Is green tea a miracle drink?

By Kathie Sutin
SPECIAL TO THE POST-DISPATCH
11/14/2005

To hear the hype, you might think it’s the Holy Grail of the quest for health.

The list of the purported benefits of this drink goes on and on. It’s been said to:

* Prevent cancer or help fight it

* Stave off heart attacks

* Reduce cholesterol

* Prevent dental cavities and promote gum health

* Enhance memory

* Protect the skin from ultraviolet rays

* Reduce the inflammation of arthritis

* Help with weight loss

* Increase mental alertness

* Improve airflow to the lungs therefore alleviating asthma

* Increase fertility in women

So what is this behemoth of beverages?

It’s green tea, a drink relatively new to the American palate but one the Chinese have been enjoying for more than 5,000 years ago.

The problem is despite all the great press green tea has received in recent years, can we be sure it really does half of what its proponents claim?

No one can say for sure.

While some studies indicated green tea is a good guy in the battle for health, experts caution against putting too much stock in it.

The scientific evidence is “unclear,” says Charlotte Ridley, assistant professor of nutrition and dietetics at St. Louis University.

“Different things that have been at least looked at in some studies,” she says. “In some areas there’s a little bit more evidence than others. Sometimes small studies find something; others don’t. In other words, we don’t have enough scientific evidence on any of this really to make any kind of firm recommendation.”

There is danger in making a judgment about anything based on a single study, she said.

“One study does not a case make. When something gets reported in the newspapers, people think, ‘Aha, this is it. This is what I should do.’ Well, it may be one study – one small study, maybe a good study or maybe not. Maybe it’s animal research. OK, it’s interesting and might be suggestive, but it’s certainly not any reason to run out and do something.

“If you see a single study and change your life and your diet on account of it, you’re going to be lurching from one thing to another every other day.”

Cynthia Thomson, assistant professor of nutritional sciences at the University of Arizona, agrees.

She is conducting two separate studies looking at changes in energy expenditure and changes in body composition in overweight women and women who have survived breast cancer.

She noted that the FDA recently denied a study that tried to link green tea to cancer prevention because of a lack of scientific evidence. But that’s not to say a possible link has been ruled out.

“If you look at the data on tea and cancer, it looks like the biological mechanisms are there,” she said. “In other words, there’s ways in which components in tea seem to reduce the number of cancer cells or kill cancer cells in laboratory models, but the human data is very limited.”

Benefits

Don’t tell all that to Lynn Heermann of St. Louis. He has been drinking tea all of his life.

He switched to green tea about three years ago when he heard it helped burn extra calories.

“I then researched that fact and found out that green tea also helps your body be more disease resistant. I have been drinking green tea since then,” Heermann, executive chef of Sassafras Cafe at the Missouri Botanical Garden, says.

Heermann says he drinks a cup or two of hot tea in the morning and a glass of iced tea in the late afternoon.

“First of all, I drink green tea because it has caffeine,” he says. “Green tea causes thermogenesis, which is a rise in body temperature, which burns calories, always a good thing when your are a chef.”

Heermann says he also favors green tea because of its antioxidants, which have been linked to lower cancer rates and lessening the affects of the aging process.

“Mainly I like the taste of green tea and a glass of hot tea wakes me up in the morning and makes me alert before I drive home at night, but the added health benefits of green tea make it even better choice.”

Antioxidants

Green tea is high in polyphenols, antioxidants that occur in tea leaves. Antioxidants, those substances that make certain veggies so good for you, have been shown to prevent cell damage by free radicals.

The jury is even out on the role of antioxidants, Thomson says.

“There’s a rationale that says antioxidants ought to be helpful and ought to have some benefit,” she says. “These have to do with the damaging of oxygen radicals that may be involved in all kinds of disease processes. Antioxidants help to lower these levels and therefore the thinking is maybe they promote health.

“If oxidants result in some of the damage that causes, say, cardiovascular disease well, someone thinks, ‘Aha, doesn’t it make sense that antioxidants should improve the situation and therefore improve health?’ ”

But, going from thinking there’s a connection and proving it is a “big step,” she says.

“You don’t know until you do the trials,” she says. “There just aren’t the clear-cut trials with green tea that say, ‘Everybody ought to be drinking this stuff.’ ”

Thomson noted that most studies showing green tea consumption may impact the occurrence of cancer have been done in Asian countries where people generally drink greater quantities of tea than Americans do – and they drink it from an earlier age.

“They’ve had exposure to tea over a lifetime so there may be some protective effect in terms of long-term exposure that we haven’t been able to measure in yet Americans because we haven’t been tea drinkers for that long,” she says.

Heal thyself

Interestingly, both Ridley and Thomson are green tea drinkers.

Ridley says she often drinks a cup in the afternoon, but she drinks it because it has less caffeine than coffee. “It’s not a really high caffeine level like the coffee I would normally drink. If I drink a lot of coffee, I don’t sleep well at night,” she says.

“I like green tea. It has a light, pleasant taste to me. The fact that maybe it has some health benefits – that’s good, but it’s probably not the reason I do it. I don’t add sugar and other stuff to it so it’s basically calorie-free.”

Despite her caveats about the health benefits of green tea, Thomson says she recommends it to her patients.

“It’s a very low-risk behavior,” she says. “And the potential is clearly there that it may modulate cancer.”

From: stltoday.com