A Guide to Good Digestion Part 2: The Stomach.

By Lydia Irving

Welcome to the second part of my introductory guide to digestion. In Part One, we learned all about the mouth and the important role of saliva and chewing in starting the process of digestion.

After the mouth, food makes its way to the stomach. The stomach is an organ located in the upper left of your abdominal area, protected by the bottom of your rib cage and below your left lung. The stomach is shaped like a rounded sack, and fits neatly between your oesophagus and duodenum. Put simply, the stomach stores food and continues the process of converting food into chains of absorbable nutrients. Just like the mouth, it breaks down food through both mechanical and chemical breakdown processes. While the mouth uses chewing and saliva as the key mechanical and chemical processes (respectively) for breaking down food, the stomach uses different – but just as interesting – processes!



While chewing is a pretty straightforward mechanism – teeth grind food into smaller parts – the stomach has a more complex mechanical method to break down food. The outer lining of the stomach comprises a series of muscles, known as bundle muscles, which are capable of contracting in multiple directions and angles. These contractions turn the stomach into a sort of washing machine motion, where food is tossed around the stomach from wall to wall! As the food gets thrown about, it breaks down into smaller and smaller pieces, ready for eventual entry into the small intestine.

Because food needs to be totally broken down by this process, and through chemicals in the stomach I’ll talk about in a moment, the stomach has to hold the food for one or two hours while the process happens! The inner lining of the stomach helps with this, because wrinkled folds called rugae are capable of stretching the stomach into a size large enough to hold and move around all the food.



Your stomach is one of the scariest organs in the body, because it contains some very powerful chemicals! If you think of the stomach as a ‘hot pot’, it would be something of a horror-movie-death-acid-cooking-pot. If you dipped your hand inside that pot of chemicals, you would quickly be eaten by acids right through to the bone. Luckily, the rest of the body is protected from the powerful chemicals within the stomach by a thick protective lining the inside of the stomach. What a relief!

The reason that the stomach contains such strong chemicals is that the stomach has to break down all of the foods we eat, from thick steaks to fibers, before they reach the delicate small intestine. To do this, the stomach is strongly acidic, with a pH ranging between 1.3-3.5 (where 7 is neutral and anything higher than 7 is basic or alkaline). The most important acid in the stomach is Hydrochloric Acid. To maintain a healthy digestive system, we should aim to keep our stomach very acidic, so the hydrochloric acid is strong and capable of breaking down foods before they reach the small intestine. If we fail to do this, pathogens can enter the small intestine, damaging the organ and stopping the body from absorbing vital nutrients.

Another crucial reason to take care of stomach acidity levels is to control acid reflux. At the top of the stomach is a sphincter that opens up to the oesophagus. It’s called the oesophageal sphincter (makes sense, doesn’t it?). When the stomach is strongly acidic (a pH level of 1-2), it indicates to the sphincter that the stomach is functioning properly, and the sphincter closes the pathway between stomach and oesophagus. If our stomach isn’t acidic enough, or that ‘hot pot’ isn’t burning strongly enough, then the sphincter can remain open, allowing the contents of the stomach (food and acid) to enter the oesophagus. This causes the horrible sensation of acid reflux, which is actually the acid from the stomach burning the oesophagus. Ouch!

Sadly, most treatments for acid reflux (like anti-acids or protein pump inhibitors) don’t actually help the stomach to return to a pH of 1-2, but just try and block the acid from rising into the oesophagus. So don’t just reach for those medications to treat reflux, but investigate why you have reflux, and work on a nutritional plan to keep the stomach acidic!

To sum up so far: our stomach is a stretchy washing machine full of strong acid, which breaks down food over an hour or two. If the stomach isn’t acidic enough, we can get acid reflux.



Another crucial chemical process to break food down happens through digestive enzymes. There are many different enzymes in the stomach and throughout the whole digestive tract. They have unique skills and have many specific roles! Typically, enzymes in the stomach help to convert foods into nutrient chains, such as amino acid chains or fatty acid chains. For example, one of the most important enzymes in the stomach is pepsinogen, which breaks down protein. Another is called intrinsic factor, which helps to unlock B12 vitamins within food.

Enzymes are produced in the lining of the digestive tract, and we can stimulate their production by eating specific foods. With a varied and healthy diet, we will produce a wide range of enzymes which can ensure that we are getting the most out of our food! However, if our diet isn’t varied enough, then production of specific enzymes will slow down.

Also, if we eat too much of a specific food, then the particular enzymes required to break down that food can struggle to keep up, causing problems. One example of this is lactose, the type of sugar found in dairy products. Breaking down lactose requires the enzyme lactase, which many of us don’t produce enough of! We call this problem of not having the enzyme required to break down a specific food an intolerance. Some of the symptoms caused by having insufficient digestive enzymes include bloating, abdominal pain, and diarrhea. If left untreated, food intolerances can cause a whole range of serious health concerns, from migraines to joint pain and eczema! These may be a result of undigested foods reaching the small intestine. The good news is that there is highly specialized testing available for intolerances, which can test up to 350 different foods to figure out exactly what you’re intolerant to! With a healthy nutritional plan, and taking care of our stomach acid and enzymes, we can help our digestive system to function optimally maintaining balance and therefore health in our bodies!


Check out these articles

On how the mouth aids digestion https://spectrumchiropractic.com.au/a-guide-to-good-digestion-part-1-digestion-begins-at-the-mouth/

On the mysterious workings of the stomach https://spectrumchiropractic.com.au/how-to-love-your-guts/