The large intestine

Once most nutrients have been digested and absorbed in the small intestine, what is left — the undigested food — moves into the large intestine.

The large intestine is about 1.5 metres long, so it is shorter than the small intestine. Then why call it 'large'? Because it is wider.

The large intestine absorbs water and some salts from the undigested food, which makes the waste semi-solid. This waste is called stool.

Stool is stored in the lowest part of the large intestine, the rectum, until the body is ready to get rid of it. Then it is pushed out through the anus. This is called egestion.

Eating fibre-rich foods — fruits, vegetables and whole grains — helps the large intestine work properly, by making stool easier to pass.

The large intestine is also home to many tiny living things, such as bacteria, that help digestion and keep the digestive system healthy. They break down undigested food, especially fibre, and make useful nutrients. Fibre-rich food and fermented foods like curd, buttermilk, shrikhand, kanji, pickles, gundruk and poita bhat are good for them.

People have known the value of good digestion for a long time. The Charaka Samhita, an ancient Ayurvedic text, talks about easily digestible food and careful use of spices such as ginger, black pepper and cumin. Modern nutrition science adds: eat at proper times, eat mindfully, and don't overeat.