Vitamin D

What it does in the body

Vitamin D is often referred to as the “sunshine vitamin” as a result of its photochemical production in the skin by the action of sunlight or ultraviolet light on 7-deyhydrocholesterol, a component found in the epidermis or the outer layer of the skin.  By promoting calcium absorption, vitamin D helps to form and maintain strong bones and works in concert with a number of other vitamins, minerals and hormones to promote bone mineralization. Without vitamin D, bones can become thin, brittle or misshapen. Vitamin D deficiency results in rickets in children and osteomalacia in adults.

Food Sources

  • Sources of Vitamin D include cod liver oil, salmon, mackerel, tuna fish, milk, egg, liver, beef and cheese.1

Recommended Dietary Allowance

  • The US RDA for Vitamin D is 200-400 IU/day. Health Canada recommends a minimum intake of 5 micrograms (200 IU) a day and upper level of 50 micrograms (2,000 IU).2

Orthomolecular Dosage Range: Very much higher than RDA levels.

  • 1,500 IU of D3/day. Orthomolecular physicians may recommend thousands of mg/day during illness.

Orthomolecular Medicine News Service, October 3, 2007. Vitamin D Boosts Health, Cuts Cancer Risk in Half.
Saul AW. Vitamin D: Deficiency, diversity and dosage. J Orthomolecular Med, 2003. Vol 18, No 3 and 4, p 194-204.

Vitamin D-deficiency rickets is surprisingly persistent in Canada, particularly among children who reside in the north and among infants with darker skin who are breast-fed without additional vitamin D supplementation. Since there were no reported cases of breast-fed children having received regular vitamin D (400 IU/d) from birth who developed rickets, the current guidelines for rickets prevention can be effective, but are not being consistently implemented. The exception appears to be infants, including those fed standard infant formula, born to mothers with a profound vitamin D deficiency, in which case the current guidelines may not be adequate to rescue infants from the vitamin D-deficient state.3,4

Vitamin D is also preventive, and therapeutic, for a wide variety of other diseases.

“There is growing evidence that the “sunshine vitamin” may be vastly more important to human health than previously thought and commonly taught. Vitamin D metabolite (1,25-dihydroxyvitamin D) receptors (VDR), writes Michael F. Holick, M.D., “are present not only in the intestine and bone, but in a wide variety of other tissues, including the brain, heart, stomach, pancreas, activated T and B lymphocytes, skin, gonads, etc. 1,25(OH)(2)D is one of the most potent substances to inhibit proliferation of both normal and hyperproliferative cells and induce them to mature. . . Chronic vitamin D deficiency may have serious adverse consequences, including increased risk of hypertension, multiple sclerosis, cancers of the colon, prostate, breast, and ovary, and type 1 diabetes.”5    (From: Saul AW. Vitamin D: Deficiency, diversity and dosage. J Orthomolecular Med, 2003. Vol 18, No 3 and 4, p 194-204.


1  Canadian Health Network. Public Helath Agency.
2  Ibid.
3  Vitamin D-deficiency rickets among children in Canada
Leanne M. Ward, MD, Isabelle Gaboury, MSc, Moyez Ladhani, MD and Stanley Zlotkin, MD PhD
5 Holick MF. Vitamin D: A millenium perspective. J. Cell. Biochem. 88: 296-307. 2003.