Herbal and botanical dietary supplements have been used as medicines for thousands of years. For example, black cohosh (Cimicifuga racemosa), which is now commonly used to relieve symptoms associated with menopause, was used by Native Americans for a variety of ailments. They boiled black cohosh root in water and drank the resulting beverage for health problems ranging from rheumatism and sore throat to “diseases of women” and “debility.” As far back as 5000 years ago, ephedra (ma huang, Ephedra sinica) was used in China and India to treat bronchial asthma and related ailments.
Many cultures around the world continue to make use of herbs and botanicals for medicinal purposes.
Historic and anecdotal information and scientific data suggest that herbal and botanical dietary supplements have a high level of biologic activity and, in many cases, act as medicines. Despite their widespread use over time, however, scientific evidence supporting their efficacy and safety is lacking.
Nevertheless, many herbal remedies are among the most popular dietary supplements purchased and used regularly in the United States.
Based on historic uses, several assumptions have been made regarding herbal and botanical dietary supplements, despite a lack of scientific evidence. For example, ginseng (Panax ginseng), which can have an unusual and almost human appearance, is recommended for common ailments such as lack of energy, lagging libido, and a poor immune system.
In addition, many herbal and botanical dietary supplements are promoted for uses that are unsupported or have been disproved. Comfrey (Symphytum officinale) has been and continues to be used for a variety of conditions associated with inflammation, including diseases of the gastrointestinal and respiratory system. No evidence supports these uses, however, and comfrey is among the herbal and botanical dietary supplements currently considered extremely dangerous. Another very popular herbal remedy, echinacea (Echinacea purpurea, Echinacea angustifolia), has been shown in three scientific studies to be ineffective at preventing or decreasing the severity of the common cold.
Perhaps the most common assumption about herbal and botanical dietary supplements is that one name refers to one “herbal medicine.” In truth, there are so many common names and parts of various plants that are used that it is sometimes impossible to identify exactly what is encapsulated in an herbal or botanical dietary supplement. Kelp, which is used in folk medicine to treat constipation, bronchitis, emphysema, asthma, indigestion, ulcers, colitis, gallstones, obesity, and genitourinary and reproductive abnormalities in both men and women, actually refers to a huge family of seaweeds and algae. It is extremely difficult to evaluate the efficacy of a substance whose origin cannot be identified.

Minerals necessary for a health diet are boron, calcium, chromium, copper, iodine, iron, magnesium, manganese, phosphorus, potassium, selenium, and zinc. To prevent illness and death from vitamin and mineral deficiencies, the U.S. government established the recommended dietary allowances (RDAs) in 1943. These values are updated routinely based on new scientific information.
Recently, dietary reference intakes (DRIs) were established by the Institute of Medicine’s Food and Nutrition Board to recommend how much of various nutrients individuals and groups of people should be consuming, not just to avoid deficiency but also to optimize health. Continuing efforts are made to explore the possibility that even higher amounts of certain nutrients may provide additional health benefits. To establish the DRIs, experts in nutrition, dietetics, statistics, nutrition epidemiology, public health, economics, and consumer perceptions reviewed the scientific evidence of safety, efficacy, toxicity, and beneficial properties of vitamins, minerals, and a few non-vitamin/non-mineral substances such as water and fiber.
The DRIs are nutrient-based reference values that include an estimated average requirement (EAR) and an RDA. When there is not enough information to determine an EAR and an RDA, an adequate intake (AI) is established. Many nutrients also have a tolerable upper intake level (UL). Vitamin and mineral dietary supplements may contain a single nutrient (such as vitamin C) or multiple nutrients (such as B-complex or multivitamins).
Doses of vitamins and minerals in dietary supplements vary from levels close to the RDA or AI to several times those levels. The DRIs are used to provide food-based dietary guidance; they are accompanied by national food guides and dietary guidelines for healthy people and provide a basis for food and dietary supplement labels. Although the DRIs and the accompanying guidelines (such as the Dietary Guidelines for Americansand the Food Guide Pyramid) specify daily goals, health professionals use these tools to help people choose diets that provide the recommended nutrients over time.
Several false assumptions have been made regarding vitamin and mineral dietary supplements. For example, vitamin A deficiency causes decreased night vision and, if very severe, blindness. Treating deficient individuals with vitamin A may indeed improve vision. However, many dietary supplements containing vitamin A and beta-carotene (a precursor to vitamin A) claim to “support good eye health.” Some consumers falsely assume that if the deficiency of a vitamin or mineral harms a system or organ, then consuming that vitamin or mineral when the body is not in a deficient state will strengthen that system or organ.
Much of the research on vitamins and minerals has investigated whether dietary supplements are superior to food.
According to two recent scientific publications by Dr. Alice H. Lichtenstein and Dr. Robert M. Russell, both from the Human Nutrition Research Center on Aging at Tufts University, the answer is no. However, most experts do agree that further research is worth pursuing.

What makes understanding and regulating dietary supplements so complex is that many different substances are lumped together in one group. Dr. Jeffrey Blumberg, senior scientist and director of the Antioxidants Laboratory at the Human Nutrition Research Center on Aging at Tufts University, contends that including all of these different substances under one heading is “worse than comparing apples with oranges.”
Dietary supplements are not foods, but they are regulated in a way that is closest to the way the FDA regulates foods. They are not drugs, but they are marketed in ways that are similar to some over-the-counter and prescription drugs. For the purposes of this blog, I have divided dietary supplements into vitamin and mineral supplements, herbal and botanical supplements, and other supplements.

Three organizations analyze dietary supplements to ensure safety, the U.S. Pharmacopeia (USP), ConsumerLab.com, and the Natural Products Association (NPA).
The USP is an independent, nonprofit organization that establishes standards for all prescription and over-the-counter drugs, dietary supplements, and other healthcare products manufactured in the United States, such as medical devices. Founded in 1820, the USP is recognized by federal law as the official body that sets standards for drugs and dietary supplements. The USP aims to improve public health by ensuring the high quality of drugs and dietary supplements by setting high standards and working with various entities, including manufacturers and healthcare providers, to meet those standards.
While drug manufacturers must comply with USP standards, manufacturers of dietary supplements voluntarily participate in the relatively new USP verification program (launched in October 2001), which consists of independent, third-party testing and evaluation of ingredients used in dietary supplements and the finished products. The USP verification program for dietary supplements is based on the use of current good manufacturing practices.
The USP also created a mark that can be placed on packaging of products that meet their specific standards. The USP mark tells you that the product contains tested and verified ingredients and final product and that manufacturing processes meet established standards. Dietary supplements bearing the USP mark contain the ingredients stated on the label; contain the ingredients in the amounts stated on the label; will be metabolized to release the nutrients for absorption in the body; have been screened for harmful levels of contaminants, including pesticides, bacteria, and heavy metals; and have been manufactured using safe, sanitary, and controlled procedures.
The USP currently verifies vitamin and mineral supplements and is in the process of continually adding similar information for herbal, botanical, and other dietary supplements. The USP web site (http://www.usp.org) provides detailed information regarding the exact brands and specific types of dietary supplements that have been evaluated and meet USP standards for purity, dissolution, and manufacturing. There is also a directory of where such dietary supplements can be purchased. For a list of current USP-verified dietary supplement manufacturers and brands.
ConsumerLab.com conducts independent product reviews of multiple brands of dietary supplements claiming to contain the same key ingredient (such as Gingko biloba). These product reviews are conducted every 24 to 36 months for each product category and include the results of blinded tests performed by academic and commercial labs that Consumer-Lab.com selects. Results are posted on their web site (http://www.ConsumerLab.com) for online subscribers, and free general information is also available. By paying a testing fee, dietary supplement manufacturers and distributors may choose to participate in the Voluntary Certification Program of ConsumerLab.com. Brands that meet the standards for identity, strength, purity, and pill disintegration are posted on the ConsumerLab.com web site and may be licensed to carry the Approved Quality Products Seal. In order to continue to carry the seal, those products must be retested every 12 months to ensure consistency. The seal indicates that a product meets recognized standards of quality, contains the quantity of ingredients stated on the label, is free of contaminants, and breaks apart properly so that it can be absorbed.
The NPA (www.naturalproductassoc.org), formerly known as the National Nutritional Foods Association, is a nonprofit organization that protects consumers and manufacturers by ensuring product quality and label integrity in the dietary supplement industry. The NPA modeled its own Good Manufacturing Practices Certification Program after the GMPs recommended by members of the dietary supplement industry in 1997. This program consists of random third-party inspections of members’ manufacturing facilities to determine whether they meet specifications for staff training, cleanliness, equipment maintenance, record keeping, and handling of raw materials. The NPA’s TruLabel Program randomly tests members’ products for “label integrity” to ensure that the product contents are as listed. Members of the NPA that manufacture dietary supplements under their own label have been required to participate in this program since 1990.

Several dietary supplements have been identified as more likely to cause harm than others. The FDA, the National Center on Complementary and Alternative Medicine, the consumer protection and education magazine Consumer Reports, and other organizations have published warnings for consumers. Review of the scientific literature and actual adverse event reports revealed that these supplements may cause organ damage, cancer, or other adverse effects; are currently the subject of an FDA warning; or pose significant theoretical risks.

Few studies have specifically examined interactions between drugs and dietary supplements in the general population, and existing reports have found only mild interactions. These articles comprised mainly case reports, estimations based on laboratory experiments (not in humans), and speculation based on pharmacology studies and theoretical risks. Lack of data, however, does not imply lack of danger.Dietary supplements may alter the activity of conventional drugs. Such interactions may occur in individuals who are particularly sensitive or immunocompromised or for drugs that have a narrow therapeutic window. In addition, response to drug and dietary supplement consumption may change with age and health status. Interactions between drugs and dietary supplements are especially likely in geriatric patients because they use more drugs and often combine prescription and over-the-counter drugs with herbal remedies. People with a chronic illness, specifically those with hepatic or renal impairment, are at higher risk of harmful interactions between drugs and dietary supplements.
Drug concentration or activity in the blood may be increased if a dietary supplement aids the absorption of the drug or if it inhibits enzyme destruction or elimination of the drug. Conversely, drug concentration and/or activity in the blood may be decreased if the dietary supplement binds components of the drug, thus preventing its absorption, or if the dietary supplement stimulates production and/or activity of enzymes that destroy the drug.
Some of the most popular dietary supplements may interact with drugs. A 2004 study at the University of Chicago Medical Center, which was funded by the National Institutes of Health and the Tang Center for Herbal Medicine Research, found that ginseng, which is commonly taken to enhance well-being, reduce fatigue, and improve immune response, decreased the effect of the anticoagulant warfarin. People who consumed warfarin and ginseng had an increased incidence of blood clots and therefore an increased risk of deep vein thrombosis. Because of ethical reasons, this study was done in healthy individuals, but the researchers believed that the results could be applied to those taking warfarin for prevention of deep vein thrombosis.
St. John’s wort, which people commonly take for mild to moderate depression, may alter the effectiveness of drugs prescribed for HIV, heart disease, depression, epileptic seizures, and cancer and may interfere with oral contraceptives. Dietary supplements containing garlic have the potential to increase the risk of bleeding if combined with other drugs that increase bleeding risk, such as aspirin and warfarin.
Interactions with Other Dietary Supplements
Although the potential for a dietary supplement to interact with others exists, currently there is not enough evidence to identify those risks. This should not be interpreted as there being no risk, however, only that none has been identified.

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