"It truly shocks the conscience that a company like Coke would try to keep customers by selling them a soft drink and telling them it's a vitamin," said Stephen Gardner, director of litigation for the group.

According to Reuters, Coke called the suit "ridiculous."

The Center for Science in the Public Interest may be on to something. Most people I know who drink Vitamin Water think that they're doing something that's healthy. But the reality is that Vitamin Water is loaded with sugar: An eight ounce serving has 13 grams of sugar, making it healthier than full-calorie soda, but only barely.

The issue is whether Vitamin Water is actually marketed deceptively. The label does warn that "These statements about Vitamin Water have not been evaluated by the Food and Drug Administration. Vitamin Water is not intended to diagnose, treat, cure, or prevent any disease."

The marketing of the product as a healthful alternative seems to be mostly done by implication: The label was designed to remind people of vitamins, but it seems unlikely that there's anything illegal about that.

More likely, the CSPI is generating publicity to get its message across: Vitamin Water is not the healthy drink you might think it is. The group is known for its attention-getting studies, such as the time CSPI conducted its own test on Wendy's and Burger King french fries and found they were still fried in unsafe levels of trans fat even though the city had banned it.