How fast are your bowels? Take the sweetcorn test to find out!

This is a neat little experiment to get children thinking about how their digestive system works and to start a conversation about how to keep bowels healthy and working properly.

Three corn cobs on a red plate

Test your bowel transit time with sweetcorn

Take the test

Step 1:

Don’t eat sweetcorn for a week – that’s right, cut it out of your diet for 7 days to make sure your system is clear of any kernels.

Step 2:

Eat some sweetcorn – obviously! Munch on a cob or have a handful-sized serving of frozen or tinned kernels. Yum yum. You don’t have to have it on its own, serving it with lunch or dinner is just fine. Take a note of the time – this is important.

Step 3:

Wait for the magic to happen! Don’t eat any more sweetcorn after your ‘test’ portion. Observe your poos and wait for the evidence to reappear in the toilet bowl. Make a note of the time that the kernels first start to appear.

Don't eat any more sweetcorn after the 'test' portion.

Why does sweetcorn show up in your poo?

The hull (or outerlayer) of a corn kernel is made up mostly of cellulose. Cellulose is sort of a rubbery substance and it does not break apart easily when chewed.

Can I do the test with any other foods?

Sweetcorn works best but you can also try the test with a portion of seeds such as sesame.



Between 24 and 36 hours is the about how soon you’d expect to see those kernels if your bowel is working well. A smooth brown sausage studded with golden jewel-like kernels. Perfect!


Less than 12 hours and you could be looking at a case of diarrhoea. Your poo might be soft and mushy or even liquidy and resemble porridge or gravy. It’s worth bearing in mind that in young children the gut sometimes moves a bit quicker, so a shorter time with a softer poo can be fine too.


More than 36 hours and you should consider if you are constipated.* Poos become small, hard, difficult to pass and look like rabbit droppings or bunches of grapes.

* For parents and carers doing this alongside their children, don't to worry if it takes 48 hours to get through – that’s normal for adults.

Poo character with mortarboard

Spotting constipation

Although this is a bit of fun, there is a serious issue behind this experiment. 34% of children in UK suffer from constipation and the signs and symptoms are often ignored or misunderstood.

If left untreated, the consequences can be devastating and long-term, impacting on the child’s well-being & education and family life.

To find out more about identifying and treating constipation in your child, read our factsheet on children's constipation.

On this page...

    Upcoming events

    Share this page