About two-thirds of American adults take at least one dietary supplement, most often multivitamin/mineral pills. And yet, of all the decisions and purchases we make pertaining to our health, selecting supplements puts us on less secure ground than nearly anything else.
That's primarily because supplements are only lightly regulated by the FDA. Manufacturers don't have to prove efficacy or safety. Federal law limits what kind of health claims can be made on labels, in ads, and on the Internet, but many marketers make illegal, unsubstantiated claims for months, even years, before the FDA cracks down on them. Still, some supplements are clearly beneficial and come in standard doses. No wonder people are confused. It's the Wild West out there.
Here are some general tips to keep in mind when—or if—you buy supplements.
- Large, long-term, well-designed clinical trials are lacking for most dietary supplements (with some exceptions, such as vitamins and minerals). The great majority of studies on supplements have been small, short, or poorly designed, and results are generally inconsistent.
- Just because supplements are sold without a prescription, are often touted as "natural," and come with no warnings on their labels, that doesn’t mean they are safe. Adverse effects are seldom reported, so safety remains a question. Supplements can have a powerful and unpredictable impact on the body, possibly affecting blood sugar, blood clotting, blood pressure, hormone activity, liver function, and more. What’s more, many supplements (particularly herbs) can interact with prescription or OTC medications.If you experience side effects from a supplement, report it to the FDA as well as to your health care provider. You can file a report at MedWatch.
- The bottles may not even contain what the labels say. Over the years there have been numerous reports of products with much less, or more, than what's listed on the labels. Worse yet, supplements have been found to contain undisclosed prescription drugs as well as contaminants. Herbs are especially problematic because they are very complicated chemically. They can vary greatly in their composition, and it’s often not clear which compounds produce the proposed effects, making herbal preparations hard to standardize. Manufacturers are supposed to follow "good manufacturing practices" to ensure identity, purity, and composition of their products, but are largely self-policing since the FDA lacks the resources to fully monitor compliance. There are private watchdogs, notably ConsumerLab.com and USP (U.S. Pharmacopeia), which analyze and certify supplements, but these are limited in scope and don't address the bigger questions: Are the products safe and do they work as claimed?
- If you have a medical condition or are about to have surgery, tell your health care provider if you are taking any supplements. Better yet, discuss them before you start taking them. Don't rely on supplements to self-treat a serious health problem. In particular, don't substitute a supplement for medication you have been prescribed.
- Pregnant or nursing women should avoid most supplements, except as advised by their health care providers. The same goes for children.
- Supplements can't substitute for a good diet or cancel out the effects of bad habits like smoking or not exercising.
- Don't be swayed by anecdotal evidence about supplements and celebrity endorsements, often found on the Internet. Testimonials are meaningless.
- Be wary of anti-aging claims. So far there is no supplement, medication, or other substance that will stop or slow the aging process.