A Discussion on Standardised Herbal Extracts
Posted on 21 December 2017 by Leonie Satori
When we consider some of the time tested methods such as right time of harvest, specific methods of harvest and drying techniques, herbalists have been using holistic methods of standardising herbs for generations. However, the modern approach to standardisation of herbs is even more complex, and involves laboratory based analytical observation concerning the different chemical compositions of the plant materials.
The concept behind standardisation of herbs is to achieve a consistent level of herbal activity of an herbal product from batch to batch. This also assists in delivering a specified level of phytochemical to achieve consistent and predictable results and eliminate the possibility of incorrect dosage.
Although there seems to be some discrepancies about what is actually considered as being a ‘standardised extract’, the following definition is one that has appropriately evolved with the actual processing techniques involved in the standardisation of herbs. According to Kerry Bone, a standardised extract is one that is manufactured to contain a predetermined and consistent amount of one or more phytochemical constituents which have been derived from the original starting material.
What did we do before modern standardisation?
A traditional pharmacopeial extract of an herb is termed as a galenical extract. This is usually a tincture or extract (ethanol and water) which is often referred to as a ‘whole’ extract as it was thought that this method extracted a comprehensive spectrum of phytochemical constituents from the plant. ‘Whole’ is not entirely the correct terminology for this type of extract, as the level of extraction depends on the percentage of alcohol and therefore there will always be some of the chemical constituents left behind. However, this terminology is used by herbalists with the understanding that it is the herb itself that is the active constituent, and the percentages of alcoholic extraction are determined by knowledge of the phytochemical constituents required for therapeutic action. Interestingly, some standardised extracts are simply galenical extracts that have been dried, fixed to a certain consistent level of a chosen marker.
“People ascribe the greatest healing power to drugs that come from farthest away, drugs that cost the most. In my long experience I have come to believe that people go to the ends of the earth to look for something they could find right on the doorstep. If only we could learn to trust Nature …” Maurice Messegue
What are the different types of standardised extracts?
There are several theories about the differing types of standardised extracts, but broadly speaking, they can be classified into four different types of standardised extracts (according to Mills & Bone) as follows:
- Extracts which have been produced under defined conditions of processing and manufacturing. The standardisation is to ensure consistency form batch to batch, allowing extensive clinical testing of these extracts. With these extracts, the clinical efficacy and safety is well established, examples of such herbs include Ginkgo biloba and Hypericum perforatum.
- Extracts which may not yet have proven efficacy in clinical trials. Standardisation here gives indication of the potency of the whole extract, but only where there is evidence showing a relationship between compounds chosen for standardisation and pharmacological activity. Examples of such extracts include Coleus forkohlii and Matricaria chamomilla.
- Extracts from herbs that have not been extensively studied and therefore the marker compounds for standardisation have no relevant pharmacological activity. Standardisation in these cases provides identification and batch to batch consistency; examples of such extracts include Echinacea angustofolia and marker compound echinacoside.
- Herbal extracts that are adulterated with isolated chemicals and sold as ‘standardised extracts’, such as extracts of kola nut or guarana with added caffeine. In this type of extract the components are isolated and purified according to market requirements and technically should not be considered as a standardised extraction.
What is phytoequivalence?
Phytoequivalence is where two herbal extracts contain the same balance of all measurable compounds, following the same phytochemical spectrum. As mentioned earlier, sometimes it is considered that the herb itself that is the active substance, therefore phytoequivalence of extracts, based on studies of the pharmacological or clinical evidence most effectively produces quality standardised extracts. In addition to these guidelines, some consider complete phytoequivalence to include the same levels of marker compounds (or their derivatives) to be achieved in the bloodstreams of humans after oral doses of the two products should also be similar.
What are the advantages of standardising herbal extracts?
Standardised extracts provides greater consistency in the safety of the preparation by delivering an herbal preparation with a more consistent phytochemical profile. Better quality control means that practitioners are provided with a more accurate dose determination and consistent clinical outcomes.
Standardised extracts are reputed to be more effective and of higher quality than traditional galenical extracts and some may say that galenical extracts have no value in modern phytotherapy. It is thought also that since many standardised extracts are tested in clinical trials, they have an important place in the practice of modern medicine.
Due to the potency of the preparation, the dosage of certain standardised extracts, especially when it comes to considering solid preparations, is much lower, therefore contributing to greater client compliance. Another theorisation is that standardisation actually increases consumer confidence in herbal preparations and enables greater acceptance by the medical profession.
What are the disadvantages of standardised herbal extracts?
The philosophy of standardisation mirrors that of synthetic drug preparation. With emphasis on a single active agent (sometimes termed a phytopharmaceutical drug), the whole phytochemical profile of the herbs can be ignored, resulting in an evitable loss of ‘synergy’ within herbal preparations. Herbs are a proverbial chemical ‘soup’ from which the body absorbs and transports selectively, that is, what is in an herbal extract is different to what cells in the body experience. When standardising an extract according to active constituents, there may only be a partial representation of the herb’s normally occurring constituents, therefore the broad range of traditionally known properties is limited to a single use herb.
In addition to this similarity with synthetic drugs, the usage of standardised extracts can be similar to allopathic prescribing, where single drug treatment is used for symptomatic illness. Certainly with high levels of consumer awareness about thoroughly researched herbs, consumers are more likely to favour certain herbs that they have heard about in the media, rather than using herbs that are not as popular, but perhaps more suited to their illness.
If compounds other than the chosen marker compounds are important for activity, and these are not also fixed at consistent levels by manufacturing processes, then the extract will not achieve ‘consistent activity’. Also, where there is some debate about quality markers (eg. Echinacea) or those based on traditional usage (eg. Eyebright), extracts on the market are variable and often of poor quality. This can also be unreliable if the analytical method is not specific towards the desired marker compounds. Certainly it would seem that if there were some standardisation of standardisation techniques, herbalists and consumers would understand exactly what they are consuming. Evidently, methods of standardisation can produce significant differences in the finished product, but some are manufacturing extracts with toxic solvents that may go against the ethics and sensibilities of those that are consuming them.
With the demand for high quantities of raw herbs and the mass production of herbs for the manufacture of standardised herbs, the quality of the raw herb is sacrificed for quantity, as the intricate levels of processing ensure a standard quality of final product. This can be perceived as man’s way of controlling nature rather than working with her. Another contentious issue is dollar value, obviously with highly involved preparation of standardised extracts, as well as clinical trials and testing, the cost of the extract to the consumer is highly inflated – this in itself can be an issue, but also the consumer may not hold the therapeutic value of an herb that is not standardised or researched in such high regard because the economic value of that herb is much lesser due to the apparent lack of processing involved in it’s preparation.
Another issue that is of concern with standardisation of herbal extracts is the influence of pharmaceutical companies and patenting of herbal extracts. Since a herb, unlike chemicals cannot be patented, but, where a significant amount of research is involved with testing and standardisation of an herbal extract, pharmaceutical companies are then able to develop an exclusive patent for their process of extraction and standardisation, therefore holding a monopoly of the market.
Standardised herbal extracts and modern herbal medicine
The modern day herbalist collects her herbal preparation from her well stocked shelf of herbal extracts, often never knowing which country that herb was grown in, exactly how the extract was made or even what the original herb looked like. Some countries’ professionals accept historical, empirical evidence as the only necessary criterion for herbal medicines efficacy – others will ban all herbal remedies as dangerous or of questionable value or some may simply want to conduct clinical trials of herbal medicines according to western pharmaceutical clinical standards.
The majority of herbal preparations used in practice are galenicals – extracts based on whole herbs prepared in a manner which best extracts the balance of constituents. However, the use of well-chosen chemical components as markers of quality is not necessarily inconsistent with this approach. Preserving the phytochemical integrity of the whole plant delivers the most active treatment, especially with reference to herbs such as Hypericum perforatum, where it is purported that hypericin and pseudohypericin have confirmed antidepressant activity, but require adequate levels of OPCs to enhance bioavailability ( in addition to several flavonoids and hyperforin).
Underneath all of this research and methodology, it would seem that standardised extracts are not in fact a guarantee of quality. A poor quality or less effective standardised extract (than a well made traditional galenical extract) can be produced due to inappropriate choice of marker compounds or poor design or implementation of analytical methods, fortifying with chemically purified active ingredients or general failure to demonstrate phytoequivalence.
About the Author
Leonie is a Naturopath & Medical Herbalist with a passion for good food, healthy living and of course, herbal medicine. When she is not consulting in her wellness clinic in Lismore or blogging about nutrition, Ayurvedic Medicine or natural health, she is studying yoga, growing her own herbs and vegetables or quietly walking in the natural bush land in Northern Rivers NSW.
Contact our health centre in Lismore to book an appointment with Leonie in our naturopathic clinic.