President Obama isn't just rewriting rules regulating the environment and the financial markets -- he is also going after the food industry.

Target and example No. 1: Cheerios.

"Based on claims made on your product's label," the FDA said in a letter to manufacturer General Mills, "we have determined (Cheerios) is promoted for conditions that cause it to be a drug because the product is intended for use in the prevention, mitigation and treatment of disease."

If the government's enforcement action against Cheerios were to hold up, the cereal would be pulled from grocery shelves and consumers would need a prescription to buy a box of those little oats.

That's unlikely, but experts say the message is clear: There is a new sheriff in town and when it comes to false, misleading and exaggerated labeling, you had better clean up your act.

"It is showing us that there is a new era," says dietician and a former advertising executive Ashley Koff. "They are saying, we are coming into town and we are going to show you what will and won't be allowed, and we're going to be going after every single claim, whether it's on a package or in TV."

Bruce Silverglade of the consumer advocacy group, Center for Science in the Public Interest, said it was a welcome and needed change.

"The Obama administration is reversing course, thank goodness, and enforcing the law," he said. "Cheerios was the first target. We hope though the FDA under the Obama administration clamps down on misleading health claims by other food manufacturers as well.

"During the Bush administration the Food and Drug Administration essentially took a policy of non-enforcement and failed to stop what became increasingly exaggerated claims, first by small food companies and by larger and larger food manufacturers," Silverglade told FOX News.

At issue are two claims made by Cheerios on their cereal box.

1. "Cheerios is clinically proven to reduce cholesterol 4 percent in 6 weeks."

2. "Cheerios can help reduce the risk of coronary heart disease, by lowering the 'bad' cholesterol."

Both General Mills and the FDA declined to comment -- but issued statements saying the two sides were in negotiations over the claims that have helped make Cheerios America's best-selling cereal, amounting to one of every 8 boxes of cereal sold in the U.S.

General Mills is a titan of the food business with an army of lawyers. If the FDA can make it back down, others will follow.