Fair warning…we are about to get a little nerdy! There is a lot going on in our digestive system, I’m going to do my best to make it easy to understand. 

Generally speaking, I don’t think many of us think about our digestion much. Unless we have digestion problems like acid reflux, upset stomach, diarrhea, bloating, gas, or something that makes us uncomfortable. 

Guess what…those problems or symptoms are our body telling us that something is wrong. We need to take that information and figure out how to resolve the problem. So let’s get into it.

First let’s just get some basics out of the way. How is digestion supposed to work? What is digestion? 

Digestion is the process of breaking down food (through mechanical and enzymatic action) in the alimentary canal so that it can be utilized by the body. In other words, it is the process of reducing the food we eat into small enough pieces that it can be absorbed and used by our bodies. 

Now, there is more to digestion than just digestion. Confused? That’s ok. I’m going to explain. 

One of the big ideas hammered home to me when I was learning about this in my Nutritional Therapy program is this: Digestion is a North to South process. It really starts in your brain, because your brain is what tells the rest of your body to do their jobs. If something is going wrong, we should start at the top and work our way down to resolve the problem. 

For the purposes of learning about digestion, let’s pretend we are sitting down to a yummy meal with friends. You choose something that sounds good to you. Here is a diagram that you can refer to so you can follow your meal through the digestion and elimination process.

Before you even put the food in your mouth, the sight and smell of it are initiating your saliva glands to start getting ready to work and produce saliva. When you finally get to ingest the food through your mouth, the saliva is there, ready and waiting with enzymes that start the breakdown of carbs, and your teeth are ready to (mechanically) break down food into smaller pieces. 

A note here: Do not discount the importance of chewing your food. 

The better we chew our food, the easier it is for the rest of the digestive tract to do its job because it isn’t dealing with breaking down large pieces of food that should have been chewed better. It really sets the rest of your digestive system up for success. 

Ok, so our food is in our mouth (chew, chew, chew) but eventually we have to swallow, right? So where does it go next? The esophagus. And then on into the stomach.

In the stomach, gastric juices, specifically, Hydrochloric Acid (HCL), Pepsin and mucus are excreted and continue the breakdown of the food. We want our stomach to be acidic. The acid kills any bad stuff lurking in our food, cleans the stomach and activates other digestive processes. The stomach churns the food and mixes it with the gastric juices. This mixture is called chyme and needs to be acidic in order for the valve between the stomach and the small intestine to be triggered to open. Once the stomach has done its job the pyloric sphincter opens and releases the chyme, into the small intestine. 

A lot happens in the small intestine, which is made up of the Duodenum, Jejunum and the Ileum. 

The acidity of the chyme stimulates the duodenum to secrete mucus as well as two hormones into the bloodstream, secretin and cholecystokinin (CCK). The secretin runs to the pancreas and tells it to release some bicarbonate and pancreatic juice, while the CCK goes and tells the gallbladder to release some bile. The pancreatic juices continue the digestion of carbs, proteins and fats, the bile emulsifies fats for absorption, while the bicarbonate neutralizes the chyme pH.

Once the chyme leaves the duodenum it is almost fully digested. Carbs become glucose molecules, proteins are now broken into amino acids and polypeptides, and fats are fatty acids and glycerol molecules and are moved into the Jejunum and Ileum for absorption. 

Inside the Jejunum and Ileum are a bunch of hair-like structures called villi and microvilli, they absorb all the nutrient molecules into the blood stream so they can be taken throughout the body for use. Glucose, amino acids and short-chain fatty acids are carried to the liver while the long chain fatty acids that require bile for absorption are taken into the lymph system. 

Anything left over and not absorbed, things like indigestible fiber, leftover bile, water and body waste like sloughed off cells are then passed into the large intestine, better known as your colon. 

What happens in the colon? Well, this is where water gets recycled, waste materials are recycled (they nourish the colon cells), gut flora can capture any nutrients that got missed and convert them to certain vitamins, and your poop is formed and expelled. 

Pretty cool that all this is happening and we don’t have to think about it, huh? 

This was a pretty high level overview of how things are supposed to work, but there are a lot of places things can go wrong and that is where the yucky symptoms come in. I will talk about a few of the ways things can go awry in a future post. (Stay tuned!)

For now, remember to chew your food and try to eat in a relaxed and enjoyable environment. Those two things can make a world of difference in your digestion.