In a previous question I addressed the issue about raw vs. cooked foods. This week I would like to take this topic one step further and talk about how raw vs. cooked foods affect digestion. The ability of a particular food to provide us with nutrients is never the end of the story when it comes to our nourishment and health. Our bodies need to absorb the nutrients found in the food in order for our body to take advantage of its health benefits! For this reason, proper digestion becomes an important consideration when it comes to maximizing the nutrients we get from the food we eat.
Just as the exact nutritional consequences of cooking depend upon the food in question, the nutrient in question, and the exact cooking method used, success in digestion of raw versus cooked foods also depends on a variety of specific factors. As a broad and general rule, the human digestive system is fully equipped with the ability to digest both raw and cooked foods. The ability to digest food is a complicated process, and it can involve both physiological and psychological components. But for the purpose of this article I want to focus on some basic steps in the "mechanics" of digestion, starting with chewing.
Digestion of raw foods places a greater demand on chewing than digestion of cooked foods because the grinding and tearing of raw foods through chewing is the only means available for exposing food nutrients to chemical activities that will be occurring later on in the process of digestion. These chemical activities include: secretion of fluids such as gastric acid and bile; secretion of digestive enzymes; and secretion of other digestion-related substances. Thoroughly chewed raw foods are well prepared to continue their journey through our digestive tract and become further digested with the help of these chemical processes. However, poorly chewed raw foods may not be able to take advantage of these chemical processes to the same degree. For example, a peptidase enzyme designed to help release an amino acid (or short amino acid chain) from a food protein may not be able to link up with that food protein as required unless chewing has made the right spot on that food protein accessible to the enzyme. We have yet to see large-scale human studies showing a direct link between raw food intake, inadequate chewing, and nutrient deficiency. But we have seen small-scale studies showing nutrient deficiency in older study participants who are demonstrated to have compromised chewing ability.
The cooking of foods can accomplish two helpful goals with respect to digestion. First, it can help make food easier to chew. Since we use minimal cooking methods at WHFoods, this difference might be fairly subtle. For example, a steamed broccoli floret might not be dramatically easier to chew than a raw broccoli floret. However, the difference might be just enough for our chewing process to prepare the floret for further digestion in a more complete way. Second, cooking can change the chemical structure of food, and in some cases, there is a temperature-based "unfolding" of certain molecules (as occurs, for example, with myofibrillar proteins in meats). For vegetables, cooking can bring about changes in cell wall structures, which is typically referred to as "thermal softening." In some cases, this thermal softening can help prepare the way for further digestion in the GI tract. In no case is cooking a substitute for chewing. Thorough chewing is essential in the case of all solid foods, whether raw or cooked. But the overall risk of digestive compromise can be greater for raw versus cooked foods whenever thorough chewing is either difficult to achieve or simply not achieved for lifestyle reasons (eating too quickly, not paying attention, etc.).