WALNUT CREEK, Calif. — Sam Williams' eyes light up the moment he takes his first sip of soda.

"Wooeee," the 6-year-old from Concord, Calif., exclaims. "I never had that before."

Until a recent Times taste test, Williams had never sampled soda. Instead, his regular fare consists of mostly milk and juice — the healthful choices, right?

Maybe not entirely.

Milk and water are recommended, according to the Dietary Guidelines for Americans 2005. Juice is advised only when consumed in moderation. And any drink made with high fructose corn syrup is out.

"It's hard to know what's the right thing to give kids these days," said Denise Michaels, a Pittsburg, Calif., mother of three, as she recently shopped for drinks to put in her children's school lunches. "Water always seems to make the list, but my kids want something sweeter."

The beverage industry is heeding that call. In the past two years, more than a dozen beverage companies have unveiled flavored water or watered-down juice products.

But are they the best options in kids' drinks?

A decade ago, 100 percent fruit juices were considered among the best, a true staple for growing children. Now, the American Academy of Pediatrics recommends limiting daily consumption to 4 to 6 ounces for 1- to 6-year-olds and 8 to 12 ounces for 7- to 18-year-olds.

The reason is sugar. Juice takes sugar from a fruit but not the fiber, which is why whole fruit is considered the more nutritious choice, says Afroz Subedar, a registered dietitian at Children's Hospital Oakland, Calif.

"Because of the rise in Type 2 diabetes," adds Geoffrey Marx, a certified nutrition consultant in Lafayette and staff nutritionist for Health Medicine Center, "we're looking harder at the sources of sugar in our diets.