Mislabeled Herbal Supplements: True or False?
Mislabeled Herbal Supplements: True or False?
You might have heard about the recent attack on herbal supplements by the New York Attorney General. There were rebuttals by the industry, pointing out reasons why the Attorney General’s action might be misguided, but so far, this information has been ignored by the authorities and by the press–who gleefully jumped on the initial story.
The controversy has yet to be resolved. The Attorney General has refused to respond to the challenges and questions by industry experts and, instead, has issued new demands.
What is the average consumer to make of all this? Do you have to become an expert in DNA barcoding and high pressure liquid chromatography to intelligently analyze the conflicting information being offered by various experts? I don’t think that should be necessary. For those that do want to get technical, I am providing a link to a good resource, “The Capabilities and Limitations of DNA Barcoding of Botanical Dietary Supplements” by Reynaud, Mishler, Neal-Kababick, and Brown.
For the rest of you, I am going to offer, instead, an easy to understand overview of the difficulties involved in proper and meaningful analysis, or testing, of herbal supplements. When you understand what is involved, and understand the difference between testing raw herbs, or herbal raw materials versus processed herbal supplements and mixtures of herbs, I think you will understand why analytical testing of finished products is not such a simple thing, and why the accusations of the Attorney General have proven so controversial.
The first question, perhaps, is what exactly are you testing for? You want to confirm the actual identity of the herb. Is is really echinacea, for example, or is it some other similar plant, cheaper perhaps. If echinacea, is it purpurea or angustifolia? Is is pure (100%) echinacea, or is it mixed with other herbs or plants (adulterated)? Is it clean, i.e. dose it contain twigs, insect fragments, dirt, and/or microbial contamination?
These are all “quality” problems–as opposed to quantity questions. We will get to quantitative analysis in a moment. These quality issues can be simple to resolve, or complicated, depending on several factors.
It is much easier to identify a whole herb, for example, than it is a ground up powdered herb. Companies have the option of buying raw herbs (bundles of leaves, flowers, roots, etc–fresh or dried–or processed herbs, i.e. herbs supplied by companies that dry and grind them to powder form. Many companies, including many of those targeted by the Attorney General, do not have the expertise or the equipment necessary to perform the quality testing and processing of raw herbs, so they rely on other vendors to do that for them. The problem is that once the raw herb is dried and ground to a powder, it is much more difficult to identify it.
Just think about it. Even you could probably identify ginseng root, or ginkgo leaf. You can see it. You can taste it, smell it, etc. You can examine it visually to determine whether there is foreign matter present, bugs, dirt, etc. Once it has been ground to a powder, you have to rely on other more complicated techniques–microscopic examination, chromatography, etc.
So the first challenge is a function of the form in which the raw material is obtained. Another challenge is the need for a reference sample. Not all herbs are as easy to identify as ginkgo leaf or ginseng. For whole herbs, you can refer to reference books, with pictures and descriptions. But for powdered herbs, you often need a reference sample for comparison purposes. One of the best techniques for qualitative evaluation of powdered herbs is thin layer chromatography (or other forms of chromatography when necessary.) But you need a reference sample. This applies to most of the more sophisticated techniques, by the way, including, according to the experts, DNA barcoding.
Another challenge to the qualitative evaluation of powdered herbs is the need to demonstrate the absence of adulterants. Unscrupulous suppliers, for example, might try to cut, or dilute, an expensive or hard to obtain herb with another less expensive herb. They will naturally choose an herb that is similar in appearance to the real herb.
So far, we have been talking about some of the challenges associated with quality evaluation of herbal raw materials. What about the end product? This leads to even greater complication.
At the risk of oversimplification, we can look at three possible routes for herbal raw materials into finished products:
- Single Herb Concentrates
- Single Herb Extracts
- Mixtures of Herbal Concentrates and/or Extracts.
I define a single herb concentrate as a final product produced by drying (dehydrating) a single herb, converting it to a powder, and packaging it in capsule or tablet form. Theoretically, this is the easiest type of product to analyze, as all you have done is remove the water (moisture) from the raw herb, powder it and package it. From a qualitative standpoint, identification and purity testing should be fairly straightforward and uncomplicated.
Single herb extracts are a different story. To produce an extract, you are selectively removing and isolating only certain of the herb’s components. You remove more than just water. Instead, you “extract” specific components by dissolving them in a solvent, and then collecting and concentrating those dissolved components, leaving everything else behind. The purpose being, of course, to produce a more potent, pharmacologically active product (assuming you know which is the active ingredient). In general, you could say you are producing an extract when you brew tea or coffee.
For purposes of our discussion, however, when you want to evaluate the quality of an extract, you are presented with an entirely new set of problems. The extract no longer resembles the original raw herb. Morphologic examination no longer applies. Chemistry now becomes mandatory. Simple tests are no longer adequate. A specific analytical chemistry procedure, most likely involving a separation step, is necessary.
Demonstrating the identity of the starting material (raw herb) may or may not be possible, depending on the nature of the extraction process. At best, you may be able to identify (and measure) certain target substances. The focus is no longer on Ginkgo, but on ginkgo flavonglycosides and terpene lactones, and on the ratio of extract to starting material.
To further complicate matters, one company’s extract can be different from another’s. Why is this? It’s easy–depending on the composition of the extraction liquid (the solvent), the temperature, the time involved, etc, the extracted components can differ. Extracting an herb with hot water, for example, as if you were making a tea can yield very different results than if you were extracting with alcohol.
It should be noted, by the way, that “DNA” is not necessarily one of the “active ingredients” that would be obtained through such an extraction process. We watch crime drama shows on tv and our impression is that DNA testing is now the universal, final word in identification–but this is misleading. DNA is not always present. It’s not always intact. It’s not always present in samples.
Identification, and even quantitative measurement, of these extracted components of herbs almost always starts with some time of separation process, usually chromatography.
If this is not already complicated enough, let’s now consider the final scenario–a mixture containing extracts of more than one herb. Imagine the complexities involved, now, in separating and identifying the active chemical constituents extracted from more than one herb. It’s not easy.
As efficient as chromatography is in achieving this, it is meaningless if reliable reference materials, or standards, are not available.
The challenges outlined above are directed at qualitative testing–identification and purity testing. Measurement of the quantity of herb or herbal active ingredients is another problem altogether, but shares one common characteristic–separation of the the components is still necessary in order to obtain a quantitative measurement. The more complex the mixture, the more complex the problem of quantitatively measuring the active or “target” ingredients.
This simplified overview is intended to provide a quick introduction as to why the analysis of herbal supplements is a process that requires the availability of validated and standardized testing methodologies and protocols. Such protocols exist. One such tool is the United States Pharmacopeia. One governmental agency charged with applying these protocols is the Food and Drug Administration.
Neither the USP or the FDA employs or supports the use of DNA barcoding for this purpose.
In conclusion, two questions remain. The most important question is this–are the products targeted by the NY Attorney General in fact misbranded and/or adulterated? If in fact they are, it gives a black eye to the supplement industry in general, and provides a serious basis for mistrust and concern among consumers. If there is product on the shelves that are misbranded in this way, we should all be grateful that the problem has been exposed. The second question, unfortunately, is, based on the methods used by the Attorney General, and his refusal to provide the details of his testing, do we know if these claims are valid or not?
Serious questions about his method of testing remain unanswered, and it is hard to understand why the testing details are not being made available. While refusal to release details of his testing methodolgy does not in itself mean his conclusions are without merit, doing so invites doubt. This is an important problem, and it needs to be resolved.