Composition of Herbal Products that are Available to Consumers

Composition of Herbal Products that are Available to Consumers. There are several advantages to using such highly processed raw materials. These include the ability to produce dosage forms that are more uniform in their composition, and the ability to preferentially concentrate the desirable constituents of a plant while leaving behind undesirable constituents.

Because products are frequently referred to generically by the name of the plant in marketing and consumer-use surveys, it is difficult to differentiate between exposure to the crude plant material or to unique, highly processed proprietary extracts that differ significantly from both the plant source and from other proprietary products. In countries where there is pre-market review and product licensing, products must often conform to published compositional standards, such as those in the United States.

Pharmacopoeia or the European Pharmacopoeia

Pharmacopoeia or the European Pharmacopoeia; and similarly named products marketed in this regulatory environment are likely to be relatively similar to each other in composition, but may be very dissimilar from products that do not meet such standards.

In addition to the broad variability in composition of herbal products that are available to consumers, problems in interpreting published scientific studies of herbal products have been reported. Wolsko et al. (2005) performed a systematic review of the “Materials and Methods” sections of 81 published studies on herbal products. They noted that only 12 (15%) of the studies reported any kind of quantitative chemical analysis of the study material, and that only 8 (10%) of those reporting analysis reported results of the analysis.

In addition, only 40 of the studies (49%) provided the Latin binomial name of the study material, only 8 (10%) identified the part of the plant used, and only 23 (28%) described the extraction/processing method used to create the product. A larger review by Gagnier et al. (2011) reported similar findings. To prevent such problems in future studies, Swanson (2002) and Gagnier et al. (2006) have published guidelines for the reporting of studies on natural products.

While some organizations that conduct safety studies adhere

While some organizations that conduct safety studies adhere to or surpass the above guidelines when selecting test articles or designing studies, it would be useful if these guidelines became standard practice, as the reproducibility and reliability of safety studies would be greatly enhanced. Unfortunately, while such recommendations are useful, selecting the article to be tested from among dozens or hundreds of products with similar or identical names but widely divergent compositions remains a major obstacle.

As with most herbal products, there may be some controversy surrounding generalizability of conclusions for a commercial entity, because commercial products are very diverse in terms of processing, composition, and intended use. Attempts to identify the predominant form of an herbal product in the market place are pure conjecture in the absence of data. This is a recurring theme for all discussions on herbal products.

The ability of the Working Group to gauge the extent of global exposure to herbal products was very limited, since the quality and quantity of data available were inconsistent across countries. Having better information on patterns of use and on product composition would provide a means to prioritize the herbal products considered in this volume for such activities as policy formulation or further research needs.

Pharmaceuticals was more abundant and accessible

While the available information on exposure to pharmaceuticals was more abundant and accessible than that on herbal products, limitations remain. For the most part, information on prescribing patterns outside the USA was not available to the Working Group. In addition, published studies indicated that patterns of adherence and persistence are suboptimal for medications used to manage or treat chronic conditions.

And while prescribing patterns are available for some drugs, such data do not exist for over-the-counter drugs; consequently, exposure estimates must be made using means similar to those used to estimate exposure to herbal products (e.g. Aloe vera, for which over-the-counter use is difficult to quantify), namely sales data and consumer use surveys. Although not widely available or widely accessible, such data for over-the-counter drugs is more informative than for herbal products sold as foods or dietary supplements because drug products with similar names are required to be similar in composition.

Exposure to herbal products or pharmaceutical drugs

As indicated above, exposure can generally be much more accurately measured for pharmaceuticals than for other agents, and therapeutic doses used in humans are often closer to those tested in experimental animals. Nonetheless, characterizing the true nature of exposure to drugs in relation to carcinogenicity is complicated by the variability in adherence to drugs and their varying patterns of use – intermittent versus continuous.

Exposure to herbal products or pharmaceutical drugs may occur as a consequence of occupational exposure of people involved in production or manufacture of these agents. Exposure may also occur as a result of water pollution by these agents. Generally, levels of occupational or environmental exposure are much lower than levels of exposure experienced by people using the respective herbal products or drugs. Almost no information was available to the Working Group concerning occupational or environmental circumstances of exposure to the agents evaluated in this volume.