What’s Going on in My Belly? Digestion 101
As a part of my integrative nutrition practice, I often teach seminars on how to create a healthy, well-functioning gut. It’s always a pleasure to share what I’ve learned and show others how they can take control of their gut health by harnessing the healing power of food.
For those who are new to the idea of food as medicine, or those who have suffered for years with gastrointestinal problems, one of the first questions they ask is, what’s going on in my belly? And the answer is, quite a lot. The digestive system (working well or not) is an extraordinary machine inside us all, so in order to improve performance and keep it in good working order, it helps to know the basics of how it works. This is your in-a-nutshell owner’s manual – and simple guide to the amazing process which takes place each time you feed your body:
It’s in your head!
Digestion actually begins in the head. We call the first phase of digestion “cephalic,” from the Greek, meaning “from the head.” It kicks in when we think about food or a tasty meal. The sheer anticipation stimulates the production of salivary enzymes in the mouth that begin to break down the carbohydrates in our food. The saliva itself is a lubricant that ensures a smooth trip down the short, muscular tube of the esophagus.
Next, it’s on the move.
Here is the way the system works:
• The food moves down the esophagus into the stomach, a balloon-like muscular bag that breaks the food into much smaller particles, physically squeezing it and secreting enzymes and powerful gastric acids (and that’s a good thing- you want your stomach to produce acid!).
• The stomach then slowly pours the processed contents of the meal, now a liquid called chyme, which has the consistency of a smoothie, into the small intestine, where most of the work of digestion takes place.
• Assisted by the pancreas, which secretes digestive enzymes, and the gall bladder, which houses bile, the small intestine breaks down the carbohydrates, proteins and fats in the chyme into their most basic components.
It’s in the pipeline.
If the stomach resembles a factory, with its nonstop pulverizing and chemical baths, the small intestine is something closer to the undersea world of Jacques Cousteau, home to exotic-looking bulbous structures and beautiful in its own way.
In the small intestine, some twenty-plus feet of tubing is folded in on itself, but the surface area is much greater than even that suggests. Completely flattened out, it would cover a tennis court! That’s because the tissue itself is corrugated, formed into tiny fingerlike projections covered with tentacles called villi. The villi snatch food as it drifts by, in much the same way that coral feeds on floating plankton.
The villi absorb the nutritional molecules into the intestinal wall, where they pass into the blood and lymph systems and from there to every cell in the body that needs them. What isn’t absorbed passes down into the colon in liquid form—the walls of the colon are like a giant sponge that sends most of the water back into the body. And in the colon, the undigested fiber is grabbed up by the bacteria who live there who ferment it into protective compounds called short-chain fatty acids.
Down the drain!
Finally, the waste products are sent packing, making the passage through the last piece of GI tract tubing, the sigmoid colon, before being eliminated or as my granddaughter might say, ‘pooped out’ of the body.
What does it all mean?
When you think about all that’s going on in your gut after you’ve eaten a meal, all those parts working together, breaking down food, extracting the nutrients, sending them to where they’re needed and eliminating the waste, it’s hard not to be impressed by the remarkable creation that is your digestive system. Seen in this light, students often gain a newfound respect for digestion and start to connect with the idea of feeding the machine wisely to ensure the engines run smoothly for years to come.
For more thoughts on how to create a vibrant diet, a healthy gut and microbiome (the bacteria that live in your gut), check out my book The Swift Diet: 4 Weeks to Mend the Belly, Lose the Weight and Get Rid of the Bloat.