Long reduced to a simple “best milk” for infants, breast milk today appears to be a much more complex fluid. The researchers describe a real living ecosystem, full of bacteria, molecules and signals that already influence the newborn’s body. A discovery that changes the way we look at breastfeeding beyond just nutrients. What happens in the bottle or at the breast could weigh much longer than the first months.
At the heart of this silent revolution, a question is of increasing interest to parents: to what extent does the mother’s diet during breastfeeding shape the milk microbiota and, through it, the future health of the baby? Studies are beginning to link what the mother eats, the bacteria present in her intestine, then in her milk, and finally those which colonize the infant’s intestine. The first responses seem to promise as much hope as new responsibilities. And they don’t just concern mothers.
Breast milk and microbiota: an ecosystem to start life
Scientists have shown that breast milk is not sterile. There we find communities of bacteria such as Bifidobacterium, Lactobacillus or Streptococcus, which participate in the healthy colonization of the baby’s intestine. This breast milk microbiota helps the intestinal barrier to form, regulates inflammation and participates in metabolic programming. With each feeding, the child therefore receives calories, but also a cocktail of microbes and molecules which train his immune system.
Another striking discovery is the possible existence of an enteromammary route: certain bacteria from the maternal intestine migrate to the mammary gland, transported by immune cells. If this mechanism is confirmed, the mother’s intestinal microbiota would directly influence that of her milk, then the baby’s intestinal microbiota. Hence the idea that the breastfeeding mother’s diet can become a discreet but important lever for the health of her child, sometimes years later.
What the mother eats, what the baby gets
The maternal intestinal microbiota strongly depends on what she puts on her plate. A diet rich in fiber, fruits, vegetables and legumes promotes greater microbial diversity and the production of short-chain fatty acids, known for their anti-inflammatory effects. Conversely, a diet very rich in refined sugars or fats leads to lower bacterial diversity and a more inflammatory profile. Some studies already link diet quality to the bacterial composition of milk and the presence of lipid and immunomodulatory metabolites.
A study published in Nature Communications, carried out on 195 mother-baby couples over six months, goes in this direction. The same bacterial strains were found in the milk and then in the intestines of children, with a strong presence of Bifidobacterium longum subsp. infantis. This early colonization is linked to the subsequent risk of allergies, obesity and metabolic diseases, and even certain neurobehavioral disorders.
Adapting your plate without pressure, such a collective issue
Concretely, more plants, legumes, whole grains and fats, while limiting ultra-processed products, supports this microbiota of breast milk. But women do not have the same access to this food nor the same conditions.