Overview of the Enzymes in Breast Milk

Breastfeeding child
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An enzyme is a type of protein that creates a chemical reaction in the cells of the body. Enzymes perform important functions that are necessary for survival including those involved in digestion and metabolism. Each enzyme has only one job, and it's specific to the type of chemical reaction that it produces. 

The Enzymes Found in Breast Milk

There are many different enzymes found in human breast milk. These enzymes play an important role in the health and development of a newborn child. The enzymes in breast milk serve a variety of functions, some of which we do not even know yet. Some enzymes are necessary for the function of the breasts and the production of breast milk, some enzymes help a baby with digestion, and some are essential for a child's development. Here are the most important enzymes found in breast milk.


Amylase is the main polysaccharide-digesting enzyme. It digests starch. Since babies are born with only a small amount of amylase, they can get this essential digestive enzyme through breast milk. After six months of age, a child's pancreas begins to release amylase.


Newborns can fully digest and use the fat in breast milk because of lipase. Lipase breaks down milk fat and separates it into free fatty acids and glycerol. Newborns get energy from free fatty acids, and lipase makes those free fatty acids available before digestion occurs in the intestines.

Lipase is also responsible for the soapy, metallic smell that refrigerated or previously frozen and thawed breastmilk sometimes has. The freezing and thawing of breast milk high in lipase can cause the fat in the milk to break down quickly, leaving an unpleasant odor. It may not smell good, but the nutritional value is still present.


Protease speeds up the breakdown of proteins. There are high levels of protease in breast milk. It is believed that this enzyme is important for digestion especially during the period right after birth.


Lactoferrin is an iron-binding protein. It helps a baby absorb iron. Also, along with white cells and antibodies, lactoferrin kills bacteria. Lactoferrin stops E. coli from attaching to cells and helps to prevent infant diarrhea. Lactoferrin also prevents the growth of Candida albicans, a fungus. Lactoferrin levels are very high in preterm breast milk and the levels go down as lactation continues.


Lysozyme protects an infant against bacteria such as E. coli and Salmonella. The levels of lysozyme in the breastmilk rise especially around the time babies begin eating solid foods. The increase in lysozyme helps to protect children from germs that can cause illness and diarrhea.

Other Enzymes in Breast Milk

There are over 40 enzymes identified in breastmilk. Some of the other active enzymes include diastase, lactose synthetase, and lactoperoxidase.

Are There Enzymes in Infant Formula?

Infant formulas do contain enzymes, but many of the enzymes found in breast milk are not in formula. Formula manufacturers add some enzymes, and some are found naturally. However, enzymes found in milk are specific to the species that make that milk. For example, human breast milk contains enzymes made for human babies, and cow's milk contains enzymes made for a cow's calf. Therefore, infant formula that is cow's milk-based does not have the same levels of enzymes as human breast milk. Even when companies add enzymes to infant formula, it cannot match what's in breast milk.

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Article Sources
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