The More I Learn About Breast Milk, the More Amazed I Am
Before I had my daughter, I wasn't particularly interested in mother's milk. Now I'm literally awake at night thinking about it.
To produce breast milk, mothers melt their own body fat. Are you with me? We literally dissolve parts of ourselves, starting with gluteal-femoral fat, aka our butts, and turn it into liquid to feed our babies.
Before and after giving birth to my daughter 10 months ago, I was inundated with urgent directives from well-meaning, very insistent health practitioners, parenting book authors, mommy bloggers, journalists, and opinionated strangers that "breast is best." The message was clear: In order to be a good mom, I had to breast-feed.
But breast-feeding is more than being a good mom. And breast milk is much more than food: It's potent medicine and, simultaneously, a powerful medium of communication between mothers and their babies. It's astonishing. And it should be—the recipe for mother's milk is one that female bodies have been developing for 300 million years.
Breast-feeding leads to better overall health outcomes for children, which is why the World Health Organization and the American Academy of Pediatrics recommend that babies be exclusively breast-fed for a minimum of six months.
Those outcomes, though, are relative: A premature infant in the neonatal intensive-care unit or a baby growing up in a rural African village with a high rate of infectious disease and no access to clean water will benefit significantly more from breast milk over artificial milk, called formula, than a healthy, full-term baby born in a modern Seattle hospital.
We're also told that breast-feeding leads to babies with higher IQs and lower rates of childhood obesity than their formula-fed counterparts. I understand why people find this appealing, but I don't plan to raise my daughter to understand intelligence in terms of a single test score, or to measure health and beauty by body mass index.
More compelling to me are the straightforward facts about breast milk: It contains all the vitamins and nutrients a baby needs in the first six months of life (breast-fed babies don't even need to drink water, milk provides all the necessary hydration), and it has many germ- and disease-fighting substances that help protect a baby from illness. Oh, also: The nutritional and immunological components of breast milk change every day, according to the specific, individual needs of a baby. Yes, that's right, and I will explain how it works in a minute. Not nearly enough information is provided by doctors, lactation counselors, or the internet about this mind-blowing characteristic of milk.
I made the choice to breast-feed around the same time I was offered a full-time job writing about food. Every morning at 7 a.m., I nurse my daughter. At the office, I pump milk two times a day. When I come home, we nurse, and then at 7 p.m., we nurse before she goes to bed. A few nights a week, I go out to dinner for work.
For six months straight, I woke up every night at 3 a.m. and pumped milk for half an hour in order keep my supply ahead of her demand. (Three a.m. is possibly the darkest, loneliest, and most quiet hour of the night, but I had the reassuring, rhythmic sound of my pale-yellow breast pump to keep me company.) For the last 10 months, there hasn't been one minute of my life when I wasn't thinking about, writing about, eating, and/or producing food.
Food points to who we are as animals—human beings with a fundamental need for nourishment, survival—but also to who we are as people: individuals with families, histories, stories, idiosyncrasies. Every day, calories, vitamins, and even clues about the culture I live in flow, drip, leak, and squirt out of my boobs, staining my clothes and making my skin sticky. And every day, I wonder what exactly goes into this miraculous substance.
"People tend to underestimate what milk is," says Katie Hinde, a biologist and associate professor at the Center for Evolution and Medicine at the School of Human Evolution & Social Change at Arizona State University. She also runs the very funny, highly informative, and deeply nerdy blog Mammals Suck... Milk!
"That's in part because you go to the store and there's an entire aisle dedicated to buying milk that is literally a homogenized, standardized food. It leads us to take mother's milk for granted."
But right now, researchers like Hinde—a mix of evolutionary biologists, dairy scientists, microbiologists, anthropologists, and food chemists—are examining milk, and the more closely they look, the more complexities they find.
Nutritionally, breast milk is a complete and perfect food, an ideal combination of proteins, fat, carbohydrates, and nutrients. Colostrum, the thick golden liquid that first comes out of a woman's breasts after giving birth (or sometimes weeks before, as many freaked-out moms-to-be will tell you) is engineered to be low in fat but high in carbohydrates and protein, making it quickly and easily digestible to newborns in urgent need of its contents. (It also has a laxative effect that helps a baby pass its momentous first poop, a terrifying black tar-like substance called meconium.)
Mature breast milk, which typically comes in a few days after a woman has given birth, is 3 to 5 percent fat and holds an impressive list of minerals and vitamins: sodium, potassium, calcium, magnesium, phosphorous, and vitamins A, C, and E. Long chain fatty acids like DHA (an omega-3) and AA (an omega-6)—both critical to brain and nervous-system development—also abound in mother's milk.
The principal carbohydrate in breast milk is lactose, which provides copious calories and energy to fuel babies' relentless round-the-clock growth. (No, new parents, you are not hallucinating—your baby did just grow out of her pajamas sometime in the middle of the night.)
Other sugars are also present, including some 150 oligosaccharides (there may be even more, scientists are really just beginning to understand them), complex chains of sugars unique to human milk. (I repeat: unique to human milk.) These oligosaccharides can't be digested by infants; they exist to feed the microbes that populate a baby's digestive system.
And speaking of microbes, there's a ton of them in breast milk. Human milk isn't sterile—it's very much alive, filled with good bacteria, much like yogurt and naturally fermented pickles and kefir, that keep our digestive systems functioning properly. So mother's milk contains not only the bacteria necessary to help a baby break down food, but the food for the bacteria themselves to thrive. A breast-feeding mother isn't keeping one organism alive—but actually hundreds of thousands of them.
Like a glass of red wine, breast milk has a straightforward color and appearance, but it possesses subtleties in flavor that reflect its terroir—the mother's body. And it turns out that like any great dish of food, mother's milk holds a variety of aromas, flavors, and textures.
The flavors of breast milk are as dynamic as a mother's diet. In the 1970s, researchers at the University of Manitoba obtained samples of breast milk from lactating women and had them evaluated by a trained panel for taste, quality of sweetness, and texture. There were variations across all samples in all categories, most notably that the milk of a woman who had recently eaten spicy food was described by tasters as being "hot" and "peppery."
The flavors of food ingested by breast-feeding mothers—kimchi, carrots, mint, blue cheese—are transmitted to their milk and, in turn, tasted by their babies.
Based on her more recent research, Julie Mennella of the Monell Chemical Senses Center in Philadelphia believes that these early breast-milk experiences help infants develop their own personal taste preferences, as well as increase their enjoyment of particular flavors.