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American Herbal Products Association’s Botanical Safety Handbook

American Herbal Products Association’s Botanical Safety Handbook, 2nd edition,edited by Zoë Gardner and Michael McGuffin. Boca Raton, FL: CRC Press, Taylor & Francis Group; 2013. Hardcover, 1042 pages. ISBN: 978-1-4665-1694-6. $119.95.

Having often referred to the first edition of this book since its publication in 1997, I have long anticipated examining an upgraded second edition. I was pleased to find that the revised content included input from a highly qualified expert advisory council consisting of Roy Upton, Soaring Bear, PhD, David Winston, RH (AHG), Daniel Gagnon, Aviva Jill Romm, MD, Tieraona Low Dog, MD, Mary Hardy, MD, and Lyle Craker, PhD. The vastly expanded content provides safety information on more than 550 species of herbs and includes new herbs, many from the Ayurvedic tradition. (A few Western herbs deserving of inclusion have been overlooked, such as rhodiola [Rhodiola rosea, Crassulaceae] and olive [Olea europaea, Oleaceae].) This advanced edition relies extensively on primary literature sources and includes research on potential interactions with drugs and selected dietary supplements. Consequently, based on weight alone, it seems to have outgrown its designation as a “handbook.”

This edition is again centered on classifying herbs by assigning each to a Safety Class; some first edition assignments have been changed after further research and reassessments. Class 1 includes herbs that can be safely consumed when appropriately used. Class 2 herbs are for those with certain restrictions, such as for external use, not to be used in pregnancy or when nursing, or other specific restrictions. A standard dose is provided for those herbs which carry a warning on excessive dosage. Class 3 herbs are only to be used under the supervision of a qualified expert, so a standard dose has not been specified for these most potent herbs such as Sichuan aconite (Aconitum carmichaelii, Ranunculaceae) or belladonna (Atropa belladonna, Solanaceae), though one is given for stillingia (Stillingia sylvatica, Euphorbiaceae). The literature-referenced content has been greatly enlarged to supply a quick summary and an expanded review of the literature in support of these classifications, which are intended to provide evidence-based and easy-to-interpret information to healthcare practitioners, herbal supplement manufacturers, and retailers.

Each herb is also designated an Interaction Class in this edition. For Class A herbs, no clinically relevant interaction should be expected due to a lack of pertinent evidence. Class B includes those for which clinically relevant interactions are plausible, based on human or animal studies, multiple case reports, and/or in vitro studies demonstrating biologically plausible mechanisms. Class C herbs have known clinically relevant interactions as evidenced by human pharmacological studies and/or case reports with probable causality.

One book cannot cover everything in detail. Certain considerations have been intentionally excluded from the assessment of herb safety, including excessive consumption and those toxicity concerns based solely on isolated constituents or from intravenous or intraperitoneal injections. The safety assessments do not include either Chinese or Ayurvedic traditional contraindications unless they can be interpreted in a biomedical context. Individual sensitivities such as gastrointestinal, idiosyncratic, and allergic reactions (outside of the Asteraceae family), and contact dermatitis generally are not included.

Other items not covered include certain types of herbs and products including little-used plants of known toxicity (a number of these herbs in the first edition have been eliminated), homeopathic preparations, essential oils (except peppermint [Mentha x piperita, Lamiaceae] and European pennyroyal [M. pulegium]), products with chemical (even inherent phytochemical) additives, or those that have been compromised by contamination or adulteration. Isolated components whose presence impacts the safety of an herb are typically identified in a Notice. Nonetheless, in certain cases, such as artemisinin in sweet wormwood (Artemisia annua, Asteraceae), or hydroquinone derived from the arbutin in uva-ursi (Arctostaphylos uva-ursi, Ericaceae), pharmacological and toxicological studies on an isolate have been incorporated to help describe the potential effect of the herb. It is also beyond the scope of this text to consistently distinguish between the relative safeties of different preparations from the same plant.

The Appendices form a valuable feature in this edition, as they did in the first. Aristolochic acid and the herbs containing it have been eliminated as banned substances from Appendix 1, Herbal Constituent Profiles, and from the main text, respectively. However, several other original entries were removed without explanation from the second edition, including cardiac glycosides, lectins, and oxalates. As a result, some valuable information is missing, such as a useful overview of cardiac glycosides found in the Class 3 herbs Apocynum spp. (Apocynaceae), lily-of-the-valley (Convallaria majalis, Liliaceae), and Digitalis spp. (Scrophulariaceae). None of these three herb entries provide as much appropriate detail, and all seem inadequate in regard to potential interactions which for Class B Convallaria and Class C Digitalis are described simply as “the same as those for digoxin and other digitalis glycosides.” In Appendix 2, Herbal Action Profiles — though Diuretics has been added — GI Irritants and Monoamine Oxidase Interaction categories have been removed. The Nervous System Stimulants category is now included in Appendix 1 as Caffeine, following the elimination of banned Ephedra species from the text.

The new Appendix 3, Herbal Interaction Profiles, provides a simple but instructive two-page summary on pharmacokinetic interactions with drugs co-authored by a leading researcher and authority on the subject, Bill Gurley, PhD. While this excellent overview sets the stage, the main actors are missing. Aside from sections on mucilages and piperine, the absence of summary lists categorizing the mechanisms of herbs from the text with a Class B and Class C designation is perplexing. This would have been a useful and valuable addition to this appendix. Similarly, the exceptional discussion by Dr. Romm, in the new Appendix 4, Botanicals in Pregnancy and Lactation, could have been enhanced somewhat for several properties covered (teratogens and mutagens, phytoestrogens, nervous system stimulants or depressants) with simple summary listings identifying those herbs that have these properties and identified in the text as contraindicated in pregnancy (as was done with Abortifacients and Emmenagogues/Uterine Stimulants in Appendix 2). Appendix 5 (formerly Appendix 3) provides lists of all herbs in Safety Classes 2a, 2b, 2c, and 3 and Interaction Classes B and C.

As an expert consensus on currently available data, these herb evaluations constitute a very valuable resource for anyone with an interest in understanding the safe use of therapeutic botanicals. Though other experts may take issue with certain assessments or particular conclusions, the referenced information supplied provides a sound framework to support the evaluations and rationales. There remains a need for updating scientific content as data expands, e.g., as from a 2010 study that found a 21.6% increased frequency for both threatened miscarriages and preterm labors in pregnant women when chamomile (Matricaria recutita, syn. M. chamomilla, Asteraceae) was used regularly.1 While the content for Class 3 herbs and some appendices could be fleshed-out, overall this book fills an essential niche by intelligently addressing specific practical issues in the broad context of botanical safety concerns. I certainly will be referring to it regularly.

—Francis Brinker, ND Author and editorTucson, AZ


1. Cuzzolin L, Francini-Pesenti F, Verlato G, et al. Use of herbal products among 392 Italian pregnant women: focus on pregnancy outcome. Pharmacoepidemiol Drug Safety. 2010;19:1151-1158.