What is so special about breast milk?

I hope everyone is aware of the advice to breastfeed a baby in the first six months of life. In this blog, I’ll explain why breast milk is so special. What are the health benefits of breastfeeding? And which components in breast milk may be responsible for these benefits?

First, what are the benefits of breastfeeding? A recent literature overview by the Dutch Institute for Public Health and the Environment shows that even healthy babies in Western countries have short and long term benefits from drinking breast milk (link). There are many benefits, including for the mother. Most of the benefits for the infant are associated with the development of its immune system. So how does breastfeeding contribute to developing the infant’s immune system?

The first group of components that are important for developing a healthy immune system are immune-active proteins. Milk contains antibodies, anti-bacterial proteins, and immune-stimulatory proteins. On the one hand, this directly contributes to the defence against infections. On the other hand, these proteins also stimulate the immune system to mature, leading to a well-developed immune system for the infant.

Milk also contains complex sugar molecules that our body can’t digest, called oligosaccharides. These oligosaccharides are used by the good bacteria in the large intestine. The oligosaccharides in breast milk thereby lead to more of these good bacteria. This contributes to the immune system in two ways. First, if there are more good bacteria, it is more difficult for bacteria that may cause infections to cause problems. Second, these good bacteria, like proteins, can stimulate the immune system to mature.

Besides the proteins and oligosaccharides, milk contains many other components. For example, good bacteria that are transmitted alive to the infant, white blood cells, immune signalling components, and others. How much all these contribute to a healthy infant is not yet known. But it indicates that breast milk is a very complex liquid with many components that in synergy lead to a well-developed immune system, and thereby a healthy infant.

So what about bovine milk? The components mentioned above are only partly present in bovine milk and infant formula. But I will discuss bovine milk-based infant formula in more detail in a next blog post.

Kasper Hettinga, September 2017

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