Читать книгу Nutrition For Dummies - Carol Ann Rinzler - Страница 37

When every useful, digestible ingredient other than water has been wrung out of your food, the rest — indigestible waste such as fiber — moves into the top of your large intestine, the area known as your colon. The colon’s primary job is to absorb water from this mixture and then to squeeze the remaining matter into the compact bundle known as feces.

Feces (whose brown color comes from leftover bile pigments) are made of indigestible material from food, plus cells that have sloughed off the intestinal lining and the bodies of bacteria, members of the microbiome (see the nearby sidebar “Prebiotics and probiotics: The good gut twins”). In fact, about 30 percent of the entire weight of the feces comprises the bodies of these microorganisms, which live in permanent colonies in your colon, where they

 Manufacture vitamin B12, which is absorbed through the colon wall

 Produce vitamin K, also absorbed through the colon wall

 Break down amino acids and produce nitrogen (which gives feces a characteristic odor)

 Feast on indigestible complex carbohydrates (fiber), excreting the gas that sometimes makes you physically uncomfortable — or a social pariah

When the bacteria have finished and their bodies have been incorporated into the waste, the feces — small remains of yesterday’s copious feast — pass down through your rectum and out through your anus. But not necessarily right away: Digestion of any one meal may take longer than a day to complete.