Tue Nov 21

Curious kids: what are tummy rumbles?

Written by Andrea Stringer, Associate professor, University of South Australia

What are tummy rumbles? – Anouk, aged 10, Coburg

This is a great question, and one lots of people ask!

There are a few different reasons for “tummy rumbles” or the (sometimes weird) noises your stomach makes.

For the most part, these are part of the normal workings of not only your stomach, but also your intestines. These are parts of your digestive system, which kicks into gear when you eat. It breaks down (digests) food and then the nutrients are absorbed by the body. Whatever is left comes out as poo (also called faeces).

Your entire digestive system (starting at your mouth and ending at the anus, or back opening of your bottom) is one hollow tube. It’s a bit similar to the water pipes in a house, that can be empty, or have water flowing though them. Sometimes your digestive system is empty and the organs are hollow and sometimes there is food moving through it.

When eating really starts

The process of digestion actually starts before you eat anything! When you see or smell or think about food (particularly food you like), your brain activates nerves that stimulate your digestive system, so it can prepare itself for food arriving.

The first step involves increasing saliva in your mouth (that “mouth watering” feeling). This is mixed with food and make it easier to chew and swallow.

Next, the cells in your stomach and intestines produce and release chemicals called enzymes to break down the food when it gets there. Your stomach starts moving in “waves” to mix all of those chemicals together.

This is where you might hear some noises. Air in your stomach can get trapped against the wall. When a wave comes through it can sound like a bubble popping, or make a gurgling or rumbling sound that you can hear and sometimes feel. The medical name for these is borborygmi (pronounced BOR-BUH-RIG-MAI).

child holds paper model of stomach and digestion

Picture your digestive system like a long tube from your mouth to your bottom. Shutterstock

An empty stomach can be a noisier stomach

When your stomach is pretty empty and then liquid arrives from swallowed saliva, acid and enzymes, you can imagine it’s going to slosh around and create some noise that can echo in there.

When you are hungry (and thinking about food) your stomach might “growl”. While your stomach is waiting for food it’s moving liquid around to get ready for it and creating pockets of air that get squashed, creating noises.

Further down your digestive tract, in the intestine, muscular waves push everything down the tube, making sure there is space for new food to arrive. This can also create noises.

Then you eat something (hopefully) delicious

The food you eat moves through your stomach and slowly into the intestine, where similar mixing movements happen break it down in the body. Air (also called gas) in the intestine makes noise when it moves, like it did in the stomach.

Even though this noise can sometimes be annoying or embarrassing, and you would like it to go away, the mixing that happens in the intestine is important. It’s how you get all of the nutrients (things like carbohydrates, fats, proteins, vitamins, minerals and more) from food.

Just thinking about eating can trigger waves of anticipation in our stomach. Shutterstock

The mixing (and the noises) mean food is mixing with the chemicals and breaking everything you’ve eaten down into small units, called molecules. Once these are small enough, the cells that line your intestine can take them in, a process called absorption.

Once the nutrients get into your blood stream, organs like your heart, lungs, brains and kidneys can use them to do their jobs in the body from pumping blood to breathing in air to telling the body what to do next.

Should you worry about tummy noises?

These are the most common causes of tummy rumbles, but they can happen after you swallow air when you talk, drink or eat and it travels into your stomach or intestines.

The noises made by your digestive system are important – they mean it is working properly. However, if the noises come with any pain or diarrhoea it could be a sign of a food intolerance or other digestive issue and you should get it checked out.

Authors: Andrea Stringer, Associate professor, University of South Australia