To Standardize or Not to Standardize
Many herbal products that are found on retailers' shelves are labeled as "standardized" for the content of a specific constituent or group of constituents. St. John's wort is standardized to 0.3% hypericin (a single chemical) content. Milk thistle is standardized to 80% silymarin (a group of flavanoids) content. Ginkgo biloba is standardized to 24% ginkgo flavone glycosides and 6% terpene lactones. Does standardization assure potency or uniformity of product or therapeutic effectiveness? The answer more often than not is probably no.
Take St. John's wort, for example. Much of the early research pointed to hypericin as the apparent antidepressant constituent. For several years herb companies have produced St. John's wort standardized for hypericin content. However, new research finds that hypericin is probably irrelevant to antidepressant effects, that it is probably an anti-viral compound. This new research is looking at hyperforin aspossibly responsible for the antidepressant effect.
Still, many people believe that 0.3% hypericin is a good "marker" of St. John's wort overall potency. But in high-performance liquid chromatography (HPLC) analyses of different batches of St. John's wort, hypericin levels will fluctuate relative to other key constituents. No one really knows whether 0.3% hypericin is a good indicator of the overall potency of St. John's wort.
Other so-called standards represent potential "marker" compounds that are related to the identity of a plant. Echinacea has been shown to be a good immunostimulant herb. Studies have shown that it will increase white blood cell activity. For years, echinacoside was the only isolated compound in the literature from E. angustifolia to which biological activity was attributed. In 1950 it was isolated and found to have mild, insignificant antibacterial activity. By 1980 echinacoside was found in 5 of the 9 species of echinacea. Therefore, it is meaningless as a marker of identity.
In the mid 1970s researchers described high molecular weight polysaccharides as responsible for the immunostimulant activity of echinacea. Research since the late 1980s has revealed that different components found in different species and even plant parts of various echinacea species are responsible for immunostimulant activity. Some of these compounds are water soluble, others are soluble in alcohol or other organic solvents. Echinacoside is not among the compounds responsible for immunostimulation!
The quest for standardized herbals has become the "holy grail" of the herb industry. It seems the proponents of standardization see it as a way to equate herbs to drugs believing that this will show consumers, health care professionals and the FDA that herbs can safely and effectively be used in place of drugs. But it is important to remember that there is a fundamental difference between herbal medicines and synthetic pharmaceuticals. The latter represents only a single chemical entity. Herbal medicines, on the other hand, generally rely upon the complex interaction of many chemical components in the plant or plant part. Herbs are not "green drugs."
Herbal standardization should begin with a company's control of its seeds and seedlings, ensuring relatively consistent plant genetics. Organic farming methods would prevent pesticides from concentrating in extracts. It's also important to know optimal growing conditions, the proper time to harvest the plants, and preparation and manufacturing procedures to assure a quality herbal product. To take the guesswork out of herbals, a company should also confirm, scientifically, that the chemical profile of several principal components (not just one) is relatively constant crop to crop, batch to batch.
In delivering predictable batch to batch consistency in herbal medicines, it is important not to lose sight of the need to offer high quality whole herb products, rather than focusing too much attention on a single chemical component.
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