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Weighing the benefits of tea

Tea leaves do contain more than 700 compounds, many with potential biological activity. It is the “polyphenols,” the “catechins” in particular, that have aroused researchers’ interest enough to generate a truckload of studies.

“Get in here and sit your ass down!”

Not exactly what you expect to hear when you are peacefully walking in San Francisco’s Chinatown. But the boisterous elderly Chinese gentleman seemed charismatic enough, and the establishment didn’t look like an opium den. Indeed it wasn’t. It was a tea house. But not your ordinary tea house.

We quickly found ourselves plunked down at a long counter along with a number of other tourists who had been dragged in from the street.

“It’s not for taste, it’s for health,” began “Uncle Gee,” who I was to learn was a local institution.

“Eighty-four years old,” he boasted, and “in perfect health!”

“Drink eight cups of tea a day; never coffee!”

“Tea full of antioxidants against cancer!”

Not only were we treated to a lecture on the “science” and history of tea, we were also ordered to try about half a dozen varieties.

“Never use boiling water, the tea will scream,” and so did he. “Don’t even dream about adding milk or sugar.”

“Steep for only twenty seconds!”

We sipped rosebud tea from Iran to ward off insomnia, and “puerh” for weight loss and heart problems. Next came Blue People Ginseng Oolong. I don’t know why the “blue.” I looked around and none of the people drinking it were turning blue. Everyone enjoyed that one. It was a truly different taste, with a hint of licorice, “a party-in-your-mouth tea,” we were told.

As our taste buds were partying, I glanced around at the dozens and dozens of jars, all with intriguing names.

“Monkey-picked green tea” for “cleansing the body” caught my attention. It wasn’t clear if this was to be applied to the outside or the inside of the body, or how the monkeys had been trained to pick tea. I wanted to ask if this was just monkey business, but didn’t dare. I did muster up enough courage to ask Uncle Gee about his favourite tea, the one that kept him young and so full of whatever. He quickly pointed to “Angel Green tea.”

“Good for high blood pressure, cholesterol, diabetes and detox.”

At $160 a pound, I suspect good for profits too, although there was no “hard sell.” The tea bash ended with Uncle Gee telling us that while we were strangers when we came in, we were now part of the family. How could I resist buying some Angel Green and Blue People?

We’ve been enjoying both teas ever since, but other than frolicking taste buds, I can’t vouch for any benefits. But tea leaves do contain more than 700 compounds, many with potential biological activity. It is the “polyphenols,” the “catechins” in particular, that have aroused researchers’ interest enough to generate a truckload of studies.

When rats are fed green-tea leaves, their blood cholesterol and triglycerides go down. Levels of such enzymes as superoxide dismutase, catalase and glutathione-S-transferase, all involved in removing foreign chemicals from the body, go up. The rats are also less prone to weight gain, apparently because of an increase in metabolism.

But in these studies, the rats consume far more tea on a weight basis than people ever can. As far as human-population studies go, some show a decrease in colon, breast, stomach and prostate cancer; but others don’t. The studies are neither consistent nor convincing, which is not surprising given that there are numerous varieties of tea, their chemical profiles depending on the type of tea, where it is grown and how it is harvested, stored and processed. Most of the epidemiological studies that have shown health benefits have focused on Asian populations, where tea consumption is much greater than in North America, and lifestyles are very different.

Laboratory studies have also been carried out with various tea components. For example, heterocyclic aromatic amines, compounds produced when meat is cooked at a high temperature, are less likely to trigger cancer in the presence of the polyphenols theaflavine gallate and epigallocatechin gallate. Such findings, along with the suggestion of increased rates of metabolism, have led to the sale of various dietary supplements based on tea extracts. Why go to the trouble of drinking tea when you can just pop a “cancer-fighting, fat-burning” pill?

But here we run into a problem. Such dietary supplements are poorly regulated; and the amount of catechins they contain can be far greater than that available from drinking tea. The high doses may indeed help to increase metabolism and result in weight loss, but the cost can be high. Just ask the teenager who walked into the emergency room at Texas Children’s Hospital with his chest, face and eyes bright yellow due to severe liver damage, after using a concentrated green-tea extract he bought at a “nutrition” store as a “fat-burning” supplement.

There was concern that he might need a liver transplant but luckily his liver, an organ that has regenerative properties, managed to recover. He did have to give up sporting activities, and will require regular liver function checkups.

Unfortunately this is not an isolated case, and such cases are not limited to green-tea extracts. Recently aegeline, a compound found in the leaves of the Asian bael tree, showed up in supplements marketed as an aid in losing weight and building muscle — despite a lack of any credible evidence. But aegeline may not be without some effect. More than 50 people suffered liver damage, two had to have liver transplants and one died after consuming a supplement containing aegeline.

The multi-hospital-based Drug Induced Liver Injury Network in the U.S. has found that liver problems due to herbal and other dietary supplements have increased three-fold in the last 10 years. Conventional medications still cause far more cases of liver injury, but they also have evidence of efficacy, which is not the case for many herbals.

I suspect that Uncle Gee would have a few devilish words to say about people who might think that they can encapsulate the benefits of Angel tea in a pill. He would likely argue that supplements cannot replicate the same rejuvenating effects he experiences from his daily tea regimen.

I must admit he did look robust and way younger than 84.

But when pushed, he did tell me that he runs six miles three times a week, and can bench press 110 pounds.

So maybe it’s not only the tea that’s keeping him young. 

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