By Eric Brand

What is the difference between full-spectrum extracts and standardized extracts? What do these terms mean and how do they affect us as Chinese medical practitioners?

1. Full Spectrum Extracts

In the context of Chinese medicine, full spectrum extracts tend to refer to products that reflect the natural constituent yield that is obtained from a traditional water decoction. Historically, most prescriptions have been prepared as a water decoction, so replicating a decoction is thought to provide the best approximation of the spectrum of constituents that Chinese medicine’s time-tested results are based upon.

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From the perspective of plant chemistry in general, one could argue that a truly full-spectrum extract would include both alcohol- and water-soluble constituents. However, only a minority of Chinese medicine’s herbal products were traditionally extracted with alcohol, so the use of alcohol and other solvents introduces a variable that was not historically present for most items. Consequently, the term “full-spectrum extract” in Chinese medicine usually refers to a water-based extract that does not focus on concentrating any one single constituent, but rather focuses on concentrating all the water-soluble material in a substance without affecting the natural ratio of these constituents.

This stands in contradistinction to “standardized extracts,” which tend to focus on specific constituents rather than focusing on a broad spectrum of substances that are all soluble in water. Items that are best suited to full-spectrum water extracts include medicinals that were traditionally prepared as a decoction, and medicinals that have numerous active ingredients and/or unknown active ingredients.

Many of the substances in Chinese medicine have multiple active ingredients and many others have active ingredients that are poorly understood. For some substances, no active ingredients have yet been identified. In order to preserve the diversity of constituents and the natural variation inherent in plant products, many users choose to use full-spectrum extracts because such extracts are comparable to the decoction that a patient would take if they boiled the herbs at home. We do not know which constituents or interactions between constituents are responsible for most of the effects observed with the use of Chinese herbal medicines, so it is prudent to use full-spectrum extracts as much as possible.

Full-spectrum extracts tend to leave the natural ratios of constituents intact, whereas standardized extracts focus on concentrating individual constituents or groups of constituents. It is quite likely that some of the effects that we observe are due to constituents or interactions between constituents that have not yet been adequately explored, so using extracts that focus on specific compounds at the exclusion of others introduces an unknown variable in many situations.

While most Chinese herbal medicines were traditionally used by decoction, there are a few items that were traditionally extracted with wine. For example, the medicinal Rou Cong Rong (Cistanches Herba) was historically used in alcohol extracts as well as water decoctions. It is now known that Rou Cong Rong contains active constituents that are soluble in alcohol but are not very soluble in water; consequently, full-spectrum extracts of items such as Rou Cong Rong often incorporate ethanol. Such items are generally an exception to the rule, and the term “full-spectrum extract” in Chinese medicine most commonly refers only to the concentrated extract obtained by a water decoction.

When making a full-spectrum extract, chemical testing is sometimes used to assess the potency of the product, but the goal differs from a standardized extract. For example, a company that makes a full-spectrum extract of ginseng may measure the ginsenoside content of both the raw material and the finished product. For the sake of illustration, let us assume that the company’s standard for the raw material specified that the crude ginseng roots must contain a minimum of 7% ginsenosides to be considered acceptable. This means that the company would accept any ginseng that contained 7% ginsenosides or more. If that company then made a full-spectrum 3:1 extract, they could expect that the extract would contain at least 21% ginsenosides, and they might test to confirm that this minimum level was attained. However, the final extract could contain 22-25% ginsenosides or more, depending on the potency of the starting material. By contrast, a “standardized extract” of 21% ginsenosides would be expected to contain exactly 21%, no more, no less, and the product could be made with whatever amount of whatever quality raw material it took to achieve this 21% target.

2. Standardized Extracts

Standardized extracts are produced by concentrating specific constituents so that these constituents are present at an even level from batch to batch. While a full-spectrum extract may vary from batch to batch (for example, one batch might contain 21% ginsenosides and the next might contain 24%), the standardized product would be consistently 21% every time. It might take a different amount of starting material to reach this target from batch to batch, but the final concentration of the chosen constituents would remain the same in each batch of the standardized extract. This stands in contradistinction to a full-spectrum extract that used the same amount of starting material for each batch, but obtained a different constituent yield from batch to batch because of the natural variability in the potency of the raw herbs.

A standardized extract is not very well-suited to products that have unknown active constituents, because it is not obvious which compounds the product should be standardized to in such circumstances. However, standardized extracts are ideal for substances that have well-characterized active ingredients, especially if there is high variability in the natural potency of the starting material. For example, an extract of a toxic product like datura flower would be potentially dangerous as a full-spectrum extract because one batch could contain 1% atropine while the next batch could contain 3% atropine. In the case of datura flower, the toxic but medicinal constituents atropine and scopolamine are very well-characterized scientifically. There is consensus that they are the principle active constituents, and safe use is only possible if these constituents are given at a consistent, predictable dosage. A standardized extract of datura flower would be safer to use because the dosage of atropine and scopolamine could be precisely calculated, and the natural variation in the flower itself would be evened out by standardization.

Both standardized extracts and full-spectrum extracts have an important place in herbal medicine, but standardized extracts are somewhat uncommon in clinical Chinese medicine because there are relatively few herbs that are used based solely upon the pharmacology of their individual constituents. In many situations, the pharmacology and mechanisms of herbal compounds are poorly understood and it is thought that many variables beyond the known active constituents are involved in their activity. Thus the complex nature of full-spectrum extracts is preferred, and consumers tend to seek suppliers that have good surrounding quality control to ensure potency and efficacy despite the fact that the products are not standardized around specific compounds. That said, standardized extracts are of potential value for herbs that are highly variable in potency and possess well-characterized pharmacologic effects that can be traced to the activity of particular constituents that the plant contains.