Could a cow really make human milk?
November 01, 2012
The frequent news about cows and other mammals producing human milk is enough to make you wonder if it might be possible for scientists to replace you and your milk.
But let us explain how science will never be able to create a cow, goat, sheep, or other mammal that can produce human milk or confer the health effects of breastfeeding.
A few pieces don’t make a puzzle. Reports of other mammals producing “human milk” usually focus on a few components of breastmilk - things like lysosyme, lactoferrin, and alpha-lactalbumin. These are all important parts of breastmilk, but human milk contains hundreds of components, and some constituents haven’t even been identified yet.
We don’t even know what the completed puzzle looks like. Of the components of human milk that have been identified, we’re still figuring out exactly why they’re there. It’s only recently, for example, that we’ve figured out why some complex sugars called oligosaccharides exist in human milk, since we’ve known for some time that they’re indigestible. (We now know that they are a form of prebiotic, fueling important probiotics in the baby’s gut). We’re just beginning to understand the function of a number of cancer-fighting components, and we’ve only recently discovered that breastmilk contains stem cells. So, these cows are producing a milk that is a far cry from human milk, in part because we’re just beginning to understand how human milk works.
Your milk is a personalized product. Even if science could create a match for many of the major ingredients in human milk, it still wouldn’t hold a candle to the milk you make without even thinking about it. The reason: the milk you make for your baby contains antibodies against pathogens you have been exposed to. If your friend, who has a cold we’ll call Virus Q, sneezes on you, your lungs will take in that virus, and your lymphatic system will send a message to your breasts to make milk with antibodies that protect your baby against Virus Q, exactly. It works the same way with bacteria you take in by mouth. To make a cow, sheep, or goat which could do this is just not possible, because they’re not exposed to the same stuff as you and your baby.
Your milk is alive. Human milk direct from the source is a “live” fluid, containing millions of live cells carrying out their respective duties in your baby’s system. Live white cells, called leukocytes engulf pathogens and T-memory cells can live for years and provide long term protection. Any manufactured, packaged, and shipped product is not alive, and can’t provide this kind of benefit. Of course, if you pump and freeze your milk, the cells in your milk aren’t alive. But a remarkable amount of protection survives pumping, freezing, defrosting, and even pasteurizing.
Your milk changes all the time, depending upon your baby’s needs. Human milk constantly changes to meet the needs of individual babies. The milk you made on day 1 of your baby’s life is different than what you made on day 10 or will make on day 100. The milk you make in the morning is different than the milk you make at night (fattier, and filled with sleep inducing neucleotides), and the milk your baby gets at the beginning of a feeding (full of brain-building sugars) is different than the milk he gets at the end (full of “good fats”). Anyone who has pumped milk will notice that at times there is a thick layer of cream at the top and at times there is a thin one - another adjustment for hour-by-hour needs of your baby. A thin layer may mean that you haven’t fed for a while and your body knows that the first priority is to hydrate your baby - hence a higher proportion of water.
Even more ways breastmilk is tailored to you and your baby. And the list goes on: Some components of your milk are specific to your (the mother’s) blood type. What you eat determines the flavor of your milk, and helps introduce the flavors of your family’s diet to your baby. Preterm milk is differently composed than full term milk. Your milk even reflects your genetic material.
There’s power in the act of breastfeeding itself. In our fascination with the impressive composition of breastmilk, we sometimes lose sight of the fact that some of its power derives from the act of breastfeeding itself. The act of breastfeeding properly forms a child’s palate, requires an interaction that supports a child’s social and emotional development, elicits the release of hormones which help mothers fend off postpartum depression. And the act of breastfeeding is probably why breastfed babies are less likely to be obese and overweight as children. Research has found that, when comparing breastfed and bottle fed babies, bottle fed babies are at higher risk even when the bottles contained breastmilk. Why? Probably because it’s not the milk but the method of feeding: breastfed babies control their intake, bottle fed babies’ intake is controlled by the person feeding them.
And it’s about your health, too. Making milk offers mothers protection against a number of diseases and health conditions. Among them are breast cancer, ovarian cancer, Type 2 diabetes, and postpartum depression. And research is accumulating showing that breastfeeding is important to long term weight, blood pressure, heart health, diabetes, and the whole constellation of problems called metabolic syndrome. It might even give you better breast aesthetics than if you have a baby and don’t breastfeed!