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The Vitamin D Newsletter January 2006

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Questions and Answers

Vitamin D Dosage

How much vitamin D should I take?

Before I answer, I have a few questions for you:

  • Where do you live (latitude)?
  • How much do you weigh?
  • What skin type do you have?
  • How much do you go into the sun?
  • What is your 25(OH)D level?
  • During what season of the year was it obtained?
  • How much do you get in your diet?
  • How much do you get in supplements?

You see, the answer is different for everyone. The question also assumes we know the ideal vitamin D blood level. We don't know for sure—around 50 ng/mL is the best current guess.

However, an easy answer is: 2,000 units a day. Life Extension Foundation sells an inexpensive pharmaceutical grade of vitamin D. Two-hundred and fifty of the 1,000 unit capsules cost about $10. Your local health food store should also carry 1,000 unit capsules. Just be sure they don't contain any vitamin A. Beta-carotene is okay, but pre-formed retinols (vitamin A) interfere with vitamin D's function. I do not advise cod liver oil; if you just have to take it, don't take more than 1 teaspoon per day. Get your omega-3s from molecularly distilled fish body oils (Trader Joe's) or by eating wild salmon or sardines. Get your vitamin D by taking vitamin D or by going into the sun, or by combining both. Rohde CM, Manatt M, Clagett-Dame M, DeLuca HF. Vitamin A antagonizes the action of vitamin D in rats. J Nutr. 1999 Dec;129(12):2246–50. Johansson S, Melhus H. Vitamin A antagonizes calcium response to vitamin D in man. J Bone Miner Res. 2001 Oct;16(10):1899–905. Rohde CM, DeLuca HF.All-trans retinoic acid antagonizes the action of calciferol and its active metabolite, 1,25-dihydroxycholecalciferol, in rats. J Nutr. 2005 Jul;135(7):1647–52.

The government says 2,000 units of vitamin D a day is safe for all adults to take without a doctors supervision. Two thousand units a day will get about 80% of Americans to a vitamin D level of 35 ng/mL or higher with no risk of toxicity. The 20% still lower than that would most likely be blacks. Heaney RP. The Vitamin D requirement in health and disease. J Steroid Biochem Mol Biol. 2005 Oct;97(1–2):13–9.

For now, if you take more than 2,000 units a day, you should do so either because you are under the care of a health care practitioner who is knowledgeable in regards to vitamin D (unfortunately, there are few of them), or because you know what you are doing. I personally take no vitamin D in the late spring, summer, or early fall because I frequently go into the sun. I take 5,000 units a day in the winter but I know what my vitamin D level is because I get it checked several times a year. If I had cancer, heart disease, Alzheimers disease, multiple sclerosis, or a hundred other common diseases, I might take more than 5,000 units a day—but I would check my calcium and vitamin D levels even more often. I would also follow my doctor's advice about standard medical treatment.

Keep in mind that if you use a sunlamp or a tanning parlor once a week during the winter, you don't have to worry about blood tests because your body will maintain adequate vitamin D blood levels. Just don't get burned.

Also, remember to take calcium tablets if you don't get adequate amounts of calcium in your diet—and most people don't. Trader Joe's sells a good Calcium/Magnesium/Zinc combination product for next to nothing.

Vitamin D Blood Test

What blood test should I have?

The only blood test that can determine vitamin D adequacy is a 25-hydroxyvitamin D test. Whenever I say "vitamin D level" I am talking about a 25-hydroxyvitamin D. Ask your doctor to order a 25-hydroxyvitamin D blood test.

Unfortunately, many doctors order an "activated vitamin D level," thinking it better to measure the most active form of vitamin D. It is not. Activated vitamin D, also known as 1,25 dihydroxyvitamin D or calcitriol, should never be obtained to determine vitamin D sufficiency. Calcitriol is often elevated in vitamin D deficiency. You cannot tell anything about your vitamin D nutrition by measuring a calcitriol level. If your doctor insists on ordering a calcitriol level to determine your vitamin D nutrition, find another doctor.

However, serious problems do exist with the technology used by some laboratories to measure vitamin D levels. Different labs will report different results when given the exact same specimen of blood. Furthermore, the same lab often reports significantly different numbers when sent the same specimen of blood at different times. In general, low numbers are more reliable than high numbers because interfering substances can easily give falsely elevated results. Prominent scientists have issued urgent calls for standardization. Dr. Graham Carter, one of my personal heroes, has dedicated his life to obtaining a standardized, and accurate, vitamin D level. His outfit in London is DEQAS, or Vitamin D External Quality Assessment Scheme. Call your reference lab and insist they participate in DEQAS. DEQAS's phone number in England is +44.(0)20.8383.3645. Binkley N, Krueger D, Cowgill CS, Plum L, Lake E, Hansen KE, DeLuca HF, Drezner MK. Assay variation confounds the diagnosis of hypovitaminosis D: a call for standardization. J Clin Endocrinol Metab. 2004 Jul;89(7):3152–7. Hollis BW. Editorial: The determination of circulating 25-hydroxyvitamin D: no easy task. J Clin Endocrinol Metab. 2004 Jul;89(7):3149–51.

If you take ergocalciferol, or "vegetarian vitamin D", be warned. Ergocalciferol is not vitamin D, but a vitamin D-like patent drug whose patent has expired. It does not normally occur in the human body and is probably a weak agonist at the receptor site, meaning it may actually partially block vitamin D actions. Ergocalciferol is the villain in most of the reported cases of toxicity in the world's literature. All bets are off in terms of measuring blood levels if you take ergocalciferol. Some of the labs can pick it up and some cannot. Do not take ergocalciferol—it is not vitamin D.

If your doctor prescribes 50,000 units of ergocalciferol (Drisdol) once or twice a week, obtain a bottle of 50,000 unit capsules of cholecalciferol and take them instead. Take one or two per week until your level is around 50 ng/mL. Then stop taking them and begin maintenance therapy at a much lower dose. You could also take one 5,000 unit capsule every day until your vitamin D level is around 50 ng/mL. Then take enough by mouth during the cold months (and go into the sun during the warm months) to keep your 25(OH)D level around 50 ng/mL. (Keep in mind that labs inside the USA usually report results in ng/mL while labs outside the USA use nM/L. One ng/mL is equal to 2.56 nM/L. So 50 ng/mL is about 125 nM/L.)

Take enough real vitamin D3 cholecalciferol to maintain your level around 50 ng/mL, year-round. A 25(OH)D level is the best, and only, way you have of knowing if you are taking enough. However, do not be satisfied with a 50 ng/mL level unless you know how you are getting enough vitamin D to explain the level (i.e., you go into the sun or take supplements). If your level is 50 ng/mL and you don't take supplements, don't go into the sun, don't use a sun booth or a UVB lamp, then the level is probably bogus. Repeat the level.

In general, keep your vitamin D level in the upper one third of the lab's reference range—about 50 ng/mL with the most commonly used test. If you take higher doses, get your calcium checked when you get your 25(OH)D level, just to be safe. If you want to be sure that your hospital is sending their samples to an accurate reference lab, ask the director of the hospital's lab to contact Professor Bruce Hollis or Professor Reinhold Vieth. Both are world-class authorities in vitamin D measurement technology.

Although 1,25-dihydroxyvitamin D (calcitriol) should never be used to diagnose vitamin D deficiency, calcitriol is important in evaluating one cause of high blood calcium, called vitamin D hypersensitivity. High blood calcium rarely occurs due to vitamin D toxicity, but calcium is elevated in people who have vitamin D hypersensitivity, although their vitamin D level will be normal, or even low. Primary hyperparathyroidism is a common cause of vitamin D hypersensitivity, as is sarcoidosis and other granulomatous diseases. It can occasional occur in cancer—about 20% of patients with non-Hodgkin's lymphoma have vitamin D hypersensitivity. Any competent endocrinologist can treat vitamin D hypersensitivity.

Effects of Higher Doses

If humans make 20,000 units of vitamin D after sunbathing for 20 minutes in the summer, why shouldn't I take 20,000 units every day?

Because of what we don't know we don't know. Someone once said all knowledge comes in three categories: (1) what you know you know, (2) what you know you don't know, and (3), the largest category, what you don't know you don't know. I know I know how to speak English; I know I don't know how to speak French; I don't know that I don't know how to speak a language that I don't know exists.

We simply don't know the effects of taking 10,000 or 20,000 units a day for year after year. Although light-skinned humans make about 50,000 of units of vitamin D after getting a sunburn (3 times the minimal erythemal dose), we also know they make progressively less and less vitamin D as their skin produces more and more melanin, thereby tanning. My 16-year-old daughter has noticed that she tans much faster when she has been taking oral vitamin D. That is, high blood levels may tell the skin to make more sunblock (melanin). Undoubtedly, other natural mechanisms exist to prevent toxicity, we just don't know. We do know that when healthy young men took 50,000 units of vitamin D every day for six weeks, average serum blood levels increased by 257 ng/mL. One young man achieved an increase of 400 ng/mL after only six weeks. Although the authors found no evidence of toxicity after this six-week experiment (serum calcium remained normal), 50,000 units a day will eventually turn your internal organs into limestone. Adams JS, Clemens TL, Parrish JA, Holick MF. Vitamin-D synthesis and metabolism after ultraviolet irradiation of normal and vitamin-D-deficient subjects. N Engl J Med. 1982 Mar 25;306(12):722–5. Barger-Lux MJ, Heaney RP, Dowell S, Chen TC, Holick MF. Vitamin D and its major metabolites: serum levels after graded oral dosing in healthy men. Osteoporos Int. 1998;8(3):222–30.

Vitamin D's Future

Where do you predict all this vitamin D research is heading?

I predict the final Food and Nutrition Board's recommendation (in about two decades) will be about 3,000 units a day. I predict that science will eventually show vitamin D deficiency is a major cause of many of the diseases of civilization. I predict that science will eventually show that many of these same diseases of civilization respond favorably to vitamin D treatment. I predict science will eventually prove vitamin D helps prevent and treat some infectious diseases, especially viral respiratory infections like influenza, croup, and the common cold. These are only my attempts to prophesize the future. Remember, only time can tell the difference between a prophet and a madman.

Vitamin D Council

Why don't you answer all your emails promptly?

I do my best. As the circulation of the newsletter grows and the popularity of the website increases, I am inundated with questions. My answer is that I do my best. During the day I work full-time to support my family. I write, and attempt to distribute the newsletter, on the weekends and evenings. If you don't get the newsletter, your server is either blocking the mailing or stripping it of its content so you get a blank e-mail. Be sure [email protected] is on your allowed list.

I can't provide personal medical advice. I can't e-mail you copyrighted material. If you have prostate cancer, lung cancer, or any type of cancer, you should take enough vitamin D so you are no longer vitamin D deficient (2,000–5,000 units a day, enough to get your vitamin D level around 50 ng/mL and keep it there). If you have MS, the same is true. If I ever got the flu, I would take one 50,000 capsule of vitamin D as a single dose—although you should know that not one scientific study exists to support such a decision. Full-spectrum lighting has virtually no UVB so it will not generate any vitamin D in your skin.

I try to alert you to all the important studies, but I miss a few. For example, a recent study showed children with low vitamin D levels are eleven times more likely to get lung infections! Another recent study showed vitamin D deficiency is a major risk factor for stroke. I spend a fair amount of time learning about vitamin D and I hope I know what I am talking about. Readers can answer most of their own questions by spending time on this website as well as reading our newsletter archives. Please feel free to read about our organization or myself. We also provide an extensive viamin D links section.

Where does the Vitamin D Council get its funding and what do you do with all the money?

We don't have any funding. We try to save the little money we have. Unfortunately, the Kettering Family Foundation just turned down our $100,000 grant request. I hoped they would fund us as they generously funded me in the late 1980s when I attempted (unsuccessfully) to reform testing in Americas public schools. Currently we operate on private donations from readers and a $5,000.00 donation that my wife and I made to the Vitamin D Council last year. The first thing we will do when we get funding is to sponsor a yearly seminar on vitamin D geared towards both health care practitioners and interested lay people. We will ask vitamin D experts from around the country to speak in plain language about practical aspects of vitamin D nutrition. If you know anyone who knows anyone with grant money please ask them to contact us. I have no doubt that God will provide, should we be doing something worthwhile.

What can I do to help?

We need funding of course, so any donations are appreciated. We also need someone who is fluent in German and can translate German medical papers into English. Email me if you are fluent in medical German and are willing to help.

Remember, we are a non-profit and rely on your donations to publish our newsletter, maintain our website, and pursue our objectives. Send your tax-deductible contributions to:

  • The Vitamin D Council
  • 1241 Johnson Ave. #134
  • San Luis Obispo, California, United States, 93401

John Jacob Cannell MD Executive Director

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.