Sunday, May 1, 2016

Follow us in the field!

We're gearing up for our next field season . . .which starts tomorrow!

There is a possibility that we may have cell phone access in Nubri! A few villages have either wifi or cell service now, and we're preparing to share the research as it happens!

First up: the comparison data from the Nov 2015 - wasting in children under 2 decreased by 21% from May 2013 to November 2015. This represents an increase in mean weight of about 2.5 pounds. And this is despite the earthquake! The figure below is a dramatic representation of us during the calculations and immediately afterward.


If you want to follow us for updates (when we can give them!) there are lots of options! We will try to blog as we can, so check here. You can also follow us on Twitter and Instagram!

Twitter: QQuinnAnthroWman
Instagram: Infancy_at_altitude

and Mallika Sarma, the graduate student from Notre Dame who will be working with us:
Twitter: @MalliGoose
Instagram: MalliGoose

Tuesday, March 1, 2016

I’ll trade you my coffee table for some breast milk . . .buying milk off Craigslist



Recently I was approached by one of our local news channels about a project on online milk buying. The reporter had purchased several samples of human milk online, and I was wondering if I would be willing to be the scientific adviser for the project.

I’ll admit something – I went into this with a motive. I really felt like I was there to protect the milk for poor interpretation, panic arising at the mere presence of bacteria in the samples. Because there are bacteria in milk. These bacteria range from harmless skin bacteria to important bacteria that will colonize the infant’s gut and provide long term benefits to the infant (Marin et al., 2009; Thompson et al., 2012). 

The reporter had 3 samples, after making dozens of inquiries. Two samples were shipped, one arrived seemingly frozen and the other a leaking mess. The third sample was picked up from the mother. The leaking mess was thrown away, and the remaining two samples were tested.

Sample 1: Total bacterial count of 700,000 CFU/gram. This is 7x what is allowed by the dairy industry for pasteurization, and 70x what is allowed by the Human Milk Banking Association of America (HMABA). This included a substantial number of coliform bacteria. Now while many coliforms are not themselves harmful, they are generally used as a measure of bacterial contamination.  

Sample 2: Total bacterial count of <10 CFU/gram. No coliforms.

Compared to the literature, these numbers are not surprising. Earlier, full sized studies of human milk purchased online has found very similar results – Keim et al., (2013) reported that 74% of 102 samples they purchased online had microbial loads >24 CFU/g; comparable data for samples from milk banks are much lower. A second study, purchasing milk online in Canada, also found high levels of bacterial contamination for purchased milk (St. Onge et al., 2015). 
Figure 1: Figure 2 from Keim et al., (2013) showing the distribution of bacteria counts in milk purchased online. Sample 1 would have been placed in the 10^5 group for total bacteria. Image: doi: 10.1542/peds.2013-1687


What seems to be the biggest risk factor for microbial growth in milk? Keim et al., (2013) reported that the amount of time the milk spent in transit was the biggest predictor of microbial growth. Geraghty et al., (2013) reported shipping conditions broke down as follows: 89% of milk samples arrived at a temperature above -20C/-4F (hard frozen) and of those, 45% arrived above 4C/39.2F (or warmer than your fridge). We know milk spoils, and human milk is no exception to the Milk Spoils rule. 

Figure 2: Milk shipping is important, and just because samples look frozen does not mean they are! Photo:Lansinoh.com
What were some other factors? Keim et al (2013) noted that “Information sellers conveyed in their advertisements about their health and behaviors were poor indicators of milk quality.” Donor claims as well (sellers claiming they were milk bank donors) and large volumes were also risk factors. It should be a general red flag that someone claiming to be a milk bank donor but selling thousands of ounces of milk online has something else going on . . .either the bank turned down the milk or the person is not associated with a milk bank despite claims otherwise. 

Keim et al., (2013) also found that the age of milk – that is the interval between when it was expressed and when it was shipped – was also a predictor of bacterial load. They hypothesized that anti-microbial properties of the milk may decline with storage time – and that assumes immediate and appropriate storage. One other potential point of risk may be at the pump itself. There have been several neonatal intensive care unit based outbreaks of bacterial infections linked to improperly cleaned pumps, and one estimate suggests that nearly 1/3 of all pumps may be improperly cleaned and potentially harbor bacteria. 

Figure 3: PSA – maybe give your pump a good scrub down today, just in case. This style of pump is especially problematic because the rubber bulb is extremely hospitable to bacteria. Photo: Etsy
Overall, I was really surprised by this. I expected the Craigslist sample to be a little dodgy, but I genuinely expected that the samples would be safe. Reading the literature, seeing our results, and digging into the online ads has really changed my mind. Buying breast milk online, especially from complete strangers is a risky game. I mean, I wouldn’t buy a dozen cookies off of Craigslist, and the same goes for milk. Both the FDA and the AAP recommend against such practices – and for evidence based reasons as shown in the Pediatrics papers and others. Things in the ads that made me curious: large volumes of milk with a young baby, packages of milk that look too uniform, poor organization of the freezer.

Figure 4: Two things I would never personally buy on Craigslist. Photo: http://wholelifestylenutrition.com
What about milk sharing? As Aunchalee Palmquist has previously reported (see her blog here) there is something different about milk sharing - it falls more under the auspices of a gift economy, and most studies show that peer to peer milk sharing does not include the same risks of bacterial contamination as milk sold AND shipped. In recent work, Palmquist report that of 867 mothers who completed their survey 100% did not participate in anonymous donation but knew or screened their donors. Almost 30% of mothers only shared with families or close friends, and a similar number (27%) of mothers had serological screening for their donors. This really highlights that we are talking about two very different practices here - milk sharing and milk selling - with possible different underlying motivations and practices.


References

I had completely forgotten a post on milk selling over at mammalssuck -  worth checking out here!

Geraghty SR, McNamara KA, Dillon CE, Hogan JS, Kwiek JJ, Keim SA. (2013) Buying human milk via the internet: just a click away. Breastfeed Med. 2013 Dec;8(6):474-8. doi: 10.1089/bfm.2013.0048.

Keim SA, Hogan JS, McNamara KA, Gudimetla V, Dillon CE, Kwiek JJ, Geraghty SR. (2013) Microbial contamination of human milk purchased via the Internet. Pediatrics. 132(5):e1227-35. doi: 10.1542/peds.2013-1687.

Keim SA, McNamara KA, Jayadeva CM, Braun AC, Dillon CE, Geraghty SR. (2014) Breast milk sharing via the internet: the practice and health and safety considerations. Matern Child Health J. 18(6):1471-9. doi: 10.1007/s10995-013-1387-6.

Marín ML, Arroyo R, Jiménez E, Gómez A, Fernández L, Rodríguez JM. (2009) Cold storage of human milk: effect on its bacterial composition. J Pediatr Gastroenterol Nutr. 49(3):343-8. doi: 10.1097/MPG.0b013e31818cf53d.

Palmquist AE, Doehler K. 2015 Human milk sharing practices in the U.S. Matern Child Nutr.  doi: 10.1111/mcn.12221. [Epub ahead of print]

St-Onge M, Chaudhry S, Koren G. (2015) Donated breast milk stored in banks versus breast milk purchased online. Can Fam Physician. 2015 Feb;61(2):143-6.
Thompson AL. (2012) Developmental origins of obesity: early feeding environments, infant growth, and the intestinal microbiome. Am J Hum Biol. 24(3):350-60. doi: 10.1002/ajhb.22254.

Sunday, January 31, 2016

Wait, there's more: milk adiponectin and child growth varies!



It was a big day for the Biomarkers & Milk group. We had an important paper accepted at Annals of Human Biology. This paper is the second paper to come out of the Milk with Altitude Project (2013 edition), and I assure you, there will be more! 

This paper is important to me because it is further evidence for a hypothesis I have been working on. As I have written before, as an anthropologist, I tend to study non-western populations, and my research is primarily concentrated with two groups: Filipinos living in Cebu, Philippines, and ethnic Tibetans living in Nepal. Recently, working with an outstanding team of undergraduates, we published a paper looking at the hormone adiponectin in milk samples from 113 Filipino women.
So why are we excited about this? In the Cebu adiponectin article, we reported something new and different about milk adiponectin and child growth. Prior to our work, a phenomenal piece by Woo et al., (2012) had shown a significant, inverse association between milk adiponectin and infant weight for age z-score. Simply put: more adiponectin in milk, less growth in the child. BUT – and here’s the cool part – they found that the slower growing children had faster growth from 1-2 years of age.
Katie Hinde over at Mammals Suck suggested that this may be an adaptive strategy to allow mothers to mediate their energetic investment in offspring. By down regulating growth while it is directly dependent on her metabolism, mothers may be able to conceive sooner. The catch-up growth from 1-2 years then, makes complete sense – children are then growing when other community members can contribute to their energetic budgets.

And we think we’ve found the corollary – such trade-offs are environmentally sensitive. In a high resource (low pathogen?) environment such as that of the mothers Woo et al., studied, this is an excellent reproductive strategy, as it allows mothers to defer some of the costs of reproduction to others. However, in a low resource (high pathogen?) environment, the resources necessary to support later growth may be unavailable, and it may be a better reproductive strategy to promote early growth – when maternal metabolism can support it.

For the Cebu study, we had mean adiponectin levels of 7 ng/mL of milk, compared to 21 ng/mL for the US women Woo et al., studied. Child weight for age (centiles) also differed – the 50th percentile for our sample was equivalent to the 5th percentile for US infants. However, when we used a similar analytical technique as Woo et al., a really interesting picture emerged (Figure 1). Our data fit almost perfectly with that of Woo et al. In their model, there is a plateau for the association between milk adiponectin and child growth at lower levels of milk adiponectin (10-13 ng/mL) followed by a decline in weight for age as milk adiponectin increases. We found a positive association between milk adiponectin and infant weight for age at even lower levels of milk adiponectin (2 ng/mL to 8 ng/mL) – however there was a plateauing of the association from about 8-10 ng/mL, or the max of our range. The distribution of milk adiponectin in our sample barely overlapped with that of Woo et al.
Figure 1: Comparison of weight-for-age percentiles by milk adiponectin between the Woo et al., study and the Cebu study. C

When you put the two datasets together, instead of forming alternative models, they form a complementary model suggesting that the association between milk adiponectin and child weight for age z-score is not a linear association but rather a bell-shaped association, where at a very low levels (<7ng/mL) milk adiponectin is positively associated with growth, a flattening of the association at levels of 7-12 ng/mL (intermediate levels) and then an inverse association between milk adiponectin and growth at higher (>12 ng/mL) levels. And because milk adiponectin had not generally been studied in non-Western populations, such association was largely missed. This is why studying milk composition in a diversity of human populations and ecological zones is so important.

We’ve replicated this in our Tibetan study, but that’s a separate post because the relationships get even more interesting. Once the Tibetan study is out, I’ll continue the discussion started here with that piece. 

References cited
Anderson J, McKinley K, Onugha J, Duazo P, Chernoff M, Quinn EA. (2015) Lower levels of human milk adiponectin predict offspring weight for age: a study in a lean population of Filipinos. Matern Child Nutr. 2015 Oct 7. doi: 10.1111/mcn.12216. [Epub ahead of print]

Hinde K. (2012) Mother’ fat sends love letter to baby via the milk express. http://mammalssuck.blogspot.com/2012/06/mothers-fat-sends-love-letter-to-baby.html?q=adiponectin, accessed Jan 26, 2016.

Martin LJ, Woo JG, Geraghty SR, Altaye M, Davidson BS, Banach W, Dolan LM, Ruiz-Palacios GM, Morrow AL. (2006) Adiponectin is present in human milk and is associated with maternal factors. Am J Clin Nutr. 2006 May;83(5):1106-11.

Woo JG, Guerrero ML, Guo F, Martin LJ, Davidson BS, Ortega H, Ruiz-Palacios GM, Morrow AL. (2012) Human milk adiponectin affects infant weight trajectory during the second year of life. J Pediatr Gastroenterol Nutr. 2012 Apr;54(4):532-9. doi: 10.1097/MPG.0b013e31823fde04.