Changes in poop quantity, quality, and color is a concern to gut microbiome scientists and parents alike. In Science of Mom’s recent post “How Often Should a Baby Poop?” she discusses the amazing variability in pooping patterns between babies and also as a kid ages. I was, of course, excited to see that she mentioned a little about the influence of the gut microbiome, but her post inspired me to think more about pooping patterns from a microbiome perspective. Individual variability First, it’s not too surprising that there’s a huge variability between infants and pooping frequency. Several studies demonstrate that each individual’s gut microbiome is unique. In the guts of healthy adults, a single, unique bacterial strain can be used to identify each individual [1]. With each bacterial strain comes some unique abilities. Various bacterial taxa digest different foods and/or produce and transport different vitamins, amino acids, and other basic nutrients. So microbiome community A may process the nutrients faster, more efficiently, or completely than microbiome community B. That difference in the microbiome community function plus the differences in human gut anatomy due to human genetics could lead to a wide range in pooping frequency. Feeding differences Second, as Science