteria from producing
foul-smelling compounds such as hydrogen sulfide, researchers
reported at the annual meeting of the American Society for
Microbiology in Washington, D.C.
Bad breath, or halitosis, is caused by anaerobic bacteria
that live on the back surface of the tongue and in the gum
pockets -- deep spaces between the gums and the teeth,
according to the study's lead author, Christine D. Wu of the
College of Dentistry at the University of Illinois at Chicago.
The bacteria "make horrible, smelly stuff," Wu said in an
interview with Reuters Health. "That's why we get bad breath."
Earlier studies by Wu and her colleagues showed that black
tea could slow dental plaque formation.
The researchers suspected that certain compounds in the tea
might be affecting the growth of bacteria and thus the
production of bad-smelling compounds.
In a laboratory study, Wu and her colleagues incubated tea
polyphenols with three species of halitosis-causing bacteria
for 48 hours. At concentrations that were lower than what is
normally found in tea, the polyphenols inhibited the growth of
these bacteria, Wu said.
At even lower concentrations, polyphenols hindered an
enzyme that spurs the formation of the malodorous hydrogen
sulfide.
The researchers tested two types of polyphenols: catechins
and theaflavins. Catechins are found in both green and black
tea, while theaflavins are found mostly in black tea.
The results don't prove that tea sweetens breath, Wu
allowed.
"All we can say is that a cup of tea will produce more than
enough of these active materials to affect the bacteria," she
said. "Remember, this is a lab study. In the mouth, bacteria
are protected by all sorts of things."
Wu hopes to look at the effects of tea on bad breath in
future studies.
