Digestive System

Overview

Your digestive system is the group of organs that turns the food you eat into energy and the nutrients your body needs. It runs from your mouth all the way down to your bottom (anus). Along the way, your food is broken down, nutrients are taken into your blood, and what is left over becomes stool (poo). The main parts are the food pipe (oesophagus), stomach, small bowel and large bowel (intestines), liver, gallbladder and pancreas. When any part of this system is upset, you can get symptoms like heartburn, bloating, tummy pain, constipation or loose stools. Most of these problems are common, mild and settle down with simple changes. Some need a doctor's help to find the cause and treat it.

Very common. Almost everyone has an upset stomach, heartburn, bloating, constipation or diarrhoea at some point. Problems like indigestion and irritable bowel syndrome (IBS — a common long-term condition causing tummy pain and changes in bowel habits) affect a large share of adults worldwide.

Everyone. Babies often have reflux and wind, children pick up tummy bugs easily, and older adults are more likely to have constipation or diverticular disease (small pouches in the bowel wall). Pregnancy, stress, travel, some medicines and long-term health conditions can all affect digestion too.

Symptoms

Common symptoms

• Heartburn or a burning feeling behind the breastbone, especially after meals or lying down
• Bloating, wind and a full or uncomfortable feeling after eating
• Tummy pain or cramping that comes and goes
• Constipation — hard stools or going to the toilet fewer than three times a week
• Diarrhoea — loose or watery stools, often three or more times a day
• Feeling sick (nausea) or being sick (vomiting)
• Changes in appetite or an unusual taste in the mouth
• Blood on the toilet paper, on the stool or in the toilet bowl

Symptoms in children

• Spitting up or bringing up milk after feeds (reflux), which is very common in babies
• Wind, colic and drawing the legs up when uncomfortable
• Loose stools or a tummy bug, which spreads easily in nurseries and schools
• Refusing food or drinking less than usual
• Fewer wet nappies, a dry mouth, sunken eyes or unusual sleepiness — signs of dehydration (losing too much water)
• Tummy pain that comes and goes, or pain that makes a child double over

Symptoms in older adults

• Constipation, sometimes made worse by painkillers or other medicines
• A sudden change in bowel habit that lasts more than a few weeks
• Reduced appetite and unplanned weight loss
• Feeling full very quickly, or difficulty swallowing
• Confusion or unusual tiredness, which can be a sign of dehydration or infection in older people
• Blood in the stool or on toilet paper

Causes

Main causes

• Eating habits — eating too fast, large or fatty meals, or too little fibre
• Infections from food or water, often called 'tummy bugs' (gastroenteritis)
• Stress and anxiety, which can speed up or slow down your gut
• Side effects of medicines, including painkillers, iron tablets and some antidepressants
• Long-term conditions such as irritable bowel syndrome (IBS), acid reflux, coeliac disease (a reaction to gluten) or inflammatory bowel disease (Crohn's disease and ulcerative colitis)
• Not drinking enough fluid, or changes in routine such as travel
• Food intolerance — difficulty digesting certain foods such as lactose in milk
• In older adults, weakening of the bowel wall can lead to diverticular disease

Risk factors

• A diet low in fibre, fruit and vegetables
• Low levels of physical activity
• Smoking and drinking a lot of alcohol
• Being overweight
• High stress levels or poor sleep
• Taking several medicines, especially in later life
• A family history of bowel problems, coeliac disease or bowel cancer
• Recent travel, or eating food that may not have been prepared safely

When to see a doctor

See a doctor urgently if:

• Blood in your vomit or stool, or black tarry stools
• Severe or rapidly worsening tummy pain
• Signs of dehydration that do not improve when you drink fluids
• Yellow skin or eyes
• A new lump in your tummy
• Difficulty swallowing or food sticking
• A high temperature with a very tender tummy

Book a routine appointment if:

• Symptoms that last more than two to three weeks or keep coming back
• A change in your normal bowel habit that does not settle
• Unplanned weight loss
• Heartburn most days, or needing heartburn remedies often
• Bloating or discomfort that affects your daily life
• Symptoms that wake you from sleep
• A family history of bowel cancer or coeliac disease

Diagnosis

Your doctor will usually start by asking about your symptoms — when they started, what makes them better or worse, your diet, your medicines and your family history. They will then examine your tummy by gently pressing on it. Often this is enough to point to a likely cause. If symptoms are persistent or unusual, they may arrange simple tests or refer you to a specialist.

Tests that may be done

• Blood tests to check for anaemia, inflammation, coeliac disease or liver and pancreas function
• Stool (poo) tests to look for infection, blood or inflammation
• A urine test or pregnancy test, depending on your symptoms
• Breath tests for certain food intolerances or stomach infections
• Ultrasound scan, which uses sound waves to look at the liver, gallbladder and other organs
• Endoscopy — a thin, flexible tube with a camera passed through the mouth to look at the food pipe and stomach, usually done with sedation
• Colonoscopy — a similar camera test that looks at the large bowel
• CT or MRI scans for more detailed pictures of the tummy
• Food and symptom diaries to spot patterns with particular foods

What to expect at your appointment

Most tests are quick and many are painless. Camera tests such as endoscopy or colonoscopy need some preparation — you will be given instructions about what to eat or drink beforehand, and you will usually be offered medicine to keep you comfortable. Ask your doctor or nurse to explain anything you are unsure about, and tell them if you feel anxious. You will usually get results within a few days to a few weeks, and your doctor will talk them through with you.

Treatment

Treatment depends on the cause, but most digestive problems improve with simple changes to diet, routine and lifestyle. If a specific condition is found — such as an infection, acid reflux, coeliac disease or IBS — your doctor will explain the options and agree a plan with you. The aim is always to ease your symptoms, protect your gut and help you feel well again.

Self-care at home

• Eat regular, smaller meals and take your time — chew well and put your fork down between bites
• Drink plenty of water through the day, and sip fluids if you have diarrhoea or vomiting
• Build up fibre slowly if you are constipated — fruit, vegetables, whole grains, beans and lentils
• Cut back on very fatty, spicy or sugary foods if they trigger symptoms
• Limit alcohol and caffeine, especially if you have heartburn
• Stay physically active — a daily walk helps keep the bowel moving
• Try to eat at similar times each day, and avoid big meals late at night
• Keep a simple symptom diary to spot triggers
• Wash your hands before eating and after the toilet, and follow food safety advice
• Ask your pharmacist before taking over-the-counter remedies, especially if you take other medicines

Medical treatments

Your doctor may suggest treatments to ease particular symptoms — for example, something to reduce stomach acid, to settle nausea, to slow diarrhoea or to soften stools. They may also suggest treatments for an infection, or changes to other medicines you take that could be affecting your gut. Some conditions, such as coeliac disease, are managed mainly through diet, with support from a dietitian. Always ask your doctor or pharmacist how to take any medicine, what to expect, and whether it is safe alongside your other medicines. Do not start, stop or change medicines on your own.

When is surgery considered?

Surgery is only needed for a small number of digestive problems — for example, removing the gallbladder when gallstones cause repeated pain, repairing a hernia, removing a growth (polyp) found during a camera test, or treating a blockage. Your specialist team would explain the benefits and risks in detail before you decide.

Living with this condition

Living with a sensitive gut can be frustrating, and symptoms can change from week to week. Learning your own triggers — certain foods, stress, eating late, or not drinking enough — gives you back a sense of control. Keep a simple diary for a few weeks and look for patterns. Small, steady changes work better than strict diets, which can be hard to keep up and may not give you all the nutrients you need.

Lifestyle tips

• Eat at regular times and avoid rushing meals
• Aim for gentle activity most days — walking, swimming, cycling or gardening all count
• Try to keep a healthy weight
• Get enough sleep, as poor sleep can worsen gut symptoms
• Reduce stress where you can, using breathing exercises, hobbies or time outdoors
• Limit alcohol and avoid smoking
• Plan ahead for travel — carry water, and be careful with unfamiliar food and drink

Diet and exercise

A balanced diet with plenty of fruit, vegetables, whole grains and fluids suits most people. If you are constipated, increase fibre gradually over a few weeks and drink more water at the same time, as fibre without fluid can make things worse. If certain foods seem to trigger symptoms, a dietitian can help you test them safely without cutting out important nutrients. Regular movement helps your bowel work properly and supports your overall health.

Mental health and emotional wellbeing

Your gut and brain are closely connected — stress and low mood can affect digestion, and gut symptoms can affect mood in return. This is very common and not 'all in your head'. If worry about symptoms is affecting your sleep, work or relationships, it is worth telling your doctor. Talking therapies, relaxation techniques and support groups can help alongside medical care.

Prevention

Not every digestive problem can be prevented, but many can be made less likely. Good hand hygiene, safe food preparation, a balanced diet with plenty of fibre, staying hydrated, limiting alcohol, not smoking and keeping active all help protect your gut.

Vaccines

Routine childhood vaccinations include protection against some infections that cause severe diarrhoea and vomiting in babies and young children. Ask your doctor or health visitor about the vaccination schedule where you live, and about any recommended vaccines before travel.

Screening programmes

Many countries offer bowel cancer screening for adults from a certain age — usually a simple stool test at home, and sometimes a camera test. The age and type of test vary by country, so check with your local health service. If you have a family history of bowel cancer or coeliac disease, tell your doctor, as you may be offered earlier checks.

Complications

If left untreated

• Dehydration, especially with diarrhoea and vomiting, which can become serious quickly in babies and older adults
• Anaemia (low iron in the blood) from ongoing bleeding or poor absorption of nutrients
• Weight loss and malnutrition if food is not absorbed properly
• Narrowing or blockage of the bowel from long-term inflammation or scarring
• Bleeding or, rarely, a hole (perforation) in the bowel, which is a medical emergency
• Ongoing pain and tiredness that affects work, sleep and daily life

Long-term outlook

The great majority of digestive problems are mild and get better, either on their own or with simple treatment. Long-term conditions such as IBS, reflux and inflammatory bowel disease can usually be managed well with the right support, and most people live full, active lives. Getting symptoms checked early means problems are found sooner, when they are usually easier to treat.

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