About Us

At O'Brien Laboratory, we are dedicated to advancing the understanding of mineral absorption and metabolism in infants, children, and pregnant and lactating women. Meet our incredible team!

Kimberly O'Brien, PhD

Principal Investigator

Kimberly O’Brien is a Professor of Human Nutrition in the Division of Nutritional Sciences at Cornell University. She received her B.S. in Biology from the University of New Hampshire and her PhD in Nutrition from the University of Connecticut, Storrs. Her professional training included fellowships with the National Institute of Child Health and Human Development, Laboratory of Theoretical and Physical Biology/Section for Metabolic Analysis and Mass Spectrometry, and the Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine. Professor O'Brien joined the faculty in the Division of Nutritional Sciences after working for 10 years as a faculty member in the Center of Human Nutrition at Johns Hopkins Bloomberg School of Public Health.

Professor O’Brien’s research has centered on studies designed to better understand mineral metabolism and bone health in infants, children, and pregnant and lactating women in both developed and developing countries. To address issues of calcium metabolism, she has undertaken metabolic studies in groups including children from osteoporotic families, pregnant and lactating adolescents, and children with chronic diseases such as cystic fibrosis and HIV infection. Her current research focuses on the impact of adolescent pregnancy, particularly among minority populations, on maternal and fetal bone health, risk of anemia, and maternal and neonatal vitamin D and iron physiology. Partitioning of nutrients between the mother and fetus is addressed at the cellular level by assessing placental mineral transporters in relation to maternal and neonatal status.

Phone: (607) 255-3743

Email: koo4@cornell.edu

Office: 230 Savage Hall

Graduate Students

PhD Candidate

Ruihan Xu, M.P.H, RDN, IBCLC

Ruihan obtained her BA at the University of Washington-Seattle and completed her MPH degree at UNC-Chapel Hill. She was also trained in the MRT-TI international lactation consultant training program during her second year of MPH. After completing the Dietetic Internship and lactation clinical practice hours, she obtained her RDN and IBCLC credential 2024. Ruihan's research interests are focused on maternal and child nutrition as well as precision nutrition, specifically on how maternal diet impacts pregnancy outcomes and breastmilk composition. Her current research work in the lab focusses on vitamin D kinetics in women of reproductive age.

PhD Candidate

Yuan (Karina) Zhang, M.S., R.D.

Karina is a registered dietitian in Canada and a first-year PhD student in O'Briens Lab. Yuan earned her B.Sc. in Dietetics and her Human Nutrition M.Sc. from McGill University in Canada. Her research experiences covered a broad spectrum of nutritional science, including clinical dietetic practice, human trials, and the intricate study of gut microbiome and metabolic processes in both human and animal models. Currently, her main study focus is understanding how gut microbiome can be affected by iron intake from animal-based versus plant-based diets and how does perturbation in the gut flora influence back on iron absorption.

Master’s in Nutritional Sciences

Mariana Bolinaga Sanz, B.S.

Mariana is originally from Venezuela. She has also lived in the Dominican Republic, Argentina, and Florida. She completed her undergraduate studies at Boston University, obtaining a Bachelor’s of Science in Nutrition on the Dietetics track. She is a first-year master’s student studying Nutritional Sciences on an Individualized track. Her main interests align with molecular nutrition and studying the absorption of micronutrients. Mariana hopes to enter the food and supplement industry after graduation.

Master’s in Nutritional Sciences

Min Ruei Lee, B.S.

Minruei obtained her bachelor's degree at Taipei Medical University and has acquired her registered dietitian credential in Taiwan. Her research interests lie in precision nutrition, particularly in the areas of nutrigenetics and the gut microbiome. Outside of academia, she enjoys jogging, swimming, photography, and hanging out with friends.

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Master's in Nutritional Sciences

Xiaotong Fei (Lindsay), B.S.

Xiaotong is originally from China. She completed her undergraduate degree at the University of California, Davis, majoring in Clinical Nutrition, and has earned the DPD certification. Xiaotong is interested in completing her dietetic internship and becoming an RD after finishing her master's studies. She is particularly interested in how dietary interventions can affect human metabolism and how precision nutrition can be implemented through scientific research. Outside of academics, she loves weightlifting, hiking, climbing, and many other outdoor activities.

PhD Candidate

Yuke Xie, M.S.

Yuke obtained her B.S. in Clinical Nutrition and B.A. in Psychology from the University of California, Davis, and earned her M.S. in Human Nutrition from the Institute of Nutrition at Columbia University. After completing her dietetic internship at the UCD Medical Center, she is now eligible to sit for the RD exam. Currently, her research focuses on vitamin D metabolism and variations in vitamin D absorption across different populations. Outside of research, Yuke enjoys watching movies, playing video games, and traveling.

Undergraduate Students

CHE - Human Biology, Health, and Society

Amy Qiao

Class of 2025

CHE - Human Biology, Health, and Society

Caitlin Slaminko

Class of 2025

CAS - Biology and Society

Elizabeth Chung

Class of 2025

CAS - Biology and Society

Jack Chen

Class of 2025

CAS - Biological Sciences

Kimberly Lin

Class of 2025

CALS - Biological Sciences

Tharra Sethurathnam

Class of 2025

CAS - Biology and Society

Waverly Shi

Class of 2025

CHE - Global and Public Health Sciences

Addy Van

Class of 2026

CALS - Biological Sciences

David Zhang

Class of 2026

CHE - Human Biology, Health, and Society

Jessica Han

Class of 2026

CALS - Nutritional Sciences

Joseph Siguencia

Class of 2026

CHE - Human Biology, Health, and Society

Juliette Ziegler

Class of 2026

CHE - Human Biology, Health, and Society

Sarah Oh

Class of 2026

CALS - Biological Sciences

Sirui Pu

Class of 2026

CHE - Nutritional Sciences

Sunny Shi

Class of 2026

CHE - Human Biology, Health, and Society

Yuxin Zou

Class of 2026

CAS - Biological Sciences

Devin Nuckles

Class of 2027

CHE - Human Biology, Health, and Society

Emily Zhang

Class of 2027

CAS - Cognitive Science

Natalia Collins

Class of 2027

CHE - Nutritional Sciences

Reid Schwartz

Class of 2027

CHE - Human Biology, Health, and Society

Sophie Mintz

Class of 2027

CHE - Human Biology, Health, and Society

Zoe Grotegut

Class of 2027

CHE - Human Biology, Health, and Society

Matthew Van

Class of 2028

Former Members

Former Visiting Scientist

Clara Yongjoo Park, PhD

Clara Y. Park is an Associate Professor in the Division of Food and Nutrition, Chonnam National University (CNU) and visiting scholar in the O’Brien lab (Feb, 2023 – Feb, 2024). CNU is one of the ten Flagship Korean National Universities and located in Gwangju, Korea. Professor Park received her BS at Seoul National University, Korea and PhD at Purdue University, West Lafayette, IN. She continued her training as a post-doctoral researcher at Purdue University and Kyungpook National University School of Medicine, Daegu, Korea before joining the faculty of CNU in 2016. Her primary research area is mineral metabolism during different life stages including pregnancy and lactation, with a focus on nutrients such as calcium, vitamin D, and iron, and health outcomes including bone health and osteoarthritis. Her secondary research interest focuses on diet assessment in centenarians and various populations and validation of these techniques. To get in touch with her, she can be reached at parkcy@jnu.ac.kr.

Former PhD Student

Alexa Barad, PhD, M.S., R.D.

Alexa is originally from Costa Rica. She completed her undergraduate degree at Texas A&M University and her Master of Science and Dietetic Internship at the University of Florida. Recently, she earned her PhD from Cornell University, where her research focused on understanding genetic and biochemical variations in iron absorption and their impact on iron homeostasis across different ethnicities. She is now beginning a new position as a Postdoctoral Scholar at the Stanford Prevention Research Center within the Stanford University School of Medicine.

Former Undergraduate Student

Alexis Viehl

Alexis graduated from Cornell University's College of Human Ecology in the Class of 2024 with a major in Human Biology, Health, and Society.

Former Undergraduate Student

Amelia Wildermuth

Amelia graduated from Cornell University's College of Human Ecology in the Class of 2024 with a major in Human Biology, Health, and Society.

Former Undergraduate Student

Angelina Tang

Angelina graduated from Cornell University's College of Human Ecology in the Class of 2024 with a major in Global and Public Health Sciences.

Former Undergraduate Student

Anna Thomas

Anna graduated from Cornell University's College of Agriculture and Life Sciences in the Class of 2024 with a major in Biological Sciences. She is currently taking a gap year, working as an Ophthalmic Technician and Scribe, and has been accepted to Rutgers New Jersey Medical School, where she will begin her studies in August 2025.

Former Undergraduate Student

Daniel Clarke

Daniel graduated from Cornell University's College of Agriculture and Life Sciences in the Class of 2024 with a major in Biology and Society.

Former Undergraduate Student

Joanne Wang

Joanne graduated from Cornell University's College of Arts and Sciences in the Class of 2024 with a major in Biological Sciences, concentrating in Biochemistry, and a minor in Information Science, concentrating in Data Science. Joanne is currently taking two gap years before attending medical school and is working as a Medical Assistant at the Vein Healthcare Center in South Portland, ME, volunteering as a hospice aide for Affinity Care Hospice, and volunteering as a mentor for the Welcoming The Stranger Program within the Maine Association for New Americans. Joanne is extremely passionate about equitable healthcare, mental health advocacy, public health data research, and outdoor movement. Joanne can be reached at jhw272@cornell.edu.

Former Undergraduate Student

Jordan Amoaka

Jordan is a recent graduate from Cornell University's College of Agriculture and Life Sciences, where she majored in Biology and Society, with minors in Global Health, Nutritional Sciences, and Healthy Futures. After graduation, she will be completing her MPH at George Washington University's Milken Institute School of Public Health. Her career interests include healthcare, combining a passion for business, public health, sustainability, and biotech/healthcare technology. To get in touch with her, she can be reached at jga57@cornell.edu.