Food is Complex and Contains Many Types of Molecules

Food is a very complex mixture of different types of very large molecules—the proteins and some carbohydrates; mid-range sized molecules—such as fats; and a wide variety of smaller molecules including vitamins, minerals, small carbohydrates like sugars, and other phytonutrients, which are protective substances found in plants (phyto = plant). Most foods you eat are a mixture of all of these different molecules, and since you need a variety of types of nutrients, your body must be able to digest these varied types of molecules in food.

The size, as well as the type of molecule, makes a difference in how a food is digested, the nutrients that are derived from it, and where these nutrients are taken up by your body. Each type of molecule has its own challenge with respect to digestion.