Breastfeeding is the ideal food for newborns and infants up to six months of life. Subsequently, it is also the perfect food, but accompanied by other foods to cover all nutritional needs. But it is not only complete from a nutritional point of view; breastfed babies have a lower risk of diseases such as asthma, type 2 diabetes, obesity or atopic dermatitis.
Also, babies and children who are breastfed have a lower risk of certain infections .
Does breastfeeding protect against infections?
There are already many studies that show that breastfeeding prevents infections. The most studied are respiratory and gastrointestinal infections, but it also protects against urinary tract infections and probably against others.
Respiratory infections
We include here upper respiratory infections (colds) and lower respiratory infections (pneumonia, bronchitis, bronchiolitis).
Breastfeeding, compared to formula, protects against respiratory infections. Breastfed babies have been shown to have fewer respiratory infections , less wheezing, and lower respiratory tract infections (such as pneumonia) in the first few months of life. Also, in the case of a respiratory infection, it will possibly be milder in breastfed babies and they will be less likely to get it than those who take formula. Also mortality from respiratory infection is much lower in breastfed babies.
Otitis media
As for ear infections, formula-fed babies experience many more episodes . This is not only due to the protection provided by the different components of breast milk, but also because the way of sucking at the breast (which we know is different from the way of taking a bottle), protects the inner ear.
gastrointestinal infections
Babies who are exclusively breastfed have fewer gastrointestinal infections (especially diarrhoea). This protection is greater when greater if breastfeeding is maintained exclusively during the first 6 months of life. Diarrhea mortality is also reduced, especially important in developing countries; in a study from Brazil, formula-fed babies had a 14-fold higher risk of dying from diarrhea than breastfed babies. In premature babies, breastfeeding has a clearly protective effect against necrotizing enterocolitis (the most frequent and serious intestinal pathology in these babies).
Other infections
As we have said previously, breastfeeding also protects against urine infections , although this effect is less well known. Protection against hand-foot-and-mouth disease , caused by the Coxsackie virus, has also been studied; 316 children with the disease were compared with 566 without the disease, concluding that breastfeeding protects against this infection during the first 2 years of life.
What elements of breast milk protect against infections?
It is known that breast milk contains antibodies that defend us against infections. However, there are many other components that, although less well known, play an even more important role.
– Immunoglobulins (antibodies). Immunoglobulin A is the main antibody in breast milk, which also contains immunoglobins M and G. Immunoglobulin A primarily protects against gastrointestinal and respiratory infections as it lines the respiratory tract and digestive system.
– Lactoferrin . It is a protein that binds to iron and transports it. Some bacteria need iron to grow; lactoferrin binds to the extra iron and prevents it from serving as food for these microorganisms. It also inhibits the growth of viruses and fungi. In addition, lactoferrin stimulates the immune system. It has been shown to prevent diarrhoea, neonatal sepsis and necrotizing enterocolitis.
– Oligosaccharides . They are carbohydrates (sugars). They prevent bacteria and viruses from entering. Recently, an association between breastfed babies and a lower risk of group B Streptococcus infection has been reported.
– Nucleotides . Their function is less well known but they do seem to be involved in immunity.
– Leukocytes . Defensive cells that are abundant in breast milk (they are also present in the blood) and appear to change in number and type at different stages
Does the protection vary according to the stage of lactation in which we are?
One of the properties of breast milk is that it changes its composition to adapt to the needs of the baby . The milk we produce in late pregnancy and during the first 2-3 days of our baby’s life is called colostrum. Later it changes to transition milk (up to approximately 2 weeks of life) and finally to mature milk.
Colostrum is often referred to as the first vaccine and, although it is not such (vaccines work differently), it is true that it plays a very important role in defense against infections. Thus, it has a higher content of lactoferrin, immunoglobulins and leukocytes than mature milk.
Regarding the duration of lactation, it seems that the longer the duration of lactation, the greater the protective effect against infections . Greater protection has been shown the longer the breastfeeding, especially after 3 months.
For example, a study carried out in the Netherlands showed that exclusive breastfeeding for 6 months was more protective than exclusive breastfeeding for 4 months and mixed breastfeeding afterwards. Another study from the UK showed that the longer the duration of breastfeeding, the lower the risk of respiratory or gastrointestinal infections. In addition, he saw that the protection lasted beyond 6 months, especially against diarrhea.
Breastfeeding continues to be beneficial in older children . Furthermore, for example lactoferrin, which has very high levels in colostrum and lower levels in mature milk, rises sharply again between 12 and 24 months.
If we do mixed breastfeeding, is there also protection against infections?
The “minimum” amount of breast milk to have this protection is not known, although it seems that the greater the amount of breast milk, the greater the benefit, especially if it is exclusive breastfeeding .
The effect of mixed breastfeeding on infections is less studied. A protective effect related to the dose or amount of breast milk received by premature and very low birth weight infants has been shown in relation to neonatal sepsis. A 2021 study compared respiratory and urinary tract infections, otitis media, and conjunctivitis in infants fed only breast milk versus those fed mixed or formula only. Protection against infection was only seen in the exclusive breastfeeding group.
However, the 2010 Dutch study did find a protective effect against infections if exclusive breastfeeding was carried out for 4 months and mixed breastfeeding afterwards.
In any case, whenever possible, mixed breastfeeding is preferable to exclusive formula feeding .
If my baby is sick, does breast milk increase his defense capacity?
Although it is not known how, there seems to be a “communication” between breast milk and the health or illness of the baby. Thus, it has been observed that the leukocytes in breast milk and the percentage of macrophages (a type of leukocytes) increase during infections in the baby and decrease after recovery. An increase in lactoferrin has also been seen during infections in the baby.
Summarizing…
Breastfeeding protects the baby against multiple infections , especially if it is exclusively breastfed for at least three months. The effect on respiratory and gastrointestinal diseases has been extensively studied, but it also has a protective effect on urinary diseases, otitis media and viral infections such as hand-foot-and-mouth disease.
Although we think that breast milk protects the baby because it contains antibodies (and it is true), there are many other components of breast milk, such as lactoferrin, leukocytes or oligosaccharides , among others, that have an even more important role in protecting against infections.
On the other hand, it seems that breast milk is capable of varying its composition to adapt to the needs of babies when they suffer from an infection , increasing, for example, the number of leukocytes and the percentage of macrophages.
