Dietary supplements are regulated in the United States, but not in the way most people assume. Unlike prescription and over-the-counter drugs, which must prove they are safe and effective before reaching store shelves, supplements can be sold without any prior approval from the FDA. The manufacturer is responsible for ensuring safety, and the FDA can only step in after a product is already on the market and causing harm. This gap between how drugs and supplements are overseen is the core of the issue, and it traces back to a single law passed in 1994.
The 1994 Law That Shaped Everything
The Dietary Supplement Health and Education Act, known as DSHEA, is the reason the supplement industry operates the way it does today. Before DSHEA, there was growing tension between supplement manufacturers who wanted fewer restrictions and regulators who wanted more. The supplement industry won. DSHEA classified supplements as a category of food rather than drugs, which fundamentally changed what the FDA could and couldn’t do.
Under DSHEA, the FDA does not have the authority to approve dietary supplements before they are marketed. A company can formulate a product, put it in a bottle, and start selling it without submitting safety data, clinical trial results, or efficacy proof to any government agency. The only exception involves “new dietary ingredients,” ones that weren’t sold in the U.S. before October 1994. For those, manufacturers must notify the FDA at least 75 days before launch and provide evidence that the ingredient is reasonably expected to be safe. But “reasonably expected to be safe” is a far lower bar than what drugs must clear, and the company decides what evidence to submit.
For every other supplement ingredient, the firm does not have to provide the FDA with the evidence it relies on to substantiate safety, either before or after marketing. The agency is left to police problems after consumers have already been exposed.
How Drug Approval Differs
The contrast with pharmaceutical drugs is stark. A new drug typically goes through years of laboratory testing, then three phases of human clinical trials involving hundreds to thousands of participants. The manufacturer must demonstrate both that the drug works for its intended purpose and that its benefits outweigh its risks. The FDA reviews all of this data before granting approval. The entire process often takes a decade or more and costs hundreds of millions of dollars.
Supplements skip all of that. No clinical trials proving the product works. No multi-phase safety testing. No FDA review before sale. The burden of proof is essentially reversed: for drugs, the manufacturer must prove safety before selling. For supplements, the FDA must prove danger after the product is already being consumed by the public.
What Manufacturers Are Required to Do
It would be inaccurate to say supplements exist in a regulatory vacuum. Manufacturers must follow current Good Manufacturing Practices, a set of federal rules covering how supplements are produced, packaged, and labeled. These rules require companies to establish identity specifications for every ingredient, conduct at least one test to verify that each dietary ingredient is what it claims to be, and use scientifically valid methods like chemical analysis or microscopic examination to confirm identity and purity.
The problem is enforcement. The FDA inspects only a fraction of the thousands of supplement manufacturers operating in the U.S. each year. When inspections do happen, violations are common, ranging from failure to test ingredients to inadequate contamination controls. A company that cuts corners may go years without an inspection, and even when violations are found, the consequences are often limited to warning letters.
The Loophole in Health Claims
Walk down the supplement aisle and you’ll see bold claims on labels: “supports immune health,” “promotes joint comfort,” “maintains cardiovascular function.” These are called structure/function claims, and they are perfectly legal as long as the manufacturer has some substantiation that the claim is truthful. The FDA does not review or approve these claims before they appear on the label.
What supplements cannot legally say is that they diagnose, treat, cure, or prevent any disease. That language is reserved for drugs. So a supplement can say “supports healthy blood sugar levels” but cannot say “treats diabetes.” To signal this distinction, every supplement making a structure/function claim must carry a small disclaimer: “This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”
In practice, many consumers either don’t notice the disclaimer or don’t understand what it means. And while the language on the label may stay within legal bounds, advertising sometimes pushes further. The Federal Trade Commission oversees supplement advertising and requires that health claims be backed by “competent and reliable scientific evidence,” defined as tests, research, or studies conducted by qualified professionals using accepted methods. But the FTC, like the FDA, has limited resources and tends to pursue only the most egregious offenders.
What Actually Ends Up in the Bottle
The consequences of this system show up in the products themselves. A 2024 study published in JAMA Network Open tested 30 weight-loss supplements marketed online and found that 23% contained hidden ingredients not listed on the label. Thirty percent contained ingredients on the Department of Defense’s prohibited list. Some individual products contained as many as 10 prohibited compounds. The hidden ingredients included stimulants, compounds banned in competitive sports, and substances with real pharmacological effects that consumers had no way of knowing they were ingesting.
This isn’t limited to weight-loss products, but that category is among the worst. The FDA maintains a database of tainted supplements and has identified over 100 weight-loss products containing undeclared pharmaceutical ingredients, including blood pressure medications, seizure drugs, and compounds not approved for use in the United States. Sexual enhancement and bodybuilding supplements are similarly problematic categories.
Even when a supplement isn’t hiding dangerous ingredients, what’s on the label may not match what’s inside. Independent testing has repeatedly found products that contain less of an ingredient than claimed, more than claimed, or substitute ingredients entirely. Without mandatory pre-market testing, these discrepancies persist until someone tests the product independently or a consumer reports an adverse event.
Third-Party Testing Fills the Gap
Because government oversight is limited, several independent organizations have stepped in to verify supplement quality. These certifications are voluntary, and manufacturers pay to participate, but they represent the most reliable signal a consumer can look for.
- USP Verified: Tests for purity, potency, and quality, confirming that the ingredients listed on the label match what is actually in the product.
- NSF Certified for Sport: Tests for banned substances, contaminants, and unsafe levels of heavy metals. Products also undergo annual facility audits and periodic marketplace sampling, where certified products are purchased anonymously and retested.
- Informed Sport: Tests every single batch of a certified product for prohibited substances, contaminants, and labeling accuracy.
- BSCG (Banned Substances Control Group): Tests every production lot against a panel of over 500 compounds, including substances prohibited in sport and pharmaceutical contaminants.
If you take supplements, looking for one of these certifications on the label is the single most effective step you can take to reduce your risk. A product without any third-party verification isn’t necessarily unsafe, but you have far less assurance about what’s inside.
Why the Law Hasn’t Changed
DSHEA has remained largely intact for three decades despite well-documented problems. The supplement industry generates tens of billions of dollars annually in the U.S. and has significant lobbying power. Consumer advocacy groups and some members of Congress have pushed for reform, but proposed legislation has repeatedly stalled.
The most recent effort, the Dietary Supplement Listing Act of 2024, would have required manufacturers to register their products with the FDA, essentially creating a public database of every supplement on the market along with its ingredients. This wouldn’t have required pre-market approval, just basic transparency about what is being sold. The bill was introduced in the Senate in July 2024, referred to committee, and went no further. Even this modest step toward visibility proved too contentious to advance.
The result is a system where the FDA knows about a supplement only when a company voluntarily notifies the agency about a new ingredient, when something goes wrong, or when the agency proactively investigates. Estimates suggest tens of thousands of supplement products are currently sold in the U.S., and the FDA has no comprehensive list of them.