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Sarah Reyes, Ph.D. Candidate in Nutritional Sciences at Cornell University and NIH Predoctoral Trainee in Translational Research in Nutrition

Sarah Reyes received her B.A. in Interdisciplinary Studies – International Studies and Human Nutrition and her M.S. in Animal Science from the University of Idaho and is completing her Ph.D. studies in the Human Nutrition Program at Cornell University’s Division of Nutritional Sciences. Sarah is an NIH predoctoral trainee on a translational research in nutrition training grant of which, until recently, former ASN president Patrick Stover was the PI. Sarah has been an ASN member since 2009 and holds the position of Secretary for the International Society for Research in Human Milk and Lactation’s Trainee Interest Group, an ASN partner organization.

1. How did you first get involved in nutrition science and research?

I come from Idaho, a rural state with high rates of chronic diseases such as diabetes and hypertension. I originally wanted to become a physician because access to quality medical care in Idaho is relatively limited for poor and rural populations. I chose to study International Studies and Human Nutrition to give me breadth of knowledge that I thought would position me competitively for acceptance into medical school. However, the more I learned about the cycles of poverty and oppression in my International Studies courses and the power of nutrition and exercise to prevent and even treat chronic disease, I realized quickly that my passion was to empower people like me—the daughter of a mixed-race couple from a blue-collar family in poor, rural America—to prevent chronic disease. I became passionate about public health and how to disrupt the systems in place that sustain cycles of poverty and oppression. I recognized that my overlapping interests in basic science and public health could be a powerful tool to create evidence-based recommendations to empower disadvantaged and marginalized members of our society achieve better health outcomes. (At the time I wasn’t aware of the term translational research, but ultimately that’s what I pursued). My interest in nutrition, specifically, was inspired by my undergraduate courses which taught me that my grandmother’s type II diabetes and neuropathy were consequence of years of subsisting on a diet nearly void of fresh fruits and vegetables and eating too much white bread, white sugar, and white potatoes (I mean it was rural Idaho—yes, the stereotype applies).

2. Tell us about your current position and the research activities in which you are involved.

I’m a PhD candidate in the Division of Nutritional Sciences at Cornell University. Kathleen Rasmussen, ScD, RD is the Chair of my doctoral committee, and I collaborate with the laboratories of Anthony Hay, PhD, at Cornell University, Mark McGuire, PhD, at the University of Idaho, and Shelley McGuire, PhD at Washington State University. In the spirit of translational research, I was intent on using basic science to advance a public health initiative for my doctoral research. I was able to leverage my Chair’s interest in women’s real-life experiences with pumping and feeding expressed breast milk with the combined expertise in microbiology and lactation physiology of my collaborators. I was particularly interested in the discordance between the way expressed milk was collected in studies cited in current recommendations for handling and storage of expressed milk at home and the way expressed milk is collected in real-life. Specifically, most studies collect milk aseptically whereas real-life is messy. Women often have to pump their milk in less than ideal conditions such as in restrooms, vehicles, and other public spaces. Plus, expressed milk is often stored at multiple temperatures and poured into several different containers. My doctoral research has focused on characterizing and comparing the human milk microbiome in real-life conditions v. aseptic collection and identifying sources of and factors associated with bacterial contamination in expressed milk. We conducted a randomized trial to do this research and I’m just finishing up the analyses of this work. Our results not only fill a critical gap needed to improve existing recommendations for handling and storage of expressed milk at home, but it also opens up questions about how differential exposure to microbes from breast milk influence the infant gastrointestinal microbiome and health outcomes. I’m excited to share some of our results for the first time at Nutrition 2018!

3. You are a student at a prestigious university, a mother of two, and pregnant?! How do you do it?

I get that question a lot! In fact, I made a YouTube video of a day in my life to give others a glimpse of how I make it work. First, I have a fully supportive and loving husband, Paul Reyes. His commitment to helping me achieve this goal is undoubtedly a huge reason why I have been able to pull off school and kids simultaneously. My hat goes off to all the single, working moms out there. I don’t know how they do it! Second, having kids has pushed me to become more intentional about my goals, to prioritize my daily, weekly, monthly, and yearly tasks needed to accomplish those goals, and to manage my time so I can maintain the energy and enthusiasm needed to be productive over extended periods of time while still being present at home.

4. What do you feel are the biggest challenges facing nutrition researchers today? 

My biggest concern for nutrition researchers is public trust. Without trust, individuals will not heed recommendations. Especially where I’m from, many are leery of dietary recommendations because some have changed drastically over time (think cholesterol and eggs). Drastic changes in recommendations are perceived as “scientists don’t know what they’re doing.” Plus, policies enacted to ensure healthy eating is equitable (e.g., trans-fat bans, soda size restrictions in NYC, school lunch policies limiting access to sugary and salty foods) are seen as attacks on individual rights and freedoms, which fuels distrust in recommendations. I think a combination of the use of rigorous study methods to produce quality science along with nutrition scientists being more vocal on social and other media platforms can help improve public trust.

5. Is there anything else you’d like to tell ASN members, especially students?

Know what your objectives are and be intentional on dedicating time to those. Expose yourself to as many learning opportunities as you can to gain breadth of knowledge and experience. For example, take a short-course on equity either online, at your university, or at another university. Become involved in things that matter to you both professionally and personally! This will keep you enthusiastic and motivated about your research and help you live a healthier life. Stay open-minded and remain objective in your pursuit of science. Finally, find a good mentor and a good advocate. A good mentor will help you learn how to conduct rigorous science and sharpen the skills you need to meet your own personal objectives. An advocate is someone who is respected in your field that can help you find and avail on opportunities that will help you achieve your goals.

[Learn more about ASN student membership here]

Sarah Reyes’ primary interests are the developmental origins of health and disease and finding equitable solutions to empower disadvantaged and marginalized populations achieve better health outcomes. Sarah’s interests are focused on the mother-infant dyad and, in particular, the breastfeeding relationship. Most recently, Sarah’s work has focused on characterizing the bacterial communities in breast milk pumped in real-life conditions. Sarah has conducted research in mammalian and bacterial cell culture, biochemical analyses, epidemiology, and microbiome research. In addition to her research interests, Sarah is interested in opportunities to use her knowledge to serve others. She recently attended the Make the Breast Pump Not Suck Hackathon where she helped design a study to evaluate the efficacy of hand expression on milk volume for incarcerated women in New Mexico. Visit her video, A Day in the Life of a PhD Mom | Ivy League, Kids, and Pregnancy.

By Corrie Whisner, PhD

I recently ran across an interesting article in the PLOS ONE journal entitled, “Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex” by Katie Hinde and colleagues at Harvard and Kansas State Universities. After the passing of International Women’s Day on March 8 and recently finishing the book Lean In by Sheryl Sandberg, I felt inspired to share Hinde’s findings and highlight the scientific side of “girl power!”

In this large retrospective analysis of dairy cow lactation records, researchers found that Holsteins produced 1.6% more milk for female versus male offspring. More interesting, is the finding that fetal sex of first-time mothers influenced milk production in subsequent pregnancies.  The advantage of having a female fetus during the first pregnancy carried over to the second pregnancy, resulting in greater milk production across both lactations regardless of whether the second fetus was male or female. The benefit of having a heifer during the first pregnancy was further documented when cows giving birth to a male in their first pregnancy showed significant increases in milk production if their second pregnancy was a female. This increase was evident when comparing data to milk production in dairy cows that gave birth to two consecutive male offspring; however, the milk production of male-female sequence mothers, did not increase to the level of female-first mothers.

According to Hinde, biologists have been interested in studying how mothers differentially allocate resources to male versus female fetuses during pregnancy. To date, little work has been done to investigate sex-biases in milk production which make this article very exciting! Reading this article definitely reminded me of the Barker Hypothesis and the earlier publication Boys Live Dangerously in the Womb, which both provide evidence for fetal programming in humans and suggest that male and female fetuses respond differently in utero to maternal cues.

Maternal milk is an ever-evolving elixir which fuels important changes throughout early development, so it isn’t hard to believe that milk production might differ between species. After reading this article I amazed to learn that mothers may allocate resources, such as milk, to the offspring sex that will receive maximal benefit. A current belief is that males from species with male-male competitive mating rituals will receive a greater investment across gestation and lactation from their mothers. Additionally, Rhesus monkeys have been found to produce energetically-dense milk, higher in fat, for their male offspring; however, female offspring received a greater milk volume which made up for the lack in energetic-density.

As research continues in this area, I wonder if we will start seeing different types of baby formula for boys and girls. Only time will tell…and to that, I say, “Let’s get MOO-ving, so we have more to talk about soon!”

References
1.    Katie Hinde, Abigail J. Carpenter, John S. Clay, Barry J. Bradford. Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex. PLoS ONE, 2014; 9 (2): e86169 DOI:10.1371/journal.pone.0086169
2.    Trivers RL, Willard DE (1973) Natural selection of parental ability to vary the sex ratio of offspring. Science 179(4068): 90–92. doi: 10.1126/science.179.4068.90
3.    Hinde K (2007) First-time macaque mothers bias milk composition in favor of sons. Curr Biol 17(22): R958–R959. doi: 10.1016/j.cub.2007.09.029
4.    Hinde K (2009) Richer milk for sons but more milk for daughters: Sex-biased investment during lactation varies with maternal life history in rhesus macaques. Am J Hum Biol 21(4): 512–519. doi: 10.1002/ajhb.20917