The importance of Standardized Herbal Extracts
In the herbal context, a standardized extract is an herbal extract made to a consistent standard. The American Herbal Products Association (AHPA) recently expanded the definition of the term, and now “Standardization refers to the body of information and controls necessary to produce material of reasonable consistency. This is achieved through minimizing the inherent variation of natural product composition through quality assurance practices applied to agricultural and manufacturing processes.”
Generally, the term has a more specific meaning: a standardized extract is manufactured to contain a consistent level of one or more phytochemical constituents that are derived from the original starting material.
Ratio (concentration ratio). This standard can be quite simple, such as the ratio of the starting herbal raw material to the finished extract. A 4:1 extract, where 4 kilogram of dried herb is processed to yield 1 kilogram of final extract.
Galenical Extract. A galenical extract is a traditional pharmacopeial extract of an herb. Guidelines have been established in the various pharmacopeias (such as earlier versions of the British Pharmaceutical Codex), which defined the method of preparation, the extracting solvent, and the ratio of the starting material (the herb) to finished product (the extract). Galenical extracts were usually in liquid form, typically tinctures and fluid extracts. However, with the modern trend to solid dosage forms, quite often a galenical extract is dried to its solid residue and incorporated into a tablet or capsule.
Galenical extracts are often regarded by herbalists as “whole” extracts in that they extract a comprehensive spectrum of the phytochemical content of the plant. While this is generally the case, it should be kept in mind that alcohol-water mixtures are selective solvents and do not extract everything that is extractable equally from the plant.
On the other hand, many standardized extracts are dried galenical extracts fixed to a consistent level of the chosen marker compound(s). Hence, they are just as “whole” as galenical extracts.
Consistent Activity. One aim of standardized extracts is to achieve consistent activity of an herbal product from batch to batch.
Guaranteed Potency. Properly manufactured standardized extracts usually will ensure consistent activity and thereby guarantee potency.
Marker Compounds. Marker compounds are characteristic phytochemicals found in a plant that are chosen to represent the standard for a standardized extract.
Active Compounds. Active constituents are phytochemicals that are important for a given therapeutic effect of an herbal extract. Marker compounds are phytochemicals that are likely to have pharmacological activity relevant to the proposed use of the extract. Sometimes the great body of pharmacological and clinical evidence available for an herb relates only to the use of one isolated, purified constituent.
Standardized herb extracts offer high-potency doses of herbs’ biologically active agents. They supply a reliable effectiveness compared to other dose-delivery forms, such as teas, tinctures, bulk herbs, fluid extracts and capsules of dried extract, and they are also more cost-effective, contrary to many herbalists’ assumptions, because high volumes of tinctures or crude herbs would have to be consumed to receive active agents in amounts equivalent to those guaranteed by standardization.
The herb content of traditional herb medicines is usually measured according to crude herb matter concentration. By contrast, standardized extract strength is expressed in terms levels of therapeutically active compounds or key biological markers, which labs confirm using chemical analysis techniques such as high-pressure liquid chromatography (HPLC) and nuclear magnetic resonance (NMR).
Chemical analysis of preparation forms other than standardized extracts reveal some examples of very poor quality. Therefore, we recommend exclusively standardized extracts because their manufacture involves tests guaranteeing a certain level of active ingredient.
Furthermore, tinctures and other crude herb preparations borrow mostly science which establishes an herb’s therapeutic value based on the performance of standardized extracts in clinical trials, a practice that is either based on ignorance or blatant deceit for profit.
In order for any herbal preparation to be clinically effective it must provide an effective dosage. This view should not be controversial. Unfortunately, the controversy arises from the fact that from a pharmacological perspective it is unlikely that the dosage schedules recommended on most herbal tinctures are sufficient to produce any real effect.
Many “authorities in the field” maintain that standardized extracts represent the future of herbal therapy, as a way to ensure consistent activity of an herbal extract from batch to batch. Standardized extracts are considered more effective and of better quality and both consumers and practitioners might conclude that the traditional galenical extracts have no value in modern phytotherapy.