When you pick up a dietary supplement with a “seal of approval” from some organization or other, you might think, “Hey, someone vetted this, so it’s totally fine for me to take!” But despite words like “verified, “certified,” or “approved,” those seals shouldn’t be confused with any sort of official approvals granted by the Food and Drug Administration, and they don’t necessarily mean the product is effective and/or safe to take.

As part of a wider look at the dietary supplements industry, our colleagues at Consumer Reports have laid out exactly what those seals mean.

“No supplement seal guarantees the safety or effectiveness of the ingredients in the bottle,” Sharon Akabas, Ph.D., associate director of educational initiatives at Columbia University’s Institute of Human Nutrition told Consumer Reports.

Instead, many of these seals are granted by organizations known for certifying products. U.S. Pharmacopeia, NSF International, and ConsumerLab.com have long histories of certifying supplements. UL, which has traditionally certified consumer products like appliances and computers, will start certifying supplements this year.

However, none of these organizations guarantees that a product has therapeutic value, and they don’t test every batch of supplements that goes to market.

Their seals are simply a good indication that the product contains the amount of the ingredient advertised on the label and that it isn’t contaminated with dangerous substances, such as arsenic, bacteria, or lead.

While seals from these companies don’t reflect the high standards for safety and efficacy set by the FDA for drugs, they’re still important, Consumer Reports says, because the agency doesn’t routinely do that kind of testing of supplements.

Manufacturers must pay to get their supplements tested and certified, which may be a reason that only a tiny fraction of the 90,000 or so dietary supplements on the market carry one of these seals. USP, for example, has verified only 139 products to date.

Here’s some more information about the four seals you may see:

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