Most people are at least roughly familiar with the basic workings of the digestive system.
When we eat food, we take it in through our mouths and the digestive process begins with chewing. Then we swallow, sending the food through the esophagus into the stomach. In the stomach, it is squeezed and mixed with digestive fluids, becoming a mixture called chyme. This chyme then passes into the small intestine, where it is further broken down and nutrients are absorbed into the bloodstream, before finally passing into the large intestine to have the last of the excess fluid drawn off and the remainder passed as waste.
There is so much more to the digestive system, though! As is true of most things in the body, this is a highly-complex system, and it is astounding that the process works as well as it does as often as it does. There are other contributing factors to the process of digestion; if your digestion is not working well, you might want to investigate some of these other avenues, too.
Digestive Enzymes, etc. — We don’t often think of the pancreas, liver, and gallbladder when considering digestion, but they play a pivotal role. The pancreas is responsible for producing a number of substances that enable digestion to occur. For instance, many digestive enzymes are produced in the pancreas (for breaking down various foods into their component parts) and insulin is produced in the pancreas (to regulate how much of the sugar we ingest gets into the bloodstream). Bile is produced in the liver (for digestion of fats). The gallbladder’s job is to store the bile until it’s needed, releasing as much as is necessary and no more.
Valves — There are valves at several points in the digestive tract, to enable food (and the mixtures it is “blended” into) to pass from one stage to the next, without allowing it to flow the wrong direction. In particular, there are valves at the junction of the esophagus and stomach, at the stomach and small intestine, and where the small and large intestines meet. If one of these valves malfunctions, it can cause discomfort and potentially lead to other problems. (Perhaps most commonly, the LES — lower esophageal sphincter — the valve separating the esophagus from the stomach, malfunctions, often due to poor positioning in relation to the gallbladder. This can lead to GERD-like and similar symptoms.1 2)
Intestinal Mucosa & Cilia — The intestines are lined with finger-like projections called cilia. These cilia are in constant motion — imagine the arms of an arena full of ballgame attendees doing the wave and you’ll have the general gist — and their movement helps move things along. As you can imagine, if they get damaged, things don’t move along so nicely anymore.
The intestines are also lined with a layer of mucus, in which reside an assortment of bacteria. The mucus protects the intestinal tissue (including the cilia!) and helps serve as a barrier so only the things which should get through the intestinal walls (like nutrients) get through. Bacteria serve a variety of functions, such as keeping bad bacteria in check, regenerating that mucosal lining, and helping draw out — and even, in some cases, producing — vitamins.3
Because of the large network of nerves that are present in the digestive tract, a disruption here can cause some surprisingly far-reaching problems. Not only can digestion become uncomfortable and/or malnutrition begin to occur, but we can even start to see mental and emotional difficulties, skin problems, etc. It’s very important for digestive health — and thus, for overall health — to continually replenish and “feed” these “good” bacteria by providing plenty of whole foods (with fiber!) and including fermented foods in the diet.
Most of us intuitively recognize the external signs of healthy digestion: we feel good, and we don’t have to pay too close attention to what’s going on in our guts. Digestion shouldn’t regularly be uncomfortable or “draw attention to itself.” Sometimes poor digestion may not be clear from general observation. If, for instance, nutrients are not being absorbed well, but there is no discomfort, it may not be immediately clear that digestion is the problem. (It may, in fact, not even be obvious there is a problem, until it has gone on for a while.)
As gross as it may sound, the appearance of our stool can act as a helpful signal of how our digestive systems are doing. Since you see it on an everyday basis, it is also a non-invasive, free way to keep an eye on how your body is doing.
Healthy stool should not be foul-smelling. I’m not saying it ought to smell like roses or anything, but those using the restroom after you should not want to curse you if everything is working the way it should.
Healthy stool should be (generally) brown, well-formed, and easy to pass. If it is very dark, or oddly colored (unless you’ve eaten something known for discoloring the stool)*, or very pale, that can indicate a problem. It should not be watery (of course) or loose, hard and segmented into pellets, or “shrivelly” and hard to pass. It should not be oily or tarry.
There is some debate over whether healthy stool should sink or float. As a rule, watch for an unexpected change in this trait.
An occasional, brief change in appearance is probably nothing to worry about, but any ongoing change should be a red flag. Any blood in the stool (which may look like blood, or may just appear very dark) should be checked out immediately.
*Foods known for their strong pigmentation may sometimes alter the stool color. Beets, for example, have sent some parents into a panic when their little ones seemed to have bloody stools. Iron supplements and activated charcoal are fairly common causes for dark stool.