Philosophers frequently distinguish knowing from understanding. Knowing can be propositional—as in knowing that something is the case, for example, that the sun rises each morning, or practical—as in knowing how, for example, to take flour, yeast, water, oil, and salt and make it into bread. The two central forms of knowing are to be distinguished from understanding. Understanding goes beyond knowing in shedding light on the why. Not just that the sun rises, but something about why it does—gravitational pull, the arrangement of the solar system, and so on. In the case of baking—not just that the bread bakes up perfectly, but why it does—the workings of yeast, the effect of oven heat, and so on.
Many people adopt diet modifications to address their digestive issues, but they only do so based on a jumble of facts they may have encountered from the internet and other medical sources. They know a bunch of “thats” but really none of the “whys”. In today’s post I’d like to help readers move on to some “whys” by developing a better understanding of the internal symphony that is conducted within their bodies with each meal. The hope is that readers will gain both a theoretical and practical boost that will result in helping them fine-tune their digestive processes in ways that will promote overall better health.
For many people, deeper understanding provides a helpful springboard for healthy lifestyle improvements. I know it has done so in my own case after I was diagnosed with gluten intolerance years ago. I initially had a hard time keeping myself from eating gluten until I dove into the science of what it was doing to my intestines and inflammation levels. Once I really understood this, gluten not only didn’t entice me, it became somewhat repulsive and so much easier to avoid. I ended up getting it totally out of my diet which resulted in a good deal of symptom-reversal and healing. Because my own experience proved so powerful, I’d like to share it with my readers and so invite you to journey down the digestive tract with me to delve into some of the important whys that will elucidate the mysterious inner-workings of the system we carry around in our torsos and perhaps motivate you to do better in taking care of it so it can take better care of you.
Where to start? Many people think of digestion as something that occurs in the stomach. This is only partially correct. Digestion begins the moment you pop food into your mouth, and your mouth itself can be considered a digestive organ. How does the mouth digest? Mainly mechanically, by the process of mastication or chewing, but this is accompanied by the release of enzymes from our salivary glands that also start the chemical process of breaking down food to something we can ultimately absorb as well as creating lubrication to help you swallow.
Your mother undoubtedly told you to chew your food well, and this is why. Your mouth is critically important for this first digestive stage. You want to send food down your esophagus that has begun to be digested so the next digestive steps that occur are not impaired. You also want to eat slowly, so as not to swallow air and create stomach bloat, but also to allow your pancreas to do its job well down the line and signal fulness and diminish your appetite.
As chewed food is swallowed, passing a clever trachea-bypassing mechanism starring your epiglottis, your esophagus goes to work. Your esophagus is lined with muscles that contract and release in order to push food down the lengthy tube that is your digestive tract, a tube that has one opening at your mouth, and the other at your, well, you know. Many people report burning sensations in their esophagus and this can be due to the well-known phenomenon of GERD, where acids from the stomach below seep upward. Less known is that people can also feel as if food is somehow stuck as it travels through the esophagus, an allergic condition known as EOE or eosinophilic esophagitis that is due to currently poorly understood allergic reactions to foods, most often gluten and dairy. This is a lesser-known form of GI distress, but it should be something we are all aware of as it can easily be mistaken for and also accompanied by GERD. If you suspect this is occurring in your own tract, you will need an upper endoscopy for correct diagnosis.
After passing through the lower esophageal sphincter—one of five that regulates the flow of food through our overall tract—your food (finally!) reaches your stomach. As in the mouth, a complex of mechanical and chemical processes starts to kick in. Your stomach contains large muscles that churn and initiate digestion, and it secretes gastrin, a hormone that stimulates secretion of gastric acid and enzymes used to aid in breaking down food.
Your stomach processes food into a substance called chime that via the pyloric sphincter passes next into your small intestine where most digestion and absorption occurs. The small intestine is a twenty foot long structure, and it secretes two hormones critical to absorption. First, secretin which slows down stomach contractions and the passage of food through the pyloric sphincter as well as signaling the pancreas to release bicarbonate to neutralize stomach acid. Next, cholecystokinin (CCK) which tells the pancreas to secrete digestive enzymes to break down food, and the gall bladder to secrete bile and break down lipids. So there is a dance in the coordinated release of the hormones gastrin, secretin and CCK which makes possible the proper communication between your stomach and small intestine.
The small intestine physically absorbs the nutrients your body needs through small hairlike structures called villi. They dramatically increase the surface area of the intestine and contain the blood vessels and lymph vessels that that transport nutrients into the larger blood and lymph systems where your body can make use of them.
It’s worth pausing here to talk about what would happen, and what does happen, when these villi don’t function properly. Celiac disease is perhaps the most well-known cause of villi “flattening”, but there can be other causes that range from certain drugs’ side-effects, particular lymphomas, parasites, the ulcer-causing bacterium Helicobacter pylori, and also small intestine bacterial overgrowth or SIBO. Malnutrition occurs as a result, not to mention various symptoms of GI distress. What this tells us is that GI symptoms ought to be taken very seriously and their root causes sought out. Stomach and bowel issues may be indicating critical metabolic disfunction, which sadly can get masked by all of the GI-relief medications now available OTC. Learning about the details and critical importance of this portion of your digestive system is a strong argument for not allowing yourself to be lured into getting by with the symptom-maskers in lieu of finding a provider who can figure out what is really going on and work on truly healing you.
Continuing along on your food’s journey, we next arrive at the large intestine, about six feet in length, where the famed gut microbiome lives. The large intestine deals with anything that hasn’t successfully digested above, and also dehydrates and stores the material you will finally excrete.
The microbiome has two main jobs. By fermenting fiber it releases gas waste, and it metabolizes any undigested food generating important metabolites such as short chain fatty acids—which support our colon, brain, and liver, and vitamins K and B12. Aside from these two functions, the other critical function it plays is in stabilizing your immune response. When your gut flora are out of whack and the bad bugs overrun the good—which can be due to poor diet, antibiotics, stress, and other factors—this can impairs the mucus layer that serves as the barrier between the bacteria and your immune cells. When the mucus thins too much, the two of them interact in a way which triggers immune reactions that inflame your gut. One result of this can be that proteins in your gut leak through intestinal walls that have now become more permeable and enter your bloodstream, making your body suddenly feel under attack. It continues the ramping up of its immune function to deal with the perceived invaders, and this soon results in mounting system-wide inflammation. Inflammation is now implicated in most major chronic diseases, so you can see how this process could lead to long-term illness and how important it is to care for your inner flora.
What can you do to maintain gut health and prevent this cascade of dysfunction? As alluded to above, lifestyle factors matter, including the usual culprits of reducing stress, getting good sleep, and exercising. Also critical is what you start the whole digestive process at the outset, namely the foods you put in your mouth. Probiotic foods help a lot—these include fermented foods like sauerkraut, yogurt with live active cultures, kombucha, and pickled vegetables—as does prebiotic fiber which gives the gut flora something good to munch on and nourish itself with. Think of foods such as onions and garlic, whole grains, asparagus, and banana. Excessive dietary sugar also sends the microbiome out of whack, degrading the intestine’s mucosal lining and promoting inflammation, so it’s good to really limit it.
While there is much, much more to know about our digestive function, I hope this overview has given readers a little taste of the delicate interplay that occurs in the human GI system, and of how important each of the different actors is for our overall health. Albert Einstein remarked that “Peace cannot be kept by force; it can only be achieved by understanding.” Applied to this context, we can say that people who struggle to eat right and “keep the peace” within their own guts—in an era when so many people routinely describe themselves as being “at war” with their bodies—will have far more success the more they understand how the digestive systems works and can appreciate its delicate operation and needs. This post has tried to offer some initial insights toward such an understanding.