How our digestive system works and keeping it healthy

This page from Great Ormond Street Hospital (GOSH) explains how our digestive system works and how to keep it healthy.

The digestive system is essentially a very long tube that stretches from the back of the mouth to the anus. When we eat, food passes down the oesophagus to the stomach, squeezed by regular contractions – this is called peristalsis. When the food reaches the stomach, it is broken down into a mushy liquid called chyme by acids and enzymes.

The chyme then passes into the small bowel, which is about 2 metres (7 feet) long in newborn babies and grows to about 6 metres (20 feet) long by adulthood. It is made up of three parts. The first section is called the duodenum which is connected to the stomach. The next section is the jejunum which makes up about one third of the entire length of the small bowel. The last and longest part of the small intestine is called the ileum which leads to the large bowel or colon. The small intestine is where all the goodness from our food is absorbed into the bloodstream. The remainder that cannot be used passes into the colon, where water is absorbed to form solid faeces or poo. This passes out of the rectum and anus.

The entire length of the gastrointestinal tract contains nerves and muscles that work together to move food through from the oesophagus to the anus using peristalsis. If a section of the intestines does not contain these nerves and muscles or they are present but not working correctly, peristalsis cannot occur so food cannot be pushed efficiently to the next part of the tract.

This is referred to as a gastrointestinal motility problem or dysmotility. There are various types: neuropathic (nerve) motility problems, myopathic (muscle) motility problems or a problem with the pacemaker cells (interstitial cells of Cajal (or ICCs) which cause the muscle contractions. There may also be a mixture of neuropathic/myopathic motility problems.

The brain and the gastrointestinal system have strong connections. Communication goes both ways; the intestine sends lots of signals to the brain and the brain sends signals which influence the functioning of the gastrointestinal system. This interconnection means that it is important for us to think your child in both physical and psychological terms to understand gastrointestinal problems and their impact.

Keeping your child’s digestive system healthy

There’s lots you can do to help keep your child’s digestive system healthy – try some of the suggestions below.

Keep a diary

If your child has digestive problems, such as constipation, diarrhoea or vomiting, it can be helpful to keep a food diary. This doesn’t have to be complicated – just note down what they eat and drink each day, alongside any symptoms they have. In time, you might notice a pattern where they feel ill after eating certain foods. Your doctor will also find the food diary helpful.

Get into a routine

Help your child to get into a toilet routine – the most important thing is not to rush. There will be times of day when your child’s bowels will open – teach them to listen to their body and go to the toilet when they need to – holding in poo can cause problems.

You might find keeping a bowel diary helpful – perhaps with small rewards when your child has a poo. The Bladder and Bowel Foundation produce one, available at 

Using the toilet

There are techniques your child can use to encourage their bowels to open – ask for a copy of the Rock and pop leaflet from ERIC.

Get comfortable on the toilet – if your child’s feet can’t touch the floor when they are sitting down, buy a small stool or step to raise their knees above hip level. Sitting in this position makes it easier to poo.

When your child has had a poo, teach them to wipe from front to back as this reduces the risk of germs in poo being transferred to the urethra and then into the urinary system. This is particularly important for girls as there is a shorter distance between the anus and urethra.

Try to avoid constipation as straining to have a poo can weaken the muscles supporting the bladder (pelvic floor muscles). If you are concerned about your child’s constipation, talk to your family doctor (GP) or local community pharmacist (chemist).

Drinking plenty of fluids

Fluids are vitally important in keeping healthy so encourage your child to drink plenty of liquid throughout the day – more if the weather is hot. It is better to drink small amounts of fluid frequently throughout the day rather than lots in one go when thirsty.

Guidance from the National Institute for Health and Care Excellence (NICE) suggest the following amounts for children and young people.

  • 7 to 12 months – 600ml
  • 1 to 3 years – 900ml
  • 4 to 8 years – 1200ml
  • Boys aged 9 to 13 years – 1800ml
  • Girls aged 9 to 13 years – 1600ml
  • Boys aged 14 to 18 years – 2600ml
  • Girls aged 14 to 18 years – 1800ml
Some drinks are better for the bowels than others – where possible, try to avoid fizzy, sugary drinks and stick to water, very weak squash or diluted fruit juice.

Eat a balanced diet

Everyone benefits from eating a balanced diet so can easily introduce this to the entire family. Have a look at the Eat Well Guide and the proportions of each food group.

Teach your child to chew each mouthful well before swallowing – the chewing action stimulates the body to release the acids and enzymes needed to breakdown food in the stomach.

Some people find that having a probiotic drink or yoghurt helps to keep the ‘good bacteria’ in the colon well balanced.

Eat fibre-rich foods

Often our bodies work better if we have some fibre-rich foods. There’s usually a wholemeal or wholegrain version available and many of them don’t taste much different. Try swapping white bread for wholemeal bread or perhaps start with one that is half white and half wholemeal. Your doctor or dietitian will advise whether your child is eating enough fibre.

See if fermented foods can help your child

Some people find that eating small amounts of fermented foods help their digestion. This includes things like sauerkraut or kimchi. There are lots of different types available so try to find one the whole family likes.

Stick to a mealtime routine

Our bodies work better when we have a daily routine. Try to have three meals a day with snacks mid-morning and mid-afternoon. When you eat a meal, sit at the table or breakfast bar so your posture is better – it can be difficult to digest our food when we eat slumped on the sofa.


Being active helps your bowels to stay active as well. The Government recommends that children and young people exercise for at least an hour a day. This does not have to be organised sports – just playing tag around a local park counts. If your child gets hot and bothered, remind them to drink plenty of fluid to replace what they lose through sweating.

Keep away from smoky atmospheres

Cigarette smoke is bad for us in lots of ways, including our digestive system. It can affect our taste buds so they are less sensitive to flavour, for instance. Try to keep your child away from smoky atmospheres. If you smoke, always go outside for a cigarette and ask for help quitting from your doctor or pharmacist.

Help your child manage their wellbeing

Stress and worry can affect our digestive system too so help your child to develop positive thinking and find ways that they can relax.

Food hygiene matters

Food can go off – develop bugs – if we don’t store and cook it properly. Check the temperature of your fridge and freezer to make sure they’re cold enough. Store raw meats at the bottom of the fridge in a sealed container. Follow the cooking instructions carefully and if it doesn’t look fully cooked, either add a bit more time or don’t eat it. Use by dates are important to make sure the food you’re eating is safe – never eat anything later than its use by date. ‘Best before’ dates only suggest when foods are at their best – they are unlikely to be bad after the best before date but might look a bit different.

Accidents will happen

When your child is learning to listen to their bowels and bladder, they may have the occasional accident. Try not to make too big a thing of it – this could lead to problems in the future.

Further information and support

ERIC – the children’s continence charity – produces lots of helpful booklets on all aspects of managing bladder and bowels, such as constipation or slow gut transit. Call their helpline on 0845 370 8008 or visit their website at

The Bladder and Bowel Foundation can also offer information and support. Call their helpline on 0845 345 0165 or visit their website at

Guts UK is the support organisation for all digestive disorders. Visit their website at for further details.

There are specific support organisations for various digestive disorders – search the directory at Contact (previously known as Contact a Family) for details. Call their helpline on 0808 808 3555 or visit their website at