Herbal Teas and Toxicity : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

Caution Urged

The Food and Drug Administration takes a decidedly more cautious view of herbal teas.

"We don't know enough about herbal teas to conclude they are safe or to predict their effects in varying concentrations on the human body," says Sara Henry, a toxicologist in FDA's Center for Food Safety and Applied Nutrition. Although FDA has approved some herbs and spices for use in flavoring, very little is really known about many other herbs on the market, she says.

Henry says she cringes when she reads the ingredients on boxes of herbal tea at her local supermarket. "Raspberry leaf tea, for example," she says. "We know absolutely nothing about the effects of consuming raspberry leaves. Caffeine has been extensively studied in animals, but nobody really knows anything about the safety of some of the herbs used in commercial herbal teas."

Henry said she is also concerned about the growing number of Oriental and Indian herbs on the market "because we don't know anything about them."

Sam Page, a natural products chemist in FDA's Center for Food Safety and Applied Nutrition, says most of the reported problems with toxicity in herbal teas have been associated with people who grow their own herbs.

"The problem is, most of these people don't have a long-term history of herbal use. Knowledge of herbs has not been passed down from generation to generation in their families, as it is in some other countries. So their experience with herbs is limited," says Page.

"Many of these herbal products are being consumed at much higher levels than the traditional uses. Many people are not cognizant of the basic premise of toxicology: 'The dose makes the poison.'"

Under these circumstances, he says, brewing your own tea "can be Russian roulette."

The case of an 85-year-old retired steelworker whose wife regularly concocted herbal teas from leaves found in their backyard illustrates Page's point. One day the man picked some leaves from an unfamiliar plant and made tea that had an unusually bitter taste. He drank one cup and within a few hours became gravely ill. Analysis of the tea leaves revealed that they belonged to the foxglove plant, from which the powerful heart drug digitalis is derived, and which can cause severe erratic heartbeat.

In another case, a 30-year-old woman died after drinking a tea she prepared from leaves of a tree she believed to be a eucalyptus. It wasn't. It was an oleander, which is poisonous.

Regulating Herbal Teas

FDA regulation of herbal teas falls into a somewhat gray area between food and drugs, according to Page. Depending on their intended use, herbs and other products, such as vitamins and diet aids, might sometimes be considered foods, sometimes drugs, and sometimes both.

FDA regards herbal teas that are consumed for their taste and aroma only (and not for medicinal purposes) as foods. Although there are no regulations governing herbal teas per se, any herb that is considered safe by FDA for use in food is presumed to be safe in tea as well.

But for centuries, herbs and herbal teas have been used for medicinal purposes. Many of today's most potent medicines, such as digitalis, morphine and opium, are derived from herbs. If an herbal tea makes a claim to prevent or cure a disease, FDA considers it to be a drug and regulates it as such. This means the tea must be approved by FDA as safe and effective for its intended use.

Most major commercial herbal tea manufacturers avoid therapeutic claims or, if they do make them, skirt them gingerly with words such as "calming," "soothing," or "relaxing." However, some herbal tea manufacturers make therapeutic claims that are highly questionable.

One California company markets a smoker's tea to help people stop smoking, a weight-loss tea to "temporarily eliminate excess water weight," an herbal laxative tea, and a tea that supposedly relieves minor sore throats. It also sells teas for pregnancy, premenstrual syndrome, and teas designed to "tone" the body.

Other companies also make questionable claims. One markets a "dieter's tea" as "a low-cal food." Another markets a tea described as "the Brazilian way of losing weight without suffering." The same company sells a tea supposedly used by Indian tribes in their fertility rites and, by implication, designed to improve sexual potency. Still another sells a "therapeutic tea of the Incas" made from a tree used by the Incas for medicinal purposes.

No data has been submitted to FDA to substantiate any of these claims.

FDA takes action against herbs on a case-by-case basis when it has reason to question their safety — usually as a result of complaints or reports of serious reactions. The agency has received very few complaints about herbal teas in recent years.

"Keeping track of herbs is an impossible task," says FDA's Page. "The herb industry is the least organized of the food industries. Herbs are sold at a multitude of small outlets, and it's very difficult to find out who sells what and how much is being sold."

FDA Investigates

As a result of growing concern, FDA last spring directed its investigators to collect samples of a number of products — most of them herbal — sold in health food stores to determine which ones might be potential health hazards or which make unsubstantiated therapeutic claims.

Because of reported problems with comfrey tea, investigators collected samples of products made with comfrey to determine the levels of the potentially toxic pyrrolizidine alkaloids in them. Comfrey leaves and roots have been found to contain as many as nine such alkaloids, but the quantities vary widely among parts and species of the plant.

The herb industry itself is also trying to find out more about the safety of certain herbs. The Herb Research Foundation, at the request of the American Herbal Products Association, has initiated a program to evaluate 200 or so commercial herbs that are commonly available but not approved for use as food flavorings. Over the next 5 to 10 years, the foundation plans to gather information on each plant, including history of use in other countries, chemical composition, pharmacological properties, reports of adverse reactions, and toxicity studies. The foundation is planning to follow the same guidelines and often consults the same experts FDA would use to determine the safety of a food additive, according to Robert McCaleb, president of the foundation.

"We expect that the results will go both ways. We'll find herbs that are safe and herbs, probably like comfrey, that are not. And we'll also find plants where conclusions are harder to draw," says McCaleb.

In 1984, faced with similar questions about herb safety, Canada established an advisory committee to review the available information on herbs and make recommendations. As a result, Canada banned the sale of some 57 herbs and required warning labels on five others that, though generally not considered harmful, could pose a health risk if used during pregnancy.

For American herbal tea drinkers, though, it might be best to play safe and heed the old proverb about those who gather wild mushrooms: "There are old mushroom hunters. And there are bold mushroom hunters. But there are no old, bold mushroom hunters."

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.