Beauty Health for Life

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.

Red wine and green and white tea could give athletes and players a boost in the sports arena by increasing the amount of performance-enhancing hormone testosterone in their bodies, according to researchers from Londons Kingston University.

However not only could the beverages help them to trophy success, it could also allow them to beat anti-doping tests. A team led by Professor Declan Naughton, from the Universitys School of Life Sciences, found that and green and white tea might reduce the amount of testosterone excreted by the body, which could distort the findings of drug tests taken from urine samples.

Testosterone is a naturally-occurring steroid hormone present in both men and women. It can increase muscle mass, boost stamina and speed up recovery. Sportspeople, however, are prohibited from taking it, or a synthetic version of it, to try to gain a competitive edge.

Although red wine is not a banned substance away from the sports field, Professor Naughtons team has erred its findings to the World Anti-Doping Agency because of the newly-discovered side effect of potential change to the amount of testosterone in the body.

"Previous research has shown the effect over-the-counter anti-inflammatory drugs can have on enzymes," Professor Naughton explained. "Since many of these drugs are derived from plants, we decided to look at the effect particular foods and beverages can have on enzymes involved in testosterone excretion. We chose green tea and then red wine because both have a huge variety of natural molecules and we wanted to see if they affected the amount of testosterone excreted in urine."

"The catechins stop enzymes tagging molecules for excretion so the kidneys dont recognise them as needing to be removed and leave them circulating in the body," Professor Naughton explained. "We found that green and white tea could inhibit the enzyme by about 30 per cent. The levels of catechins in a strong cup of green tea matched those we used in our experiments."

The increased levels of testosterone from drinking green and white teas may provide a boost. "Its like having extra testosterone without actually taking any," Professor Naughton said. "By not excreting it from the body, athletes could potentially increase their testosterone levels for improved performance.

The team found that a compound in red wine, known as quercetin, partially blocked the action of an enzyme called UGT2B17, which looks for testosterone and then sends a message to the kidneys to excrete it.

Professor Naughton stressed that the research had so far been conducted in test tube experiments and had yet to be trialled on humans. "A full clinical study would be needed to determine the effects on people but, if the same results were found, it would confirm that compounds in red wine can reduce the amount of testosterone in urine and give a boost to testosterone levels," he explained.

The effect of red wine on an individual would vary because of factors such as weight, fitness, health and diet, making it hard to estimate how much was needed to improve performance, Professor Naughton said.

Teetotallers are not exempt from the effects. In fact, the alcohol content of red wine has very little impact because non-alcoholic molecules are responsible for inhibiting testosterone excretion.

The team also found the results were the same for red wine extract in supplement form. The active compounds such as quercetin are found in many foodstuffs as well as supplements.

The findings have been published in leading international journal Nutrition.