Our hospital has acted to protect the safety of our patients. No longer will we administer dietary supplements unless the manufacturer provides a third-party written guarantee that the product is made under the F.D.A.’s “good manufacturing practice” (G.M.P.) conditions, as well as a Certificate of Analysis (C.O.A.) assuring that what is written on the label is what’s in the bottle.

The good news is that we’ve been able to find some vitamins, amino acids, minerals and a handful of other supplements that meet this standard. For example, melatonin has been shown to affect sleep cycles and has a record of safety, and we identified a product that met manufacturing and labeling standards.

The bad news is that this was a vanishingly small percentage of the total group. Around 90 percent of the companies we reached out to for verification never responded. They didn’t call us back, or their email or manufacturing addresses changed overnight. Of the remainder, many manufacturers refused to provide us with either a statement of G.M.P. or a C.O.A.; in other words, they refused to guarantee that their products were what they said they were. Others lied; they said they met G.M.P. standards, but a call to the F.D.A. revealed they had been fined for violations multiple times. Perhaps most surprising, some manufacturers willingly furnished information that their product didn’t meet standards — like one company that provided a C.O.A. showing that its product contained 47,000 International Units of beta-carotene, when the label stated 25,000.

Now, when parents in our hospital still want to use products whose quality can’t be assured, we ask them to sign a waiver stating that the supplement may be dangerous, and that most have not been studied for their effectiveness. “Use of an agent for which there are no reliable data on toxicity and drug interactions,” the waiver reads, “makes it impossible to adequately monitor the patient’s acute condition or safely administer medications.”

What can other individuals who are concerned about supplement safety do? They can look for “U.S.P. Verified” on the label — this proves the supplement has been inspected and approved under the United States Pharmacopeial Convention. Unfortunately, fewer than 1 percent of the 55,000 or so supplements on the market bear this label. The real answer is that, until the day comes when medical studies prove that these supplements have legitimate benefits, and until the F.D.A. has the political backing and resources to regulate them like drugs, individuals should simply steer clear.

For too long, too many people have believed that dietary supplements can only help and never hurt. Increasingly, it’s clear that this belief is a false one.