The Invisible Breasts of the Free Market

Allo-Mother’s Milk Part I discussed cultural, historical, and evolutionary perspectives of allo-mother’s milk. Here Allo-Mother’s Milk Part II continues…

Right now numerous entities are developing a “milk” supply for clinical intervention. Examples of this endeavor are Prolacta and the non-profit Human Milk Bank Association of North America. One critically important application for donor milk is that it reduces the risk of necrotizing entercolitis in NICU babies. A recent meta-analysis of randomized, controlled trials revealed that premature babies that consumed commercial formula were 4 times more likely to develop this dangerous infection than premature infants that consumed donor milk (Ben et al. 2012).

These "milk" supply efforts rely on donated milk from women screened for heath and lifestyle. After donation, milk undergoes processing to make it safer (e.g. pasteurization). These processes, while important for protecting the recipient, can also neutralize some of the beneficial bioactive constituents in milk. Moreover the overhead costs and clinical applications of these milk banks and commercial entities limit the general public’s access to human milk. 

And the general public is clamoring for raw, unpasteurized human breast milk.

As stated by Geraghty et al. 2011 “A first step in understanding how to share raw, unpasteurized human milk is simple: just enter key words such as “breast milk” or “human milk” into an Internet search engine along with another descriptor such as “buy, purchase, sell, want, for sale, or share.” This action produces a variety of links to donor milk banks, classified advertisements, blogs, chat rooms on social networking sites, and random posts.”

I’ll be honest, selling human breast milk -unscreened, unregulated- on the internet is terrifying to me on numerous levels. Let’s just set aside my humanist concerns about how the current economic climate induces women to upregulate milk synthesis to make ends meet, potentially compromising their own health and their baby’s health. This keeps me awake at night because of the basic deficits in our fundamental understanding of breast milk.

We don’t know what is in milk.

 Yay for Terran Echegoyen-McCabe and Christina Luna!

Although we know that in general milk contains hundreds, maybe thousands, of bioactive molecules, a systematic description of everything in human milk does not exist. There are constituents that are crucial for the infant’s health and development that are not yet in commercial formulas such as immune factors, oligosaccharides, growth factor, cortisol, and beneficial bacteria. This is why people are keen to buy breast milk, and willing to go online to do so.
     

But in terms of buying milk from faceless strangers on the internet, we have no idea what is in that specific milk. Milk can include viruses, pathogenic bacteria, drugs, and poisonous toxins. HIV, E. coli, and meth are rare and the probability that they are the milk being traded online is slim, but its not zero. If I was at the hospital and I had a choice between Bag A and Bag B for my blood transfusion, and Bag A definitely didn’t have HIV or meth, and Bag B probably didn’t, guess which bag I'd choose. I certainly wouldn't say "Let's have my lucky quarter decide- heads, Bag A and tails, Bag B!" 

And lots of potentially dangerous things in milk aren't quite so rare- such as BPA, cytomegalovirus, and over-the-counter drugs.

Moreover the value of human breast milk is by volume. The composition can not be evaluated by the consumer. Now, I expect that most people are likely providing healthy, safe milk via the internet. But just as some unscrupulous drug dealers cut cocaine with talcum powder, internet milk may be padded with cow’s milk or tap water. At least the drug dealer has some incentive to not sell weak blow. The drug dealer wants to keep customers coming back- and not to kick his ass. Those constraints don’t apply to people selling human milk on the internet. The benefit of cheating is very high, the risk of getting caught is very low, and the consequences if caught are NOTHING. 

We don’t know how or why milk constituents vary.

Studies have shown that concentrations of constituents in milk vary across lactation within mother or among mothers at any given time, but we don’t entirely know how much or why (Hinde & Milligan 2011). Sure, we know that colostrum is different than mature milk, but that’s a simple dichotomy. This isn’t the bulk candy aisle where mixing and matching gummy worms and chocolate covered pretzels provides the perfect synthesis of savory and sweet.

Across infancy there are critical windows of metabolomic, neurobiological, skeletal, and physiological development. Sometimes there are do-overs and catch up, but sometimes there isn’t. The functional development of the mammary occurs during pregnancy when a woman’s placenta and fetus can hormonally signal to her mammary gland. For this reason scientists hypothesize that the milk a mother synthesizes is specific to her infant precisely at that time, linked to that infant’s developmental trajectory and her own condition. Although there may be benefits to allo-mother's milk from an evolutionary perspective, when observed in other mammals allo-mother's milk supplements mother's milk, its not usually a replacement.

We don’t know what all these constituents do in the baby.

That’s right, I said it.

Lovely Adelaide

We. Don’t. Know.

There are relatively few studies that look at the consequences for the infant as a result of variation in the concentration of milk constituents and milk volume among mothers. Fortunately, this area of research is expanding due to new assay methods and renewed intellectual interest in inter-individual differences. Milk is the new British Empire- the sun never sets on lactation science. Dairy milk is a leading global industry and unlocking the fundamentals of mammary gland biology is critical for cancer research. If we had all the answers to milk- the sum total of what it is and what it does- that would be fantastic. But research takes money and time, especially when studying incredibly complex humans who develop slowly.

And in the meantime, I can swing over to Only the Breast, browse the profiles of women and photos of their robust babies, and buy "liquid gold" for $2/oz. 

So what is the solution?

 

Obviously we have to tip the scales of supply and demand.

Goal #1: Reduce the Demand for “Grey” Market Human Breast Milk

RISK AWARENESS Solution: Effectively communicate the risks and dangers of purchasing unscreened human breast milk from strangers. One way to do that would be to… oh… I don’t know… hows about you forward this blog post?

IMPROVED FORMULA Solution: Parents who want to feed their baby breast milk, but for whatever reason can't, are buying internet milk because they don’t want to use formula. If a more representative formula were available (cost effectively), its likely that fewer parents would take the risk of internet breast milk. Commercial infant formulas need to better reflect the complex biofluid that is human milk. Advantageously, many companies are interested in doing just that. Commercial formula R&D teams are actively translating new data on mother’s milk into food science. 

Goal #2: Increase the Supply of Breast Milk

MORE HUMAN MILK Solution: Expand the current national network of milk banks, donor programs, and private industry similar to the management of our national blood supply. (American Red Cross… I am looking in your direction). Just as many hands make light work, many boobs produce substantial volumes of life-saving donor milk, at low per individual cost. This would generate a larger supply of donor milk, increase screening of donated milk, and standardize “best practices” for collection and storage. Such a plan would have to guard against potential problems of the commercialization of human fluids (very tricky). It would also require the improvement of processing techniques so as to retain the bioactivity of milk constituents. Most importantly, the products of these efforts can not be restricted exclusively to clinical settings like the NICU. We must find a way to make them safely and economically available to the general public.  

The solutions outlined above are contingent on fundamental milk science research. We can’t communicate the specific risks without broadly surveying milk composition across women. Similarly, infant formula can’t be improved without a better understanding of how bioactive constituents in milk affect babies. Lastly, we need to optimize milk processing techniques to maximize safety without neutralizing important bioactive constituents. Research of this magnitude requires substantial investment in the form of research grants, but the benefits to human health and nutrition are substantial.

The US Department of Health and Human Services oversees the National Institutes of Health, the leading funders of human health research in the US. Currently, Strategic Initiatives of the DHHS include the goals to:

-Promote Early Childhood Health and Development

-Implement a 21st Century Food Safety System

-Accelerate the Process of Scientific Discovery To Improve Patient Care

Breast milk, and the online trading of it, has implications for all of these initiatives. If these topics matter to you and you think funding research on mother's milk is important, I encourage you to contact DHHS Secretary Sebelius and/or your senators and representatives in Congress.

References:

Ben et al. 2012. The Benefits of Expressed Maternal Milk and Donor Breast Milk for Preventing Necrotizing Enterocolitis in Preterm Infants: Systematic Review and Meta-Analysis. J Nutrition Disorder Ther 2:2 doi.org/10.4172/jndt.1000110

Geraghty, Heier, & Rasmussen. 2011. Got milk? Sharing human milk via the Internet. Public Health Rep. 126:161-4.

Hinde & Milligan. 2011. Primate milk: proximate mechanisms and ultimate perspectives. Evol Anthropol. 20:9-23

And naturally just as I finished writing this post I discovered a kickass article over at Slate.

Allo-Mother’s Milk (Part I)

Wait, what? 

Yes, women other than the mother provide breast milk for babies. Throughout human history and across cultures there are numerous documented practices of allo-maternal nursing. 

Within Islamic culture, there is the practice of “milk kinship.” This is a cultural construct of a familial relationship, analogous in many ways to “god-parents” among Catholics. In such instances infants are nursed by a woman not their mother, and consider her biological children “milk brothers” and “milk sisters.” In this way life-long social bonds are established and maintained throughout childhood, adolescence, and adulthood. And these relationships are in place in the event of the death of the biological parents (Parkes 2005).

Wet-nursing was a prevalent practice before the advent of commercial formula. Throughout the Renaissance and into the early 20^th Century, poor women were hired to nurse the infants of wealthy women. Physiologically the period of lactation, especially early and peak lactation, requires the mobilization of maternal body fat and skeletal minerals. When mothers are losing weight, ovarian function is suppressed and women do not experience a menstrual cycle (Valeggia & Ellison 2009). Once mothers recover from this “depletion” of their bodily stores, they can conceive. In this way inter-birth intervals are often correlated with the duration of exclusive breastfeeding (but not always). 

By hiring wet-nurses, wealthy women were able to shorten inter-birth intervals and produce large families by forgoing the somatic costs of lactation. In contrast, the poor women would often neglect their own infants and bias nursing behavior toward paying customers. The mortality rate for the biological infants of wet nurses was estimated to be quite high. Disentangling infant mortality due to wet-nursing from the immuno-socio-politico-ecomonic context in which it occurred becomes damned tricky, especially when relying on historical records. Take home message; wet-nursing was contingent on wealth disparity and generally had bad outcomes for oh, let’s randomly say, these guys. 
                              

 

Allo-maternal nursing is not just a cultural invention of humans, it has been observed in many other mammals (>70 at last count).  A review by Roulin (2002) discussed the prevalence of the behavior and considered several evolutionary explanations. Identifying the functions of allo-maternal nursing is quite important. Synthesizing milk is costly- a repeated theme on Mammals Suck…Milk!- so why would natural selection favor mothers who nourished young not their own? 

Here are the most compelling hypotheses, to my mind, in playlist form:

1. U Can’t Touch This

(aka milk stealing)

In species that give birth in large colonies, infants may be able to “steal” milk and nimbly evade females that would otherwise not nurse them. This is observed in elephant seal rookeries (Reiter et al. 1978). Weaned pups will travel the beach suckling from sun-basking females who are slow to notice that they are nursing some other kiddo. Upon the realization, females will bark and attempt to bite, but by then the pup has scampered away. Elephant seal pups that use milk stealing tactics can grow to twice the size of normal weanlings and are colloquially called “super-weaners.” From the female’s perspective, the small amount of milk stolen is likely less costly than the energy it would take to be super vigilant and punishing sooooo… we can infer that its cheaper from a selective perspective to just take the hit.

2. Nothing’s Gonna Stop Us Now

(aka misplaced maternal care)

The gestation and delivery of a mammalian baby triggers the release of hormones, coursing through a mother’s brain and body, sending an overwhelming signal to “love” & nourish the little bundle of joy. For example, oxytocin is an ancient mammalian hormone that is important for milk let down and the establishment of the mother-infant bond. There are numerous overlapping neurobiological, behavioral, and physiological systems for mothers to take care of infants, because infant survival among mammals requires maternal investment to some extent.

Next time you are at the airport, look at the number of rivets that hold the wing to the plane. Does any one rivet hold the wing on? No. All those rivets are there so that if one, or two, or five fail- the plane KEEPS FLYING. 

Selection did the same thing with mutations that enhanced maternal effort- favoring redundancies and fail-safes. Selection is not effing around on this one. Because maternal effort is so critical for female reproductive success among mammals, there are a motherload of adaptations for motherhood.

But sometimes the infant dies when hormones are still compelling the mother to bond (Thierry and Anderson 1986). In such circumstances some primate mothers will continue to nurture the dead corpse for hours, days, or even weeks. Alternatively, high-ranking females will occasionally kidnap the infant of a lower-ranking female. Sometimes these kidnapping events stick and the adoptive mother nurses the infant, sometimes the biological mother gets her infant back, and sometimes the infant gets sick, hurt, or dead. And every now and then there is a glitch in the matrix- females are too mothering and nurse other females’ babies like the junk lady in Labyrinth collects dolls. Such rare and less common events are when the dial of functional adaptations are turned all the way to “11.”  Although these behavioral manifestations aren’t adaptive for those particular individuals, the underlying architecture upon which they originate is adaptive.

3. Cooperation

(aka cooperative breeding)

Some species are characterized by cooperative breeding in which related or unrelated adults contribute to rearing infants of a dominant breeding pair. Contributions can include provisioning breeding females (and pups as they are weaned), baby-sitting, territorial defense, and in some species females will nurse the dominant female's babies. Among meerkats, pups will suckle from allo-mothers who have lost their litter or who have spontaneously started lactating (Scantlebury et al. 2002). This allo-nursing is unidirectional from subordinate females toward the pups of a dominant female. The benefit to the pup is clear, but for the allo-mother is less clear. The evolution of cooperative breeding social systems are complicated, but are often attributed to kin selection or reproductive queuing.

4. Tit for Tat

(aka reciprocal altruism)

Bi-directional allo-nursing occurs when two females nurse each other’s infants. Among some species of mice, two females will share a nest and take turns going on foraging expeditions and staying behind and nursing all the pups at the nest. The females nurse their pups and the other pups equivalently. About half the time the two females are sisters, but these reciprocal arrangements are just as often between unrelated females. Moreover the arrangement can be stable across multiple birthing seasons (Weidt et al 2008). Such an arrangement likely involves the dual benefit to the pups of better protection from predators and shorter inter-nursing intervals (which may improve growth).  

5. Rockin’ Pneumonia

 (aka enhanced immune function)

Mother’s milk is not only nutritive, but is integral component to defending the infant against pathogens and entrains the infant’s developing immune system. Milk includes maternal antibodies, commensal bacteria, and special sugars for beneficial bacteria to consume (future post topic). Infants who suckle from multiple females may be boosting their immune system from the diverse exposures they get from allo-maternal milk.This may technically be a sub-category of reciprocal altruism or milk stealing because while the benefit to the infant is clear, the benefit for a female nursing a non-biological infant is less straight-forward without minimal costs or a tit-for-tat exchange.

________________________________________________

Although allo-maternal nursing occurs in many mammalian species, most of our understanding of it comes from opportunistic studies and arm chair hypothesizing. There is so much that is not known about the advantages and disadvantages of drinking allo-mother’s milk (Milligan et al. 2008). Our superficial understanding is particularly alarming because human milk is becoming a multi-million dollar cottage industry involving millions of units annually. 

continuted in Part II

References:

Milligan LA, Gibson SV, Williams LE, Power ML. 2008. The composition of milk from Bolivian squirrel monkeys (Samiri boliviensis boliviensis). Am J Primatol. 70:35-43.

Parkes. 2005. Milk Kinship in Islam. Substance, Structure, History. Social Anthropology 13: 307-329.

Reiter, Stinson, & Le Boeuf. 1978. Northern Elephant Seal Development: The Transition from Weaning to Nutritional Independence. Behav Ecol Biol 3: 337-367.

Roulin A. 2002. Why do lactating females nurse alien offspring? A review of hypotheses and empirical evidence. Animal Behaviour. 63:201-208.

Scantlebury M, Russell AF, McIlrath GM, Speakman JR, Clutton-Brock TH. 2002. The energetics of lactation in cooperatively breeding meerkats Suricata suricatta. Proc Biol Sci. 269:2147-53.

Thierry & Anderson. 1986. Adoption in Anthropoid Primates. Int J Primatol. 7: 191-216.

Valeggia C, Ellison PT. 2009. Interactions between metabolic and reproductive functions in the resumption of postpartum fecundity. Am J Hum Biol. 21(4):559-66.

Weidt, Hofmann, and König. (2008). Not only mate choice matters: Fitness consequences of social partner choice in female house mice. Animal Behaviour, 75:801-808.

Mammals Suck on Skeptically Speaking!

Last week, I was interviewed by Desiree Schell on Skeptically Speaking, a radio show out of Edmonton, Canada. The program originally aired on Mother’s Day, but the podcast can now be streamed or downloaded here. We had a great time talking about functional development of the mammary, whether or not breast milk is that much better than formula, agenda-driven science, wet-nurses and allo-maternal nursing, misconceptions about breast-feeding, and the social contract of science funding. Good times! Following my interview, Kayt Sukel, author of Dirty Minds, is interviewed about the neurobiology of parenting. Check check check it out!

Also here is a belated "YAY Mothers and Allo-Mothers!" 

(FYI check out Kate Clancy's allo-mother post)!

I am pretty sure that this must be an artist’s representation 

of my mother and a baby me. 

UPDATE: If you don't have time to listen to the podcast, the interview got an awesome write up here with all the key take home points in their intended context. Yay!

Italy? Autumn? Milk? YES PLEASE!

Today is the last day to submit abstracts for the 16^th biennial meeting of the International Society for Research in Human Milk and Lactation Sept 28-Oct 1, 2012. The theme is “Breastfeeding and the Use of Human Milk Science & Practice” but submitted abstracts can and will run the gamut of milk and lactation research. The preliminary program looks kickass and its bound to be a spectacular meeting. See you in Trieste!

Canary in the Coal Mine: Breasts, Lactation, and the Environment

“Breasts: A Natural and Unnatural History” by Florence Williams was released this week by Norton Publishing. I am generally a sucker for non-fiction books about science and medicine, and obviously mammary glands are my stock and trade, so I went into the book with high expectations and no little amount of fear. As Aimee Ploudre cautioned during grad school “Expectations are disappointment under construction.”

Well no caution was necessary; this book is superb.

Early in the introduction, once Williams reminds us that breasts “turn babies and grown men into lunkheads,” she goes directly to the heart of the matter – “Its remarkable how little we know about their basic biology. We know some things: they appear out of nowhere at puberty, they get bigger in pregnancy, they’re capable of producing prodigious amounts of milk, and sometimes they get sick.” And thus begins a detailed and engaging journey through their evolutionary origins, their role in cultural constructs, and their status as "canary in the coal mine" for environmental toxins.

Williams gets a standing ovation* just for stating that although all mammals have mammary glands, “only humans have breasts the way we do, with our pleasant orbs sprouting out of puberty and sticking around regardless of our reproductive status.” It kills me every time I review a manuscript about non-human primates in which the authors uses the term “breasts.” Even better, she effectively explores the two perspectives in the scientific community about the evolutionary process that favored the human breasts: sexual selection or natural selection.

This measured, balanced approach to understanding breasts is a key feature of the book, weaving together alternative hypotheses, strengths and weaknesses of empirical data, theoretical foundations, and implications for women, babies, and men.

Yes men. In one of the more poignant chapters of the book, Williams discusses the breast cancer cluster among Marine servicemen and sons of marines stationed aboard Camp Lejeune in North Carolina. A number of environmental toxins such as the industrial chlorinated solvents trichloroethylene (TCE) and perchloroethylene (PCE) permeated some of the water supply exposing service-persons and their families. The causes of breast cancer in women, other than radiation, are very difficult to determine. How old a woman was when she got her first period, reproductive history, and underlying genetic predispositions interact in complex ways to affect a woman’s risk of developing breast cancer. Therefore identifying how environmental toxins contribute to breast cancer in women is confounded by contributing factors deriving from motherhood. For this reason, Marine servicemen provide some of the most compelling evidence that environmental exposure to toxins increases breast cancer risk.

 Jim Fontella was based at Camp Lejeune in 1966 and 1967. 

He was diagnosed with breast cancer in 1998.

And many of those toxins *heart* your body fat, especially in the mammary fat pad full of those lovely estrogen receptors toxins can bind to. Toxins make their way to your breasts, set up shop, and hang out for decades. On the plus side, when you lactate you can mobilize those toxins into breast-milk and shed them from your body. But the really crappy downside is that toxins are transferred directly into your developing infant’s body. Ruh roh.

Moving up the food chain, toxin concentrations increase in biomaterial. Mammalian babies exist one trophic level above their adult parents because the complex biofluid that is milk is composed, in part, of maternal tissues. Babies basically eat their moms. Populations that consume foods from high on the food chain, or lots of food packaged in plastics, have some of the highest levels of toxins in their milk. Human milk, were it to be sold in a grocery store, would “exceed the federal safety levels for some chemicals in food.” 

For these reasons, Williams posits “Breasts are our sentinel organ. They offer us a window into our rapidly transforming world and the excuse to steward it better.” Personally, I would have gone a couple steps further and substituted ‘mandate’ for ‘excuse’ in that sentence. A lot of our food is grown, fed, or packaged in persistent organic pollutants, the consequences of which are barely understood. Research studies are needed to compel legislation to make our food safer. 

In fact, just this week, a paper came out in PNAS that reports how exposure to environmental toxins affects mammary gland development in the rhesus monkey! Pregnant rhesus monkeys were fed bisphenol A (BPA) during the third trimester to attain levels comparable to those found among women living in the US. At birth, the “density of mammary buds was significantly increased in BPA-exposed monkeys, and the overall development of their mammary gland was more advanced compared with unexposed monkeys.” These changes in mammary development are likely to lead to changes in milk synthesis and potentially increases in breast cancer risk, as has been previously found in rodent models. Dr. Patricia Hunt, a co-author on this study, has done pioneering work on understanding how BPA is a hormonal disrupter, and is featured prominently in “Breasts.”

To momentarily digress, primate models in this type of research are going to be critically important, and not just to replicate and validate research in rodent models. Environmental toxins are likely to have unique consequences in the developing human and non-human primate that may not be able to be detected in a mouse. Monkeys, like humans, have long life spans so they have a longer time to accumulate and retain environmental toxins than do rodents. Most humans and non-human primates have very expanded neurodevelopment during infancy and environmental toxins impair cognition and possibly psychological development. Primates usually produce a single infant at a time so toxins transferred from mothers via the placenta and breast-milk are concentrated in one infant rather than distributed among a litter of pups. Lastly humans, not even considering the modern obesity epidemic, have more body fat that stores toxins than do rodents so our toxic "load" is potentially higher per unit body mass.

Many other topics are covered in “Breasts” – the Texan advent of breast augmentation, the nuts and bolts of milk synthesis, and how mother’s milk promotes a healthy intestinal microbiota long before we get the memo from Jamie Lee Curtis about Activia. And an important take home message is that despite the toxins in breast-milk, other beneficial factors in breast milk compensate. This book covered so much I didn’t know about breasts, even after years of conducting milk research, reading lactation articles, and talking with awesome colleagues- some of whom are featured in this book! (Aside, Williams does a phenomenal job of capturing the joie de science of both Olav Oftedal and Bruce German).

Florence Williams has delivered a Breast “Silent Spring” if you will, one that will be of substantial value and information to scientists and policy-makers as well as our mothers and daughters… and fathers and sons. 

_____________________________________________________________

*Turns out my lactation biology hat out-ranks my primatologist cap because I was so overjoyed by the breast/mammary distinction I magnanimously forgave her referring to the potto as “a monkey” instead of the strepsirhine it is.

Florence Williams’s book tour may bring her to your neck of the woods: Boston, New York, Washington DC, Boulder, Denver, Seattle, San Francisco, Salt Lake City.

_____________________________________________________________

Florence Williams. 2012. Breasts: A Natural and Unnatural History. Norton.

Andrew P. Tharp, Maricel V. Maffini, Patricia A. Hunt, Catherine A. VandeVoort, Carlos Sonnenschein, and Ana M. Soto. 2012 Bisphenol A alters the development of the rhesus monkey mammary gland. PNAS. Early View DOI:10.1073/pnas.1120488109

Help us Understand Mother's Milk!

As an undergraduate (when everything makes perfect sense and isn't complex and messy- aka fantasy land), I learned that primate mothers will allow juveniles to suckle if they are hurt or sick or stressed. Makes sense! Injured or sick animals may not be able to forage effectively and snuggling with mom is comforting.

But wait a second- where are the data?

These events are relatively rare and are not a main target of research effort. This means that there is little information about the prevalence and context in which this behavior occurs.

Let’s fix that.

Human Behavioral Ecologists: Pretty please fill out this survey.

Primatologists: Pretty please fill out this survey.

xoxo,

Katie

PS: Although I generally agree with Irwin Bernstein that “the plural of anecdote is not data,” we’re going to ignore that for now.