Osteoporosis and vitamin D

AbstractBone “density” (bone mass/bone volume) declines with age from the menopause in women and from about age 55 in men. This fall in bone density (osteoporosis) weakens the bones and leads to a progressive rise in fracture rates, particularly in women. Many risk factors contribute to the bone‐losing process, but one which attracts increasing attention is calcium absorption.The main physiological regulator of calcium absorption is vitamin D. This is manufactured in the skin under the influence of UV‐light and then converted to more potent metabolites in the liver and kidney. Although the serum levels of the most potent metabolite 1,25(OH)2D3 (calcitriol) are generally normal in osteoporotic women, treatment with small doses of calcitriol (about 0.25 μg daily) has a remarkable effect on absorptive performance and slows down the rate of bone loss. Improved synthetic metabolites are under development.There is likely also to be greatly increased scope for the use of vitamin D itself in osteoporosis. With advancing age, there is a tendency for men and women to be exposed to less and less sunlight, which is the main natural source of vitamin D. Vitamin D levels, therefore, decline with