Herbal Teas and Toxicity

by Food and Drug Administration (FDA)

There was an Old Man of Vienna, who lived upon tincture of senna;
When that did not agree, he took chamomile tea,
That nasty Old Man of Vienna.

— Edward Lear, The Book of Nonsense

The old man of Vienna apparently found out what generations of herbal tea drinkers have discovered: that senna is a powerful laxative if taken in large amounts and that chamomile is a soothing relaxant that, among its many purported virtues, aids digestion.

Hopefully, though, the old man of Vienna was not allergic to ragweed. Because if he was, he might have had a reaction to chamomile tea — as did one 35-year-old American woman several years ago who went into anaphylactic shock after a few sips. Chamomile is a member of the same plant family as ragweed, asters and chrysanthemums, and people allergic to those plants had better be cautious of chamomile.

Herbal teas have been enjoyed for centuries throughout the world. But they have been the subject of controversy in the United States since their introduction into the mainstream marketplace two decades ago.

Comfrey, Lobelia and Sassafras

Comfrey tea has been implicated in liver disease, although only two such cases have been reported in the United States. In one instance, a 47-year-old woman developed a liver ailment after consuming up to 10 cups of comfrey tea a day and taking comfrey pills by the handful for more than a year in an attempt to cure her stomach pains, fatigue and allergies.

Although comfrey has enjoyed considerable popularity because of its supposed universal healing properties, there is reason to believe it is hazardous to health. Comfrey roots and leaves contain pyrrolizidine alkaloids, which have been found to cause cancer in rats. Celestial Seasonings, the industry leader in herb tea sales, dropped comfrey from its product line 10 years ago, and it was banned in Canada in 1989.

Lobelia tea can cause vomiting, breathing problems, convulsions, and even coma and death when used in large amounts. Lobelia, also called Indian tobacco, was used to treat asthma and bronchitis throughout the 19th century and experienced renewed popularity in the 1960s, when it was smoked by some young people to achieve a mild, legal "high." It supposedly produced the same feelings of mental clarity, happiness, and well-being when imbibed as tea.

In his book The Honest Herbal, pharmacognosist and former dean of the School of Pharmacy at Purdue University Varro E. Tyler says eating, drinking or smoking lobelia is "sheer folly." "Lobelia is pretty toxic. It's really not safe enough to use unless the dose is closely controlled," he says.

The Journal of the American Medical Association recently reported the case of a 25-year-old woman who developed abnormal menstrual bleeding as a result of drinking large amounts of "seasonal tonic," a homemade herbal brew. The woman was drinking the tea in an attempt to assuage her appetite so she could lose weight. The tea included a number of ingredients, three of which — tonka beans, melilot and woodruff — contain coumarin, an anticoagulant (blood thinner). The woman was also taking high doses of vitamins and other medicines that can intensify the effects of anticoagulants.

Aromatic sassafras tea, once popular as a stimulant and blood thinner and as a reputed cure for rheumatism and syphilis, causes cancer in rats when taken in large amounts. Oil of sassafras and safrole, major chemical components of the aromatic oil in sassafras root bark, were taken out of root beer more than 30 years ago. And sassafras bark was banned from use in all food. Safrole-free extract, however, is allowed in food.

Nevertheless, herbal teas are a commercial success. They are purchased for their aroma and flavor and as a supposedly healthy alternative to caffeine beverages. Some are bought as home remedies for their alleged medicinal benefits.

Since the 1960s, when they experienced renewed popularity as part of the back-to-the-earth and natural foods movements, consumption of herbal teas has steadily increased. Today, a half dozen other herbal tea manufacturers share the shelf with more traditional teas made from orange and black pekoe at the supermarket. In fact, at least two pekoe tea manufacturers, Lipton's and Bigelow, have their own line of herbal teas.

Sales figures indicate consumers spent $118.6 million last year on herbal teas at major supermarkets, up 9.8 percent from the previous year. This does not reflect herbal tea sales at smaller grocery stores and health food stores, for which figures are not available.

Safe or Unsafe?

But how safe is it to relax, prop your feet up, and sip a cup of tea containing, say, chamomile flowers, spearmint leaves, lemon grass, raspberry leaves, rosebuds, and orange blossoms?

Many herb experts would say that, when consumed in reasonable amounts, major commercially packaged herbal teas are safe. They point out that, overall, there are very few serious reactions to herbal tea. Problems arise, they say, when teas are consumed in excess, when they are used for medicinal purposes, when an uninformed consumer mistakenly uses unsafe herbs, or when, as in the case of comfrey, a long-revered herb may be found to have toxic properties that were previously unknown.

"There are a lot of raw herbs available — everything from A to Z. And a lot of people are doing their own thing ... buying herbs from natural foods stores and blending their own teas," says Angie Dorsey, a spokeswoman for Celestial Seasonings, which markets 20 herbal teas. "But most major herbal tea manufacturers are not using any dangerous herbs."

Celestial Seasonings, she said, brews teas for flavor and aroma, not for medicinal purposes. In selecting herbs, the company is guided by a list of 258 herbs and spices compiled by the Herb Research Foundation from regulations that FDA has published. "We avoid any herbs that are borderline or questionable in safety," she says.

To further insure the safety of its teas, the company tests its herbs for herbicides and pesticides and maintains an herbarium to check the identity of imported herbs. Because some safe herbs have toxic look-alikes, it is easy to confuse one with another, Dorsey said.

Mark Blumenthal, executive director of the American Botanical Council, says that, in general, herbs that are sold as foods and teas have been used with relative safety for centuries.

"The idea that the herbs in your favorite tea may be toxic is, at the very least, misleading. If such everyday herbs were toxic, there would be a flood of poisoning cases among millions of herb users in this country alone. In fact, reports of adverse reactions to herbs are few." Blumenthal notes, however, that almost any substance can be toxic in large enough doses.

About the Author

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