An ingredient in green tea that
helps reduce blood sugar spikes in mice may lead to new diet strategies for
people, according to Penn State food scientists.
Mice fed an antioxidant found in
green tea—epigallocatechin-3-gallate, or EGCG—and corn starch had a significant
reduction in increase in their blood
sugar—blood glucose—levels
compared to mice that were not fed the compound, according to Joshua Lambert,
assistant professor of food
science in agricultural sciences.
"The spike in blood glucose level is
about 50 percent lower than the increase in the blood glucose level of mice
that were not fed EGCG," Lambert said.
The dose of EGCG fed to the mice
was equivalent to about one and a half cups of green tea for a human.
Lambert, who worked with Sarah C.
Forester, postdoctoral fellow, and Yeyi Gu, graduate student, both in food
science, said EGCG was most effective when the compound was fed to the mice
simultaneously with corn starch. For humans, this may mean that green tea could
help them control the typical blood sugar increases that are brought on when
they eat starchy foods, like breads and bagels that are often a part of typical
breakfasts.
"If what you are eating with
your tea has starch in it then you might see that beneficial effect,"
Lambert said. "So, for example, if you have green tea with your bagel for
breakfast, it may reduce the spike in blood glucose levels that you would
normally get from that food."
The EGCG had no significant
effect on blood sugar spikes in mice that were fed glucose or maltose,
according to the researchers who released their findings in the online version
of Molecular Nutrition and Food
Research. Lambert said that the reason blood sugar spikes are reduced
when the mice ate starch, but not these sugars, may be related to the way the
body converts starch into sugar.
An enzyme called alpha-amylase
that is produced in both the mouth and by the pancreas helps break down starch
into maltose and glucose. EGCG may inhibit the enzymes ability to break down
the starch, the researchers indicated, since they also found that EGCG reduced
the activity of alpha amylase in the pancreas by 34 percent.
If the mechanism holds in humans,
this may mean that people who want to limit the blood sugar spike should skip
adding sugar to their cup of green tea.
"That may mean that if you
add sugar into your green tea, that might negate the effect that the green tea
will have on limiting the rise in blood glucose level," Lambert said.
Lambert added that the green tea and the starch would
need to be consumed simultaneously. For example, drinking a cup of tea well
after eating a piece of toast would probably not change the blood sugar spike.
For the study, researchers
separated mice into several groups based on body weight. After a fasting
period, the mice were given common corn starch, maltose, or sucrose. One group
of mice received EGCG along with the feed, while a control group was not fed
the compound.
The researchers then tested the
blood sugar levels of both groups.
Lambert said the researchers next
step is to test the compound on people.
"The relatively low
effective dose of EGCG makes a compelling case for studies in human
subjects," the researchers said.
No comments:
Post a Comment