The No. 2 U.S. cereal maker behind Kellogg Co. said the move affects 29 brands, including Rice Chex and Golden Grahams. The company did not disclose the cost of the whole-grain makeover.

Some big U.S. foodmakers have changed their offerings recently amid America's growing obesity problem. McDonald's Corp. launched meal-sized salads, Kraft Food Inc. has been promoting the South Beach Diet and Campbell Soup Co. removed artery-clogging transfatty acids from its Pepperidge Farm Goldfish crackers, among other moves.

Cereal makers have historically tended to use milled or refined grains, whose processing takes away the grain's health-promoting bran and germ portions.

But health experts say eating whole or unrefined grain could help reduce the risk of ailments like heart disease, cancer, diabetes and obesity.

STILL AS TASTY?

General Mills, which introduced Wheaties in 1924 and Cheerios - originally called Cheeri Oats - in 1941, said shoppers can expect to find the new "Whole Grain"-labeled cereal boxes on supermarket shelves within the next few weeks, and that the roll-out will continue into the new year.

Among its brands that are already whole grain are Cheerios, Wheaties, Total and Wheat Chex. The ingredient switch won't kill the taste, the company said.

General Mills said that after taste tests conducted with more than 9,000 people across the United States, the new whole-grain cereals were liked just as much or even better than the previous types.

Whole grains are thought to help lower cholesterol and blood pressure and improve how the body processes insulin and glucose. Compared with their highly processed and refined counterparts, whole-grain cereals also contain more beneficial micronutrients, antioxidants, minerals and fiber.

According to the American Dietetic Association, whole grains are made up of all parts of the grain: the bran (or fiber-rich outer layer), the endosperm (middle part) and the germ (the nutrient-rich inner part). Eating a variety of whole-grain foods brings the nutritional benefits of all parts of the grain, experts say.

General Mills shares were down 5 cents at $45.04 on the New York Stock Exchange last week afternoon.