The old adage “you are what you eat” was meant to be a reminder that our daily food habits will have an effect (directly or indirectly) on our body composition and health. As we shall explore, this is partly true, though it is a bit more complicated when we get into the details. Perhaps we might say that we are what we absorb, since eating foods and absorbing or utilizing their nutrients is not always the same thing; especially in individuals with poor digestion. Reduced nutrient absorption, however, is just one facet of poor digestive health. In fact, various symptoms related to the digestive process (i.e., indigestion/dyspepsia) are some of the most commonly experienced symptoms by individuals worldwide; and the use of prescription, OTC and dietary supplements to aid digestion or relieve dyspeptic symptoms is rampant in the United States. This monograph will discuss both the fundamental principles of digestion and absorption, along with the most common dysfunctions related to digesting and absorbing nutrients from dietary sources. We will also review ways in which digestion can be improved using lifestyle changes or dietary supplementation.