On food labels, they base the percentages on a 2,000-calorie adult diet. So looking at the label above for two crackers, a grownup would see that they provide less than 1 gram of fiber, only 3% of the person’s daily needs. So that means he or she would have to eat other foods to get 100% of the fiber needed each day.

Similarly, the person would see that the crackers provide nothing toward the daily goals for vitamin A, vitamin C, calcium, or iron.Food labels aren’t ideal for kids because t...