How does digestion work?

Digestion is the process of breaking food into small molecules the body can use. It starts in the mouth, where chewing and saliva begin the breakdown, then continues in the stomach, where acids and enzymes turn food into a soupy mixture. Most nutrients are absorbed in the small intestine, whose lining is folded into millions of tiny projections to maximise surface area. The large intestine absorbs water and forms waste. The whole journey can take a day or two from start to finish.