Lawrence Trevelyan Weaver - White Blood: A History of Human Milk

Human milk is the best food for babies and provides all the nutrients needed for about the first six months of life. It contains nutrients that serve the unique needs of the human infant, such as certain polyunsaturated fatty acids, particular milk proteins, and iron in a readily absorbable form. Human milk also contains immunological and bioactive substances, absent from commercial infant formulas, which confer protection from bacterial and viral infections and may aid gut adaptation and development of the newborn.

thus spake the World Health Organization ( who ) at the beginning of the twenty-first century, expressing the consensus view that breastfeeding is the best way to feed newborn babies because of the superiority of human milk over all other alternatives. These words were composed by me and three colleagues when we were invited to produce guidelines for the who European Region on the Feeding and Nutrition of Infants and Young Children in 2000. There is nothing new about this message, which has been articulated many times before, in different words, by diverse voices, in distant eras, and it is now supported by a massive body of evidence derived from scientific research, clinical trials and population surveys.

Human milk contains all that the baby needs to develop and thrive during early life. Studies of infants that have been exclusively breastfed by healthy mothers show that from whatever country, continent or culture they come from they have the potential to grow at identical rates. It is the sole and sufficient source of nutrition until about six months, when complementary foods are required in addition to mothers milk. The opening statement above represents how we think about human milk now, and is the starting point for an account of how babies have been fed from antiquity to the modern day, and why it matters. Four themes run through this book, as threads binding its chapters together.

The first theme is the vitality of human milk, which is the lifeblood of the newborn baby. Just as blood courses through the body carrying everything it needs to flourish, so milk bears from mother to baby all that the infant requires to be nourished and survive. Human milk is a vital fluid in two senses of the word. It bridges the gap between the blood-borne nutrition of the fetus in the womb and the solid diet to which the baby becomes accustomed when weaned. In the absence of safe alternatives, human milk can greatly reduce the risk of premature death in infancy.

The second theme is transformation or transmutation, the processes by which human milk has its miraculous effects: how it is produced (lactogenesis and lactation) and what happens to it when it reaches the baby (digestion, absorption and metabolism). Mothers breasts and babys guts, the origin and destination of human milk, the pathway of nutrients from mother to young after birth, operate together in a way akin to the placenta and uterus before birth. The nutrition, metabolism, growth and development of the newborn depend on their coordinated function.

The third theme is reproduction and nutrition, which are the essential tasks that all living creatures must accomplish if they are to thrive and perpetuate themselves. For mammals, including humans, milk plays a critical role in both, serving dual purposes. As a unique biological fluid, human milk contains a perfect blend of nutrients and a vast array of other substances that together nourish and protect the newborn. It also helps them to adapt to life outside the womb and to grow, develop and thrive.

The fourth theme is the morbidity the baby may suffer from deprivation of human milk or improper feeding with inadequate alternatives to mothers milk. Colic, diarrhoea, malnutrition, rickets and sometimes death are some of the consequences of the wrong sort of milk feeding, often prevented or cured by human milk. Early life is a critical period when the ways in which the newborn is fed may have not just an immediate positive or negative effect on its health but also long-term consequences. Denial of human milk increases the risk to babies of infection, for instance, and may weaken emotional bonding with mother.

While breastfeeding is a biological reality, the ways in which it is conceived and carried out are culturally variable in both time and place. It may be performed by mother or another lactating woman, such as a wet nurse. It may be replaced by what in the past was called dry or hand feeding and nowadays usually termed bottle, formula or artificial feeding. The four themes introduced here are developed, chronologically and historically, to tell the story of how, within changing views of nature, culture, philosophy, medicine and science, we have come to think of human milk in the twenty-first century.