Vitamin D myths and advice for patients

As the mountain of vitamin D research showing its importance grows to Everest heights, you may be wondering about some statements that are thrown around as “truth.”

Here are some fun vitamin D myths to pass along to friends, family and loved ones, because, when it comes to vitamin D, you want to get your dose (even of information) just right.

1. Just go out in the sun, already. That will fix everyone’s vitamin D levels. Right? Is it true that you can get enough vitamin D from the sun? Um, well, that depends on who “you” is.

For example, our media tends to assume we’re all Nicole Kidman pale — hence the widely cited recommendations that 10-15 minutes of daily sun can suffice. If you’re darkly pigmented (whatever your ethnic background), studies show that, if you live north of L.A., you would need to be out, at minimum, from November to May, fully naked, for two solid hours at midday to get enough vitamin D. Talk about a recommendation being far off the mark!

For many working, non-Nicole Kidman Americans, it would be actually physically impossible to get enough vitamin D, using the sun only.

2. Okay, I hear you, but I get a lot of sun — that should do it, right? See, the stinker is that you can get so much sun, you’re sunburned, and still not get enough vitamin D.

How exactly, is that? Vitamin D is blocked by sunscreen, by glass, by shade, by fog, and even by tall buildings. That means you can get sunburned through a car window and still make almost no vitamin D. In fact, once your skin begins burning, it starts to actually off-load and break down the vitamin D it just made. Even if you’re low.

3. Hey, isn’t sun bad for you? The interesting thing is that vitamin D, sun, and that worst of all skin cancers — melanoma — appear to be nastily snarled together in a three-way physiologic tug-of-war. What does that mean?

Turns out that low vitamin D levels are associated with increased risk of melanoma (even when you control for lifetime sun exposure), but that more sun (especially burns) means more risk of melanoma. All together, the paradox between vitamin D and melanoma may explain why sunscreens (which block vitamin D) have been shown, in several studies, to actually increase the risk of melanoma.

So what do you want for optimum health? Probably, to have a great blood level of vitamin D, and (if you’re Nicole Kidman-pale), as little sun as possible.

4. Just drink milk, already. All this talk of supplements is clearly a ruse to make money. Right? First, no one should be sucking down lots of full-fat milk — not for optimum health.

Second, even if you go the non-fat-milk approach, how many glasses of milk would a non-pregnant adult need to drink to get the generally acknowledged 1,000 units a day for vitamin D maintenance? Try 10 (count ‘em – 10!) glasses a day.

The amount of vitamin D put into milk was chosen so that small toddler-kiddies would not be overdosed on vitamin D. Unfortunately, lactose intolerance is also very real — and much more common among African Americans (estimated at 70%). Which means that, we, as a nation, chose to put vitamin D additives in the one place where the population that needs it most couldn’t get it.

5. So if my blood test is normal, that means I’m okay. Right? For all those of you who are staying up with your vitamin D checks, congratulations — you’re taking a simple, cheap and side-effect-free way to promote your health.

However, you may want to find out what “normal” means to your lab. Even your personal doctor may not be aware that almost all labs report “normal” based on the average (or median) of all that lab’s test results. With as many as 80-90% of African Americans vitamin D deficient, your lab’s “normal” may actually calculate out to “low.”

So what is “normal”? For one thing, it’s higher than almost all lab cut-offs. How do we know that? First, some studies looked at how high a human’s vitamin D level needed to be to block your body from sending out a distress-type hormone (called PTH). That blood level was way higher than a lab’s calculated “normal.”

Second, studies that looked at how high a vitamin D level needed to be to stop some of the problems of low vitamin D (like receding gums – yes – that’s a well-studied result of too-low a vitamin D), found that blood levels had to be much higher than a calculated lab’s “normal.”

Finally, researchers went to the source — when they checked the blood levels of equatorial agriculture workers in Third World countries (who still live the way almost all humans did only a few generations ago), they found, as you could predict, levels that are much higher than our labs’ “normal.”

6. Vitamin D prevents fractures by strengthening bones. Right? One of the best things about vitamin D is that it can reduce the number of fractures in the elderly. But what was a shocker to researchers was that it achieved this result, weirdly, by preventing falls from ever happening in the first place.

Vitamin D is crucial for normal muscle function, and when it gets really low, people can get something called a hip girdle sway — if you’re wondering what that looks like, imagine that slow, painful-looking, Frankensteinish, entire-leg-hip swing a frail elderly person in a wheeled walker does to take a step. Replacing vitamin D allows muscles to repair and function so that people actually don’t fall.

Bottom line? You can overdose on vitamin D. There are reasons, despite all the mountains of encouraging research, why no one, officially, has said how much every person should take every day.

The first reason is that no public official wants to step forward and be the one to say that, in order to be “normal,” vast numbers of Americans need to take a supplement … for life.

The second, better, reason is that we’re not all the same. Personalized vitamin D replacement and maintenance is the way to go. Get your blood level tested, get good advice on your result and replacement, then make sure it’s re-checked (and re-checked again) to verify you stay in a healthy range.

Jan Gurley is an internal medicine physician who blogs at Doc Gurley.

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  • http://tarl.net/tarl Tarl Neustaedter

    So….

    What *IS* the level of vitamin D a blood test should show? Or where can we find out what the healthy range is?

    All this article says is “whatever you thought your answer was, it’s wrong” without providing any useful information as to what it should be.

  • AnnR

    Great post!

    It’s a popular topic but not one you often get this much detail about.

  • Manalive

    I regard the new emphasis on vitamin D as a fad.
    It’s lab data in search of a disease.

  • greg zurbay

    If you search you tube for the sunshine vitamin video you will get a good idea how important D is, but the post is a very good heads up. My opinion is you are playing russian roulette if you ignore the present research ( which started to show up 10 years previous ). Health insurance companies will likely mandate D supplements to help keep health care costs down at some point.

  • Charles Cohn

    A couple of apropos comments on this article:

    1. The Life Extension Foundation recommends 50 ng/ml as a minimum healthy blood content for Vitamin D, which is much higher than most recommendations. (Life Extension Magazine, January 2010, page 9)

    2. A recent MedPageToday article found that most of the OTC Vitamin D supplements they tested were seriously short of their advertised potencies.

    Charles Cohn
    6311 Mark Trail, Austell, GA 30168 770-944-7510
    “Live forever or die trying”

  • http://minochahealth.typepad.com/ doc

    Vitamin D deficiency is unquestionably a growing epidemic even among so called healthy individuals. http://bit.ly/bm7QqR
    However, patients hear variable interpretations of their “normal tests” from their health care providers as well as from the labs running those tests. Even this very informative article by Dr. Gurley does not provide specifics, probably because there are so many unknowns that remain unanswered.

  • johnlinz

    Regular sun tanning machines can produce up to 20,000 IUs of vitamin D in a single visit. Maybe one day they will be called the health machine.