Vitamins

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Vitamins

• Presented by Dr. Deena Abdel-Hadi
• Moderator Dr. A. B. Hamam

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Vitamin B12 (cyanocobalamin)

• - Vitamin B12 is derived from cobalamin in food ,
  mainly animal sources , 2ry to production
  by micro-organisms.
• - Humans cant synthesize vitamin B12.
• - The cobalamins are released in the acidity of
  the stomach combine there with R proteins
  IF, traverse the duodenum,
  where pancreatic proteases break down the R
  proteins, are absorbed in the distal ileum via
  specific receptors for IF cobalamin.

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• Characteristic
• 1. Slightly soluble in water.
• 2. Stable to heat in neutral solutions.
• 3. Labile in acid or alkaline solutions.
• 4. Destroyed by heat.
• 5. Castle intrinsic factor of the stomach
  required for absorption.

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• Biochemical Action
• 1. Essential for maturation of RBCs in BM.
• 2. Metabolism of nervous tissue.

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Daily Requirement

• Infants
• 0 - 6/12 0.3 ug/day.
• 6/12 - 1 yr 0.5 ug/day.
• Children
• 1 - 3 yr 0.7 ug/day.
• 4 - 6 yr 1.0 ug/day
• 7 - 10 yr 1.4 ug/day.

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Effects of Deficiency

• Juvenile pernicious anemia
• - Rare Autosomal recessive disorder results from
  an inability to secrete gastric IF or secretion
  of a functionally abnormal IF.
• - Other Causes
• 1. 2ry to gastrectomy.
• 2. Celiac disease.
• 3. Inflammatory lesions of small bowel.
• 4. Long term drug therapy (neomycin).

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• Clinical Manifestations
• - Prominent symptoms _at_ 9/12 to 11 yr of age.
• - Smooth, red painful tongue.
• - Neurologic manifestations ataxia,
  parethesias, hypo- reflexia,
  babiniski responses, clonus coma.
• - Weakness, irritability anorexia.
• Lab. Finding
• - Serum B12 lt100 pg/ml.
• - High serum LDH level.
• - absent IF activity in gastric secretion.

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• - Schilling Test
• In which, after body stores of the vitamin are
  saturated, a tracer dose of radio-active B12 is
  given by mouth, with or without IF, urinary
  excretion measured over the next 24 hr.
• Defective absorption in the presence of IF,
  shown by urinary excretion of less than 5 of the
  dose, occurs when an extensive length of distal
  ileum is resected or diseased, or when bacterial
  over-growth occurs within the bowel lumen.

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• Treatment
• - A prompt hematological response follows
  parenteral administration of vitamin B12 (1 mg),
  with reticulocytosis in 2-4 days.
• - The physiological requirement is 1-5 ug/day.
• - If there is neurological involvement, 1 mg IM
  daily X 2/52.
• - Maintenance therapy is 1 mg IM vitamin B12
  monthly.

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• Effect of Excess
• Unknown
• Sources
• 1. Muscle organ meats.
• 2. Fish.
• 3. Eggs.
• 4. Milk .
• 5. Cheese.

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Folate ( Folic Acid)

• The disease is caused by a deficient intake or
  absorption of folic acid .
• Folic acid is absorbed throughout the small
  intestine ( the specific nature of folate
  receptors transport via the intestinal cell is
  not clear) .
• Surgical removal or disorders of small intestine
  may lead to folate deficiency.

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• Dietary deficiency is usually compounded by rapid
  growth or infection, which may increase folic
  acid requirements.
• The needs are also increased with accelerated
  tissue turnover, as in hemolytic anemia.
• Human cows milks provide adequate amounts of
  folic acid. Goats milk is clearly deficient.
  Unless supplemented, powdered milk may also be a
  poor source of folic acid.

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• Daily Requirement
• Infants
• 0 - 6/12 25 ug/day.
• 6/12 - 1 yr 35 ug/day.
• Children
• 1 3 yr 50 ug/day.
• 4 6 yr 75 ug/day.
• 7 10 yr 100 ug/day.

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Effects of Deficiency

• Megaloblastic Anemia of Infancy
• Clinical manifestation
• - Megaloblastic anemia has been reported in
  VLBW, its peak incidence at 4 - 7 month of age.
• - Irritability, failure to gain weight chronic
  diarrhea.
• - Hemorrhages due to thrombocytopnia occur in
  advanced cases.

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• Laboratory Findings
• - Macrocytic anemia (MCV more than 100 fl).
• - Low reticulocyte count.
• - Nucleated RBCs.
• - Neutropenia thrombocytopenia ( long standing
  deficiency ).
• - Large neutrophils with hyper segmented nuclei
  ( more than 5 of neutrophils have 5 or
  more nuclear segments).
• - Low serum folic acid less than 3 ng/ml (5 - 20
  ng/ml).
• - Levels of RBCs folate (150 - 600 ng/ml).

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• Treatment
• 1-5 mg/day P.O. or parenterally.
• 50-100 ug/day for a week (doubt diagnosis).
• 1 ug/day parenterally (for ? B12 deficiency).
• Folic acid therapy should be continued for 3 -
  4 weeks.
• Sources
• 1. Green vegetables.
• 2. Fruits.
• 3. Animal organs (liver kidney).

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Vitamin C (ascorbic acid)

• Characteristics
• 1. Water soluble
• 2. Easily oxidized, accelerated by
• - Heat.
• - Light.
• - Alkali oxidative enzymes.
• - Traces of copper or iron.

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• Biochemical Action
• 1. Integrity maintenance of intracellular
  material.
• 2. Facilitates absorption of iron conversion
  of folic acid to folinic acid .
• 3. Metabolism of tyrosine phenylalanine
• 4. Regulation of serum phosphatase in infants.

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• Daily Requirement
• Infants
• 0 - 6/12 30 mg/day
• 6/12 - 1 yr 35 mg/day
• Children
• 1-3 yr 40 mg/day
• 4 - 6 yr 45 mg/day
• 7 - 10 yr 45 mg/day

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• Effects of Deficiency
• 1. Scurvy.
• 2. Poor wound healing.

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• Scurvy
• - Ascorbic acid is essential for the formation of
  normal collagen.
• - Breast milk contains about 4 - 7 mg/dl of
  ascorbic acid is an adequate source of
  vitamin C .
• - Deficiency of vitamin C in the mothers diet
  may result in scurvy in their breast-fed
  infant.

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• - The need for vitamin C is increased by
• 1. Febrile illnesses, particularly infectious
  diarrheal diseases.
• 2. Iron deficiency.
• 3. Cold exposure
• 4. Protein depletion.
• 5. Smoking.

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• The tendencies to hemorrhage, defective tooth
  dentin loosening of the teeth are caused by
  deficient collagen.
• Because osteoblasts no longer form their normal
  intracellular substance (osteoid), endochondral
  bone formation ceases the bony trabeculae that
  have been formed become brittle fracture easily
  .
• In sever scurvy there may be
• - Degeneration in skeletal muscles
• - Bone marrow depression.
• - Cardiac hypertrophy.
• - Adrenal atrophy.

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• Clinical manifestations
• - Rare in the newborn infant.
• - Peak incidence at 6 - 24 month of age.
• - Presented as vague symptoms of irritability,
  tachypnea, digestive disturbances loss of
  appetite.
• - There is general tenderness (legs).
• - Petecheal hemorrhages may occur in the skin
  mucous membranes.
• - Hematuria, melena, orbital subdural
  hemorrhages may be found.
• - Delayed wound healing.
• - Ground-glass bone X ray appearance.

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• Treatment
• - The administration of 3 - 4 oz of orange
  juice or tomato juice daily will quickly
  produce healing, but ascorbic acid is
  preferable.
• - The daily therapeutic dose is 100-200 mg or
  more,P.O. or parentally.

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• Effects of Excess
• oxaluria

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• Sources
• 1. Citrus fruits
• 2. Tomatoes.
• 3. Berries.
• 4. Cantaloupe.
• 5. Cabbage.
• 6. Green vegetables.
• Cooking has destructive effect.