Cholecalciferol by Ray Sahelian, M.D. Benefit of cholecalciferol verses ergocalciferol

Vitamin D3 or cholecalciferol is produced in skin and is sequentially metabolized by the liver and kidney to the biologically active form 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. It is a seco-steroid hormone that regulates calcium homeostasis within the body. The actions of 1,25(OH)2D3 are modulated through the vitamin D receptor (VDR). VDR belongs to a superfamily of nuclear receptors that transduce hormonal signals from the immediate environment and transactivate genes in response to these signals.

Types of Vitamin D
Supplemental vitamin D is available in 2 distinct forms: ergocalciferol ( vitamin D2 ) and cholecalciferol ( vitamin D3 ). Vitamin D3 has proven to be the more potent form of vitamin D in all primate species, including humans. Vitamin D3 can also be produced in the skin through exposure to sun. Subsequently, Vitamin D3 is metabolized by the liver and kidney to the biologically active form 1,25-dihydroxyvitamin D3.

Cholecalciferol helps the body to regulate the transport of calcium from the digestive system through the bloodstream to bone. It also assists in the retention of calcium and phosphorus. Nature's Way Vitamin D is 100% natural cholecalciferol.  The dry form is specially formulated for easy absorption.  It contains no artificial ingredients or preservatives.

Cholecalciferol and cancer
Epidemiological studies and work on experimental animals strongly suggest a protective effect of cholecalciferol vitamin D3 (1,25(OH)2D3) against colon cancer and several other cancers. The correlation between decreased morbidity and mortality of cancer and exposure to sunlight is known. The many biological functions of vitamin D that contribute to cancer prevention have only recently begun to be appreciated. Once activated 1,25-dihydroxyvitamin D [1,25(OH)2D3] functions as a potent inhibitor of normal and cancer cellular proliferation.

Cholecalciferol and bone fracture
The effect of cholecalciferol (vitamin D3) on the risk of fall and fracture: a meta-analysis.
QJM. 2007 Feb 17; Jackson C, Gaugris S, Sen SS, Hosking D. From the Evidence Research Unit, Macclesfield, UK, Merck & Co. Inc., Whitehouse Station, New Jersey, USA, and Nottingham City Hospital, Nottingham, UK.
We evaluated the effect of supplementation with cholecalciferol (excluding the potential effect of calcium supplementation) on the risk of fall and fracture, primarily in postmenopausal women, using a systematic literature review of MEDLINE, EMBASE, BIOSIS and the Cochrane Database of Systematic Reviews for the period January 1985 to June 2005. Our primary meta-analyses examined the effect of cholecalciferol on the risk of fall or fracture; additional analyses examined baseline and difference between baseline and final levels of several serum and urinary biochemical markers. There is a trend towards a reduction in the risk of fall among patients treated with cholecalciferol  alone compared with placebo, suggesting that cholecalciferol should be an integral part of effective osteoporosis management.

Cholecalciferol or ergocalciferol supplement?
The case against ergocalciferol (vitamin D2) as a vitamin supplement.
Am J Clin Nutr. 2006 Oct;84(4):694-7. Houghton LA, Vieth R. School of Nutrition and Dietetics, Acadia University, Wolfville, Canada.
Supplemental vitamin D is available in 2 distinct forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Pharmacopoeias have officially regarded these 2 forms as equivalent and interchangeable, yet this presumption of equivalence is based on studies of rickets prevention in infants conducted 70 y ago. The emergence of 25-hydroxyvitamin D as a measure of vitamin D status provides an objective, quantitative measure of the biological response to vitamin D administration. As a result, cholecalciferol has proven to be the more potent form of vitamin D in all primate species, including humans. Despite an emerging body of evidence suggesting several plausible explanations for the greater bioefficacy of cholecalciferol, the form of vitamin D used in major preparations of prescriptions in North America is vitamin D2. The case that vitamin D2 should no longer be considered equivalent to cholecalciferol is based on differences in their efficacy at raising serum 25-hydroxyvitamin D, diminished binding of vitamin D2 metabolites to vitamin D binding protein in plasma, and a nonphysiologic metabolism and shorter shelf life of vitamin D2. Vitamin D2, or ergocalciferol, should not be regarded as a nutrient suitable for supplementation or fortification.

Source of cholecalciferol or vitamin D3
Cholecalciferol has an origin from animal products such as sheep wool. The sheep are not killed. The wool is sheared, and lanolin from the sheep wool is chemically altered in the lab to produce vitamin D3 or cholecalciferol.

Q. I would like your thoughts on whether taking vitamin D3 cholecalciferol is okay for someone who is allergic to wool.
   A. I have not heard of any problems arising from the ingestion of cholecalciferol in someone who is allergic to wool, but I cannot be 100 percent that it is completely safe since I am not familiar with the details of the manufacturing process of cholecalciferol from sheep wool.

Cholecalciferol questions
Q. I read on a web site that "Vegans usually obtain vitamin D from the action of sunlight on the skin or by taking fortified foods such as soya milk, margarine, breakfast cereals and vitamin supplements which are made from yeast or other fungi. Fortified vegan products contain D2 ( ergocalciferol ). Vegans are careful about their source of Vitamin D as D3 ( Cholecalciferol ) which is animal-derived." I'm vegan, does this mean I should not take a product with cholecalciferol but rather take ergocalciferol?
   A. It appears to be true that Vitamin D in the form of cholecalciferol is derived from an animal source such as sheep wool. Therefore, this would make it fine for a vegetarian but not for a very strict vegan who believes that even a vitamin derived from wool is not acceptable. The sheep are not killed. The wool is sheared, and lanolin from the sheep wool is chemically altered in the lab to produce vitamin D3 or cholecalciferol.
 
Q. I have seen research stating that vitamin D2 should not be used, only vitamin D3 cholecalciferol, as a milk additive and for personal health reasons.
   A. The preliminary research states that cholecalciferol is preferable to ergocalciferol. However, we have not seen any long term human studies in a head to head comparison of the two forms to know for certain, but for the time being cholecalciferol is probably the better choice.