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!

Selected Honors:

🏆 March of Dimes Award

🏆 SUNY Chancellor's Award for Excellence in Scholarship and Creative Activities.

Kimberly O'Brien, PhD

Principal Investigator

Dr. Kimberly O'Brien is a Professor of Human Nutrition in the Division of Nutritional Sciences at Cornell University. She earned her B.S. in Biology from the University of New Hampshire and her Ph.D. in Nutrition from the University of Connecticut. Her postdoctoral training included fellowships at the National Institute of Child Health and Human Development and the Children's Nutrition Research Center at Baylor College of Medicine. Prior to joining Cornell, she served for 10 years as a faculty member in the Center for Human Nutrition at the Johns Hopkins Bloomberg School of Public Health.

Dr. O'Brien's research focuses on mineral metabolism, maternal and child nutrition, and bone health. Her work seeks to better understand how nutrients such as iron, calcium, and vitamin D are absorbed, utilized, and transferred between mother and child during pregnancy and early life.

Current research in the O'Brien Laboratory examines maternal and fetal bone health, anemia risk during pregnancy, maternal and neonatal vitamin D and iron physiology, and the cellular mechanisms that regulate nutrient transport across the placenta. Her work combines clinical studies, stable isotope methodologies, and advanced mass spectrometry to improve understanding of maternal and child health in diverse populations.

Phone: (607) 255-3743

Email: koo4@cornell.edu

Office: 230 Savage Hall

Lab Managers

Lab Manager

Hawa Saif, B.S.

Hawa obtained her B.S. in Biological Sciences at Binghamton University. Previously, Hawa worked on Infectious disease diagnostics and antimicrobial resistance in the Department of Population Medicine and Diagnostic Sciences at CVM. Current research interests include foodborne bacterial infections and how micronutrient data status affects molecular markers and health outcomes.

Lab Manager

Jamie Pollak, B.S.

Jamie graduated from Cornell University with a degree in Human Biology, Health, and Society and a minor in Healthcare Policy. Throughout her time at Cornell, Jamie pursued a wide range of experiences that shaped her interest in medicine. She served as Captain of the Women's Club Lacrosse team, worked as an EMT, Student Manager for Cornell Football, and coached youth lacrosse. She enjoys working directly with people and is especially interested in the intersection of research, nutrition, and patient care. Jamie plans to pursue a career in medicine and is excited to contribute to research that advances women's health and improves our understanding of maternal and child nutrition.

Postdocs

Postdoctoral Associate

Janine Comrie, Ph.D.

Janine earned her B.A. at Yale University with an individualized Special Divisional Major titled Nutritional Sciences and Food Systems Studies. Her undergraduate curriculum encompassed diverse scientific and sociological subjects related to human nutrition and food systems. Janine earned her Ph.D. in Molecular Nutrition from Cornell University, working on multiple projects investigating how gut microbes influence the processing of dietary nutrients. This research enabled Janine to gain skills performing genetics and metabolomics techniques. Janine also completed Cornell’s Didactic Program in Dietetics and plans to later pursue certification as a Registered Dietitian. After doing extensive work with bacterial culture and animal model systems in her Ph.D. research, Janine is now shifting her focus to working on clinical studies that directly investigate human nutrition. She is currently working to characterize gut microbiome profiles associated with iron absorption in people consuming either an animal-based or a plant-based diet.

Graduate Students

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.

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 earned her B.Sc. in Dietetics from McGill University and obtained her Registered Dietitian license in Canada. After completing one year of clinical practice, she pursued a thesis-based M.Sc. in Human Nutrition, where she got inspired by the influential role of the gut microbiota in health. In Dr. O’Brien’s lab, Karina investigates the relationship between gut microbiota and iron absorption in humans, focusing on how plant-based and omnivorous diets affect iron metabolism and gut microbial health. Her research interests lie at the intersection of clinical nutrition and physiological mechanisms, to investigate preventative healthcare through human trials and multi-omics methodologies.

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Master's in Nutritional Sciences

Xiaotong Fei (Lindsay), B.S.

Xiaotong (Lindsey) Fei is a second-year master’s student in Nutritional Sciences at Cornell University. She is conducting research in Dr. Kimberly O’Brien’s lab, focusing on the development and validation of a new database for heme iron calculation and the investigation of associations between dietary iron intake and biomarkers of iron status across different populations. After completing her master’s research at Cornell, she plans to pursue a Dietetic Internship and become a Registered Dietitian, with a particular focus on sports nutrition. Here is Lindsey’s website, including more of her achievements throughout her academic journey: https://xtfei6.wixsite.com/xiaotong-site

Master's in Nutritional Sciences Candidate

Zhangfan (Flora) Lyu, B.S.

Zhangfan is originally from China. She completed her B.S. in Nutritional Sciences (Metabolism, Health and Disease concentration) from McGill University. She is now a first-year master’s student on the Individualized track. Her research interests lie in human clinical nutrition. Outside of academia, Zhangfan loves hiking, doing work-outs, and traveling.

Undergraduate Students

CHE - Human Biology, Health, and Society

Yuxin Zou

Class of 2027

CAS - Biological Sciences

Devin Nuckles

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

CAS - Biology & Society and Economics

Jessica Park

Class of 2027

CHE - Human Biology, Health, and Society

Rose-Lynn Okongwu

Class of 2027

CALS - Biological Sciences and Business

Evelyn Hidy

Class of 2027

CHE - Human Biology, Health, and Society

Matthew Van

Class of 2028

CHE - Human Biology, Health, and Society

Grace Liu

Class of 2028

CAS - Biological Sciences

Marcello Popelka

Class of 2028

CHE - Human Biology, Health, and Society

Aidan Aldea-Lustig

Class of 2028

CHE - Human Biology, Health, and Society

Sophia Brandstaedter

Class of 2028

CHE - Human Development

Eden Park

Class of 2028

CHE - Human Biology, Health, and Society

James Hakimi

Class of 2028

CHE - Human Biology, Health, and Society

Zarif Jamal

Class of 2028

CHE - Nutritional Sciences

Selina Gu

Class of 2029

CHE- Nutritional Sciences

Nicole Byrnes Cortinas

Class of 2029

CALS - Biological Sciences

Derek Yang

Class of 2029

CHE - Human Biology, Health, and Society

Maddie Moger

Class of 2029

CHE - Human Biology, Health, and Society

Sabine Ballou-Aares

Class of 2029

CHE - Global and Public Health

Jacob Warner

Class of 2029

Former Members

Former Master's Student

Min Ruei Lee, M.S.

Minruei obtained her bachelor's degree at Taipei Medical University and has acquired her registered dietitian credential in Taiwan. She obtained her master's degree at Cornell University in 2026 and is now pursuing a PhD in genomics at the University of Colorado. Her interests lie in precision nutrition, particularly in the areas of nutrigenetics and the gut microbiome.

Former Undergraduate Student

Addy Van

Addy graduated from Cornell University's College of Human Ecology in the Class of 2026 with a major in Global and Public Health Sciences.

She will be spending the next two years working as a Clinical Research Coordinator at Weill Cornell Medicine before applying to graduate programs. To get in touch, please reach out at abv35@cornell.edu

Former Undergraduate Student

Sirui Pu

Sirui graduated from Cornell University's College of Agricultural & Life Sciences in the Class of 2026 with a major in Biological Sciences.

Post graduation, he will be teaching High School Biology as a part of the Teach for America teaching corps

Former Undergraduate Student

Juliette Ziegler

Juliette graduated from Cornell University's College of Human Ecology in the Class of 2026 with a major in Human Biology, Health, and Society.

Former Undergraduate Student

Joseph Siguencia

Joseph graduated from Cornell University's College of Agricultural & Life Sciences in the Class of 2026 with a major in Nutritional Sciences.

He says "I worked in the O’Brien Lab for 3 years. I accomplished many things here, however I am most proud of my senior thesis on “Determining a Method for Evaluation of Iron Content in Human Stool Samples”. I will always be grateful to Dr. O’Brien and the memories I made with everyone in this Lab. I will continue my research career post-grad and plan to enroll in Medical School in the future.”

Former Undergraduate Student

Jessica Han

Jessica graduated from Cornell University's College of Human Ecology in the Class of 2026 with a major in Human Biology, Health, and Society.

She plans to take two gap years where she will take the MCAT and work at a dermatology clinic in NYC.

Former Undergraduate Student

David Zhang

David graduated from Cornell University's College of Agricultural & Life Sciences in the Class of 2026 with a major in Biological Sciences.

Former Undergraduate Student

Emily Fenner

Emily graduated from Cornell University's College of Agricultural & Life Sciences in the Class of 2026 with a major in Biological Sciences.

Former Master's Student

Mariana Bolinaga Sanz, M.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. In 2026, she completed her Master's in Nutritional Sciences at Cornell University. Her main interests align with molecular nutrition and studying the absorption of micronutrients. Mariana now works at The Coca-Cola Company.

Former Undergraduate Student

Amy Qiao

Amy graduated from Cornell University's College of Human Ecology in the Class of 2025 with a major in Human Biology, Health, & Society.

Former Undergraduate Student

Emily Zhang

Natalia is a Human Biology, Health, and Society major at Cornell University's College of Human Ecology in the Class of 2027.

Former Undergraduate Student

Caroline Gordon

Natalia is a Chemistry and Biological Sciences major at Cornell University's College of Arts & Sciences in the Class of 2028.

Former Undergraduate Student

Natalia Collins

Natalia is a Cognitive Sciences major at Cornell University's College of Arts & Sciences in the Class of 2027.

Former Undergraduate Student

Kimberly Lin

Kimberly graduated from Cornell University's College of Arts & Sciences in the Class of 2025 with a major in Biological Sciences.

Former Undergraduate Student

Tharra Sethurathnam

Tharra graduated from Cornell University's College of Agriculture and Life Sciences in the Class of 2025 with a major in Biological Sciences.

Former Undergraduate Student

Caitlin Slaminko

Caitlin graduated from Cornell University's College of Human Ecology in the Class of 2025 with a major in Human Biology, Health, & Society.

Former Undergraduate Student

Jack Chen

Jack graduated from Cornell University's College of Arts & Sciences in the Class of 2025 with a major in Biology & Society.

Former Undergraduate Student

Elizabeth Chung

Elizabeth graduated from Cornell University's College of Arts & Sciences in the Class of 2025 with a major in Biology & Society.

Former Undergraduate Student

Waverly Shi

Waverly graduated from Cornell University's College of Arts & Sciences in the Class of 2025 with a major in Biology & Society.

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.