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Newsletter: Test your knowledge

Posted on: August 20, 2005   by  John Cannell, MD


This month we have a ten question quiz on the latest vitamin D research. Here’s a primer.

Question: Name a rat poison crucial to health and safer than water.

Answer: Vitamin D

Yes, cholecalciferol is a rat poison1, 2. If it’s a rat poison, why did Professor Heaney just recommend up to 4,000 units every day?

Heaney RP. The vitamin D requirement in health and disease. J Steroid Biochem Mol Biol. 2005.

The answer is dosage. To demonstrate the point, I recently swallowed an entire bottle (100 capsules) of vitamin D (40,000 units) in front of a skeptical audience to convince them that vitamin D is safer than water. Here’s why. Eight glasses of water a day is fine for healthy adults. Ten times that amount, eighty glasses of water, will make you sick from water intoxication.

Humans need about 4,000 units of vitamin D a day (from all sources). Ten times that amount, 40,000 units, is very safe in a single dose, as I demonstrated to the audience. Therefore, vitamin D has a safer therapeutic index than water.

(Taking the entire bottle certainly got the audience’s attention. I think they were paying close attention to see if I would drop dead. By the way, if you were to take 40,000 units every day for months you would get vitamin D toxicity, after years of such doses you would probably die. After taking 40,000 units at one time – equivalent to two days at the beach – I simply stayed out of the sun for several days.)

A rat poison safer than water – but why do we need vitamin D? Within the last several months, scientists published impressive new evidence that vitamin D is involved in a staggering array of diseases: age related cognitive decline, heart disease, breast cancer, tuberculosis, Parkinson’s disease, prostate cancer, chronic pain, fractured hips, premenstrual syndrome and diabetes.

Good time for another quiz.

1. Vitamin D reverses inflammatory changes associated with age-related memory impairment.

A. True
B. False

True. Researchers from Ireland were the first to demonstrate that vitamin D3 acts as an antiinflammatory agent and turns old brains into young brains – at least as far as inflammatory cytokines are concerned. This research suggests vitamin D may prevent, or even treat, age related cognitive decline3!

2. Your blood sugar is closely associated with your vitamin D level.

A. True
B. False

True. Researchers in Australia added to the growing evidence that sun avoidance may have caused the epidemic of type 2 diabetes. The Australians’ findings were straightforward and powerful. The higher your vitamin D level, the lower your blood glucose4.

3. In July, a group from Minnesota found that 100% of elderly patients admitted for fragility fractures were vitamin D deficient despite the fact that half of them were taking vitamin D supplements.

A. True
B. False

True. The authors found that women taking supplemental vitamin D had average levels of 16.4 ng/ml while women not taking supplements had levels of 11.9.ng/ml, both dangerously low. None of the 82 women got enough sun or took enough vitamin D to obtain a level of 40 ng/ml. These were fragility fractures, not fractures caused by unusual trauma. That is, their bones just sort of fell apart5.

4. Women with the lowest vitamin D levels had five times higher risk for breast cancer.

A. True
B. False

True. Women with 25(OH)-vitamin D blood levels less than 20 ng/ml were more than five times more likely to be diagnosed with breast cancer than were women with levels above 60 ng/ml. That is five, repeat five, times less likely6!

5. Avoiding the sun doubles the risk of prostate cancer.

A. True
B. False

True. Again, the risk of avoiding the sun is clear, this time in another study with prostate cancer. However, the authors pointed out that sun exposure increases the risk of skin cancer and believed that proper vitamin D supplementation ”may be the safest solution to achieve an adequate vitamin D status7.”

I also believe supplementation is the only way to go for many people. African Americans are simply unable spend adequate time in the sun. In addition, the sun ages the skin and that fact alone will keep many Americans out of the sun. That said, I go into the sun whenever I can. The reason is simple: it is the most conservative thing to do. Until we know everything the sun does – and it does more than just make vitamin D – the conservative approach is to mimic our ancestors and the environment in which human evolved, whenever we can. Therefore, it makes sense to sunbathe sensibly in the late spring, summer, and early fall and take supplements or use UVB lamps the rest of the time.

6. South Korean researchers associated vitamin D deficiency with Parkinson’s Disease.

A. True
B. False

True. Actually, they showed that certain genetic malformations (VDR polymorphisms) are more likely in-patients with Parkinson’s Disease, implying an association with vitamin D and Parkinsonism8.

7. Researchers in England discovered that patients with chronic pain have phenomenally low vitamin D levels.

B. False

True. The authors added to the evidence that severe vitamin D deficiency is associated with chronic pain. They found that 88% of their patients with chronic pain had levels less than 10 ng/ml. If they treated their patients, they did not report it. However, Swiss researchers recently treated chronic pain patients with vitamin D and reported the pain “disappeared” within one to three months in most of their patients. This is the second open study that showed adequate doses of vitamin D dramatically improve chronic pain9, 10, 11.

8. Severe vitamin D deficiency is common in TB patients. Some English doctors don’t the difference between ideal and “normal” levels. Most American doctors don’t know the difference either.

A. All are true
B. All are false
C. Some are true and some are false

All are true. First, the authors reviewed the impressive animal evidence that vitamin D can help treat TB. Then they reported that most of their immigrant TB patients had undetectable vitamin D levels. Then they reported the normal range for their lab was between 5 to 47 ng/ml but “normal” was any level greater than 9 ng/ml. Finally, the researchers reported they treated their patients with “normal daily doses” of vitamin D, without reporting how much they gave. Apparently, they gave just enough to get patients above 9 ng/ml12.

Keep in mind that different laboratory technique result in different ranges for 25(OH)-vitamin D levels. Now matter what technique is used, ideal levels can roughly be defined as any level above the median. In this case, as you will see below in Dr. Heaney’s article, the doctors should have treated their patients with 4,000 units a day. They should also watch for evidence of vitamin D hypersensitivity, which can occur when treating tuberculosis patients for vitamin D deficiency.

We can only mourn for the poor immigrants who have to suffer from both TB and vitamin D deficiency. Of course, few physicians in the USA know the difference between the Gaussian definition of “normal” (average ranges for the population tested) and the ideal definition of “normal” (levels above 32 ng/ml). Getting commercial reference labs to report ideal 25(OH)-vitamin D levels should be a priority of everyone involved in trying to end the epidemic of vitamin D deficiency.

9. Virtually all nephrologists give renal failure patients a vitamin D-like drug. Virtually all renal failure patients are severely vitamin D deficient. Some nephrologists know the difference between vitamin D and calcitriol.

A. All are true
B. All are false
C. Some are true and some are false.

All are true. Finally, the truth about renal failure patients: most of them are vitamin D deficient despite taking vitamin D analogs! Most nephrologists prescribe activated vitamin D (calcitriol) or vitamin D analogs but not vitamin D.  Calcitriol and vitamin D analogs do nothing to prevent vitamin D deficiency. Renal failure patients need both vitamin D and a calcitriol-like drug. Moreover, 400 units a day of vitamin D will not correct their deficiencies. As you will see below, they need up to 4,00013.

P.S. If you think nephrologists know the difference between vitamin D and calcitriol, read this months paper from some nephrologists at the University of Texas. They discuss the importance of vitamin D in preventing and treating heart disease. (I think adequate vitamin D nutrition may prevent more cardiovascular deaths than cancer deaths.) However, I read the Texas paper three times and still don’t know if the authors know the difference between vitamin D and calcitriol. I hope they know the difference between cholesterol and testosterone. (Some cholesterol is metabolized into steroid hormones, vitamin D is a prehormone; testosterone is a steroid hormone, calcitriol is the most potent steroid hormone in the human body)14.

10. Professor Robert Heaney proved, again, that he is a gentleman and a scholar.

A. True
B. False

True. In the most important clinical paper published this month, Heaney gave the three best reasons why we should all maintain minimum levels of at least 32 ng/ml, the level that:

  • effectively suppresses PTH,
  • maximizes calcium absorption,
  • maximally improves glucose tolerance.

Then he goes on to show that some of us, especially African Americans, will need to take 3,000 to 4,000 units every day to maintain healthy 25(OH)-vitamin D blood levels15.

He then defends the Institute of Medicine’s (IOM) recommendation that we only take one-tenth that amount as the best science that was available in 1997. I admire Dr. Heaney for trying to cover for the IOM. The truth is that both Dr. Heaney and Dr. Holick told the IOM that 2,000 units a day was not toxic and would prevent both adequate treatment and meaningful research. The IOM then proceeded to ignore the only two vitamin D experts on the panel.

Writing two years later, Professor Reinhold Vieth came up with dozens of studies the IOM overlooked. These studies conclusively showed 2,000 units a day could not be toxic. Furthermore, Vieth found the literature published before 1997 clearly showed 10,000 units a day was unlikely to be toxic. Vitamin D toxicity probably starts around 20,000 units a day, and then only if taken for months or even years16.

Imagine. A rat poison safer than water and crucial to health.

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