The Truth About Vitamin D Toxicity --
John Jacob Cannell, MD• Vitamin D Toxicity Fears Unwarranted• Cholecalciferol, Not Ergocalciferol, Is SafeAlthough there are documented cases of pharmacological overdoses from
ergocalciferol1, the only documented case of pharmacological—not industrial—toxicity from cholecalciferol we could find in the literature was intoxication from an over-the-counter supplement called Prolongevity.
2 On closer inspection, it seemed more like an industrial accident, but it was interesting because it gave us some idea of the safety of cholecalciferol.
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1Ergocalciferol Vitamin D2. A vitamin D-like, patented drug that is not naturally present in the human body. Ergocalciferol is derived from fungal and plant sources by activating ergosterol with ultraviolet light, is only half as potent as cholecalciferol (real vitamin D), and may even block some of cholecalciferol's beneficial effects. It is more toxic and is the cause of most of the reported cases of vitamin D toxicity.
2Koutkia P, Chen TC, Holick MF. http://www.ncbi.nlm.nih.gov/pubmed/11439958">Vitamin D intoxication associated with an over-the-counter supplement. N Engl J Med. 2001 Jul 5;345(1):66-7. • Therapeutic IndexAs a physician, I know that psychotic patients should drink about 8 glasses of water a day. However, many would hurt themselves by regularly drinking 40 glasses a day (called compulsive water intoxication). So you could say that water has a therapeutic index of 5 (40/8).
Heaney's recent research indicates that healthy humans utilize about 4,000 units of vitamin D a day (from all sources).
3 However, 40,000 units a day, over several years, will hurt them.
4 Therefore, vitamin D has a therapeutic index of 10 (40,000/4,000)—twice as safe as water. We are not saying vitamin D is
as safe as water, we are saying vitamin D is
safe when used in the doses nature uses.
3Heaney R, Davies K, Chen T, Holick M, Barger-Lux MJ. Human serum 25 hydroxycholecalciferol response to extended oral dosing with cholecalciferol, Am J Clin Nutr. 2003;77;204-10.
4Vieth, R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety, Am J Clin Nutr. 1999;69:842-856 • Sun Supplies 10,000 Units of Vitamin DThe single most important fact anyone needs to know about vitamin D is how much nature supplies if we behave naturally, e.g., go into the sun. Humans make at least 10,000 units of vitamin D within 30 minutes of full body exposure to the sun, what is called a minimal erythemal dose.
6 Vitamin D production in the skin occurs within minutes and is already maximized before your skin turns pink.
Fear of the fatal form of skin cancer, malignant melanoma, keeps many people out of the sun. The problem with the theory is that the incidence of melanoma continues to increase dramatically although many people have been completely avoiding the sun for years.
4 We are not saying sunburns are safe, they are not. We are saying that brief, full-body sun exposure (minimal erythemal doses) may slightly increase your risk of skin cancer but it is a much smarter thing to do than dying of vitamin D deficiency.
5Holick MF. Environmental factors that influence the cutaneous production of vitamin D. Am J Clin Nutr. 1995 Mar;61(3 Suppl):638S–645S.
6Hemminki K, Zhang H, Czene K. Incidence trends and familial risks in invasive and in situ cutaneous melanoma by sun-exposed body sites. Int J Cancer. 2003 May 10;104(6):764–71. • Hypersensitivity, Not Toxicity