Natural standard herb and supplement reference: evidence based clinical reviews

This is a very well referenced source providing detailed evidence-based systematic reviews for almost 100 herbs and supplements. It is particularly valuable for those clinicians who are using or who wish to use herbal medicine in their everyday practice and for doctors and patients who wish to know more about the efficacy and tolerability of herbal medicines. The volume confirms that although a few complementary treatments have been assessed in well-designed clinical trials, high quality information relating to effectiveness, dosage, mechanism of action and safety is limited or controversial for most therapies tested. As a result for almost all the products listed it is not possible to guarantee strength, purity or safety of products even though some have been shown to have clinical benefit. More than 100 health professionals have contributed to the volume, mostly physicians and pharmacists but also nurses, microbiologists, educationalists, herbalists and other alternative practitioners and over 40 contributors make up the Editorial Board. The text is arranged alphabetically starting with Acidophilus and finishing with Yohimbe Bark. The layout is highly structured and easy to use as a reference source. The main headings are synonyms for the substance, clinical ‘bottom line’, grades of scientific evidence, summary table, dose and standardization of formulation, adverse effects, interactions and use in pregnancy. The grades of scientific evidence range from A to F with levels below B representing no evidence or evidence against the clinical effectiveness of the product. Grade A implies that there are more than 2 studies of reasonable design supporting the use of the substance and Grade B that there are one or two clinical trials. Overall Grade A evidence is rarely very good and the studies do not compare with the outcome trials undertaken within conventional medicine in terms of design, statistical power and analysis. Based on A and B grades there are a few surprises. I am sure that those physicians managing dementia and heart disease would be surprised that Ginkgo biloba and Ginseng are useful for enhancing memory and that Hawthorne gets an A Grade for the treatment of congestive heart failure. The latter benefit appears to be for Grades 1 and 2 New York Heart Association Classification, which is notoriously difficult to define accurately. Hepatologists might also like to know that Milk Thistle improves liver function tests in patients with chronic liver disease and urologists might be interested that Pygeum Africanum and Saw Palmetto might improve symptoms and reduce the size of the gland in patients with benign prostatic hypertrophy. Otherwise most of the findings are as expected. Ephedra remains a very toxic substance with no clinical benefit and adverse effects and addiction potential similar to amphetamines and cocaine. Several dietary agents appear to lower the serum cholesterol – barley, soya, almonds, yeasts, garlic and fish oils and some evidence exists for feverfew in migraine prophylaxis and for St. John's Wort in depression. A number of agents are confirmed as having some analgesic or anti-inflammatory activity – Boswellia Serrata, Devil's Claw, Glucosamine, hypoglycaemic effects – Bitter Melon, Gymnema Sylvestre, and others appear useful for sleep disturbance – Valerian Officinalis, Melatonin. Cranberry juice and echinacea may be useful for urinary and upper respiratory infections. The two final appendices, A and B, relate to drug interactions and conditions tables. In Appendix A a list of possible pharmacodynamic and pharmacokinetic interactions are listed. Unfortunately, reporting is generally low or goes undetected and the interactions are mostly based on additive effects of similar acting drugs, expert opinion and anecdote rather than clinical studies. The best evidence available relates to St. John's Wort, its interactions with antidepressant drugs and its effect as an enzyme inducer/inhibitor. Appendix B deals with the different medical conditions for which herbs and supplements have been used. These are also arranged alphabetically and identify treatments for which Grades A-D evidence is available. This section is likely to be consulted even more than the main alphabetical section as a rapid treatment reference. In conclusion, this volume represents a most reliable source of up-to-date and balanced information on herbal medicine and the use of supplements. It provides an extremely useful systematic and easy to read resource for all drug prescribers with evidence-based reviews to identify the small amount of wheat from the large quantity of chaff in this area of alternative medicine.