We occasionally make decisions based on a ‘gut feeling’. Could there be more to this figure of speech than perhaps meets the eye? After all, our stomach is home to the longest organ we have – the intestine. And this sees to a number of functions in addition to digestion.

The intestine has a significant influence on our well-being: we only feel good if the intestine’s own nervous system is ‘happy’. This system consists of millions of cells and works independently of the body’s control centre, the brain. For this reason, the intestine is sometimes called the body’s ‘second brain’.

A healthy intestine is important for health and well-being. Don’t leave your intestinal health to chance! Here you will learn how the intestine works and how you can look after it. Among other things, this includes regular bowel cancer screening.


The primary task of the intestine is to absorb nutrients and fluids in order to distribute them around the body via the blood. To this end, muscles that extend all the way through the digestive system slowly push our food forwards. The indigestible leftovers then disappear down the toilet after between one and three days.

How quickly our food works its way through the body is determined by the ‘second brain’ alone. It consists of up to 200 million nerve cells and is an important part of our immune system. It determines which food components are absorbed by the intestine and which it is better off avoiding.

Our actual brain isn’t involved in digestion, but it needs to be kept up to date at all times on how the intestine is doing. The intestine therefore sends signals and information to the brain. Less communication is needed in the other direction. The ‘second brain’ also responds sensitively on its own to stress, fear and other emotions.

Our gut flora

By eating and drinking, we not only keep our body going, but also feed billions of microorganisms that together form the microbiome, otherwise known as gut flora.

  • Digestion: The microbiome turns indigestible dietary fibre into useful fatty acids that provide our intestinal mucosa with energy.
  • Vitamin production:  Microorganisms in the intestine provide us with, among other things, vitamins B1, B2, B5 and K, without which our metabolism wouldn’t work.
  • Neutralisation of toxins: The gut flora can turn potentially toxic food components into harmless elements, in so doing offering protection from, for example, carcinogenic substances as well as making some drugs effective.

The ‘good’ microbiome additionally prevents large numbers of harmful organisms from spreading throughout the intestine. The body’s own immune cells then see to the rest. Close to three quarters of these live in the intestine.

Composition of the digestive system

Our food passes through a number of stations as it makes its way through the entire digestive tract. The intestine is a key part of the journey. It connects the stomach to the anus like a winding muscle tube.

The teeth break food down and the saliva begins to digest it. The tongue moves the broken-down food back and forth and sends small portions in the direction of the oesophagus.

The oesophagus uses rhythmic motions to move the broken-down food downwards. At the other end, the stomach opens.

The stomach breaks the food down even more and works it into a pulp. It moves this along to the small intestine by means of circular contractions, sometimes ‘growling’ in the process.

The longest section of the intestine loops multiple times in the abdominal cavity. In the small intestine, the nutrients in the pulped food are transferred to the bloodstream.

In the large intestine, fluids and salts are extracted from the pulped food. The gut flora lives in this part of the intestine.

The stools collect in this final 15 to 20 centimetres of the intestine, ready to be excreted. At the end of this are the sphincter muscles.

Use and care

Plenty of exercise, little alcohol and not smoking will reduce the risk of bowel cancer. You can also help your intestine to work and boost its health by paying attention to what you eat.

Balanced and varied diet (for all the nutrients you need)
Little salt and sugar (to prevent high blood pressure and tooth decay)
Gentle cooking (to preserve the nutrients, for full flavour and to avoid burning the food)
Conscious consumption (for more enjoyment of your food and a healthy sense of being sated)
Body consciousness (for an active intestine and to combat being underweight or overweight as well as various lifestyle diseases)
Wholemeal products such as bread or pasta and potatoes (for dietary fibre and energy)
Three handfuls of vegetables and two handfuls of fruit a day (for vitamins, dietary fibre and minerals)
Animal products such as cheese in small amounts, one to two portions of fish and max. 300–600 g of meat a week (for protein, animal fats, minerals, vitamins)
Fats such as rapeseed oil and olive oil (for unsaturated fatty acids, vitamins)
At least 1.5 l of fluids in the form of water, diluted fruit juices and unsweetened herbal teas

Possibilities for early detection

Bowel cancer can be detected early on in a routine check-up that enables you to effectively prevent the disease. Doctors are often able to pick up signs of the cancer early on and swiftly remove any early stages.

Anyone with statutory health insurance is entitled to a voluntary screening from the age of 50. Women aged 50 and up can have their stools tested for traces of blood which aren’t visible; from the age of 55, they are also entitled to the first of two colonoscopies. Men can choose between these two options upon turning 50.

Bowel cancer early detection is for people who are not showing any signs of and are not specifically at risk of bowel cancer. Insured persons with pre-existing bowel diseases should go for check-ups earlier and more regularly.

Good to know

  • At best, probiotic foods have only a temporary influence on microbiome health. You are better off focusing on having a diet which is high in dietary fibre and on eating fermented foods such as sauerkraut, natural yoghurt and quark. Your gut flora will thank you for it and your purse or wallet will too.
  • Laxatives and anti-diarrhoeal medicine are probably not carcinogenic. But if constipation and diarrhoea occur frequently, this can be a sign of health issues that should be clarified by a doctor.
  • A colonoscopy is usually repeated after ten years as the risk of developing cancer during this period is very low. This is because it takes early-stage bowel cancer around ten years to develop into cancer.