Wednesday, July 16, 2008

Understanding Herbal Medicine Potency

Herbal Medicine Potency: Standardized Versus Concentrated Extracts

With the explosion of consumer use of herbal medicines, it is important to have some understanding of the means by which these botanical supplements are classified with regard to potency. Most herbal preparations, whether in the form of capsule, tablet or tincture, are derived from a number of different processing techniques applied to freshly harvested plants. Once processed, these herbal supplements can then be rated in one of two categories: Standardized Extracts or Concentrated Extracts.

Standardized Extracts

Extracts are usually "Standardized" when there is specific knowledge of the therapeutic properties of the compound or compounds within the plant preparation. Once this therapeutic property is known, the amount of compound responsible for elicting the therapeutic effect can be quantified and each extract preparation can then be standardized to a specific percentage of active constituent. This percentage is identified by a ratio of the amount of active compound to dilutent or carrier compound.

Extracts can also be standardized without specific knowledge of the active constituent. In this case, standardization is defined by the percentage of a key component within the compound which is not necessarily the active ingredient. A classic example of this is St. John's Wort. Most extracts are standardized to 0.3% hypericin, despite inconclusive evidence that hypericin is the compound which exerts St John's Wort's antidepressant effect.

Concentrated Extracts

Sometimes herbal extracts are not standardized; rather their potency is expressed as a ratio known as a concentrate. Specifically, this is a pseudo-quantitative measurement of the strength of the extract expressed by its concentration relative to raw, unprocessed plant. For example, a 1:5 concentrate defines one part of extract as equivalent to five parts of raw plant. This designation is less useful than standardization because it does not quantify active compound. In general, those manufacturers complying with Good Manufacturing Practice today are predominantly utilizing standardization rather then concentration.

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