Digestion - how does it work?

You may be wondering how the stomach works and what happens when food leaves the mouth. How does digestion actually work? What happens in the intestines? And what constitutes a good end product (poop)? In three parts, we will explore the journey of food from beginning to end. It’s a fascinating physiological journey that we believe will be beneficial for you to know more about.

The Gastrointestinal Tract

The gastrointestinal tract measures a whopping 7 meters from mouth to anus. You may have heard that there is an upper and a lower part. While that’s true, those who think that the upper and lower parts are unrelated are mistaken! It’s all one continuous tube, and what happens at the start affects the final outcome.

Fast or Slow Digestion

How long does it take from start to finish, or from food to poop? It varies depending on whether one has a fast or slow digestive system. It can take anywhere from 8 to 36 hours. The most optimal time is 24 hours, allowing you to digest food properly, absorb nutrients, and also have a bowel movement every day. But wait, must one go to the toilet every day? No, many people don’t, and we don’t want to create performance anxiety; we just want to provide you with a goal to aim for.

Where do we start? Well, in the mouth. Here, food should be chewed thoroughly, preferably into a liquid consistency. Digestion actually begins in the mouth, where enzymes are secreted to start breaking down the food. By chewing properly, you essentially do the prep work for the stomach, which doesn’t need to start from scratch.

Enzymes and Hydrochloric Acid

Through the esophagus, food travels down to the stomach, where it mixes with digestive juices that contain enzymes and hydrochloric acid. The pH level in the stomach is very low, creating an acidic environment. Therefore, it’s beneficial to take probiotics with food since the pH in the stomach is slightly higher at that time. By not drinking large amounts during meals, you can avoid diluting digestive enzymes and stomach acids unnecessarily. Instead, drink 30 minutes before a meal or 1.5 hours after.

After about 4 hours, the food is ready to be pushed further down the system. This timing can vary depending on what you’ve eaten; juice passes through more quickly than broccoli because it requires less work to break down. In the duodenum, food is mixed with bile and more digestive enzymes, before winding its way through the small intestine and large intestine.

In part 2 of how the stomach works, you can read about what happens in the intestines, where it happens, how nutrients are absorbed, and what little helpers are present to facilitate the process.

Sofia Antonsson
Reg. Dietitian, Belly Balance