WASHINGTON, DC: It emerged today (Wednesday) that the US Food and Drug Administration fired a warning shot across the bows of Coca-Cola earlier this month, demanding that it revise the label on its Diet Coke Plus brand.

Specifically, it's the 'Plus' to which the FDA has taken exception, alleging that the drink lacks enough nutrients to justify the term.

According to FDA guidelines, foods may use 'Plus' only if they contain at least 10% more of the reference daily intake or daily reference value of a nutrient than a similar product.

And in Coke's case, the FDA also dusted-off a longstanding rule that "does not consider it appropriate" to fortify snack foods such as carbonated beverages.

The warning letter sent two weeks ago to the Atlanta behemoth is also intended to deter other manufacturers of nutrient-enhanced beverages, from energy drinks to enhanced waters, that have recently materialized on store shelves.

Observers see it as a signal that the FDA will more intensively police marketers' product-benefits claims.

But hunkered down in its Atlanta fortress, Coke remains defiant, saying that it has no plans to change the label. Purports a spokesman:  "We take seriously the issues raised by the FDA in its letter."

Then the single-finger salute … "This does not involve any health or safety issues, and we believe the label on Diet Coke Plus complies with FDA's policies and regulations."

Data sourced from Wall Street Journal Online; additional content by WARC staff