Physiological Role of V
Absorption and Excretion
Deficiency Signs

I.  Physiological Role of V

  1. All criteria for essentiality have been met
  2. At both pharmacological and physiological levels, V decreases blood lipid levels
  3. V may have a catalytic or enzymatic function in bone metabolism or formation
  4. V may have a role in labile methyl metabolism in chicks
  5. In vitro studies have indicted that V may have a specific physiological role as a regulator of Na, K-ATPase
  6. Haleperoxidase which facilitates formation of carbon-halogen bonds require V in lower forms of life (reviewed in J. Nutr. 126:2452S, 1996). V deprivation affects thyroid peroxidase in rats (Magnes. Trace Elem. 9:219, 1990)

II.  Absorption and Excretion

  1. Absorption of V is low, with most excreted in feces
  2. Excretion of absorbed V is largely through the kidneys

III.  Requirements

  1. 10 to 25 ug of V/Kg diet was insufficient for rats and chicks under certain conditions
  2. V deficiency has not been identified in humans even though diets generally supply < 30 ug/day (J. Nutr. 126:2452S, 1996)
  3. An estimated daily dietary intake (EDDI) of 10-20 ug has been suggested for humans (J. Nutr. 126:2452S, 1996)

IV.  Sources

  1. Tricalcium phosphate contains .025-.25% V
  2. Some feed samples contain 100 ug/kg: Pasture herbage (dry), 80; oats, 60; oat straw, 120; milk (wet) < .1; liver, fish, muscle, not over 10
  3. Shellfish, mushrooms, parsley, dill seed, and black pepper are rich in V (J. Nutr. 126:2425S, 1996)

V.  Deficiency Signs

  1. V-deprived rats
    1. Elevated hematocrit and increased Fe in blood and bone
    2. Reduced number and survival rate of pups in rats fed < 10 ug V/kg diet over 4 generations
  2. V-deprived chicks
    1. Reduced growth
    2. Depressed wing and tail feather development
    3. Increased hematocrit
    4. Increased epiphyseal plate and decreased primary spongiosa in bone. Abnormal iodine metabolism (Magnes. Trace Elem. 9:219, 1990)

VI.  Toxicity

  1. Industrial exposure through inhaled airborne particles causes irritation of nose and throat, a anorexia, nausea, and diarrhea
  2. Toxicity to ruminants observed at 10 mg/Kg body weight (about 300 ppm in diet) or above
    1. Clinical signs: diarrhea, dehydration, emaciation, listlessness, and prostration listed in order of occurrence
    2. Gross pathological signs: Congestion of liver and lungs, diffuse petechiae covering kidney and heart, ulcers in the rumen, hemorrhagic inflammation of the intestinal tract
    3. V above 10 ppm toxic to chickens
      1. Depressed body weight of laying hens
      2. Decreased production (at 30 ppm) and hatchability (at 60 ppm) of eggs
    4. Maximum tolerable levels
      1. 50 ppm for cattle and sheep
      2. 10 ppm for poultry

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