A new analysis from New York Attorney General Eric T. Schneiderman suggests that Americans are spending billions of dollars a year on ground up radish, rice mustard, primrose, alfalfa, spruce and houseplants. If this sounds like the most unappetizing plate at an avant-garde vegan restaurant, think again: It’s what the attorney general found when his office conducted DNA testing on six popular dietary supplements sold as house brands at four major retailers — GNC, Target, Wal-Mart and Walgreens.

The attorney general’s results cohere with those of a 2013 study in which Canadian researchers found no trace of the purported contents in a third of the 44 supplements they tested. But both teams found a whole lot else, some of which people with food allergies wouldn’t like in their bodies. The Canadian researchers found black walnuts in gingko biloba pills and an herbal laxative in St. John’s wort capsules, for example. Failure to list these ingredients on supplement labels is illegal — for good reason.

Representatives of the lightly regulated $13 billion dietary supplement industry fired back quickly, challenging the attorney general’s methods. Some outside experts agreed that the processing that supplement ingredients undergo might make it difficult to find the bits of DNA that the attorney general’s researchers were looking for. But even if that’s true, it doesn’t excuse the unlabeled filler ingredients the researchers found. It also doesn’t vindicate an industry that sells hope-based medicine with minimal federal oversight.

Adulterated supplements should be no surprise. A 2013 Journal of the American Medical Association analysis reported that “the FDA Tainted Supplement Report listed 332 adulterated products since December 2007.” But, it found, “only 222 of these products (69%) were recalled by the FDA.” Part of the problem was that the Food and Drug Administration didn’t even have the right contact information for a fifth of supplement makers. Moreover, an accompanying JAMA commentary noted, “Given the limited regulation of these products, it is likely that the number of recalls grossly underestimates the number of products on sale with unapproved ingredients.”

Though there is surprisingly little the law bars the industry from doing, supplement manufacturers can’t make any specific claims about efficacy of their products in the treatment of disease. That’s because government experts don’t rigorously evaluate them the way they do pharmaceuticals. Even so, The Post’s Jason Millman pointed out, a 2012 Health and Human Services Department study found that a fifth of the weight loss and immune support supplements it studied came with labels advertising “prohibited disease claims.”

The dietary supplement business has required more federal regulation for years. Congress should finally see to it.

Editorial by The Washington Post