Human Milk: The Original Personalized Medicine

Jae Kim, MD, PhD / February 2016


The realization that new mothers of preterm infants get when they may not have enough mother’s own milk (MOM) for their child is a highly stressful event and one that now can be increasingly bridged by the use of donor human milk. A crisis and conflict forms because very low birth weight infants getting only preterm formula for the first few weeks of life have been shown to fare worse, with higher risks of developing necrotizing enterocolitis and/or sepsis than infants feeding human milk. 

The rapidly increasing availability of donor human milk from commercial and non-profit sources enables more mothers to have access to human milk while they are challenged to make their own. There are increasing concerns however that in some cases access to donor human milk provides a crutch for mothers and healthcare professionals to avoid the hard work and added costs of lactation and pumping milk for their babies. 

Most NICUs I have visited have not seen a surge in donor human milk at the expense of MOM but a few have experienced soaring costs with adoption of a donor human milk protocol, particularly if they had not placed a strong enough emphasis on lactation support with their entire healthcare team. The work involved in building a competent, sustainable lactation support team is challenging. Covering the cost of donor human milk too has not been fully resolved with Medicaid and insurance companies. 

There is a risk now of forgetting or not appreciating the value of MOM. There is quite the movement to push for exclusive human milk intake for preterm infants but perhaps less emphasis on why it should predominantly be mother’s own. So what is the value of MOM over donor human milk and what are the potential aspects that may turn up in the future? How big a deal is it that a child cannot feed on their own mother’s milk? 

Here are some take home points of why MOM is still the best:

  1. Cellular content: Human milk is a rich living tissue like blood. The direct transfer of human cells such as immune cells like neutrophils, macrophages, natural killer cells, etc. is lost with donor human milk and with any freezing of MOM. The best source of these cells is taking it directly from the breast. The recognition of a rich probiotic community of organism found in MOM is also an important cellular component of MOM that is lost with heat treatment such as pasteurization of donor human milk. MOM has the richest collection of human and bacterial cells to protect the preterm infant.
  2. Rich bioactive compounds: There are literally hundreds of different compounds found in human milk that are affected by degradation of time, cooling and heat pasteurization that make donor human milk much less potent compared to MOM in providing the most active compounds from this list of hundreds. Fresh MOM is the most bioactive form of human milk.
  3. Immunologic identity: MOM contains a unique profile of cellular immunity that is based on mother’s own experience with infection and pathogens in the environment, including those she experiences in the NICU. This exposure to the same context as her infant may be an important method by which she can provide protection to her fragile child.
  4. Microbiota and the milk: We are only beginning to touch the surface of understanding the microbiota (microbes) that are present in the gut of the preterm infant and how MOM may be providing early influences to the development and maintenance of the preterm gut microbiota.
  5. Oligosaccharides (mother specific): MOM contains over 150 different types of sugars called oligosaccharides that are responsible for providing a critical defense against infection of all types (bacterial, viral, fungal) of infection. Fortunately these sugars are minimally affected by time, heat and cold but the highly specific matchup of mother-baby with milk sugars is still poorly understood.
  6. Vitamins: The fat soluble vitamins such as vitamin A and D are important vitamins that have widespread health benefits. We are realizing that vitamin levels in mothers influence heavily that of their newborn. This pathway is a unique opportunity to use mother’s diet to augment their own babies vitamin stores to given them ample access to these important compounds.
  7. Fatty acids: Dietary intake of fat in mothers is also highly correlated to the fatty acid profile of their infants. So although a mother cannot change the fat proportion of her milk by eating more fatty foods, she can dramatically alter the fatty acid profile of her milk and confer a healthier fatty acid profile (such as omega-3 fatty acids) to her infant through her milk.
  8. Drugs: Some unique situations arise now with the epidemic use and abuse of prescription narcotics. Mothers that are being treated on very high opioid drugs can continue to provide MOM to their infants with an understanding that a small quantity of drug (generally <1%) passes through their milk to their child and may soften the withdrawal symptoms of their child. (Please note: this remains a highly controversial area for people and more experience/data need to be summarized to derive the best practices here)
  9. Environmental toxins: Human milk is also a mechanism whereby toxins and unwanted chemicals in mother’s bodies are excreted out into their milk. This is a challenging area of milk research as we need to better understand the long-term importance of the trace amounts of these environmental toxins on infants. Most mothers would rather pass on their own specific risks of exposure rather than take those risks of other milk donors. Generally however since donor human milk is pooled from several to several thousand donors, there is an averaging down of environmental risk with donor milk.

So, there are still very many compelling reasons to focus primarily on lactation support of mothers to generate the maximum potential for MOM rather than just on donor human milk. Mothers need to be told that they are specially designed to provide milk for their own babies and that donor human milk is an inferior substitute. MOM is the original personalized medicine! Providing donor human milk is a wonderful bridge for us to give to vulnerable preterm infants, but is a means to an end of enabling mothers to ultimately feed and ideally breastfeed their infants long-term to give the best health outcomes to their babies. Any ideas on how we can reinforce this message? How about a onesie that says “I got it from my Mommy” and a Psy* video to match?

Looking for more on this subject?
Read “Pumping up the Volume in the NICU.”

*The music performer Psy, of “Gangnam Style” fame


About the Author

Jae Kim is an academic neonatologist and pediatric gastroenterologist and nutritionist at UC San Diego Medical Center and Rady Children’s Hospital of San Diego. He has been practicing medicine for over 23 years both in Canada and the USA. He has published numerous journal articles, book chapters, and speaks nationally on a variety of neonatal topics. He is the Director for the Neonatal-Perinatal Medicine Fellowship Program at UC San Diego and the Nutrition Director of an innovative multidisciplinary program to advance premature infant nutrition called SPIN (Supporting Premature Infant Nutrition, He is the co-author of the book, Best Medicine: Human Milk in the NICU. Dr. Kim is a clinical consultant with Medela, Inc.