Last Friday, April 27, marked the first time that the U.S. Food & Drug Administration (FDA) has sent warning letters with NDI-related language since 2010, prompting industry to wonder: Has NDI enforcement arrived?

In 2010, the agency warned supplement maker Unlimited Nutrition that its products contained piracetam—a nootropic drug—that did not meet the definition of a dietary ingredient. Before that, in 2004, FDA sent warning letters to 12 marketers of products containing the steroid androstenedione and asserted that their products were adulterated. Androstenedione, however, was already on its way to become a controlled substance, said Steve Mister, president and CEO of the Council for Responsible Nutrition. “FDA was just piling on at that point.”

Before 2004, no other NDI-related warning letters had been issued. Only a handful of warning letters has been issued in nearly 18 years—since 1994 when the Dietary Supplement Health and Education Act (DSHEA) gave FDA the authority to require NDI notifications.

“You can’t fault the agency for enforcing what’s clear on the face of the statute,” said Mister of the DMAA warning letters. “If you have an NDI, you must file.”

What is curious, though, is that FDA has so rarely taken the initiative to enforce the statute. “Industry shouldn’t be surprised,” said Todd Harrison of law firm Venable, LLP. “There is no doubt that DMAA is a new dietary ingredient. But FDA has allowed this to go on and on and on. FDA has created this issue through non-enforcement.”

FDA insisted in last week's warning letters to 10 sellers of DMAA-containing workout products that their products were adulterated because DMAA—a synthetic stimulant linked to the geranium plant—does not have a New Dietary Ingredient (NDI) notification to its name.