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Newsletter: Vitamin D on the web

Posted on: January 2, 2003   by  John Cannell, MD


If Professor Robert Heaney of Creighton University, the calcium and vitamin D expert, is right, then the damage from widespread vitamin D deficiency may well be enormous. In an ominous warning, Dr. Heaney recently wrote, “the cost of vitamin D deficiency, while yet to be fully reckoned, may well be massive.”1

If Professor Michael Holick of Boston University (the man who has written the relevant chapters in Harrison’s Principles of Internal Medicine for the last 15 years) is right, then we should all have our calcidiol [25(OH)D] levels checked every year2.

However, we can not all have Dr. Heaney or Dr. Holick as our personal physician. Where do concerned patients go to keep up-to-date on the rapidly changing field of vitamin D nutrition? What about your own physician? If you read this Newsletter regularly, the chances are quite good that you know more about vitamin D and vitamin D deficiency diseases than your personal physician does. That is not a criticism; it is a sad fact of life for busy clinicians who have been erroneously taught in medical school that all the vitamins one needs can be obtained from a normal diet. The fact is that very little of the vitamin D in your body comes from your diet. It comes from ultraviolet radiation striking your unprotected skin.

We know many people now go to the web to stay current on medical advances. We decided to compare several heavily trafficked web sites, to see who is giving the most accurate and up-to-date clinical information about vitamin D. We excluded sites that give primarily biochemical information, such as the fine site at UC Riverside: http://vitamind.ucr.edu/about.html

1. First we visited the National Institutes of Health3.

The NIH site states rickets is now rare in the USA due to vitamin D fortification of milk. Actually, rickets is making a dramatic comeback in the USA4.

NIH says “one cup of vitamin D fortified milk supplies about one-fourth of the estimated daily need for this vitamin for adults.” Actually, if milk contained the required amount of vitamin D, one glass should give you about 25% of the 400 IU needed to prevent rickets and osteomalacia, not 25% of your daily need. And the NIH site does not mention that milk frequently contains less vitamin D than is listed on thelabel5.

More importantly, as the NIH site later points out, the government has never determined your daily need for vitamin D (Recommended Daily Allowance or RDA), only the Adequate Intake (AI) needed to prevent rickets and osteomalacia. A recent discovery by some of the biggest names in vitamin D research (Heaney, Davies, Chen, Holick and Barger-Lux) found humans utilize about 4,000 IU a day of vitamin D a day (if we can get it), not the 200 to 600 IU the government recommends. Whoops, off by a factor of ten6!

To the NIH’s credit, their site does not repeat the sunlight hysteria promulgated by the dermatologists. Instead, the NIH speaks to the importance of moderate and safe sun exposure. However, they give an outdated discussion of vitamin D and osteoporosis, a very brief and incomplete discussion of vitamin D and cancer but no discussion of vitamin D and heart disease, hypertension, autoimmune illness, osteoarthritis, diabetes or depression. Most disturbing, they say nothing about the importance of getting your calcidiol [25(OH)D] level checked.

NIH goes on to say, “Consuming too much vitamin D through diet alone is not likely unless you routinely consume large amounts of cod liver oil. It is much more likely to occur from high intakes of vitamin D in supplements.” Actually, to our knowledge, vitamin D toxicity in adults has never been reported from vitamin D supplements, unless an industrial manufacturing error occurred. Likewise, we are unaware of any case in the literature of vitamin D toxicity from cod liver oil in adults; vitamin A toxicity seems more likely. We challenge the NIH to support both assertions. Virtually all the vitamin D toxicity reported in the literature is iatrogenic (doctors using high doses to treat hypoparathyroidism or osteoporosis) and involves the synthetic vitamin D, ergocalciferol (not the natural form of vitamin D, cholecalciferol). The few verifiable cases of non-iatrogenic toxicity reported in the literature involve industrial accidents such as mistakenly using the industrial oil or concentrated industrial crystals in the kitchen7, 8.

The Vitamin D Council awards the National Institutes of Health a failing grade.

2. The Merck Manual website has two pages; the first is clinical use page. The site incorrectly says rickets is rare in the USA. More disturbing, we find no discussion of the myriad of diseases associated with vitamin D deficiency. There is no recommendation about treating routine vitamin D deficiency, nor are there recommendations for routinely obtaining calcidiol [25(OH)D] levels. We are glad to see the Merck manual’s calcidiol [25(OH)D] reference range [25 to 40 ng/ml (62.4 to 99.8 nmol/L)] for healthy persons is better than most of the sites we reviewed although their lower limit (25ng/ml) is lower than vitamin D scientists now recommend.

The second Merck Manual page is on toxicity. The site says, “Toxic effects have occurred in adults receiving 2500 μg (100,000 IU)/day for several months,” indicating, accurately, the relatively high amounts of daily vitamin D needed to cause toxicity. The Merck manual should be congratulated for independently looking at the toxicity research, instead of relying on the outdated and inaccurate toxicity warnings from the Institute of Medicine’s Food and Nutrition Board (FNB). (FNB says anything above 3,800 IU of vitamin D a day may cause toxicity although one can get 20,000 IU after a few minutes at the beach and most homo-sapiens have gotten at least 5,000 IU a day for 99% of the time they have been on the planet via sun-exposure)9.

Like the NIH, the Merck Manual misses the big point. Why did God (or Nature if you think like I do) design a system in which humans make 20,000 IU of vitamin D within minutes of summer sun exposure. Why did she arrange for such robust and rapid production of a substance (cholecalciferol) that the body will quickly turn into one of the most potent (if not the most potent) steroid hormones in the body (calcitriol or 1,25-dihydroxyvitamin D), a hormone that has endocrinological, paracrine and autocrine functions and, like all steroids, acts by damasking the genome? Is it wise to mess with Mother Nature by following the
recommendations of the American Academy of Dermatology and obsessively prevent every ray of sunlight from ever striking your unprotected skin10?

We were impressed with the Merck Manual’s accurate toxicity data and their range for calcidiol (although inaccurate, it is better than most). However, the complete lack of testing and treatment recommendation will leave the patient and the doctor with no idea what to do. The Vitamin D Council awards the Merck Manual website an unsatisfactory grade.

3. The third website is WebMD, the most highly trafficked commercial site on the web.

I could find no page about vitamin D on WebMD, but WebMD should be congratulated for some of the best recent reporting on the importance of vitamin D. Web MD cannot be held responsible for inaccurate statements being made by physician “experts” they quote. None of the quoted “experts” are vitamin D scientists.

Unfortunately, WebMD has no page (we could find) that discusses 25(OH)D levels, toxicity or any current clinical advice on what to do if you are vitamin D deficient. Overall, WebMD is unsatisfactory.

4. Next we looked at The Linus Pauling Institute at Oregon State University: http://lpi.oregonstate.edu/infocenter/vitamins/vitaminD/index.html
They have an excellent discussion of the physiology of vitamin D but state that 25(OH)D (calcidiol) is biologically inactive. Most vitamin D scientists disagree with that conclusion and recent research indicates calcidiol is an active steroid hormone11.The confirmation that calcidiol [25(OH)D] is biologically active has enormous scientific, medical and financial consequences (for those who own stock in vitamin D analogue companies) and will be discussed in detail in a future Newsletter.

The Linus Pauling Institute site then goes onto discuss many of the illnesses associated with vitamin D deficiency, with heart disease and hypertension the two most obvious omissions. They incorrectly state vitamin D toxicity has resulted from doses between 10,000 And 50,000 IU. I reiterate Reinhold Vieth’s challenge and ask the Linus Pauling Institute to produce any scientifically valid studies showing toxicity in doses below 40,000 IU a day. They are apparently unaware of Vieth’s classic work:http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10232622&dopt=Abstract

Most importantly, I could find no discussion of healthy 25(OH)D (calcidiol) levels, an egregious error for any site but especially important to a site like Linus Pauling that has listed most of the illnesses associated with vitamin D deficiency. Their recommendations for vitamin D intake to prevent vitamin D deficiency are totally deficient and will, in fact, guarantee vitamin D deficiency for anyone who avoids the sun and strictly follows their recommendations.

Overall, Linus Pauling Institute receives a failing grade.

5. Then we looked at Life Extension Foundation (LEF), a highly trafficked commercial site which sells supplements and prides itself on beating the medical establishment to the draw. For example, LEF recommended low dose aspirin ten years before the medical establishment12.

The Life Extension Foundation Magazine has recently ran two good articles on vitamin D, including an interview with Professor Michael Holick: http://www.lef.org/magazine/mag2003/apr2003_report_vitd_02.html

However, their protocols, medical abstracts and recommendations on vitamin D are either non-existant or inadequate. Overall, Life Extension is beating no one to the draw, they draw an unsatisfactory.

Last, we looked at the most popular “natural” site on the web, Dr. Mercola: http://www.mercola.com/index.htm

Here, if you do a search for “vitamin D,” some of the articles you find include:

Clearly the most informative, up-to-date and useful site we found. Dr. Mercola recommends testing, stresses the importance of the right test [25(OH)D] and suggests you be under a physician’s care should you be found vitamin D deficient.

Dr. Mercola gets an A. I just hope your physician is as knowledgeable.

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