6 Herbal medicines and dietary supplements – an overview

Part 6

Herbal medicines and dietary supplements – an overview

Frederick W. Fraunfelder MD

Dietary supplements are prevalent worldwide and play a significant role in the treatment of human disease. In the United States, allopathic physicians are at the early stage of learning how to treat patients with natural remedies and other forms of alternative medicine. Elsewhere, however, alternative remedies have been embraced more fully. In Germany, for example, the German Federal Health Agency created a Commission E, which has allowed for a more sophisticated approach to assessing the efficacy and safety of dietary supplements and herbal medicines; and health insurance in Germany frequently covers costs for doctor-prescribed herbal remedies. Approximately 50% of the population of the United States takes herbal products compared to 70% of the population of Germany. From published studies, only half of patients report supplement use to their physician as many consider naturally occurring products to be safe (Eisenberg 1998).

Dietary supplements represent a US$60 billion industry worldwide. While strong arguments can be made by the natural product industry that the majority of dietary supplements are safe, especially when taken in proper doses, severe toxic reactions can and do occur. Physicians and patients need to be aware of these side effects, especially as many herbal products interact with prescription medications (Coxeter et al 2004).

Frequently, ophthalmologists are the first to identify dietary supplement adverse reactions as loss of vision, and eye side effects can be the first symptoms noted by patients (Fraunfelder 2004, 2005a). Systemic adverse events may not be recognized until much later, i.e. urinary tract cancer from Aristolochia fangi (Nortier 2000) or death from chronic liver damage from comfrey (Symphytum officinale) (Anderson et al 1989).

Regulatory Issues and Classification

Regulation and classification of dietary supplements is a confusing subject, and standards vary from country to country. In the United States, it is estimated that dietary supplements represent a $20 billion industry. The US Dietary Supplement Health Education Act of 1994 (DSHEA) allows herbal product companies to make “structure or function” claims but disallows “disease” claims. In other words, herb A can claim to maintain healthy eyes; but herb A cannot make a claim that it treats glaucoma. While this seems straightforward, the FDA is unable to keep up with erroneous and sometimes illegal disease treatment claims made by the dietary supplement industry. Unlike prescription drugs, which fall under the US Food, Drug, and Cosmetic Act, dietary supplements are not required to prove premarketing safety or efficacy and only need to conform to the DSHEA to be legal. This creates a particularly difficult situation in which the FDA must prove a medication is dangerous after it is marketed before it can withdraw it from the market. For example, ephedra was withdrawn after causing adverse cardiovascular effects and death (Ling 2004). Even with the DSHEA, many supplements are marketed illegally, as evidenced by a study in the Journal of the American Medical Association, which researched the marketing practices of dietary supplement companies. This study showed that 55% of retailers make illegal disease claims of treatment, prevention, diagnosis and cure of specific diseases through self-treatment with various herbal medicines and nutritional supplements (Morris et al 2003).

Classification of dietary supplements is also a difficult issue. In many countries, including the United States, different parts of the plant are harvested; and the collection and extraction of ingredients vary from company to company. Is the root, the flower, the stem or the seed being used for therapeutic benefit? How much of an herb is in the marketed product? Ginseng was evaluated by the American Botanical Council in 2001, and it was found that only 52% of marketed ginseng products actually contained any ginseng (Dharmananda 2002). Because of issues such as these, the World Health Organization (WHO) has published guidelines on cultivating, collecting, classification, quality control, storage, labeling, distribution and postmarketing surveillance of herbal medicines, which if adhered to worldwide would simplify the classification process (WHO Guidelines 2004).

The following herbal medicines and dietary supplements are described in this book because the ocular side effects are significant and well documented: Canthaxanthine, Chamomile, Chrysanthenemum, Datura, Echinacea purpurea, Ginkgo biloba, licorice, niacin, vitamin A and vitamin D (Fraunfelder 2004, 2005a). There are many other herbs and supplements used to treat eye disease. Many are associated with adverse ocular events; these are summarized in Tables 6.1 and 6.2.

Table 6.1

Dietary Supplements Used to Treat Eye Disease

Condition Herb or Supplement Used
Conjunctivitis, unspecified

Nov 21, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on 6 Herbal medicines and dietary supplements – an overview
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