Lazy Larry brownies contain melatonin. So does the drink called NeuroSleep, which I wrote about this morning in The Checkup as a potential sleep aid.

The FDA last Thursday issued a warning letter to the brownie makers, telling them that the agency considers the brownies unsafe because they have melatonin as an ingredient.

The brownies are under fire because they’re considered a food, not a dietary supplement. The latter may include melatonin as an ingredient; the former may not. NeuroSleep is on more solid ground because it’s considered a dietary supplement.

Melatonin is a neurohormone that the human body produces to help regulate the sleep cycle. Synthetic melatonin is used as a dietary supplement to treat some sleep disorders.

According to FDA regulations, ingredients used in conventional food must either be classified as approved food additives or be among the ingredients classified as “generally recognized as safe,” or GRAS. Melatonin has not been shown to be safe when used as a food ingredient.

The rules are different when it comes to dietary supplements. The FDA doesn’t exert much regulatory activity over dietary supplement ingredients; manufacturers are expected to ensure that the ingredients they use in their products are safe.

One of the concerns is that an unsuspecting consumer buying a melatonin-laced brownie may not be aware that he or she is ingesting a dietary supplement, whereas a person buying a dietary supplement drink probably knows what he or she is getting into.

As the lines between conventional foods and dietary supplements continue to blur, watch for this issue to pop up more frequently.

Chris Noonan, scientific and regulatory affairs adviser to the Neuro line of drinks (not “beverages,” as those are considered in the same class as conventional foods), would welcome some further guidance from the FDA. “This has nothing to do with the safety of melatonin,” he says, “but about the presentation of supplements as food.”

“I would rather the FDA establish a better distinction between food and dietary supplements and enforce that distinction, so brownies can’t be marketed as dietary supplements.”