The Food and Drug Administration’s lethargic regulation of dietary supplements containing a dangerous stimulant described in recent reports in The Times is a classic example of what happens when industry representatives infiltrate the agency that is supposed to regulate them. The worrisome ingredient is BMPEA, a chemical nearly identical to amphetamine that is added to weight-loss and workout products in an effort to enhance their effect. Whether it does so is unclear, since there have never been tests of its effectiveness and safety in humans.

As noted in The Times, the F.D.A. was actually the first agency to suspect that BMPEA had been added improperly to supplements that listed among their ingredients a little-known plant called acacia rigidula. Experts say that listings like this are often tip-offs that the manufacturer is trying to disguise a chemical additive as a natural botanical extract. The agency tested 21 popular supplements that listed acacia rigidula on their labels and found that nine of them contained BMPEA.

The F.D.A. did not, however, recall the products, name them or issue a health alert. By contrast, in December, Canadian health authorities found the chemical “a serious health risk,” issued a public health alert and forced a recall of JetFuel Superburn, which they found to contain BMPEA and another amphetamine-like stimulant.

Much of the responsibility for the F.D.A.’s sluggish response must fall on Dr. Daniel Fabricant, who left a senior position at the Natural Products Association, a trade group for supplement makers and sellers, to head the F.D.A.’s division of dietary supplement programs in early 2011 and who jumped back to the trade association as its chief executive in the spring of 2014. He has been succeeded at the F.D.A. by several acting directors; the current one is Cara Welch, from the same trade group. Both dragged their feet on BMPEA.