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14. Vitamins & Trace Elements

14. Vitamins & Trace Elements. What are Trace Elements?. Trace elements are those elements that occur in human and animal tissues in mg/kg amounts or less. Essential when: deficient intake ►impairment of function restoration with physiological amounts of only

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14. Vitamins & Trace Elements

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  1. 14. Vitamins & Trace Elements

  2. What are Trace Elements? Trace elements are those elements that occur in human and animal tissues in mg/kg amounts or less. Essential when: deficient intake ►impairment of function restoration with physiological amounts of only that element prevents/alleviates impairment.

  3. Trace Element Functions amplification- small amounts produce dramatic effects on the body e.g. Fe deficiency & anaemia specificity- cannot be effectively replaced by chemically similar constituents homeostasis- regulated mechanisms for absorption, storage and excretion - storage proteins such as ferritin & metallothioneins important in regulation of Fe, Zn, Cu interactions- overabundance of one trace element can interfere with metabolic use of another e.g. large dietary Zn affect Cu absorption.

  4. Copper essential trace metal present in many intracellular enzymes e.g. cytochrome oxidase, superoxide dismutase, tyrosinase, - present in plasma in association with the copper-binding protein, ceruloplasmin. Laboratory Assessment: 1. serum copper : ~10-22 µmol/L, ~ 90% bound to ceruloplasmin 2. serum ceruloplasmin - normal adult levels 200-600 mg/L - levels useful in interpretation of serum copper levels. 3. urinary copper : ~ 0.1µmol/day

  5. Copper balance

  6. Vitamins • Definition: • unrelated organic catalysts that are necessary in trace amounts for normal metabolism • Classification: • Water soluble: • B-Complex: B1 (thiamine), niacin, folate (9), riboflavin (B2), pyridoxine (B6), cyanocobalamin (B12), • Others: ascorbate (C) • Fat-soluble: • A (retinol), D (cholecalciferol), K (phytomenadione), E (tocopherol)

  7. Vitamin deficiency Causes: • Inadequate intake with normal requirements • Impaired absorption • Impaired metabolism (e.g. vitamin D) • Increased requirements e.g. pregnancy • Increased losses • Functions typically intracellular • Plasma concentrations do not reflect intracellular levels or function – unreliable • Tissue concentrations most reliable but not always easily available

  8. Water-soluble Vitamins– folate (B9) & B12 not considered here

  9. Fat-soluble Vitamins

  10. VITAMIN DEFICIENCIES

  11. Complications of Thiamine (vitamin B1) Deficiency (Beri-beri)

  12. Complications of Niacin Deficiency (Pellagra)

  13. Complications of Riboflavin (vitamin B2) Deficiency

  14. Complications of Ascorbate (Vitamin C) Deficiency

  15. LESIONS IN SCURVY

  16. Classification of Vitamins

  17. HypervitaminosisClassically seen with fat-soluble vitamins: A, DSeen with excessive vitamin nutritional supplements • Hypervitaminosis A • Acute toxicity: neurologic symptoms: headache, vomiting, stupor, papilloedema • Chronic toxicity: neurologic, skeletal (loss of cortical bone), cutaneous (fissuring, ulcers), hepatomegaly with parenchymal damage. • Symptoms subside with discontinuation of excess vit A intake • Hypervitaminosis D: ▲intestinal absorption of Ca, PO4 ► hypercalcaemia, hyperphosphataemia, bone resorption ►renal calculi, osteoporosis, metastatic calcification

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