Nutrition / Metabolism

Nutrition & Metabolic Studies

Nutrition & Metabolic Studies
Dr. William W. Wong
Professor of Pediatrics, Baylor College of Medicine

Since the discovery that fatty acids labeled with deuterium are taken up into adipose tissues in the early 1930’s, tracers labeled with stable isotopes have become an important analytical tool in human nutrition and metabolic studies. For example, glucose is the principal substrate for metabolism in the brain and hypoglycemia can lead to seizures, unconsciousness, mental retardation and death. The development of glucose labeled with the stable isotopes of hydrogen and carbon has enabled scientists to further understand glucose metabolism and therefore, the cause of hypoglycemia. Because minerals have important regulatory and structural functions, the stable isotopes of minerals also enable the nutrition researchers to assess mineral requirements in children during the critical period to minimize the immediate effects of mineral inadequacies on growth and development and to prevent long-term consequences such as osteoporosis. Since energy is required for muscular activity, growth, reproduction, and synthesis of metabolites such as proteins, fatty acids, nucleic acids and steroids, the doubly labeled water (D218O) method has emerged as the reference tool for the assessment of energy utilization under free-living conditions. Energy inadequacy can lead to growth retardation and excessive energy is the leading cause of the global obesity epidemic. Furthermore, the 13CO2 urea breath test represents the first FDA approved, commercialized stable isotope method for the diagnosis of Helicobacter pylori infection. The availability of several amino acids with multiple labels of 15N, 13C and D has allowed researchers to study protein metabolism both at the whole-body level and at the level of individual plasma proteins. This has led to a better understanding of the mechanisms responsible for the continuous loss of body proteins and the decreased availability of nutrient transport proteins in stressed states such as chronic infections, multiple trauma, cancer and sepsis. Therefore, the applications of stable isotopes in nutrition and metabolic studies are essentially limitless and will continue to make significant contributions in our understanding of nutrient requirements and their metabolic pathways.

William W. Wong, PhD Professor of Pediatrics, Baylor College of Medicine