In the past month’s series on nutrition, I explained how the manner in which we eat can affect us as much as our food choices can. We looked at the vital roles that cooking and chewing play in digestion, and the importance of eating slowly and not too much. And I described the digestive tract from the mouth to the stomach. I think it’s important that everyone understands at least the basics of how their organs work, so let’s look at the rest of the digestive tract this time.
Although we may have teeth and reality TV, we’re more like worms than we like to think. We’re all just a bunch of cylinders, with a tube of the outside world running through us. Worms put dirt in theirs, we put marshmallows in ours.
After the mouth, esophagus, and stomach, food enters the small intestine, which is about 23 feet long. It’s where most nutrient absorption takes place, and all the value of good nutrition hinges on good absorption. At the beginning of the small intestine, a bunch of gastric juice is injected from the pancreas and gallbladder, which neutralizes the acidic food coming from the stomach, and makes the nutrients more absorbable. The pancreas produces a blend of digestive enzymes that break down the different components of food – fat, carbohydrates, and protein. The gallbladder squirts out bile (which is produced in the liver) to make fats absorbable.
The lining of the small intestine is composed of many folds, covered with tiny hair-like protrusions called villi (which are further covered with tinier hairs called microvilli). These greatly increase the surface area of the small intestine to maximize nutrient absorption. Some inflammatory conditions, such as celiac disease (gluten intolerance) and bacterial overgrowth of the small intestine (SIBO) can damage this membrane, leading to malnutrition.
The small intestine is followed by the much shorter but wider large intestine (most of which is called the colon). Food spends a very long time in the large intestine, where water and some remaining nutrients are absorbed, and stool is compacted and waits to be liberated. Finally, the stuff we can’t digest, along with waste products from throughout the body, leaves the rectum as stool. About 60 percent of its dry weight is bacteria.
Where does it come from? Riding along with us in our intestines are about 100 trillion microorganism passengers. There are about 500 different kinds, most of which are bacteria. They’re known as our “gut flora,” and they do all sorts of useful things for us, such as helping us digest things, protecting us from harmful microbes, synthesizing some vitamins, stimulating growth of intestinal cells, and assisting the immune system. We acquire these microscopic pals by eating food that’s contaminated with them or deliberately cultured with them (like yogurt and sauerkraut), and by taking them in supplements known as probiotics.
So, as we’ve seen, our environment (what we select from it based on taste) literally passes through us. We make the outside world into ourselves. It’s a practice worth taking seriously. Besides the healthy eating practices I discussed previously, some of the main factors in good absorption are having enough gastric juice, having healthy gastric membranes, having a strong and healthy population of gut flora, and having a relaxed nervous system.
Cultivating a relaxed nervous system has many additional benefits, so spend time in nature, eat in a calm environment, get massages, meditate, do whatever works for you to become peaceful. As for gastric juice, insufficient enzyme secretion is pretty common. Consider a good digestive enzyme complex, taken at the beginning of a meal. I’ve had at least a hundred patients who have overcome longstanding digestive problems just by supplementing for a while with digestive enzymes. Some people who have trouble digesting fat do well to take a product that also contains ox bile. Finally, promote healthy gut flora by eating live, fermented/cultured foods on a regular basis, and occasionally taking a course of probiotics (especially after using antibiotics).
If you’re interested in learning more about the big picture of eating and nutrition, check out the four week course I developed for The Dragontree, called How to Eat.
Dr. Peter Borten