|Dr. Tieraona Low Dog, medical director of the Treehouse Center for Integrative Medicine, Albuquerque, NM. |
NEW YORK—Now that you're getting used to asking patients about what herbs they take, go a step further, and find out how they are using them.
"Herbal medicine" can be as simple as a cup of freshly brewed chamomile flower tea, or it can be a complex daily gobble of pills and gel caps containing highly processed plant extracts. As with conventional pharmaceuticals, the particular preparation of an herbal substance is critical in determining its effects.
In short, you need to know your tinctures from your teas, and your decoctions from your extracts, said Dr. Tieraona Low Dog, at Columbia University's Botanical Medicine in Modern Practice conference. People use these terms indiscriminately, but their meanings are quite specific, said Dr. Low Dog, medical director of the Treehouse Center for Integrative Medicine, Albuquerque, NM.
• Teas: Synonymous with infusions, teas are the oldest, cheapest and most common way to prepare medicinal herbs. Infusions are by nature not as strong as concentrated, chemically-processed extracts. On the spectrum from "food" to "drug," they're closer to the food end of the scale. But if made with good quality, fresh or dried plant parts, they can definitely have physiologic effects. Teas are made with approximately 1 oz. of herb steeped in roughly 16 oz of boiling water. Medicinal teas can remain potent for a day or two, but beyond two or three days they deteriorate.
"Among Hispanics and Native Americans, teas are the preferred way to use herbs. Even in urban environments, few people from these cultures use capsules or tinctures," said Dr. Low Dog, who was an herbalist and midwife for years before attending medical school. She added that infusions are a primary means of delivery in traditional Chinese herbal medicine. Contrary to the current trend toward making medicinal teas tasty, many traditional herbalists hold that the worse it tastes, the better it is for you.
• Decoctions: In contrast to teas, which involve steeping leaves or flowers in boiling water, decoctions involve actually boiling or simmering the plant parts—usually roots or barks—in larger quantities of water for longer periods. Typically, 1 oz. of herb is simmered in 24–32 oz of water. Decoctions are also common in Chinese medicine, the remedies often involving complex plant combinations. Decoctions are for plant parts that are inherently less water-soluble. Because they tend to remain potent only for limited times, and must be used within a day or two of preparation, infusions and decoctions are rarely found as "off-the-shelf" commercial preparations.
• Poultices and Compresses: A poultice involves direct application of plant parts—usually crushed, boiled or specially prepared in some way—to an afflicted area of the body. A compress is simply a cloth soaked in an herbal infusion, and applied to the body.
• Tinctures: By definition, a tincture is a water-ethanol extraction with a solute-to-solvent ratio of less than 1 (1 kg herb to 5 liters of solvent is pretty typical). The ratio should be on the label of a tincture product, and Dr. Low Dog cautioned against "tinctures" that do not disclose this critical information.
The alcohol content of tinctures may range from 25% to 90%, and patients who have alcohol problems should be cautioned against using them. The main virtue of a tincture is potency, which tends to be higher than what can be obtained with a tea or decoction of the same plant.
There are many commercially available herbal tinctures. If the alcohol content is over 70%, a tincture may actually be sterile, which can extend its shelf-life. Under 70%, "you do not destroy all the colliforms and yeasts, you just keep them static. This can be a problem for immunocompromised patients or those with cancer," said Dr. Low Dog. "A lot of products out there are under 40% alcohol, and some of them contain 105–107 organisms/ml." Products containing glycerine should have concentrations of at least 60% to prevent microbial growth.
• Fluid Extracts: A fluid extract is like a tincture, except the solute-to-solvent ratio is 1 to 1 (1 kg plant to 1 liter solvent). This means a typical fluid extract should be five times stronger than a typical tincture of the same plant.
But Dr. Low Dog said the terms are used fairly interchangeably even by manufacturers, making it extremely important to check the strength of a product by looking for the solute to solvent ratio.
• Standardized Extracts: Standardized extracts are a recent innovation, part of a movement to bring modern analytical chemistry into herbal medicine. A standardized extract is manufactured to deliver a precisely quantified amount of an index compound or set of compounds within the herb—hypericin in St. John's Wort or ginkgolides in Ginkgo biloba, for example. Extractions are done with a variety of solvents including hexane, supercritical CO2, ethyl acetate, ether or some form of alcohol. Measurement of the marker compound is done with high-performance liquid chromatography or other advanced assay techniques.
Standardization promises greater potency, and more precise dosing, putting these products a lot closer to the "drug" end of the spectrum. Standardized products are available in liquid, tablet, and gel cap form. "In many cases, you do get a better product," said Dr. Low Dog.
The problem is, the index compound may not be physiologically important. A whole herb contains dozens of potentially active compounds; the marker used to standardize a product may simply be the easiest one to assay. And even assuming the index compound is clinically important, there may or may not be a lot of data to support standardization to a particular level.
It is also possible that the physiologic effect of an herb reflects a synergy involving many constituents. There may be a very good reason why traditional Chinese and Native American herbalists tend to favor whole plant infusions and tinctures over single-constituent extracts.
The introduction of analytical chemistry has raised the overall quality of many herbal products, and it opens a door to greater knowledge of plant biochemistry. But the mere fact of standardization is no guarantee that a particular herbal product is good medicine, Dr. Low Dog said.