A food journey through the body

The journey continues into the intestines, starting with the small intestine. Can you imagine that your small intestine is around 5 meters long? And that its total surface area amounts to approximately 200 m2, roughly equivalent to the size of a tennis court, due to folds and other projections (villi)? This 400-fold increase in surface area is important when it comes to ensuring that nutrients from our food can be absorbed in sufficient quantities.

 

The small intestine is divided into three sections: the duodenum, the jejunum and the ileum. On leaving our stomach, the chyme first enters the duodenum, where the small intestine is connected to the pancreas and the gallbladder, organs that are important for the digestive process in the intestines. The pancreas produces enzymes that are released into the small intestine and supports the breakdown of proteins, fats and carbohydrates. In addition to this, via the bicarbonate contained in the pancreatic juice neutralises the acidic chyme as it leaves the stomach. The gallbladder stores the bile fluid that is produced in the liver and enters the small intestine through the bile duct. The most important components of the bile fluid are the bile acids that are important for fat digestion.  The chyme is thus combined with and digested by the digestive juices of the pancreas, bile fluid and the enzymes produced in the intestine. The large majority of nutrients, i.e. protein, fat and carbohydrates and vitamins, minerals and trace elements, are broken down into smaller components in the small intestine and transported to the body through the intestinal wall .
The final section of the gastrointestinal tract is the large intestine (colon), which is approximately 1.50 meters long and ends at the rectum. The large intestine contains the intestinal flora - i.e. your large intestine is occupied by approximately 10 billion intestinal bacteria for every millilitre of colonic fluid . The role of the intestinal flora is to ferment fibers.

In comparison with the small intestine, not so much takes place in here in terms of digestion. The primary function of the large intestine is to remove water from the remaining chyme and thereby make it more concentrated, producing the faeces that are excreted through the anus. The length of time that the faeces remain in the anal canal depends on the amount of fibre in your diet – if you eat a high-fibre diet, the transport time is faster. By way of comparison, the chyme transit time in the large intestine is 2 – 3 days with a diet that is low in fibre, or 1 – 2 days with a high-fibre diet . The European Food Safety Authority (EFSA) recommends daily consumption of 25g of fibre  .