due to metabolizing induction drug) Decreased endogenous synthesis (via 25- hydroxylation in the liver and subsequent 1-hydroxylation in the kidney). strict vegetarian people sharply increase the risk of deficiency if sunlight exposure is inadequate. Patients with chronic liver disease or malabsorption or parathyroidectomy. Obese people have lower levels of the circulating form of vitamin D, probably because it is deposited in body fat masses less bioavailable vitamin D. Dark-skinned individuals may require extra vitamin D because melanin acts like a sun-block, prolonging the time required to generate vitamin D. PEOPLE AT GREATER RISK OF DEVELOPING VITAMIN D DEFICIENCYĥ. Women after labor: the serum concentration of vitamin D and Ca++ falls rapidly. Newborn infants: who are absolutely breastfed require vitamin D supplements because mother milk does not contain significant levels of the vitamin. Older people (> 50 years) due to: The decrease of ability of skin to convert 7- dehydrocholesterol to pre-vitamin D3. Regulation of cell growth and development (particularly WBCs and epithelial cells).ġ. Integrated function with parathyroid hormone in stabilization of Ca++ level in blood. Essential for normal bone growth during childhood and for maintaining bone density and strength during adulthood (as it increases Ca++ absorption from foods + increases Ca++ deposition into the skeleton). A fall in blood Ca++ stimulate active vitamin D production stimulates Ca++ absorption from food + release of Ca++ from bones + renal excretion of Ca++. NB: A healthy liver and kidneys are essential for optimum vitamin D status.īiosynthesis and Activation of Vitamin D 3 Stored in Liverĭaily Requirment = 10μg vitamin D = 400 IU vitamin D.ġ.Calcium metabolism (main function): Vitamin D regulates Ca++ levels in the blood and tissues. ![]() ![]() When needed by the body, it is then activated by the kidney to 1, 25 - di hydroxy vitamin D3. After absorption from foods or production in the skin, vitamin D is stored as 25-hydroxy- vitamin D3 in the liver. However, vitamin D3 is the preferred form for humans as its bioavailability is twice that of vitamin D2. ( Ergocalciferol) VITAMIN D 2 (Cholecalciferol) VITAMIN D 3 Found in plant life Synthesized in the body Synthetically derived supplement Naturally derived supplement Moderately increases vitamin D levels in the body Significantly increases vitamin D levels in the body Alternative form appropriate for vegetarians Recommended by experts for optimal bone and immune support Vitamin D2 (ergocalciferol) is another form of vitamin D synthesized by certain fungi and is used in many supplements. Vitamin D3 (cholecalciferol) is synthesized from 7-dehydrocholesterol in sun-exposed skin and found naturally in animal products such as eggs, fish and liver. The term “Vitamin D” refers to a family of related compounds biosynthesized from cholesterol and ergosterol. Presentation on theme: "Vitamin D, E & K Fat soluble vitamins.
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