Mineral Bioavailability

Research Overview

The long-term research goal of the Mineral Bioavailability Laboratory is aimed at gaining a greater understanding of the molecular mechanisms concerning the protective roles of vitamin D and calcium in the development of osteoporosis and colon cancer and the development of better disease prevention strategies. Osteoporosis and colon cancer are serious health problems in the elderly.

Twenty percent of women in the United States (US) have osteoporosis. Forty percent of persons 80 years and older in the US have had a bone fracture - a serious life event that can often be the precipitating cause of eventual death or loss of ability to perform the daily activities of living that leads to the need to enter long-term nursing care. It has been shown that persons with low calcium intakes and a lower efficiency of calcium absorption are at increased risk for hip fracture. Our current working hypothesis is that age-associated changes in vitamin D-induced cell signaling lead to a diminished intestinal calcium absorption response to a low calcium intake, which increases the risk of bone loss and fracture. A better understanding of the molecular determinants of low calcium absorption could have several practical implications for public health, such as: improved early detection screening strategies for the identification of people at high risk of developing osteoporosis; development of better osteoporosis prevention program strategies; as well as the possible development of novel disease treatment approaches.

Colon cancer is the third most common cancer among men and women in the US, and is the second leading cause of cancer deaths, accounting for 48,000 deaths annually. Ninety percent of colon cancers occur in people over age 50. Besides the obvious personal costs of increased mortality and morbidity of the older patient with osteoporotic bone fracture or colon cancer, these prevalent diet-related chronic diseases add a multi-billion dollar cost to the national annual health care bill. Our working hypothesis is that a high calcium diet is chemoprotective because it activates colonic extracellular calcium sensing receptors that alter colonocyte cell signaling, in an unknown way that reduces the propensity to develop colon cancer. Our studies are aimed at strengthening the scientific evidence of the importance of the extracellular calcium sensing receptor as a key molecular mediator of the chemoprotective effects of a high calcium diet on colon carcinogenesis. In collaborative population studies we are also investigating the role of high iron stores in colon cancer risk. The findings from these studies may have important public health ramifications as they would provide a better scientific foundation for developing optimal diets to reduce the risk of colon cancer and osteoporosis, as well as providing a guidepost for establishing optimal dietary mineral intake recommendations. The latter may be particularly important in the context of accumulating evidence that high mineral intakes or status may have a detrimental effect on the risk of some cancers and other diseases.

Capabilities

The laboratory has the basic capabilities in cell and molecular biology techniques, including cell culture, viral and nonviral cell transfection, and cell transport studies, along with experience in mouse husbandry and breeding and genotyping.