A recent U.S. Food and Drug Administration (FDA) warning letter sent to CytoSport, makers of Muscle Milk, calls into question the company's use of the word "milk" for products that contains milk-derived ingredients, but no actual milk. But the case is notable for another reason entirely: A year ago, the Federal Trade Commission (FTC), which specializes in labeling regulation, reviewed the use of "Muscle Milk" in conjunction with the disclaimer "Contains no Milk" and found that the label was not deceptive to consumers.

"I don't recall an instance where the two agencies have taken seemingly contradictory positions," said Ivan Wasserman, FDA lawyer and partner at Manatt, Phelps & Phillips, Washington, D.C. He added that this type of warning letter from FDA is not common. "The whole second part of the letter is nutrient content claims and those are common," said Wasserman, "But to say a trade name in itself is misleading is relatively rare." It's not clear if the FDA knew about the FTC's 2010 file [PDF].

The popular sports nutrition brand has made a big push into mainstream grocery over the last several years. Nutrition Business Journal estimates that total CytoSport sales were $200 million in 2010 with 20 percent growth, and that drinks such as Muscle Milk account for about $50 million in sales.

CytoSport's reaction

CytoSport addressed the warning letter in a press release, stating: "While CytoSport is proactively and openly addressing the FDA's labeling concerns, it is important for CytoSport's retail partners and for consumers to understand that at no point has the FDA raised any questions or concerns about the safety of Muscle Milk products."

CytoSport likened the FDA's inquiry about use of the word "milk" in the name Muscle Milk to "when the dairy lobby complained that other industries or products like Soy Milk, Almond Milk, Coconut Milk and Rice Milk are using the word 'milk' in connection with a product other than fluid dairy milk, all of which appeal to lactose intolerant consumers just as Muscle Milk does."

Will CytoSport be required to change its brand identity? This warning letter would seem to put their brand name in play with respect to FDA, said Wasserman, but the question remains to be answered. CytoSport will have to convince the FDA in order to keep its brand name and label claims.

One possible solution could be similar to the FDA's regulation for labeling "nondairy" foods [PDF] that contain a caseinate ingredient. "You have to say [the ingredient] is derived from milk on the label," said Wasserman. These ingredients are identified by a parenthetical statement in the ingredient list, for example: "sodium caseinate (a milk derivative)."