November 12, 2012
The finding could benefit humans with metabolic syndrome, a cluster of symptoms that include elevated blood glucose levels, which are linked to an increased risk of diabetes.
A team led by Joshua D. Lambert of Pennsylvania State University fed fasting mice corn starch, maltose, sucrose or glucose and pretreated some of them with EGCG. Mice that received corn starch and EGCG had a 50 percent reduction in post meal blood glucose levels in comparison with animals that did not receive EGCG. EGCG did not impact animals that received maltose, sucrose or glucose, suggesting that the compound may affect the way the body converts starch into sugar. In further experimentation, EGCG reduced the activity of alpha amylase, a starch-digesting enzyme secreted by the pancreas, by 34 percent.
"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," stated Dr Lambert, who is assistant professor of food science in agricultural sciences at Penn State. "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."
Since EGCG doesn't appear to reduce the effect of sugars, consuming sweetened green tea with a starchy food would still result in blood sugar spikes. "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," Dr Lambert explained.
The dose of EGCG used in the current study was equivalent to the human dose of that found in a cup and a half of green tea. "The relatively low effective dose of EGCG makes a compelling case for studies in human subjects," the authors conclude.
