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Tannic acid and tea

You want complicated? Tea – now that’s complicated.

In the e-Alert “Model T” (5/22/03) I told you about the amino acid in tea called L-theanine, which helps the body fight viral, parasitic, fungal, and bacterial infections. In response, I received an e-mail from an HSI member named Joseph who had a question about another component of tea:

“All this tea news is great, but what about the tannic acid in tea? I recall reading an article that said tannic acid (the same item used in tanning leather!) wreaks havoc on joints, leading to arthritis. Supposedly the tea-drinking Brits have a very high incidence of arthritis.”

After checking several sources, I can’t confirm that the British have an unusually high incidence of arthritis, so we’ll have to take Joseph’s word on that one. Tannic acid is the astringent agent used in leather tanning, but different plants have different tannic characteristics. More to the point: tea isn’t used to tan leather, but the tannins extracted from oak, birch, eucalyptus, willow, and pine, are.

As for the tannins in tea, I’ll have more on that, but first, here’s HSI Panelist Allan Spreen, M.D., with his take on Joseph’s question:

“Tough one. There are nutrient therapists who deliberately use tannins as part of their therapy, as some seem to have helpful properties. There’s always the question of what’s doing the good (or bad), of course. Is it the tannins, the theophylline, or something else in the tea?

“To complicate the picture there are green teas, well known to have benefits in several areas. However, some have caffeine and some don’t (as is true with other compounds on board), which complicates the picture somewhat. Also, it’s recently been found that black teas have therapeutic abilities along with the green varieties (and would be expected to have more tannins on board).”

In other words: there’s no pat answer to this one. When you say “tea,” you’re talking about a universe of varieties with a wide range of characteristics. And when you start sorting through the available literature about tea and tannic acid, the picture doesn’t get any clearer – anything but.

I found three sources claiming that research shows tea drinkers are less likely to suffer from arthritis and rheumatoid arthritis (no specific references to studies were named). But I found another piece – written by George E. Meinig, D.D.S., F.A.C.D. – that made a case for the caffeine in tea increasing rheumatoid arthritis risk by causing a calcium-phosphorus imbalance. And according to Dr. Meinig, the problem is compounded when sugar is added.

As for the specific effects of tannin, one theory holds that mucin (the protective mucous that lines the interior of the digestive system) protects us from most of tannic acids’ negative effects. Another source claims that tannic acid has anti-inflammatory and germicidal properties.

And to top it all off, I found an article that simply stated: “There is no tannic acid in tea.”

If that were true, it would make for a much simpler answer to Joseph’s question.

To Your Good Health,

Jenny Thompson
Health Sciences Institute

Sources:
“Tannins” Animal Science Department, Cornell University, ansci.cornell.edu
“Caffeine” George E. Meinig, D.D.S., F.A.C.D., Price Pottenger Nutrition Foundation, price-pottenger.org
“Green and Black Tea” The Happy Herbalist, happyherbalist.com
“Tannic Acid in Tea” MashTea Gholee Cyber Tea House, farsinet.com



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