From The January 2001 Issue of Nutrition Science News

Backtalk

What's The Difference Between A Marker Compound And An Active Ingredient?

Standardized extracts are more than a single chemical component in an herb fixed to a certain level. True standardization encompasses the entire production process, from seed to shelf. The goal is to control, as much as possible, the complete chemical composition of each extract.

Today's American herbal marketplace is influenced by a strong trend toward the use of "standardized" botanical extracts. The purpose of standardization is commonly believed to serve as content control of a "marker" compound, which is one of the constituents in the plant that is singled out for special attention during the manufacturing process. The heightened interest in standardized extracts is due to the perception that standardization somehow guarantees the extract potency.

However, the use of standardized extracts in the United States is often based on an inaccurate or incomplete understanding of what standardization actually means. In fact, standardization—when properly performed—entails much more than merely controlling the content of a particular marker compound. The presence of a marker compound at a reproducible level often has little to do with ensuring extract potency. In fact, the addition of purified compounds in order to achieve "standardization" actually defeats the purpose of standardization and may result in the creation of a misbranded or adulterated product.

In an effort to clarify the misperceptions concerning standardization and marker compounds, the American Herbal Products Association (AHPA)—a national trade association based in Silver Spring, Md., representing hundreds of growers, processors, manufacturers, and marketers of herbs and herbal products—has recently produced a white paper discussing the topic in detail. The following is adapted from the AHP white paper.

Standardization actually consists of the body of information and controls that serve to ensure batch-to-batch reproducibility of an extract; that is, standardization is comprised of adherence to a consistent recipe and to a wide variety of raw material and process controls. The goal is to control the complete chemical composition of the extract—although a considerable amount of variability will usually remain. The complex nature of standardization cannot be reduced to the mere quantity of one constituent or group of constituents. However, in cases when markers have powerful pharmacological effects such as with certain alkaloids, the content of that active ingredient has an elevated relevance to the standardization of the extract. In such cases, it may be justified to focus attention primarily on a single compound or group of compounds.

The holistic concept of standardization is based on the recognition that the physiological effect of any given compound or group of compounds can be heavily influenced by the matrix in which they occur. Some compounds in the plant may enhance or diminish the physiological effects of others. Other compounds, while having no direct physiological effect, may nevertheless influence the stability, solubility, and bioavailability of the physiologically relevant compounds. As a result, it is important to consider the entire spectrum of chemicals in the material, and to implement standardization measures that will control the entire spectrum and not just one constituent.

The narrower concept of ensuring that each batch contains a particular marker content is more properly understood as adjustment—known in Europe as "normalization," not standardization. Adjusting to a minimum, maximum or target concentration of a constituent is appropriate only when the constituent is known to be an active ingredient. It should ideally be achieved through the mixing of extract lots rather than either by spiking (adding purified marker or active compounds) or dilution (adding fillers or other inert ingredients).

The above discussion makes it clear that standardization is a complex process. In order for it to play its intended role in enhancing batch-to-batch extract reproducibility, it must be thoroughly understood and carefully implemented. Above all, standardization must not be equated with control of marker content; reproducibility of marker content is merely the by-product, not the primary purpose, of proper standardization. In fact, an excessive focus on a particular marker may actually diminish product quality.

—Staci Eisner, technical director at ExtractsPlus and trustee of the American Herbal Products Association

"It's really a marketing tool. By paying to have your products tested, you are getting marketing exposure. When people see your name it's a good thing, but it costs a lot of money to participate. We stand behind the quality of our products, and I don't think we need a seal in order to say that we provide good ingredients. The companies that participate are huge, and they have the extra marketing budget to throw around and do this. I definitely think that it's going to have an impact on the industry—we have already received calls from several consumers."

—Marcy Clow
Director of Research and Quality
Rainbow Light
Santa Cruz, Calif.