The U.S. Food and Drug Administration announced this week that it sent warning letters to several companies alleging that their dietary supplement products containing Phenibut (a GABA analogue) or DMHA (chemically similar to DMAA) were adulterated and/or misbranded, in violation of the Federal Food, Drug, and Cosmetic Act (FDCA). Both the legal bases for the warning letters, and the method that FDA used to announce them, are interesting and important for all manufacturers and marketers of dietary supplement products to understand.

Unlike most warning letters relating to dietary supplements, the Phenibut and DMHA letters did not include any allegations regarding promotional claims or violations of good manufacturing practices. Instead, the agency alleged that the mere presence of either ingredient in a dietary supplement product renders it unlawful, because neither Phenibut nor DMHA is – according to the agency – a "dietary ingredient." Under the Dietary Supplement Health and Education Act (DSHEA), the term "dietary ingredient" is defined as (among other things) "a dietary substance for use by man to supplement the diet by increasing the total dietary intake."

The legal implications are potentially significant. Notably, the warning letters do not include any allegation that either ingredient, or any product containing either ingredient, is unsafe. While the major trade associations have called into question their safety, the FDA did not have to. If the agency can demonstrate that an ingredient is not a dietary ingredient, then a product labeled as a dietary supplement containing that ingredient violates the FDCA, regardless of whether the ingredient is unsafe. This does not mean, however, that the FDA's position is indisputable. After all, what exactly does it mean to increase total dietary intake? Might this be subject to legal challenge? Until someone is willing to challenge the FDA's position in court, this issue will remain open to debate.

The way in which the FDA announced this action also merits attention, as it likely signals an effort to improve deterrence with more robust and aggressive communication. This "Constituent Update" referenced former FDA Commissioner Gottlieb's statements regarding the agency's new efforts to provide faster access to consumers on supplement information, including an "Ingredient Advisory List," which it describes as a "newly launched, rapid-response tool." We expect to see more announcements and press releases regarding future actions against dietary supplements in the coming weeks and months.