Human milk provides virtually all the protein, sugar, and fat your baby needs to be healthy, and it also contains many substances that benefit your baby’s immune system, including antibodies, immune factors, enzymes, and white blood cells. These substances protect your baby against a wide variety of diseases and infections not only while he is breastfeeding but in some cases long after he has weaned. Formula cannot offer this protection.
If you develop a cold while breastfeeding, for example, you are likely to pass the cold germs on to your baby—but the antibodies your body produces to fight that cold also will be passed on through your milk. These antibodies will help your infant conquer the cold germs quickly and effectively and possibly avoid developing the cold altogether.
This defense against illnesses significantly decreases the chances that your breastfeeding baby will suffer from ear infections, vomiting, diarrhea, pneumonia, urinary tract infections, or certain types of spinal meningitis. Infants under the age of one who breastfed exclusively for at least four months, for instance, were less likely to be hospitalized for a lower respiratory tract infection, such as croup, bronchiolitis, or pneumonia, than were their formula-fed counterparts. Even infants in group child care programs, who tend to catch more germs due to their close proximity, are less likely to become ill if they are breastfed or fed their mothers’ milk in a bottle.
All humans have a very large number of bacteria that normally reside in their intestines. Some of the bacteria serve normal and healthy functions, and some can cause disease such as diarrhea. Human milk encourages the growth of healthy bacteria in the intestinal tract of the breastfed baby. It does this by promoting a generally healthy environment and, in part, through substances called prebiotics, which are found in human milk. Since human milk stimulates the growth of these “friendly” strains of bacteria, other bacteria such as E. coli, which are more likely to cause disease, are inhibited from growing, multiplying, and attaching to the lining of the intestine, where they can cause infection. It has been well established that formula-fed infants have much higher rates of diarrheal diseases which may require visits to the doctor or sometimes to the hospital for intravenous fluids.
Breastfeeding and Allergies
Breastfeeding is recommended for many reasons. With regard to allergy prevention, there is some evidence that breastfeeding protects babies born to families with a history of allergies, compared to those babies who are fed either a standard cow’s milk based formula or a soy formula. In these “at risk” families, breastfed babies generally had a lower risk of milk allergy, atopic dermatitis (commonly known as eczema), and wheezing early in life, if they were exclusively breastfed for at least four months. It is presumed that immune components in maternal milk provide protection against these allergic diseases. Although the long-term benefits of breastfeeding on allergies remains unclear and studies have not carefully evaluated the impact on families without a history of allergy, exclusive breastfeeding is recommended as the feeding of choice for all infants.
Transfer of the human milk antibodies and other immunologic substances may also explain why children who breastfeed for more than six months are less likely to develop childhood acute leukemia and lymphoma than those who receive formula. In addition, studies have demonstrated a 36 percent reduction (some studies show this reduction to be as high as 50 percent) in risk of sudden infant death syndrome (SIDS) among babies who breastfeed compared to those who did not, though the reasons for this are not fully understood. Recent research even indicates that breastfed infants are less likely to be obese in adolescence and adulthood. They are also less vulnerable to developing both type 1 and type 2 diabetes.