Abstract
The most important nutrients affecting bone are vitamin D, Calcium and Phosphorus. The active form of vitamin D is 1, 25-dihydroxyvitamin D; it increases intestinal absorption of calcium and phosphorus and in concert with parathyroid hormone, increases bone resorption. So blood levels of calcium and phosphorus are maintained for normal mineralisation of newly synthesized bone matrix. A deficiency of vitamin D leads to rickets in children and to osteomalacia in adults, though nutritional deficiencies of vitamin D are nowadays rare. Rickets and osteomalacia are usually the effect of other causes: malabsorption syndromes, steatorrhoea, long-term anticonvulsant therapy, chronic renal failure, etc. Milk and milk products contain calcium, other foods provide very little calcium. The requirement of the human body depends on age, pregnancy and lactation. If calcium intake is low, this can be compensated by increased intestinal absorption of calcium. In increasing age and in menopause, calcium requirements are greater. This can be prevented by estrogen replacement therapy. In food phosphorus is mostly present in sufficient quantity. In rare instances disturbances may come from phosphorus-deficient diet, phosphate-binding antacids and in familial hypophosphatemia. Deficiency of vitamin C sometimes causes osteoporosis; vitamin A-intoxication gives cortical hyperostosis in children and increased bone resorption in adults. Excessive fluoride ingestion can lead to osteosclerosis; in osteoporosis sodium fluoride and calcium help to increase formation of normally mineralized bone. (Drukker - Gieten)