Digestive enzymes are proteins that break food down into pieces small enough to absorb. Your body makes its own, mainly in the saliva, stomach, pancreas and small intestine. Proteases break down protein, amylases break down starch, and lipases break down fat, while other enzymes handle particular sugars and fibres.
Digestive enzyme supplements contain a blend of these enzymes from several sources. Many are produced by fermentation using microorganisms such as Aspergillus fungi, which makes them suitable for vegetarians. Others come from plants, including bromelain from pineapple and papain from papaya. On labels you will often see each enzyme listed with an activity unit, such as HUT, DU or FIP, because how active an enzyme is matters more than its weight.
Supplements are designed to work alongside the enzymes your body already makes, usually taken at the start of a meal. They are different from pancreatic enzyme replacement therapy, a prescription medicine for people whose pancreas does not make enough enzymes. Persistent digestive symptoms always deserve a conversation with your GP rather than trying to manage them on your own.