McDonald's this week began making apples standard with its children's meals, and while the fruit may not be a nutrient blockbuster, it has many appealing characteristics, such as soluble fiber and antioxidants, especially in the skin. Apples are likely to have high loads of pesticide residue, so organic versions may be a better choice, but nutritionists say the fruit still makes a great low-calorie snack that offers variety and easy storage.