Medicinal Properties of Herbal Teas are a Matter of Debate
October 10, 1986 - Boston Globe / Living Arts - Alexis Beck

Since their introduction into the mainstream marketplace almost two decades ago, herbal teas have been a subject of controversy. Although the commercial success of these teas is based, at least in part, on their role as healthy, alternative caffeine-free beverages, it is their safety that has been in question. Most experts agree, however, that when consumed in reasonable amounts, commercially packaged herbal teas are safe.

The problem of potential toxicity and adverse reactions seem rooted in the claims and beliefs that certain herbs have magical or medicinal properties and the subsequent and sometimes excessive use of these teas as a drug or cure. Both the FDA and several herbal tea manufacturers, including Celestial Seasoning, are in agreement about where the risks lie.

"We spend a lot of time and money on quality control," explains Susan Eastman of Celestial Seasonings, which includes selecting the herbs, testing them individually and in combination with one another, and avoiding any controversial plants that, according to an agency like the FDA, may be questionable.

"The issue of toxicity arises in those teas that are processed by a small company, that are usually sold in bulk in independent health food stores, that may contain herbs within the blend that are classified as questionable by the FDA, or when a harmless herb is unknowingly contaminated with a poisonous substance like a pesticide, or when a herb contains active ingredients unknown to the manufacturer, that when brewed will cause an adverse reaction in people," Eastman continued during a recent telephone interview from her Boulder, Colo., office.

The fact is, herbs are plants, and plants throughout history have been the source of some of the most potent drugs. Digitalis, for example, is derived from the foxglove plant and morphine and opium from the poppy seed; these are substances that can stimulate the heart, sedate the brain and temporarily eliminate pain. As useful and sometimes vital as both morphine and digitalis are, they both are also potentially fatal.

In 1975 the FDA evaluated 171 herbs commonly used for brewing teas. Of these, 91 were determined to be safe, 53 were classified as of undefined safety and 27 were placed in the unsafe category.

Most experts agree that the teas to avoid are those containing lobelia, sassafras, comfrey, tonka bean, wormwood, shavegrass, burdock, pennyroyal and pokeroot. Overdoses of these herbs, or more often their toxic extracts, have been shown to be carcinogenic in laboratory rats or cause symptoms including diarrhea, labored respiration, severe headache, cramps, nausea, vomiting and an increased pulse rate in humans.

"The bottom line is we don't know enough about herbal teas to conclude they are safe, or specifically predict their effect in varying concentrations on the human body," explains Paula Fairfield of the FDA's Boston office of Consumer Affairs.

Yet soaring sales figures indicate that consumers are spending upwards of $200 million annually on teas and bulk herbs for their flavor, and some are buying for their alleged medicinal qualities as well.

Botany defines an herb as a seed-producing plant with a non-woody stem, which dies down at the end of a growing season. The Herb Trade Association's definition is broader, taking into account plant parts that are known for their savory, aromatic and other qualities.

Cinnamon, jasmine, fennel, clover, lemon grass and rosehips are safe and familiar examples of these plants or plant parts which are extracted or dried and valued for their savory, aromatic other qualities, according to the trade association'' definition. Nutmeg and mistletoe, on the other hand, can be deadly when brewed in tea.

Most of this potential trouble is caused by the active ingredients that can be present in some of these plants. These compounds come in several varieties: acids, tannins, essential oils and the more potent alkaloids (such as morphine and nicotine) and glycosides (such as digitalis). Since some alkaloids and glycosides build up in body tissue, it's possible for even small amounts to cause a potential problem. But usually these active ingredients are present in low concentrations, so moderate consumption (two to three cups daily) of these teas is not problematic for a person in good health. The point is that the amounts of these compounds in brewed teas can vary greatly, depending on how, when and where the plant was grown, the parts of the plants used and how the tea is brewed.

From time to time new evidence leads the FDA to drop a previously accepted herbal product from its GRAS list, those food substances "generally recognized as safe."

For example, until 1977, sassafras was considered safe, but further research determined that safrole, a natural chemical constituent of sassafras caused liver cancer in laboratory rats. It is acceptable as a food or additive, only if it had been rendered safrol-free.

Certain herbal teas, though classified as safe, can have some unexpected drawbacks. Chamomile tea, for example, hailed for its soothing effects, may cause severe allergic reactions in individuals sensitive to ragweed other plants in the ragweed family such as chrysanthemums, aster and yarrow. According to the FDA, there have been two reported cases of anaphylactic shock, which were linked to its consumption. But such severe reactions are quite rare.

Another herb, senna, considered by the FDA to be a GRAS substance, also has been recognized as a safe and effective laxative by the advisory review panel that evaluated ingredients in over-the counter drug preparations. But if too much of it is consumed or it is brewed in too concentrated a form, severe diarrhea and dehydration can result. In addition, chronic use can seriously irritate the large intestine. For an acquaintance, a Brookline business owner who considers herself nutritionally conscienscious, a cup of comfrey tea, intended to ease her chronically upset stomach, turned into frightening bout of stomach cramps, explosive diarrhea and eventual dehydration. Credited with purifying the blood and easing stomach ailments, this herb in the for of tea is available in health food stores despite the fact its safety is classified by the FDA as "undefined." It contains an alkaloid, lasiocarpine, which has induced liver cancer in rats and can poison the liver, according the pharmacist Dr. Varro E. Tyler in his book, "The Honest Herbal."

"You have to be very careful when you use herbs for more than their flavoring ability; in fact, until we're more sure about them, until we know how to use them and how much, perhaps the results are not worth the adventure," says Klein who is now a regular user of mint tea.

An extreme example of marketing herbal teas involves a group of teas manufactured by Traditional Medicinals of northern California. They are in health food stores and supermarkets under such names as "Smooth Move," "Smokers Tea," "PMS Tea," "Weightless Tea," "Mothers Tea," "Pregnancy Tea," "Female Toner," "Easy Now" and "Herbal Pharmacy." But more than half of them, on closer examination, turns out to be classified as drugs.

This company is both a food company and a licensed drug company in the state of California and can, as a result, include herbs in their teas that are otherwise banned from foods.

The most striking example of this is in the company's "Smoker's Tea," which contains lobelia, one of the 27 herbs considered unsafe for food use by the FDA because of the alkaloid lobeline, which allegedly acts as a substitute for nicotine without the additive side effects. But according to the FDA, lobelia is a poisonous substance, an overdose of which can produce vomiting, sweating, paralysis, a rapid but feeble pulse and in extreme instances, coma and death.

"The concentration of lobeline in even a box of our tea will not have a toxic effect, if taken according to our package directions (1 cup every hour not to exceed 12 per 24 and should not be used for more than 6 weeks) but will make eliminating nicotine easier," says the company's Vice President, Lynda Sadler, who is former President of the American Herbal Products Association.

While FDA has authority over the use of herbs in food, drugs and cosmetics, its effectiveness is limited by the preponderance of new products and the multitude of small outlets in which they may be sold. Fairfield encourages consumers to report reactions to herbal teas, even if they are minor, to FDA's regional office in Stoneham (279-1479).

Perhaps the old cautionary proverb among those who gather wild mushrooms says it best: "There are old mushroom hunters and there are bold mushroom hunters. But there are no old, bold mushroom hunters."

Thus if you choose to drink herbals teas, especially if you plan to brew your own, be absolutely sure you know what you are drinking; if you have any question about the contents, you might be better off having a good old cup of coffee. Then, at least, you know what you're up against.