Chapter 43: Plant- and Animal-Derived Dietary Supplements

INTRODUCTION

Dietary supplements include vitamins, minerals, plant-and animal-derived preparations, amino acids, and a variety of other “natural” and “traditional” remedies with established history of use. Within the United States regulatory context, dietary supplements are distinct from medications because this term is reserved for drugs approved by the US Food and Drug Administration (FDA), which are regulated more rigorously in terms of safety and effectiveness. Although these products are distinct from medications, they contain xenobiotics that have many physiologic effects on the human body.

Many dietary supplements sold in the United States are based on diverse traditional healing practices from around the world, and they are often derived from plant and animal sources.

The study of plant- and animal-derived dietary supplements is complicated by the lack of standardized nomenclature. A variety of common, proprietary, and botanical names can cause confusion. A single plant preparation often has many common names, in addition to its botanical name. For example, Datura stramonium is also known as Jamestown weed, jimson weed, angel’s trumpet, devil’s apple, thornapple, apple of Peru, and tolguacha. Likewise, one common name for a plant refers to several plants. “Mandrake” refers not only to the belladonna-alkaloid–containing Mandragora officinarum but also the podophyllum-containing Podophyllum peltatum. Thus, accurate classification of plant- and animal-derived dietary supplements is difficult and often confusing. Using both common and botanical names, when possible, allows for more precise communication.

This chapter discusses the history, epidemiology, and regulation of plant-and animal-derived dietary supplements. Pharmacologic principles related to products derived from plants and animal sources are considered, as well as issues related to adulteration and contamination of supposedly natural products. The toxicities of select examples of plant- and animal-derived dietary supplements will be discussed. It is beyond the scope of this chapter to evaluate the effectiveness of dietary supplements for their purported uses. Reported traditional indications are mentioned in some cases to provide context without implying that the evidence for or against purported indications for these products was evaluated.

HISTORY AND EPIDEMIOLOGY

Since ancient times, people of nearly all cultures have used plant- and animal-derived dietary supplements to treat disease and promote health. A 60,000-year-old Iraqi burial site contained eight different medicinal plants.¹⁰⁴ The Egyptian Ebers papyrus, written circa 1500 B.C., lists 160 medicinal plants and their intended uses, including the use of salicin-containing willow bark to treat pain.³³ The Hippocratic Corpus, compiled around 400 B.C., contains many descriptions of herbs, including a number of recipes for plant-based gynecologic remedies; it prescribes the use of a likely extinct silphium plant to “create a wind in the womb” to induce abortion or expel a dead fetus.¹⁰⁸ In the first century A.D., the Greek physician Dioscorides wrote De Materia Medica, which described the indications for use of more than 600 plant- and animal-derived preparations, many of which are still used ...