Nutrition is critical to normal growth and maintenance of skeletal tissue. This research program focuses on the nutritional regulation of skeletal tissues by examining the biochemistry and gene expression within the extracellular matrix (proteoglycans and collagen). Importantly, there are clinical trials of bone turnover and bone mass to determine how nutritional intake influences the development of osteoporosis.
The major focus in the laboratory is to determine how loss of body weight contributes to the risk of osteoporosis. Evidence shows that subjects who diet and lose weight also lose bone. Our goal is to determine mechanisms that regulate the rate of bone turnover and bone loss during caloric restriction. Bone turnover is measured in the urine and blood (e.g., pyridinium cross-links, serum osteocalcin) using techniques of spectrophotometry, HPLC, and radioimmunoassay. Calcium absorption (using stable isotopes) and bone-regulating hormones are examined in these studies to address mechanisms of regulation. In addition, studies examining gastric bypass patients are in progress to understand how obesity surgery influences calcium homeostatsis and bone mass. Due to the high rate of morbidity and mortality associated with osteoporotic fractures, we also use a rat model to better understand how nutrition regulates bone turnover, composition, and biomechanical properties. We also examine the regulation of bone turnover in disease states associated with changes in bone mass. For example, we have studied how glycemic control and hormones regulate bone turnover in insulin-dependent patients with diabetes. We have used biochemical markers of bone turnover to estimate the rate of growth in clinical and equine studies. In addition, the regulation of lipids in bone and connective tissue is an ongoing interest in the laboratory.