Gut Health and Digestion

How your body turns food into fuel, and how to keep your gut happy

Digestion is how your body breaks food into the nutrients it can absorb and use for energy, growth and repair. A well-functioning gut is one of the quiet foundations of feeling good.

The journey of a meal

Stage	What happens
Mouth	Chewing and saliva (the enzyme amylase) start breaking down starches. Food becomes a soft ball called bolus.
Oesophagus	Muscular waves (peristalsis) move food down to the stomach. No breakdown happens here.
Stomach	Acid and the enzyme pepsin turn food into a liquid called chyme over 2 to 4 hours. Protein digestion begins.
Small intestine	The main site of digestion and absorption. Bile and pancreatic enzymes break down all the macronutrients, and nutrients pass into the blood. Most water is absorbed here too.
Large intestine	Reabsorbs remaining water, works on fibre, and forms waste. This is where most of your gut bacteria live.

How long does it take?

Food takes roughly 6 to 8 hours to pass through the stomach and small intestine, then can sit in the large intestine for a day or more. A total of 24 to 72 hours is normal. Fibre-rich fruit and vegetables move through faster, while protein and fat-rich foods such as meat take longer.

Signs of a happy gut

A healthy gut usually means

Regular bowel movements, once or twice a day
Stools that are well-formed and easy to pass
No ongoing bloating, gas or pain

Worth paying attention to

Persistent bloating, gas or discomfort
Ongoing constipation or diarrhoea
Unexplained changes worth raising with your GP

Meet your microbiome

Your gut is home to around 200 species of bacteria, viruses and fungi. Many are helpful and even necessary for a healthy body. Greater diversity in your gut bacteria is linked with better physical and mental health.

Eat plenty of fibre from a variety of plants, both soluble and insoluble.
Include fermented foods, and consider a probiotic if it helps you.
Stay hydrated, move regularly, protect your sleep, and manage stress, since the gut and brain are closely connected.

Where to learn more: the NHS, the British Nutrition Foundation, the British Dietetic Association (BDA), and Guts UK. Ongoing gut symptoms, or anything that concerns you, are worth discussing with your GP rather than self-diagnosing.

This leaflet is general nutritional guidance for education only. It is not medical advice, diagnosis or treatment, and it does not replace advice from your GP or a registered dietitian. Always check with a qualified professional before making significant changes, particularly if you have a health condition, are pregnant, or take medication.