Popcorn may be America's favorite snack food. Preserved cobs of popcorn thousands of years old have been found in Peru, Mexico, and the American Southwest. Memories are made of popcorn balls at Halloween and stringing popcorn to decorate the Christmas tree. Today, sitting through a movie without a bag of crunchy kernels is almost unthinkable.

Popcorn is the ideal snack. Eaten without oil or butter, it's a skinny 27 calories per cup. Since it's a whole grain with a high fiber content, it has a well-deserved recommendation from both the American Cancer Society and the National Cancer...