How does stomach acid work?

We hear a lot about stomach acid, specifically in reference to heartburn, GERD (gastroesophageal reflux disease) and indigestion. Digestion itself is an incredible evolutionary feat that we often overlook as our bodies work to break down what we eat and convert it into energy to keep us moving. How does stomach acid work in this equation?

There are many parts to the digestive process, involving various chemicals and substances that our body creates to aid and complete the process, and stomach acid plays a major part of this. Having too much stomach acid can cause us problems like heartburn, but without it, we’d be in pretty bad shape. So, what is stomach acid and why is it important to maintain a healthy level?


Stomach acid (also known as hydrochloric acid or HCl) is, as the name suggests, an acid. This means that it’s corrosive. This corrosive substance is instrumental in the digestive process as it allows us to absorb the nutrients that we need by helping to the body break down proteins and other nutrients into a form that we can use as fuel.

While stomach acid does not directly digest the proteins that we require, it does activate an enzyme within our bodies known as pepsin. Pepsin then helps to convert proteins into amino acids which can then be absorbed by our bodies. These pepsin enzymes themselves come from a substance known as pepsinogen which is secreted from the walls of the stomach when we eat.


Stomach acid is also very important for dealing with infections and other, possibly harmful, microbes that work their way into our stomach. It’s impossible to prevent at all contamination of our food and everything we ingest will contain at least some microbes, bacteria, or fungi.

Luckily, that’s why we have stomach acid. Stomach acid plays a huge role in sanitising our food as we ingest it, as the acidic nature of our stomach ensures that these potentially harmful invaders are destroyed or deactivated.


The digestive system is just that: a system. That means that it’s important that all the pieces work together in order to keep us healthy. When stomach acid is released it also produces other chemical signals that tell other parts of the body that we’re eating and that they need to get ready for what comes next.

Once we’re done digesting and we have no use for the extra acid, it’s important that the pancreas knows to produce other chemicals, like bicarbonate, which can then be used to neutralise stomach acid.


As you can see, stomach acid serves an important function in the digestive process and our lives would be extremely different without it. However, sometimes we don’t look after our acid levels properly, either by eating too much spicy or fatty food or eating more than our body can process efficiently. This can cause excess acid to escape the stomach and work its way up to our oesophagus, causing heartburn.

So, while acid is our friend most of the time, it’s important that we take care not to push our digestive tracts too far.


If you’re suffering from heartburn caused by excess stomach acid, you probably want to treat it as quickly as possible so you can get on with your day.

There’s a few ways you can tackle heartburn when it strikes. You could try a natural home remedy such as loosening your clothing or drinking chamomile tea, or you could take an over the counter antacid like Rennie**.

Rennie tablets contain two naturally-occurring antacids called calcium carbonate and magnesium carbonate which neutralise excess stomach acid by turning it into water & other natural substances.

**Rennie Peppermint. Always read the label.

Natural home remedy