Shopping for Dietary Supplements: Understanding Safety Concerns
It used to be that food was food and drugs were drugs. Nowadays, it's not always easy to tell them apart. Consumers are faced with a great variety of products—falling somewhere between medicine and food—promoted as medical treatments and as part of a well-balanced diet. Welcome to the ambiguous world of dietary supplements.
The word "dietary" may lead people to believe such supplements are as safe as the foods we eat. While this is often the case, many of them have health effects—and side effects—comparable to medications. However, since dietary supplements are not as strictly regulated, like drugs, consumers need to be watchful and well-informed about purchasing these products. In fact, a group of medical experts writing in JAMA (the Journal of the American Medical Association) in 2003 stated that “dietary supplements are subject to less regulation than virtually any other products available for public consumption.”
The Nature of Dietary Supplements
Dietary supplements are edible products that contain one or more substances—usually natural—formulated to achieve a specific health effect. Three main groups of dietary supplements are:
Nutritional supplements—provide nutrients that are naturally present in food and have well-established health-related functions. These nutrients are isolated from foods and often provided at much higher concentrations. Examples include:
- Amino acids
- Fatty acids
- High-dose vitamins and minerals
Botanical supplements—herbal products containing concentrates or extracts from plants. Examples include:
- Gingko biloba
- Saw palmetto
- St. Johns wort
Miscellaneous supplements—these include a variety of non-herbal substances from many sources not normally found in the diet, but purported to have beneficial health effects. Examples include:
- Shark cartilage
- DHEA (a steroid hormone precursor)
- Chondroitin sulfate
Safe and Effective
Safety and effectiveness—that's the bottom line when it comes to any health product. It is the job of U.S. Food and Drug Administration (FDA) to ensure that medications are reasonably safe and effective. But this is not the case for dietary supplements.
Government regulators consider dietary supplements to be more like food than medicine. Therefore, supplement makers are not held to the same strict approval standards as the drug industry. One reason for this is that dietary supplement manufacturers cannot afford to do the level of research necessary to meet these FDA standards for safety and effectiveness. Drug companies spend tens of millions of dollars on such research.
In 1994, Congress passed the Dietary Supplements Health and Education Act (DSHEA). This act states that a dietary supplement may be sold without scientific evidence of effectiveness as long as no specific health benefits claims are made in its advertising or labeling. The manufacturer can only provide information about the intended use or potential benefits of the product. For example, a gingko label may not say: "effective treatment for Alzheimer's dementia." But, it can say: "may be useful for boosting memory in the elderly."
A Closer Look at Safety
DSHEA also allows lower safety standards for dietary supplements. Manufacturers need only show that their product is "reasonably expected to be safe," but DSHEA does not specify what evidence is required to make this safety assertion. In addition, once a product is on the market, it is up to the government to show that it is unsafe and that it should be withdrawn. Such a withdrawal is called a post-market recall. These recalls do occur with drugs as well, but many consumer-advocacy groups claim that the public is at greater risk with dietary supplements because they do not undergo the stringent pre-market scrutiny that drugs do. For example, the substance “ephedra” was recently banned from US sales after a number of deaths, strokes, and heart attacks were attributed to its use.
Still, others argue that comparable vigilance is not necessary for these "natural" products, which are often gentler and less toxic than highly concentrated, chemically based drugs. While this may be true, "natural" does not mean "safe." Plants, after all, produce some of the most powerful poisons on earth. Additionally, we know for fact that vitamins and minerals in mega doses cause toxicity. Furthermore, studies suggest that up to 20% of patients taking prescriptions drugs also take dietary supplements. So even if a supplement is considered safe, it can still interfere with the function of other medications a patient is taking.
Another issue closely related to safety and effectiveness is the concentration and purity of the product. When you purchase an FDA-approved drug, you know exactly what you're getting, down to the last milligram.
This is not always true of dietary supplements. Herbs, in particular, often contain many different constituents in addition to the active ingredient. In fact, studies have shown that some supplements contain no active ingredients at all, while others contain much higher concentrations than the label indicates. It is also not uncommon for supplements to contain substances that are not listed on the label, some of which may be biologically active.
Currently, the government is not responsible for assuring that what's on the label of a dietary supplement is actually in the bottle.
Still Considering Dietary Supplements?
Given all this ambiguity, is it possible to safely take a dietary supplement and expect a positive result? Yes it is.
By adhering to a few simple rules and doing some homework before purchasing any supplements, this vast and perplexing marketplace need not be so daunting.
American Academy of Family Physicians
American Dietetic Association
Canadian Council on Food and Nutrition
Dietitians of Canada
Phil B. Fontanarosa PB, Drummond R, DeAngelis C. The need for regulation of dietary supplements–lessons from ephedra. JAMA. 2003;289:1568-1570.
Last reviewed May 2008 by Dianne Scheinberg MS, RD, LDN
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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