HLTB11H3 Lecture Notes - Lecture 9: Xerophthalmia, Nyctalopia, Carotene

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20 Mar 2019
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Liver, eggs, dairy, yellow/orange/red fruits & vegetables: role in metabolism. ; i. e. , skin & epithelial tissues, immune function, reproduction & growth: consequence of de ciency. Night blindness; xerophthalmia; increases susceptibility to infections: toxicity. Preformed vit a (supplements & animal foods) highly toxic. One of the carotenoids (1) preformed vitamin a = retinol; animal sources (2) retinol and retinal are inter-convertible (3) retinoic acid once formed can not be converted back to other forms (4) beta-carotene can be converted to retinal. Beta-carotene: beta-carotene is converted to retinol, conversion is inef cient. Not all beta-carotene is converted to retinol. 1 ug rae = 12 ug beta-carotent from food: beta-carotene circulates in the blood. Observational studies suggested that high levels of bet-carotene may reduce the risk of lung cancer in smokers. Vitamin a & cell differentiation: maintenance of epithelial tissues: epithelial tissue: in eyes, intestine, lungs, skin, etc, has an important barrier function, abnormal epithelium increases risk of infection.

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