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Vitamin D by Ginny Isbell, PharmD

Vitamin D is a Fat Soluble Vitamin, which has also been classified as a hormone.

Many people are deficient in Vitamin D due to lack of sun exposure. Increased skin pigmentation, wearing sun protection, and limited outdoor activities limit our exposure to UVB radiation and therefore we have a decrease in the synthesis of Vitamin D3 by our skin.

Vitamin D deficiency has been linked to stroke, cardiovascular disease, osteoporosis, osteomalacia, several forms of cancer, some autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, type I diabetes, type 2 diabetes, depression and schizophrenia.

Known Benefits of Vitamin D:

  • Vitamin D aids in the absorption of calcium
  • Stimulates bone remodeling
  • Helps the pancreas release insulin

There is research showing Vitamin D can be effective in the treatment of type 2 diabetes, osteoporosis, osteoarthritis, hypertension, cardiovascular disease, metabolic syndrome, multiple sclerosis, polycystic ovary syndrome, musculoskeletal pain, depression, epilepsy, and in the prevention of cancer.

There are Vitamin D receptors in bones, skeletal muscles, pancreas, intestines, kidneys, brain, heart, spinal cord, male and female reproductive organs, thymus, adrenal glands, pituitary and thyroid gland. This proves that Vitamin D has many functions other than aiding in calcium absorption.

We acquire most of our Vitamin D from sunlight, but we absorb small amounts of Vitamin D from red meat (liver) and fish (sardines, salmon, mackerel, tuna and shrimp).

D3 versus D2:

  • D3 is 10 times more active at the receptor site
  • D2 is not found in animals-it is manufactured
  • D2 has a greater potential for toxicity than D3

Those who are particularly at risk for deficiency include the elderly, dark skin individuals, overweight individuals, and those who limit sun exposure.

Based on the Literature we recommend that most infants take Vitamin D3 1,000 IU daily, children 2,000 IU daily, and most adults take at least 5,000 IU daily. We would like to maintain 25(OH)D blood levels between 50-100nmol/L.


Cannell JJ, Hollis BW. Use of Vitamin d in clinical practice. Alternative Medicine Review 2008 March;13(1):6-20.

Holic MF. Vitamin d deficiency. N Engl J Med 2007 July 19;357(3):266-81.

Holic MF. Vitamin d: importance in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin
Nutr 2004; 79:362-71.

Holick MF, Chen TC. Vitamin d deficiency: a worldwide problem with health consequences. Am J Clin Nutr 2008;

Smith PW. Vitamins: hype or hope? a concise guide for determining which nutrients you really need. Traverse City (MI):
Healthy Living Books, Inc; 2004. p. 17-19.

Vasquez A, Manso G, Cannell J. The clinical importance of vitamin d (cholecalciferol): a paradigm shift with implications
for all healthcare providers. Alternative Therapies 2004 Sept-Oct 10(5):28-36.