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Last Reviewed: August 2013

Get the Facts

Make An Informed Decision

About lower respiratory infections

Babies don’t get to choose whether they are fed breast milk or formula, but you do.  And since your choice can affect your child’s healthy development you need to get all the facts.

Respiratory infection is probably the most common medical problem among infants and children. It is estimated about 3% of all infants are hospitalized with a moderate to severe respiratory infection, such as bronchitis, asthma and pneumonia.

Research shows infants who were exclusively breastfed, that is, they receive no food or drink other than breast milk, for four or more months, were 72% less likely to be hospitalized for a lower respiratory infection than if they were fed formula.

What causes lower respiratory infections?

Respiratory infections usually begin when an infant is exposed to germs (viruses or bacteria). These germs can be spread by breathing in droplets from another person’s infected cough or sneeze. Germs can also live on surfaces, such as countertops or door knobs as well as on hands and clothing.

Viral infections, like the common cold, occur frequently in infants and young children.  Most often these illnesses stay in the upper respiratory tract (nose and throat) and create all the symptoms we associate with the common cold. Sometimes, the illness becomes more severe, for example, pneumonia and bronchitis may develop in the lower respiratory tract (lungs).  The respiratory syncytial virus (RSV) is the most common cause of lower respiratory tract infections. RSV occurs most often between two and eight months of age and can become a serious illness requiring hospitalization.

How does breast milk protect children against lower respiratory infections?

Breast milk provides an infant with immunoglobulins, proteins, enzymes and other disease fighting elements, active in preventing infections.

Many compounds in breast milk help to fight a respiratory infection.  Some of these components include SigA (an important immunoglobulin), lactoferrin (a whey protein) and lysozyme (an enzyme).

Lysozyme and lactoferrin work together to destroy invading viruses and bacteria. While lactoferrin takes away necessary nutrients from viruses and bacteria, lysozyme enzymes attack their cell walls. Immunoglobulins, such as SigA, bind the bacteria or virus preventing it from spreading throughout an infant’s body.

The more of these substances an infant receives, the better an infant’s body is able to fight off infections or reduce the severity of illness. Formula does not contain any of these naturally occurring compounds. So, although breastfed infants are still susceptible to viruses, this enhanced disease fighting ability may partially explain why breastfed infants are less likely to be hospitalized for a lower respiratory tract infection.

About the scientific research

What kind of scientific review was this?

This was a systematic review/meta analysis of seven studies. The analysis evaluated the risk of hospitalization in 3,201 breastfed subjects and 1,324 non-breastfed subjects. The studies reviewed were conducted in developed countries among children less than one year of age with no other medical condition.

The researchers examined the association between breastfeeding and hospitalization for lower respiratory tract diseases.

The studies were adjusted for smoking and socioeconomic status, both of which could influence the risk of having a lower respiratory infection.

What were the results of the review?

The review determined that exclusive breastfeeding for four or more months is associated with an overall 72% reduction in the risk of hospitalization for lower respiratory infections compared with infants who were formula-fed.

Is there an opportunity for more research?

There are many factors that could influence these outcomes besides smoking and socio-economic status.  There may be factors in the behaviour of women who exclusively breastfeed that influence the development of lower respiratory tract infections requiring hospitalization.  Further research could be done to investigate the role played by those factors.  There is also an opportunity to further investigate the effect of breastfeeding against the frequency of lower respiratory infections and not only the cases which result in a hospital admission.  Further research, however, may be limited by the fact that not all lower respiratory infections are reported.

What were the results of the review?

The review determined breastfeeding is associated with a significant reduction in the risk of severe lower respiratory tract infections.



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Revised: Thursday October 10 2013

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