James Fleet

Fleet is the Margaret McKean Love Endowed Professor in Nutrition, Cellular and Molecular Sciences at The University of Texas at Austin. He holds a B.S. and Ph.D. from Cornell University and has previously held faculty appointments at Tufts University, the University of North Carolina at Greensboro and Purdue University.

Fleet's research focuses on the molecular and physiological functions of vitamin D as they pertain to the control of calcium metabolism and the prevention of cancer. His research employs the tools of molecular biology, genomics and genetics to address questions relevant to human health and disease prevention. He has published 158 primary journal articles, book chapters and reviews and has been invited to speak on his work around the world.

He has a strong commitment to graduate education and contributed to the establishment of the Tufts University School of Nutrition Science and Policy. He also served as graduate program director at the University of North Carolina at Greensboro for two years and at Purdue University for 14 years.

Fleet's research has received more than $16 million in direct funding from the National Institutes of Health, the U.S. Department of Agriculture and the American Institute for Cancer Research. He served as a contributing editor for Nutrition Reviews, has been on the editorial boards of The Journal of Nutrition and Endocrinology, and is an associate editor for the Journal of Steroid Biochemistry and Molecular Biology. He has also been a standing member of several NIH study sections.

He has organized FASEB Summer Conferences and a summer workshop on Big Data Analysis for Biomedical Researchers and has served on the program committees for the Vitamin D Workshop, where he currently serves as CEO, the American Society for Nutrition, the American Institute for Cancer Research and the American Society for Bone and Mineral Research.

Fleet received the Mead Johnson Award from the American Society for Nutrition in 2001, was honored as a University Faculty Scholar from 2004-09 and as a Distinguished Professor at Purdue University, and was named a Fellow of the American Society for Bone and Mineral Research in 2019.

Fleet is a nutritional scientist who takes a mechanistic approach to studying the molecular and physiological functions of vitamin D in two major areas: (a) calcium and bone and (b) colon cancer prevention. His research uses cell and animal models and employs the tools of molecular biology, genomics and genetics to address questions relevant to human health and disease prevention.

Fleet's research program has focused on the physiologic functions and molecular actions of the vitamin D hormone, 1,25-dihydroxyvitamin D, in two major areas: (a) the control of whole-body calcium homeostasis and (b) as a modulator of colitis and in the prevention of colon cancer.

In the area of calcium and bone homeostasis, his work has linked calcium absorption to building bone mass during growth and protecting adult bone mass. Over the last decade, he extended this interest to the use of mouse genetics to identify the natural genetic variation that regulates calcium and bone metabolism, examining the interaction between genetics and the dietary environment. This work has demonstrated that the genetics controlling physiologic adaptation of calcium and bone metabolism to low dietary calcium intake are distinct from the genetics controlling basal calcium and bone metabolism.

In the area of colitis and cancer, Fleet's research has evaluated the role of vitamin D as a regulator of innate immunity by shifting macrophage polarization away from proinflammatory M1 macrophages to wound-resolving M2 macrophages and by blunting myeloid-derived suppressor cell (MDSC) T-cell suppressive function. He has also developed and utilized unique animal models that have allowed the role of vitamin D status in the development of colitis and cancer to be tested. Within these areas, his research group has extensively used genomic tools, including RNA-seq, ATAC-seq, ChIP-seq and single-cell RNA-seq, to better understand the mechanisms by which 1,25-dihydroxyvitamin D regulates gene expression in target tissues.