The tin of 7UP rolls to a stop at my feet. I pick it up, scowling at the kid on a bike who'd tossed it and missed the litter bin. The can is green and shiny: "Put some play into your every day," it says. "Escape to a carefree world ... Don't grow up. 7UP." And underneath, in tiny print, the real info (though you need a calculator to get to the truth): the lemon- and lime-flavored drink contains a trace of salt, no fat, no fiber and 34.98 grams of sugar — eight teaspoons — and 135 calories. That's enough energy for an hour's cross-country running. It's cheap, too. Half the price of milk.