With only 1 gram of sugar per serving, Cheerios is one of the least sweet U.S. cereals.

It's almost as sugar-free as the ultimate "but-it's-good-for-you" cereal, shredded wheat.

As for Cheerios' myriad line extensions -- that's another story. The majority of them, including Honey Nut, contain 9 grams of sugar per serving, and all 12 extensions together average 8.5 grams.

The proliferation of Cheerios with added sugar comes at a time when General Mills has been an industry leader in cutting sugar in cereals marketed to children. Kid brands like Trix that had 12 or 13 grams of sugar a few years ago now have 10 grams, and the company is working on hitting single digits.

Flavored Cheerios are part of the "family" segment of the cereal business: They're aimed at all age groups.

Bolstering sugar in extensions of an otherwise low-sugar brand isn't uncommon. Kellogg's has done the same with its Special K brand.

And such sugar surges aren't necessarily surprising, said Marcia Mogelonsky, a food industry analyst at market researcher Mintel.

Cereal is basically oats, corn, wheat or rice, and "there are only so many taste profiles you can have without adding sugar," she said.

For some context: Cheerios and many breakfast cereals have less sugar per serving than such common breakfast offerings as popular yogurt brands and frozen waffles with syrup.

MIKE HUGHLETT