Vitamin D (Cholecalciferol)

Requirements:

• RDA:
  
  200 I.U. for adults
  400 I.U. for infants, children, adolescents, pregnant and lactating women
• Daily Optimal Intake:
  
  200 - 400 I.U.

Supplement Forms:

• 1, 25 dihydroxycholecalciferol - biologically active form of vitamin D for patients who cannot convert vitamin D
• Vitamin D 2 - synthetic form
• Vitamin D 3 - naturally occurring form

Labs:

• 1, 25 dihydroxycholecalciferol
• Cholecalciferol (D3)

Food Sources:

• Beef 100 gm. (9-25 I.U.)
• Butter 100 gm. (35 I.U.)
• Chicken 100 gm. (60 I.U.)
• Cream 100 gm. (50 I.U.)
• Egg yolk 100 gm. (25 I.U.)
• Halibut 100 gm. (44 I.U.)
• Herring 100 gm. (320 I.U.)
• Lamb 100 gm. (20 I.U.)
• Mackerel 100 gm. (1100 I.U.)
• Pork 100 gm. (45 I.U.)
• Sunshine - 20 minutes per day on bare skin
• Salmon 100 gm. (150 - 550 I.U.)
• Shrimp 100 gm. (150 I.U.)
• Sardines 100 gm. (1150-1570 I. U.)

Signs and Symptoms of Deficiency:

• Rickets - in children:
  
  Bossing of the skull
  Costochondral beading (rachitic rosary)
  Delayed sitting and crawling
  Enlargement of epiphyseal growth plates, especially in radius and ulna
  Failure of fontanelles to close with delayed teeth eruption, stunted growth, bow legs or knock knees
  Reduced mineralization of skull away from sutures
  Restless
  Sleep poorly

• Osteomalacia - in adults:
  
  Burning mouth and throat
  Demineralization of bone especially in the spine, pelvis, and lower extremities
  Diarrhea
  Nervousness

Causes of Deficiency:

• Anticonvulsive drug therapy
• Celiac disease
• Crohn's disease
• Cushing's disease
• Dark skin
• Decreased intake of vitamin D
• Hypothyroidism
• Intestinal surgery
• Kidney or liver disease
• Malabsorption
• Poor exposure to sun
• Ulcerative colitis
• Vitamin D-resistant rickets

Adverse Effects and Toxicity:

• Reports that 1,000 - 3,000 I.U. per day in children may produce symptoms of toxicity:
  
  Calcification of soft tissues - kidneys, lungs, tympanic membrane of ears
  Constipation
  Diarrhea
  Headaches
  Nausea and vomiting
  Polydipsia
  Polyuria
  Weakness

Drug/Nutrient Interactions:

• Anticonvulsants interfere with vitamin D and vitamin K
• Prednisone or other cortisone-like drugs interfere with the renal conversion of vitamin D to its biologically active form (1, 25 dihydroxycholecalciferol)
• Phenobarbital prevents biological availability of vitamin D
• Primidone, long term, leads to vitamin D deficiency
• Phenytoin decreases absorption of vitamin D
• Mineral oil, long term, can cause fat soluble vitamin deficiency, including vitamon D
• Isoniazid decreases synthesis of active form of vitamin D
• Glutethimide increases metabolism of vitamin D resulting in a decrease in vitamin D stores
• Glucocorticoids diminishes vitamin D bioavailability
• Furosemide (and other thiazides) used with vitamin D leads to hypercalcemia
• Colestipol reduces vitamin D absorption
• Cimetidine decreases 25 hydroxylase vitamin D activity in the liver
• Cholestyramine causes vitamin D malabsorption
• Anticonvulsants decreases the effectiveness of vitamin D on bone mineralization and overall metabolism
• Phenolphthalein decreases vitamin D absorption

Biochemical Functions:

• Increases absorption of calcium from the intestines by stimulating the synthesis of calcium binding protein
• Increases renal reabsorption of calcium
• Increases resorption of calcium from the bone to increase serum calcium

Clinical Indications:

• Aging prevention
• Benign prostatic hypertrophy (BPH)
• Cancer prevention
• Congestive heart failure
• Crohn's disease
• Diabetes mellitus
• Menopause
• Osteoporosis
• Psoriasis
• Psoriatic arthritis
• Cancer prevention, especially colon and breast
• Fractures
• Rickets

Copyright 1998 - 2008 by L. Vicky Crouse, ND and James S. Reiley, ND. All rights reserved (ISSN 1527-0661).