Herbal medicine remains controversial in the medical community, in spite of scant but mounting clinical evidence supporting its efficacy and safety. Some argue that alternative medicine is the antithesis of a Western methodology geared towards strict controls and isolated variables. Others argue that it is inappropriate to examine traditional medicine within a modern clinical framework, and that the kind of holistic health regimens adopted by practitioners of alternative medicine make them difficult to study. Even for supplements whose clinical results have been inconclusive, there is often a long and established history of effective use in cultures predating clinical analysis and randomized trials.
The modern medical community often focuses almost myopically on empirical data acquired by controlled clinical trials, calling this “evidence-based medicine”. Clinical trials gather data using a statistically significant number of individuals who are first screened, then separated into distinct groups to test an experimental variable against a control, or placebo, group.1 In 1991, the federal government established the National Center for Complementary and Alternative Medicine (NCCAM), a subsidiary of the Department of Health and Human Services. This government-run organization uses a clinical framework to determine the effectiveness of various alternative healing practices.2 Since its inception, NCCAM has spent more than $800 million researching the effects of homeopathy, naturopathy, traditional Chinese medicine, Ayurveda, herbal supplementation, and many more alternative schools .
The randomized trials conducted under NCCAM and other similar organizations have yielded encouraging empirical evidence for a number of individual herbs. Chamomile has shown promise for both sleep and anxiety disorders, St. John's wort for depression, lemon balm for improved memory, echinacea for a number of respiratory conditions, hawthorn for heart disease, and garlic to lower cholesterol levels.3 However, no single clinical study can be regarded as conclusive. It takes several studies (at least) to be able to draw any scientific conclusions about effectiveness of an herb as a treatment for a particular health problem. Because controlled clinical trials are expensive (typically between $20,000 and $200,000 or more per clinical trial), few herbal companies can afford to do even one good clinical trial, let alone the multiple clinical trials that would be required to support a sound scientific consensus.
Herbs,and especially complex herbal formulas, offer unique challenges compared to drugs, or even single-compound dietary supplements like Vitamin C. Where drugs are single compounds that can be tested in isolation, herbs may contain hundreds or even thousands of compounds, some of which may be unique to the particular herb, while others may be common across many related, or even all herbs. The proportions of these various compounds may vary according to the time of harvest, manner of processing, growing location, subspecies, soil and weather conditions, and even from one plant to its nearest neighbor. Standardized extracts may address the prime or “marker” compound, but do nothing to address the variances in any other compounds.
The chemical complexity of herbs, coupled with the the many other variables already in any human population, often makes it even more difficult to assess the scientific value of any given clinical trial of herbs. In addition, the fact that herbs are in the public domain, rather than patentable, means that anyone who does perform clinical trials on herbs, generally does it for the benefit of the public at large. As a result, single-ingredient government studies are the vast majority of CAM studies done, and the results of those studies are, so far, mostly inconclusive. So when all is said and done, it is really no wonder that the evidence of hundreds of years of traditional use, so far, remains the best and most conclusive evidence for the efficacy and safety of traditional herbal medicine.