DIGESTIBILITY IS NOT DIGESTIBLE Dr. Wysong

Of course it's important that what is eaten be digestible. All that goes in should not also all come out. But where there is a valid notion, there will always be found an invalid marketing scheme. Digestibility tests are used to determine how much food is absorbed. It is assumed from this that food "A," because it is 95% digestible, is better than food "B," which is 90% digestible. But that would imply that if food "C" were 100% digestible, with zero fecal output, it would be the best food of all. Not so. Digestive tract health and the movement of food through the intestines where different elements are absorbed, depends upon a portion of food being indigestible. Certain kinds of food components such as fibers and oligosaccharides not only help maintain the health of the digestive tract but encourage the growth of friendly microorganisms that fight pathogens and exert a range of other health effects. Digestibility tests attach simplicity to that which is incredibly complex. Measuring how much is absorbed compared to how much is lost or excreted says nothing about the merit of what is absorbed. Nutrition is a tissue-level biochemical phenomenon, not a simple subtraction between what is eaten and what is excreted. Nevertheless, some pet food producers will promote their food based upon its digestibility percent. This must be seen for what it is, a ruse to create false confidence in a processed pet food so that people will feed it exclusively. Not only is digestibility not a true measure of value, it ignores that there is no generally accepted method for de­termining digestibility. This disagreement among the experts results from poor understanding. Since digestibility expert "A" disagrees with digestibility expert "B" and vice versa, we can disagree with either of them and have the backing of an expert. The wise approach to nutrition is to forget the lab tests and experts, feed dogs and cats as they are designed, and let the digestibility chips fall where they may. Mother Nature has things pretty well figured out and she is the only true expert.