If you're watching calories, choose bars that provide less than 250 calories per bar. The original sports bars provided 60 to 70 percent of calories from a mix of simple and complex carbohydrates. Either probably works as long as fiber is included in the mix. Look for a bar that provides at least 3 grams of fiber. In a recent survey reported by Environmental Nutrition, protein content ranged from 2 to 27 grams per bar among 28 bars evaluated.
Some protein is good, but too much of it is hard on the kidneys.
It's best to choose a bar with no more than 20 grams or 30 percent of total calories from protein. Sports bars traditionally come fortified with vitamins and minerals. While it may be argued that you could just as easily take a vitamin-mineral supplement, as long the level of fortification doesn't exceed 100 percent and you don't eat too many sports bars, the extra vitamins and minerals probably aren't an issue. As for herbs, bee pollen and other special ingredients that may be added to bars, the amount added generally isn't enough to have either a positive or negative effect. Sports bars are not cheap.