Are Dietary Supplements Safe? Here’s What We Learned From The Experts

If you're considering dietary supplements, make sure you know what you're getting into. Here's how to tell whether you're making a safe decision.  

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Most Americans have some experience with dietary supplements.

Head into any grocery store or pharmacy and you’ll see them: Dozens of lime-green bottles, carefully arranged under a big sign that says something like “nutrition” or “natural health.”

Each bottle is packed with tablets, capsules, and pills, with labels extolling the virtues of things like fish oil and probiotics. Look closely, and you’ll see asterisks beside these benefits, and on the back of the bottle, a disclaimer from the U.S. Food and Drug Administration (FDA).

Whether you give your kids Flintstone vitamins (the most delicious cartoon-based vitamin, in our humble opinion) or you’re hopping on the collagen powder trend to try to improve your skin health, you’re likely using some type of dietary supplement in your everyday life.

About 76 percent of Americans take dietary supplements, according to the Council for Responsible Nutrition (CRN), a supplement industry advocacy group. The majority of Americans express confidence in the safety, effectiveness, and quality of those products.

Still, unless you’ve made a concerted effort to learn about the supplement industry, you might not know exactly how those supplements work—or whether they even contain the active ingredients you’ve paid for. As we learned, dietary supplements vary greatly in terms of benefit, risk, and even product quality. If you’re considering any type of supplement, here’s everything you need to know to make an informed decision.

How does the FDA regulate dietary supplements—and why aren’t they more strictly regulated?

Let’s start by addressing the most common criticism of dietary supplements: They’re poorly regulated.

Pick up any bottle of vitamins and you’ll see the word “supplement” somewhere on the label. You might also see this message: “This product is not intended to diagnose, treat, cure, or prevent any disease.” You’ll almost always see this one: “These statements have not been evaluated by the Food and Drug Administration.” Why doesn’t the FDA take a bigger role?

That’s a somewhat complicated question, because the FDA does regulate the industry to some degree. Dietary supplements have been popular for decades, but the industry has changed substantially since Congress passed the Dietary Supplement Health and Education Act of 1994.

According to the law, supplements aren’t medications, they’re a class of food. And they’re not subject to the rigorous FDA oversight afforded to medications. Supplement manufacturers have to clearly label their products, but they don’t have to explicitly prove that they’re safe before bringing the products to market.

“A dietary supplement is defined as a food,” says Joseph Feuerstein, MD, who is a board-certified physician practicing at Stamford Hospital and assistant clinical professor of medicine at Columbia University College of Physicians and Surgeons. “But while [a supplement] may come as a capsule in the same way as a medication comes in a capsule, you can’t assume that it has the same quality of manufacturing and safety as a medication.”

That’s not to say that the market is completely unregulated. The FDA explains their approach on their website:  

“In general, FDA’s role with a dietary supplement product begins after [emphasis added] the product enters the marketplace,” the site reads. “That is usually the agency’s first opportunity to take action against a product that presents a significant or unreasonable risk of illness or injury, or that is otherwise adulterated or misbranded.”

In other words, if a supplement seems dangerous, the FDA will step in.

Dietary supplement manufacturers are legally required to report “serious adverse events” that occur after a product hits the market. They’re also required to keep records of those events and present them to the FDA as needed.

“Dietary supplements are absolutely regulated,” says Steve Mister, president and CEO of the CRN. “The FDA has oversight over our labels, they control what ingredients are considered legal, and they oversee the manufacturing of the products. …Food products don’t have the adverse event reporting requirement, but supplements do. Our regulations are quite a bit more stringent than [regulations] are for food.”

The FDA can recall supplements if they make misleading claims or if they present a serious danger to consumers. Supplement manufacturers must also register their facilities with the FDA, and they’re subjected to fairly strict labeling requirements.

Still, our sources agreed that supplements aren’t held to the same rigorous standards as pharmaceuticals. What’s to stop a supplement manufacturer from selling sugar pills as multivitamins?

Dietary supplement manufacturers are required to follow the Current Good Manufacturing Practice (CGMP) rule, which ensures that supplement manufacturers follow the same practices established for food manufacturers. Violators face fines and recalls. Additionally, many manufacturers are part of industry trade groups that enforce their own standards (as we will discuss later).

Mister says that the FDA has plenty of power, but he believes that the administration doesn’t always have the resources to exercise that power.

“We’re always talking to the FDA about doing more enforcement,” Mister says. “We do know, quite candidly, that there are products in the marketplace that should not be there. They’re patently illegal, because they’re putting [in] ingredients that shouldn’t be there, or they’re making claims that they shouldn’t be making. The thing is, they’re already illegal—what we need is a more active FDA with the resources to enforce existing laws.”  

When used properly, dietary supplements can be beneficial.

We love the idea of taking a tiny capsule that will instantly resolve all of our dietary deficiencies. As you might have guessed, though, that’s not exactly how supplements work. Used incorrectly, they’re potentially dangerous, but used under supervision, they can be an inexpensive means of improving health.

“Full disclosure, I use dietary supplements all the time,” says Feuerstein, referring to his medical practice. “It’s just that I do it in a clinical setting where I know what I’m giving, where it comes from, and what the purpose of it is—and it’s under a physician’s supervision.”

The FDA also specifically notes that certain supplements can be beneficial. Folic acid supplements, for instance, can reduce the likelihood of some birth defects, so obstetricians often recommend them to pregnant women.

We mentioned that to Feuerstein, who quickly noted that an overabundance of folic acid may increase the risk of certain cancers (although researchers are still studying the extent of the link). While a person is less likely to experience harmful side effects when taking water-soluble supplements—for instance, folic acid or vitamin C—Feuerstein recommends a cautious approach.

“All fat-soluble vitamins, in high enough doses, can cause toxicity,” he says. “You don’t get a prize for getting too much of a nutrient. You usually get a problem.”

Mister notes that according to the CRN’s research, most consumers tell their physicians about their supplement use.

“For consumers, their most trusted source of information [regarding supplements] is their doctors,” he says. “We encourage people to talk to medical professionals—nurse practitioners, doctors, naturopaths, and pharmacists—when making decisions.”

Herbal dietary supplements can present other issues.

There’s also a big difference between nutrient supplements (such as vitamin capsules) and botanical supplements.

“A botanical—an herbal supplement—has a myriad of physiologically active ingredients,” Feuerstein says, “and you can get [supplements] in a dose that would have a significant effect on the human body.”

Some toxicologists believe that the growing herbal supplement industry should be subjected to additional regulations or, at the very least, additional scientific study. Botanical supplements can have unexpected side effects, since they’re pharmacologically complex.

“If you’re using that type of supplement, you should be seeing someone who’s trained in herbal medicine, because it can interact in medications or other supplements and can be toxic,” Feuerstein says.

“It’s important to talk to [health professionals] about the supplements you take,” Mister says, “particularly if you’re also using prescription medications.”  

Is there a way to choose safer supplements?

If you’re thinking about taking a supplement, you might want to check to see whether you can get the same effect by modifying your diet. For example, if you are looking into taking a folic acid supplement, consider eating more cereals, leafy green vegetables, or pastas. If you believe you have a nutrient deficiency, you should speak with your physician.

“That doesn’t mean Dr. Google,” Feuerstein says. “Google isn’t your doctor. It’s basically a glorified medical textbook … it can’t provide the advice you need.”

He notes that dietary deficiencies can’t be self-diagnosed, since the human body is complicated. Vitamin D levels, for instance, typically rise in the summer months, since people are exposed to more sunlight. As such, a person who needs a vitamin D supplement in the winter might need to stop supplementing during the summer.

Some organizations analyze dietary supplements before they get to market.

Let’s assume that you’ve done your homework—or, rather, your clinical work. You’ve spoken with a medical professional, you’ve had relevant tests, and you’re fairly certain that you need a specific supplement. What’s your next step?

“Since 2002, some of the top United States [supplement] manufacturers have voluntarily undergone testing and supervision via the United States Pharmacopeia [USP], which supervises them independently of the government,” Feuerstein explains. “They voluntarily undergo testing by the USP, which also oversees medications … These supplements would be de facto pharmaceutical-grade substances.”

USP-verified supplements have a green symbol that indicates they’ve been tested for heavy metals and impurities. USP verification isn’t available for all types of supplements, however.

“USP is one type of independent certification,” Mister says. “NSF is another one, and UL is another. Those are probably the three best-known organizations for supplement testing.”

We should note that those organizations have different standards for evaluating supplements, so it’s important to research them carefully before relying on the labels. Feuerstein also recommends looking at other countries’ supplement laws.

“In Europe, herbal supplements are made by pharmaceutical companies that have herbal divisions,” he says. “For example, Madaus, which is a German pharmaceutical company, also makes herbal remedies. In Germany, these are prescription strength, and they are prescribed by physicians.”

“So I use the German pharmaceutical-grade product that I know is high quality, I know it’s at the correct dose, and I use it according to the specifications of Commission E [a German scientific advisory board]. I’m literally using this instead of a medicine.”

That doesn’t mean that you should rush out and load up on those supplements, of course.

“I do not advise that people do this via Google,” Feuerstein warns. “I advise they go see someone who knows how to supplement safely and is medically trained.”

With all that said, are dietary supplements worth the trouble?

Well, yes. They can be helpful, even if they’re not officially “intended to diagnose, treat, cure, or prevent any disease.” They’re also fairly inexpensive, for the most part, especially when compared with medications.

We asked Feuerstein whether he’d endorse new regulations on the dietary supplement industry. He says that that decision is best left to other people—in particular, patients.

“I do like the availability of supplements,” he says. “I’m not sure that introducing more layers of regulation, so that they’re regulated like medications, would be a good thing. But my primary concern is the health of patients, so I think it’s important to emphasize that people should make these decisions with the help of appropriately trained medical professionals.”

Mister agrees with that assessment.

“The 1994 law carefully balanced consumer safety with consumer access,” he says, “and we think the law struck the right balance. We wouldn’t want to see pre-market approval for these products. That would resemble the way that pharmaceuticals are regulated, and it would absolutely cut down access. It would increase prices and limit consumer choice.”

We can’t stress this enough: If you’re considering taking any dietary supplement regularly, speak with a physician.

We realize that we’re repeating that point, but that’s because it’s absolutely critical. To take supplements safely, you need to speak with a medical professional who can assess possible interactions, monitor side effects, and recommend a safe dosage.

“It is important to talk to one of those people about the supplements you take, particularly if you’re also using prescription medicines,” Mister says. “Research brands individually, and then, of course, talk to your healthcare practitioner. Talk to them about the supplements that you use and ask if they have recommendations.”

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