Nestle (Stock Quote: NSRGY) can no longer claim that its Boost Kid Essentials nutritional drinks can increase immunity and prevent illness leading to missed school days, government regulators say.

Nestle product advertising says the nutritional drink can reduce the incidence of illness including upper respiratory tract infections, protect kids from cold and flu viruses and reduce the duration of diarrhea, according to the Federal Trade Commission. However, those claims were unproven and are considered false and misleading, the FTC says.

The Food and Drug Administration usually contests misleading claims in product labeling, but since commercials and other advertisements in particular were in question, the FTC, which handles claims made in ads for over-the-counter drugs, is involved.

“… Clinical studies do not prove that drinking Boost Kid Essentials reduces the general incidence of illness in children, including upper respiratory tract infections, reduces the duration of acute diarrhea in children up to the age of thirteen, or strengthens the immune system, thereby providing protection against cold and flu viruses,” the agency said in a complaint against the company.

Probiotics, which line the inside of straws that come with the drinks, are the source of the company’s health claims.

The National Center for Complementary and Alternative Medicine has backed the use of probiotics to help make lactose more tolerable for consumers with lactose intolerance.

While some consumers and health experts say that probiotics, which are considered “good bacteria,” do help regulate the digestive systems, studies have failed to confirm that they’re more than simply a highly-advertised fad, the FTC suggests.

Last year, Dannon settled a class-action lawsuit after it claimed that its Activia yogurt helped promote a healthy digestive tract even though studies were inconclusive.