Osteoporosis is a metabolic bone disease in which the amount of bone tissue is reduced sufficiently to increase the likelihood of fracture. Calcium supplements, with or without vitamin D, cut the overall risk of bone fractures, revealed by Australian researchers.
Although low bone mass is the major factor in osteoporotic fractures, there may also be qualitative and architectural changes in bone with aging that lead to increased fragility.
The researchers pooled information from 29 previously published trials, involving more than 52,500 people over the age of 50, who had been treated for an average of 3.5 years. In trials reporting on bone fracture risk, calcium supplements, with or without vitamin D reduced this by 12%.
Calcium is crucial to all physiological function. It must be obtained from the diet, but since an intake of only about 1 g per day is adequate, shortage is rare; the net daily turnover (the absorption rate into blood, and excretion rate in the urine) is only about one-tenth of that amount again.
The absorption of calcium from the intestinal tract requires vitamin D, and together with parathyroid hormone, vitamin D also controls the body’s calcium balance, mobilizing it from the bones to maintain the plasma concentration within a very narrow range.
Vitamin D helps the body absorb calcium. People can get vitamin D from sunshine with a quick (15?20 minute) walk each day or from foods such as liver, fish oil, and vitamin-D fortified milk. During the winter months it may be necessary to take supplements. Four hundred mg. daily is usually the recommended amount.
Exposure to sunlight is the primary method of obtaining vitamin D. In clear summer weather, approximately ten minutes per day in the sun will produce adequate amounts, even when only the face is exposed. In the winter, it may require as much as two hours. Many people don’t get that amount of winter exposure, but are able to utilize the vitamin that was stored during extra time in the sun over the summer.