Disease States
Vitamin D deficiency:
The classical manifestations of vitamin D deficiency is rickets, which is seen in children and results in bony deformaties including bowed long bones. Deficiency in adults leads to the disease osteomalacia. Both rickets and osteomalacia reflect impaired mineralization of newly synthesized bone matrix, and usually result from a combination of inadequate exposure to sunlight and decreased dietary intake of vitamin D.Vitamin D deficiency or insufficiency occurs in several other situations, which you might predict based on the synthetic pathway described above:
- Genetic defects in the vitamin D receptor: a number of different mutations have been identified in humans that lead to hereditary vitamin D resistance.
- Severe liver or kidney disease: this can interfere with generation of the biologically-active form of vitamin D.
- Insufficient exposure to sunlight: Elderly people that stay inside and have poor diets often have at least subclinical deficiency. Ironically, it appears that hypovitaminosis D is very common in some of the most sunny countries in the world - the cause of this problem is the cultural dictate that women be heavily veiled when outside in public. Sunscreens, especially those with SPF ratings greater than 8, effectively block synthesis of vitamin D in the skin. However, people that use such sunscreens religiously live in industrial countries where many foods are supplemented with vitamin D, and vitamin D deficiency is thereby averted by dietary intake.
- Vitamin D toxicity: Excessive exposure to sunlight does not lead to overproduction of vitamin D. Vitamin D toxicity is inevitably the result of overdosing on vitamin D supplements. Don't do this! Ingestion of milligram quantities of vitamin D over periods of weeks of months can be severely toxic to humans and animals. In fact, baits laced with vitamin D are used very effectively as rodenticides.
(published with permission in writing from:http://www.vivo.colostate.edu)
