Your breast milk contains numerous valuable components to help your baby thrive—many that the formula industry is unable to replicate. Here are some of the most important ingredients found in breast milk and how they benefit your child.

1. Proteins

The proteins in breast milk are more easily and completely digested by babies than other types of proteins.  Some examples include:

• Taurine:  An amino acid found in breast milk that has an important role in the development of the brain and eyes. 

• Lactoferrin:  This is an iron-binding protein that limits the availability of iron to bacteria in the intestines and alters which healthy bacteria will thrive in the digestive system.  It is found in the highest concentrations in colostrum, but persists throughout the entire first year.  It protects against bacteria such as staphylococci and E. coli.

2. Self-Digesting Fats

Fat is a valuable source of energy for babies.  The fat content of breast milk changes, with fat levels typically low at the beginning of a feeding and high at the end.  Some examples include:

• Lipase:  This enzyme breaks down fat so it can be better absorbed into the bloodstream.  Fat is a valuable source of energy for babies and is important to brain development.

• Linoleic and linolenic:  As newborn babies grow, the nerves are covered with a substance called myelin that helps the nerves transmit messages to other nerves throughout the brain and body.  To develop high-quality myelin, the body needs these fatty acids, which are found in large amounts in breast milk.

• Docosahexanoic acid (DHA) and arachidonic acid (AA):  Long-chain polyunsaturated fatty acids that optimize cognitive function and vision, and have a significant impact on the growth of the central nervous system.   

3. Hormones and Enzymes

These ingredients have been shown to influence a baby's metabolism, growth, and physiology.  Some examples include:

• Epidermal Growth Factor:  Present in breast milk in significant amounts, it helps to maintain the development of tissues in the digestive tract and elsewhere. 

• Lysozyme:  This is a digestive ingredient that has a strong influence on the type of bacteria in the intestinal tract. Lysozyme is a natural form of protection from infectious organisms like Salmonella and E.coli.

4. Vitamins and Minerals

Vitamins and minerals in breast milk are more completely absorbed by the baby, directing nutrients to the baby's blood where they need to be instead of to their stool.  Calcium, phosphorus, and iron are three important minerals found in breast milk that have high bioavailability (the amount available for the infant to use).  To enhance the bioavailability of nutrients, breast milk contains substances that aid in the absorption of other nutrients.  For example, vitamin C in human milk increases the absorption of iron.  

5. Immunoglobulins

All types of immunoglobulins, or antibodies (antibodies are a protein produced by the body's immune system that recognizes and helps fight infections and other foreign substances in the body), are found in breast milk, with the highest concentration in colostrum.  Secretory IGA, a type of immunoglobulin that protects the ears, nose, throat, and GI tract, is found in high amounts in breast milk throughout the first year. 

By Sandi Schwartz - Science writer and mom