The U.S. Food and Drug Administration sent a warning letter to General Mills Inc. last week asking it to change how it promotes the health benefits of Cheerios. The FDA told General Mills to stop promoting Cheerios, the country’s best-selling cereal, as a product that can lower cholesterol levels, reduce heart disease and reduce the risk of cancer. The agency said that claiming the cereal can lower cholesterol levels by 4 percent in six weeks amounts to marketing it as a drug and violates the federal Food, Drug and Cosmetic Act. A local branch of the FDA gave the Minnesota-based...