01.3: The magic of milk

Every mother's milk is unique, and always changing

Every mother's milk remains a unique and ever-changing food, providing a vast and changing array of hormones, enzymes, growth factors and nutrients over time, even between feeds and between breasts, and certainly between babies. The infant can influence the composition of the milk, tailor-making their supply, by the subtle interactions between breast and baby during feeding.

Within the normal range, some babies create a milk supply higher in fat than the average 7%, and smaller in volume. Others thrive on a greater quantity of less calorie-rich milk.

When the mother pays attention to the baby's signals and feeds as needed, she can reasonably expect a baby to be contented and grow, if nothing in her milk is causing gut problems, but the presence of antigens to which the baby has been sensitised, and the legacy of her own past infant feeding, often results in infant food sensitivity, which can cause misery instead of contentment to be the norm. For more on this see later modules.

The mother's body is sampling her environment

The mother's body is actively sampling her environment, via the air she breathes and the food she eats. All that she comes into contact with will be assessed and processed by her body. Her milk will reflect it, as sensitised cells from both her gut and her airways will migrate to the breast, and there specific antibodies against all potential threats will be made.

This migration is made via pathways referred to as the entero-mammary (gut to breast) and broncho-mammary (respiratory system to breast) circulations.

The breast is part of the immune system

Additionally, every mother's milk contains literally hundreds of species and strains of different microbes that her body has learned to thrive with. These friendly bugs, along with the mother's immune cells, form the basis for the development of a healthy gut microbiome in the child.

Key point
The breast is a basic part of the human immune system, although many health professionals are unaware of its central importance. The breast is an important bridge from the womb to the world; babies are born to be breastfed.

The effects of not being breastfed, and instead getting a diet of heavily-processed food from birth, will always be unpredictable and detrimental, both immediately and throughout life. Many ill effects can be passed on to the next generation, born from the bodies of those not well breastfed.

How astonishing

Pregnancy and birth, and early life stress are being investigated in relation to development of immune disorder, often without controlling for infant feeding, although feeding is affected by birth and stress and known to alter outcomes: it is “the single most important postpartum element in neonatal metabolic and immunologic programming.”

Cabrera-Rubio R, Collado MC, Laitinen K, Salminen S, et al. The human milk microbiome changes over lactation and is shaped by maternal weight and mode of delivery. Am J Clin Nutr 2012; 96(3): 544. DOI: 10.3945/ajcn.112.037382.