Abstract
Since author was fascinated by the important functions of calcium (Ca) for the regulation of intracellular metabolism, author has focused the studies on Ca metabolism. A parameter which evaluates bone strength is essential for the study of Ca/bone metabolism and the prevention of osteoporosis. Therefore, a machine for measurement of bone strength was developed. Dual-energy X-ray absorptiometry (DXA: bone densitometer) is used very widely in human studies, and has proved to be safer and more accurate than other techniques. Author carried out DXA to determine whether it is suitable for the measurement of low bone mineral density (BMD) in small animals. The estrogen-deficient model rat produced by ovariectomy and the estrogen- and Ca-deficient model rat produced by ovariectomy and a low Ca diet were also evaluated to clarify whether these animal models were useful as osteoporotic models. For prevention of osteoporosis, it is necessary to take enough Ca and to carry out moderate physical activity. However, Ca intake has never been sufficient in Japan. Therefore, the effects of different Ca sources, other nutrients which affect Ca metabolism and physical activity on bone metabolism were examined. It is well known that a reaching a high peak bone mass at a young age and minimizing bone loss with aging and/or the menopause are also important for prevention of osteoporosis. Therefore, the effects of diet and daily physical activity on the BMD of pre/post menopausal women were investigated using DXA from the viewpoint of osteoporosis prevention.
