By David Bunting rAHG, Herbal Affairs Director, Herb Pharm
Standardization is probably one of the most controversial and misunderstood concepts in herbal medicine. What most people think of when they hear the word “standardization” is chemical standardization or more precisely, phytochemical standardization. Here, an extract contains a quantified amount of a phytochemical found in the plant and that quantified amount is included on the label. For example, a stated amount of St. John’s wort extract standardized to contain 0.3% hypericin. So, why the controversy?
In a traditional context, phytochemically standardized extracts are thought to be only concentrated fractions of a plant and thus not relevant to whole plant medicine. Directly related to this, they are considered to be more drug-like in effect due to the focus on only certain phytochemicals while excluding others. Frequently there is also the belief that ‘industrial’ solvents are used to make standardized extracts. While some or all of these conditions may be true for certain standardized extracts, they are certainly not true of all. So, the controversy often reflects a lack of understanding of the diverse ways in which standardized extracts can be made.
Assayed extracts are whole plant extracts such as a tincture that have one or more phytochemicals tested and quantified, or assayed. If the results are used in labeling the extract, it is standardized. Producers of this type of extract often use in-house or pharmacopeial phytochemical specifications for acceptance of their starting material. Starting with a set minimum of the phytochemical in the herb will typically ensure, especially with a standardized extraction procedure in place, that the finished extract will contain a minimum amount of the chosen phytochemical from batch to batch.
A closely related form of standardized extract is where a whole plant extract is concentrated without any further adjustment to the phytochemical content in the finished extract. These are often in the form of a concentrated liquid or paste, but can be a dried or powdered extract. Saw palmetto is a good example. While there are several extraction methods and various solvents that can be used, it is easy to achieve a high level of fatty acids in the concentrated liquid. This is due to the simple fact that saw palmetto fruits yield high and fairly consistent amounts of fats. Here, phytochemically restrictive extraction methods or industrial solvents like hexane can be used, but do not need to be.
To produce standardized powdered extract, or PE, concentrated pastes or liquids are taken to dryness. This not only yields a dried extract that can be encapsulated, but it also reduces the extraction solvent residues to trace amounts. In many cases, powdered extracts are also subsequently adjusted to meet the finished requirement. Whether standardized to strength only, or to phytochemicals, a stronger than required extract is diluted with more material to achieve the labeled strength. If a carrier was used, the added diluent will often be the same material. As with solvents, there are a wide variety of materials to choose from, some innocuous and others questionable. But the native fraction of the finished extract may still represent whole plant.
In some cases, the desired phytochemicals are specifically targeted through process, solvent or both. These are the controversial standardized extracts that many people typically think of in a negative light. And certainly, many in this class of standardized extracts deserve the negative image. Especially in the realm of solvents, one needs to distinguish between extracts based on solvents. Historically, ginkgo and milk thistle were produced with a number of unsavory industrial solvents. But as extraction techniques improve similar phytochemical results can be achieved with water and ethanol.
The philosophical challenge remains with these particular extracts. They may represent more whole plant characteristics than some of their commercial counterparts, but they still can be thought of to have a more drug-like activity due to their high level of target phytochemicals. In this example, the flavone glycosides and terpene lactones in ginkgo and the silymarin in milk thistle are disproportionately high. For some that is unacceptable. For others, using these extracts especially where overt pathologies exist can be an acceptable compromise between whole herb and full on drug therapy.
There are more rarely used methods to produce standardized extracts such as spiking. Here the desired phytochemical is added in an isolated state to a whole plant extract to boost or fortify the amount of the phytochemical in the extract. In these cases, this added ingredient must be labeled or else the product is misbranded. And while these misbranded products can be found in the marketplace, reputable manufacturers do not produce them. Keep in mind that these also need to be cost effective additives, so the choices are rather limited compared to the scope of available extracts.
This article conveys some of the complexities that make it impossible to consider standardization as a single process or as a single product type. And more importantly it shows the vast differences in the many types of standardized extracts available, the inputs that define them and their respective qualities. While it is often easier to broadly generalize about complex subjects so they fit neatly in our worldview, it may be time for us to reconsider standardized extracts on an individual, case-by-case basis.


*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.