The chemical composition of plants is fascinating and complex, including alkaloids, glycosides, vitamins, minerals, bitters, tannins, mucilagens, and saponins.
The complexity sometimes makes it difficult for the noneducated to differentiate therapeutic from toxic plants. Some herbs are typically used as tonics, commonly given for extended times to enhance cognitive, metabolic, or immune function (eg, ginkgo, garlic, spirulina). On the other hand, herbs like St John’s wort, kava kava, and echinacea are mainly prescribed as treatment for more specific illnesses.
Therapeutic indices will vary and may be unpredictable, particularly in children. Children’s dosages cited by many herbal guides are age-dictated, expressed as fractions of an adult dose, and strictly anecdotal.
An article by an herbalist recommending usage of St John’s wort, kava kava tea, catnip, and kola nut singly or in combination for management of attention deficit (hyperactivity) disorder in children suggests the consumer “follow the manufacturer’s recommended dosage guidelines.”
Clinical studies are sometimes cited but a more critical look often reveals notable shortcomings with design and conclusions. Improving technical skill and design are slowly evolving for better research, particularly in Europe? H Yet little, if any, safety evidence, as with many pharmaceuticals, pertains to pregnancy or pediatrics. A voluntary recall of ginseng products in New York, Connecticut, Ohio, and Massachusetts came after New York State teachers reported that students were drinking ginseng extract that contained up to 24% alcohol.
Quite a few herbs can increase risk of miscarriage. Feverfew, often used in treatment and prevention of migraine headaches, may initiate uterine contractions and has been used to help expel afterbirth. Experience herbalists know that herbs may interact with each other, pharmaceuticals, and foods with ramifications for efficacy and toxicity.
Herbal products, for example, are increasingly used for management of insomnia, anxiety, and depression, even in adolescents. Many herbal references omit warnings for potential interactions of such herbs with certain antidepressant medications, particularly monoamine oxidase inhibitors and even certain foods. Recently, popular diet teas containing herbal laxatives have been associated with misuse, resulting in cramping, diarrhea, dehydration, and even some deaths in patients with eating disorders.
Scientific clinical evidence for efficacy is so lacking for most popular herbal products but public demand is so great that in Germany the Commission E-Monographs were generated. These allow use of specific herbs for specific medical purpose if “reasonable” anecdotal evidence for efficacy exists and no specific safety risk has been demonstrated. In the United States, the Dietary Supplement and Health Education Act of 1994 allowed, to the dismay of many, manufacturers of supplements to state biochemical evidence of efficacy but not to make clinical claims.
Optimistically, one might suggest that the purpose of the Act was ultimately to assure safety through research. Undoubtedly, it was hoped that with public demand the ensuing manufacturing and marketing competition would entice the well-organized research companies (previously not interested in nonpatentable supplements) to develop more quality assurance products. Although labeled, standardized herbal products are available at health food stores, compensating for natural variability in bulk herbs, quality assurance has been a concern.
The American Botanical Council studied more than 400 commercially available ginseng products, a project spanning several years and funded by private sector money. The biochemical essence of ginseng in its various forms is well-documented. Results not yet published indicate that many products did not meet claimed standards for content (personal communication, American Botanical Council). The Council hopes to be able to set future standards for quality.