VITAMIN 'D' SYNTHESIZE IN HUMAN COLON-
Dihydroxycholecalciferol bound to its receptor functions as a potent antimitotic, prodifferentiating, proapoptotic hormone in different cell types and tissues. Epidemiological studies have linked low human serum concentrations of the vitamin D precursor hydroxycholecalciferol to colorectal cancer incidence. We have demonstrated in human colorectal tissue and cells the conversion of the precursor to dihydroxycholecalciferol, as well as the existence of the vitamin D catabolic pathway. These findings suggest a role for the colonic vitamin D system in tumor prevention. Low calcium intake has been found to be associated with human colorectal cancer incidence. In mice fed calcium equivalent to a low human intake, the degradative vitamin D pathway was increased, mainly in the ascending colon. Refeeding the mice high levels of vitamin D and calcium lowered tissue 25-hydroxycholecalciferol 24-hydroxylase activity, but only replenishment of folic acid normalized expression of the degradative pathway completely. Normalization occurred also when mice consuming low calcium diets were fed soy or the phytoestrogen genistein. These results indicate that colonic vitamin D synthesis is not only under stringent control of nutritional calcium, but also of folate, a methyl donor, which suggests epigenetic control of vitamin D hydroxylases. -
2007-03-20 05:54:58
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answer #1
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answered by Anonymous
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Bacteria synthesize Vitamin K in the colon. Patients on some long term antibiotics may not have enough of these "good bacteria" in the colon, thus develop a vitamin K deficiency, often manifest by bruising and bleeding.
Edward A. Doisy was awarded the Nobel Prize in Physiology or Medicine for his work on Vitamin K.
2007-03-20 12:52:44
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answer #2
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answered by greydoc6 7
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Vitamin K can be synthesized in the human colon by the bacteria there. A vitamin K shot is given to newborns to help them with blood clotting since they do not have the bacteria in their colon yet. Vitamin D can be synthesized in the skin in sunlight. The rest we have to take in everyday. A,B C,E
2007-03-20 12:44:44
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answer #3
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answered by science teacher 7
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E. coli in the human colon are able to synthesize vitamin K as part of their anaerobic metabolism
2007-03-20 12:54:21
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answer #4
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answered by citizen insane 5
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