What You Need to Know About Supplements

By Temma Ehrenfeld and Sherry Baker @temmaehrenfeld
October 13, 2022
What You Need to Know About Supplements

The belief that supplements are harmless because they’re “natural” is a myth. They may not contain what you think, and they’re not necessarily harmless.

Supplements can be expensive. So, be sure you’re getting what you’re paying for and that there’s actual evidence the supplement could help you — and won’t do harm.

The belief that supplements are harmless because they’re “natural” is a myth. Nature has produced many poisons. Also, we’ve heard so much hype about “natural products” that it’s hard to remember those capsules you’re taking didn’t fall from a tree.

They are manufactured and sometimes contain contaminants or materials that are not listed on the ingredients label. What’s more, taking too much of certain supplements can be harmful.


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The U.S. Food and Drug Administration (FDA) does regulate both dietary supplement products and dietary ingredients — up to a point. The FDA regulation of dietary supplements falls under a different set of rules than those covering "conventional" foods and drugs. Specifically, manufacturers and distributors of dietary supplements and dietary ingredients are prohibited from selling products that are adulterated or misbranded. 

That means the supplement manufacturers are responsible for evaluating the safety and labeling of their products before marketing to make sure they safe. What’s more, supplements are not drugs and cannot claim they are intended to treat, diagnose, prevent, or cure a disease or condition.

Supplement labels and ads must not make medical claims, such as “reduces pain” or “treats heart disease,” the FDA points out. The FDA also has the authority to take action against any adulterated or misbranded dietary supplement product being sold.

Because supplements aren’t regulated or clinically tested like drugs, however, there’s no guarantee that their contents match the label. While rare, sometimes the contents of mislabeled or contaminated supplements are not exposed until people taking them become ill.

People may also be paying for specific herbal products that contain something else, without their knowledge. A case in point: When Canadian researchers tested 44 popular herbal products from 12 companies, they found that a third had no trace of the plant on the bottle’s label — but another plant instead. The rest had been contaminated with other plants or contained mostly fillers.

In a famous example of mislabeled supplements, research by the New York Attorney General's office revealed popular supplements sold as GNC, Target, Walmart, and Walgreens store brands were contaminated or did not contain the correct ingredients listed — and the stores were told to stop selling the products.

The good news is that the FDA has created the Dietary Supplement Ingredient Advisory List, to warn consumers about ingredients in supplements that may be harmful.

You’re best off getting your nutrients from food, in any case. Over and over, when scientists identify a food that promises a health-boosting effect, supplement manufacturers identify a particular ingredient that they can package to sell. But that doesn’t mean sufficient research has been done to show the supplement ingredient — whether a vitamin, herb, or amino acid — may improve or protect your health.

Moreover, too much of certain supplements can increase your health risks. Forexample, excess vitamin A has been associated with osteoporosis and an increased risk of hip fractures.

Maybe you’re taking vitamins known as “antioxidants” like vitamin C and beta-carotene to help prevent heart disease or cancer. You may have heard advice based on early lab studies, which suggested that higher antioxidant levels might prevent what’s called “free-radical damage” tied to cancer. But most studies in people don't support that theory, says John Swartzberg, MD, chair of the editorial board of the University of California Berkeley Wellness Letter.

Several studies suggest beta-carotene may increase the risk of lung cancers in smokers. In fact, cancer patients should talk to their doctors about their use of antioxidants or other vitamins that might potentially negatively impact their cancer treatment.

We’d all love a cure for the common cold. About 75 mg of zinc in a lozenge or syrup may shorten the duration of colds by a day if you take it within 24 hours of the first cold symptom. But in higher doses taken regularly, zinc can impair your immune system. Swartzberg says you can forget about commercial formulas that contain a medley of supposed cold cures, including vitamin A.

What about taking probiotics

The microbiome (the collection of all microbes, such as bacteria, fungi, viruses, and their genes that naturally live on our bodies and inside us) plays an important role in human health and wellness, according to National Institute of Environmental Health Sciences researchers. Eating foods that contain probiotics, including yogurt, sauerkraut, and other fermented products, can help digestion and have other health benefits. Many probiotic supplements are also available.

But not all probiotics in products like yogurt or supplements may be active, or active enough to be beneficial. To help consumers identify yogurt products that contain live and active cultures, the International Dairy Foods Association provides the Live & Active Cultures seal (which is voluntary and not required by law); look for it on refrigerated and frozen yogurt containers.

Meanwhile, the independent testing company LabDoor reports on the level of active probiotics in supplement brands.

The greatest risk here is that you’ll take useless supplements rather than more effective action, such as the proper medical care or healthy lifestyle measures. For example, people who learn that they carry a gene related to Alzheimer's disease risk are more likely to take ginko biloba, which has not been proven effective to prevent dementia. They’d be much better off increasing their exercise, which may reduce their risk of dementia.   


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October 13, 2022

Reviewed By:  

Janet O’Dell, RN