Did you know how good breast milk is?

Many people are curious about why everyone from infant care experts to the WHO recommends breastfeeding. The secret lies in the composition of breast milk.
Why do babies need breast milk? Most people will directly say: Because breast milk is the basic nutrition for infants and young children. The carbohydrates, fats and proteins we need in daily life are all present in breast milk. However, if you think that breast milk only has these ingredients, you are underestimating breast milk. In fact, breast milk contains some very rare but key ingredients, that is: biologically active substances in breast milk.

01. What are the active substances in breast milk?

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What are bioactive substances in breast milk? As the name suggests, they are substances with active functions other than basic energy and nutrition in breast milk.

These substances have biological activity and physiological functions, including cells, active proteins, cytokines, active fat substances and active carbohydrates, such as whey protein, immune protein family, human milk oligosaccharides (HMO), nerve growth factor (NGF), etc. In short, it is a super luxurious gift package that meets the various growth needs of babies.

Some of these substances can be digested and absorbed and can also exert biologically active functions, possessing both nutritional functions and biological activities; while others can directly exert biological activities [1].

(Picture from the Internet) 02. What is the function of active substances?

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So what is the key role of these active substances? -- Enhance immune function.

After birth, babies actually have no "acquired immunity". Therefore, when faced with a sudden bacterial environment, whether it is air or breast milk contamination, babies are in a very vulnerable state, and it takes a long time to build up acquired immunity. Breast milk contains a large amount of active immune substances that can be directly transferred to babies through breastfeeding, enhancing their immune system development and helping them resist bacterial infection.

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Because of this, for babies, the earlier the breast milk, the more active immune substances it contains; especially the colostrum in the first 7 days, which can be said to be the "liquid gold" for newborns. The concentration of some immune substances in it is several times that of mature milk.

As shown in the figure below, the content of various bioactive substances in breast milk gradually changes over time.

*Changes in active ingredients in breast milk over time[1]
As shown in the figure, the active ingredients in breast milk are particularly high in colostrum from 1 to 7 days old. For example, the green squares represent the changes in IgM protein in breast milk over time (IgM is the abbreviation of immunoglobulin M, which is the immune protein with the largest molecular weight and has strong bactericidal immunity): the IgM in colostrum is more than 5 times that in mature milk, providing very strong immune protection for babies.

In simple terms, this diagram tells us that the protection from the mother does not only last during pregnancy, but also continues after birth through breast milk, especially colostrum feeding [2].

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In summary, our research on breast milk has found that:

The value of breast milk is not only to provide nutrition and energy for the baby;

A series of biologically active substances contained in breast milk play a key role in promoting the development of immunity for newborn babies.

Ref.

1 Ballard, Olivia, and Ardythe L. Morrow. "Human milk composition: nutrients and bioactive factors." Pediatric Clinics 60.1 (2013): 49-74.

2 Ren, Qiqi, et al. "Longitudinal changes in the bioactive proteins in human milk of the Chinese population: A systematic review." Food science & nutrition 9.1 (2021): 25-35.