Officials at the Center for Science in the Public Interest in Washington said when companies claim their products will maintain a "healthy immune system" consumers believe this means those products will help ward off disease. However, while vitamins A, C and E are important for the functioning of just about every system in the human body, there's little evidence to suggest, for example, drinking Crystal Light with those vitamins will have any impact on the average person's immune system, said Bruce Silverglade, the center's legal affairs director.

Likewise, Green Giant Immunity Boost consists of frozen broccoli, carrots, pepper strips and seasoning, which Silverglade says is a perfectly healthful food, but maintains there is no evidence to support the claim the product "supports a healthy immune system" or provides the promised "immunity boost."

In a formal complaint, the non-profit group said the agency should stop such claims and set new rules for food companies requiring them to base future claims on solid scientific evidence.