The truth about vitamin D

Is the idea that everyone needs more of it justified?


Shattered Infinity/Flickr

The Statement: “If your skin is super pale, you’re already well aware of your must-have items: sunscreen with a high SPF, and a hat (for shade). But a new study suggests you might also need some vitamin D supplements.” Huffington Post, 10/04/2011

The claim about vitamin D making the rounds right now is that pale people should top up on the supplement du jour because they may not get enough from the sun. Doctors already prescribe it for various reasons, from preventing falls among the elderly to easing chronic pain and boosting levels of the vitamin—produced in the skin after sunlight exposure—in anyone living in a cloudy climate.

Testing of vitamin D levels is now widespread, as is the idea that everyone needs more of the stuff. At last count, the Nutrition Business Journal reported that sales of vitamin D in the U.S. made the leap from $40 million in 2001 to $425 million in 2009. But is this notion that vitamin D should be a fixture in most medicine cabinets justified?

According to Dr. Clifford Rosen, an osteoporosis expert at the Maine Medical Center Research Institute and one of the world’s leading experts on vitamin D, the obsession with checking levels in the blood started about a decade ago and “now won’t stop.” In the U.S., Medicare payments to cover vitamin D testing went from about $1 million a decade ago to $129 million in 2008. “It’s the most overused test in clinical medicine,” Dr. Rosen said. “Patients with bone disease or gastrointestinal disorders should be checked but it should never be part of the routine examination.”

In fact, the evidence shows taking extra vitamin D doesn’t help for a number of conditions for which it’s prescribed, most people get enough, and over-use may actually be harmful.

Let’s begin with a popular claim: that chronic pain can be alleviated with vitamin D supplements. Dr. Sebastian Straube, physician-scientist at the University Medical Center Göttingen, led a Cochrane review on the subject.After analyzing only studies of high methodological quality (randomized double-blind trials) the supposed link between vitamin D deficiency and chronic pain fell apart.

“As far as treatment studies are concerned,” he said, “we found a striking contrast in study outcome between randomized double-blind trials that by virtue of their study design minimize bias and other (non-double blind) studies that are more prone to bias. The latter largely do suggest a beneficial effect of vitamin D treatment, the former largely don’t.” (See here for more detail.) Furthermore, “We did not think the evidence in this area was of sufficient quality to guide clinical practice. There is a need for more and better studies in the future.”

And what about all those folks who burn easily or avoid the sun and may need to gobble down vitamin D, as the HuffPo suggests? According to Dr. Rosen, “The only reason pale people may need more vitamin D is that they are not in the sun in part due to concerns about melanoma. Solar exposure accounts for 60 per cent or so of the serum vitamin D level. But even casual exposure to sun for about 10 minutes per day can generate enough of the vitamin for some people.” And you also get the vitamin through your diet, particularly in foods such as fatty fish (salmon, tuna), cod-liver oil, and eggs.

Dr. Rosen was part of a 14-member expert committee brought together by the nonprofit scientific body the Institute of Medicine at the request of the United States and Canadian governments to determine whether people were getting the right amount of vitamin D and calcium. They concluded—based on an examination of some 1,000 publications and studies on the subject—that most North Americans had adequate amounts of vitamin D in their systems from their diets and exposure to the sun.

As for those who have been identified as at-risk for vitamin D deficiency, Dr. Rosen said these groups include melanoma patients, people who can’t absorb the vitamin (as a result of inflammatory bowel disease or liver disease, for example), some African Americans due to the dark pigmentation of the skin, people on anti-convulsants, and elders who are institutionalized. More broadly, the Canadian Cancer Society guidelines on vitamin D suggest, “You’re probably not getting enough vitamin D if you: are over 50, have dark skin, don’t go outside very much, wear clothing covering most of your skin.”

But even those who are at-risk should remember: more is not necessarily better. “The level of vitamin D needed for optimal function in many tissues is not yet defined,” according to JAMA. The Canadian Cancer Society says the most common side effect of too much vitamin D is high calcium levels, or hypercalcemia, which can cause nausea, vomiting and poor appetite.

“There may be risks with high doses,” cautioned Dr. Rosen. “It does good for reducing fractures in osteoporotic individuals, but for chronic pain, autism, multiple sclerosis, the flu—there’s no evidence vitamin D is effective.” Still, the sunshine supplement continues to fly off the shelves.

*Thank you to reader Fotis Xipolitakis for requesting a post on vitamin D. He wrote, “Health Canada recommends that most people have no need to take supplements but everybody’s doctor is saying it will do no harm so why not, it can’t hurt. My beef with this that it leads to a culture of supplementation bringing with it costs for supplements, false ideas, and potential self-medication.”

Science-ish is a joint project of Maclean’s, The Medical Post, and the McMaster Health Forum. Julia Belluz is the associate editor at The Medical Post. Got a tip? Seen something that’s Science-ish? Message her at or on Twitter @juliaoftoronto


The truth about vitamin D

  1. Personally, I take this stuff, but only in winter. This is mostly because I spend fewer than 10 minutes a day outdoors in winter (will go days on end without leaving the house, sometimes). I (and others) have noticed an observable pickup in my mood during the otherwise dreary winter months. I would be “pale skinned” too, but I think I get out enough in summer. I’d also heard you can easily take fatal doses of Vitamin D, but I’ve since been told this is pretty much impossible.

  2. I have taken vitamin/mineral supplements regularly since the 1970s. My stance has been a rather cautious one in that I have avoided mega-potencies. I usually take a bit less than the manufacturer recommends. I normally alternate by taking some pills one day, others the next, or only taking 1/2 tablet etc. Taking them all on the same day seems overkill, since I think I am eating well.

    Nevertheless, I have noticed that the potencies of even the regular strengths have steadily climbed over the years, giving me pause to reassess my supplementation regime, particularly in light of two recent studies, one about high potency vitamin E increasing the risk of prostate cancer, and another about fish oil/omega 3 actually accelerating ageing, due to its readiness to oxidize. I was taking 400 IU of vitamin E every other day, which I thought was relatively conservative, since the majority of the vitamin E on the market is 800 IU. It turns out that 400 IU is still 1300% of the recommended daily allowance! I am going to be much more attentive to the RDA in the future.

  3. What about us northern-latitude Canucks?  We’re scared of the skin cancer in the summer, and the sun disappears on us anyways in the winter.  Many darker-skinned new Canadians also dress so wrapped up, even in summer, that there isn’t a whole lot of UV getting through.

    So yeah, I am more than comfy with 1000 IU per day when I think of it (that would be 3, maybe 4 times a week).  It is actually quite hard to take sooooo much that you’ve got hypercalcemia to contend with.

  4. I take low-dose Vitamin D simply because I avoid sun exposure. But I am very skeptical of the claims and hype surrounding this particular supplement at the moment, especially all the talk about Vitamin D preventing cancer. Also interesting that a study was released yesterday showing that men who take Vitamin E supplements are more at risk of developing prostate cancer than those who don’t. We tend to overlook the fact that supplements can be harmful, especially mega-doses.

  5. The double blind studies are designed to fail; what fool would consider 800, or even 1200 i.u., sufficient vitamin D?

    How about at least 5000 i.u. per day?

    Vitamin D supplementation works- providing one reaches repeltion levels (50-80 ng/ml, 25 OH).

    What current vitamin D supplement taker in this range would EVER stop taking it?

    Not one in a trillion.

    Vitamin D, actually the body’s most potent steroid hormone, is an absolute requirement for health. It controls cell function, prevents bacterial and viral infection, and reduces telomeric aging.

    Stop this absurd preoccupation with minute amounts, recognize the body will make up to 20,000 i.u. per day in sunlight, and recalculate research accordingly.

    The only people I know who suffer early onset chronic disease are those who avoid the sun.

    Skin cancer?

    More people die from accidental drowning than from squamous cell carcinoma.

    Melanoma rates have risen ONLY in the demographic of indoor workers and those who habitually wear sunscreens- look it up!

    Flu infection is determined by blood levels (or lack thereof) of vitamin D. It is therefor a choice as to whether you allow yourself to be vulnerable to such viruses.



    • You were doing so well until the last flu bit.  Flu infection is determined by (1) lack of immunity to the (2) strain of virus you just rubbed into your eyeball / inhaled / shook hands with.

    • Melanoma rates have risen with the popularity of outdoor activities, cheap vacation packages, skimpy clothing, and indoor tanning. UV exposure causes skin cancer, not lack of Vitamin D. That’s why Australia has the world’s highest skin cancer rates.

      • Have you ever heard of the expression “correlation does not imply causation”.  Melanoma rates have risen with toxic-chemical containing sunscreens.  To suggest that our population of fat, video-game playing, tv-watching, drive everywhere service industry workers spends more time outside in the course of a year than we did 50 or 100 years ago is, well, just plain ignorant. 

        Not so long ago, the majority of our population worked outside on a daily basis, and they didn’t get skin cancer.

        • James: I think the key point is we only need about 15 min per day of sunlight on our arms and face to get all the sunlight we need for nutrition purposes. I am including a link to an interview with Dr. Michael Hollick on his book “The UV Advantage” . If you search on the word “melanoma” you will see his views on this point.  

        • That’s a lovely theory, but it’s wrong. UV rays are a known human carcinogen. One hundred years ago, people didn’t spend all day at the beach in a bikini. They wore heavier clothing, even if they worked outdoors. Tans were considered ugly. There’s no evidence that chemicals in sunscreen cause skin cancer. The Canadian Cancer Society, the American Academy of Dermatology, and Canadian Dermatology Association have all released statements to that effect. I tend to trust their review of the literature over yours.

          • The Canadian Cancer Society and the other organizations you cite are far more concerned with putting processed crap in pink boxes and staying employed than they are in finding cures for anything, but you keep on believin’.

          • What a fascinating world view you have. Have fun at your conspiracy of the week club.

        • coming from a farm family…you may have heard of the farmers tan…hats worn far down over the face meant only the lower portion was tanned and other than your hands , no other part of your body got sun…..interesting to go to a wedding in late summer and see the men and women with white faces from below the eyes and dark dark tans below that…we would have sweat running down our backs and legs…but we didnt uncover because of the insects and working with dust and dirt etc etc

  6. I think there is a good deal of research that disagrees with Dr. Rosen.  Most reports say that we need 4000 IU or more of Vitamin D to keep or serum levels high enough to make a difference. Here are some references:
    Doctors Health Press 1 –
    Doctors Health Press 2 –
    UC San Diego –
    UCLA –

  7. Another lame attempt by the sickness industry to demonize vitamins. 

    Just thirty minutes in the sun in a bathing suit produces 10,000 IU of Vit D, and now they’re trying to tell me that I shouldn’t take the higher dose supplements?  The reason people get sick in the winter is mainly because they don’t get any Vit D from the sun.  This is just common sense.  I take a minimum of 3000 IU a day in the winter.

    As for skin cancer, the crap you put on your skin to prevent it, coupled with the associated blocking of Vit D. production is what causes that.  I haven’t used sunscreen once in the last several years, and I have worked many full days in the sun without a shirt.  In addition to my normal diet of fresh veggies from my garden, no GMOs and organic meat and eggs from the local market, I eat a full watermelon a week during the summer, which (at that rate of intake) massively reduces your propensity to sunburn.  I have blue eyes and fair skin.

    Almost 100, 000 Americans die every year from prescription drugs.  How many people died from Vitamins (and mineral and herbal supplements) in the US in 2009?  That would be ZERO.  Vitamins do not hurt you. Why this is such a leap for people to believe is frustrating beyond belief.

    • James: The drug companies cannot make a dime from Vitamin D so it does not get the publicity it deserves.  Every doctor should be asking his/her patients about their intake of Vitamin D but they don’t because they don’t know about it.  Meanwhile their mail box is full of promotional material from the Drug Companies.

      • In the US: annual vitamin D sales: $425 million in 2009.  Testing for vitamin D levels: $129 million annually.  (Both figures from this article)

        Yeah, sure there’s no money in Vitamin D.  It’s always amusing when the supplement lobby acts as if their billion-dollar industry is just a few kindly grandmothers hand-squeezing vitamins from wholesome organic vegetables to distribute out of the goodness of their hearts.  “Be sure to take your Nana’s Olde-timey Vitamin D (tm*), sweetie.”

        And this, James? “The reason people get sick in the winter is mainly because they don’t get any Vit D from the sun.  This is just common sense.”  That’s not common sense… that’s fantasy, without solid evidence.  Even if Vitamin D supplementation is beneficial – and I’m quite willing to be convinced it is – that doesn’t lead logically to “this is the main reason for winter illness”.

        * “Nana’s Olde-timey Vitamin D” is a registered trademark of Nanacorp.  May not contain Vitamin D.  No health benefits are claimed, for amusement use only.

    • If you worked in the field of pharmaceuticals you would know that herbal supplement are NOT tested. Why?? well let’s just say that it is a loosely controlled product and there is much more to that.
      I am not going into the details of biochemistry here…you would need some chemistry knowledge to understand it; all I can say here is that vitamins in excess DO cause diseases and well… then you can die and no one will say that vitamins killed you because vitamins caused the disease and actually the disease killed you. In this sense vitamins play an INDIRECT role, causing a negative outcome.

  8. I’m nearly 70 and have never been sick, and I attribute this to the fact that I’ve been taking supplements (Calcium, magnesium, vitamin D, vitamin C, Omega-3, glucosamine sulfate) in large doses for several decades.

  9. 4 mths ago doctor (kidney spec.) put me on vitamins D and told me to keep taking the drugstore D
    400 IU as well.  Pharmasist told me not to take my D anymore as it would be too much.  Go to specalist yesterday, and he told me to start taking D @ 1000 IU as well as prescription D. Im confused. Im type 2 diabetes taking insulin.  Who to believe?

  10. It is likely that behind every study and report is corporate money in the form of research grants or other financial assistance. That maybe why there are so many opposite recommendations that “more is good” and many that “less is good”.
    The result is that no one knows for sure, not even your doctor. You have to decide who and what to believe, pay your money and take your chances.

  11. The fact that this is sponsored by McMaster Health and Medical Post makes this sound like medical advice. We live in Canada, some of us north of the 49th parallel (at least those who do not live in Toronto) and cannot get vitamin D from the sun, from Sept to March due to the sun’s angle through the atmosphere. Ask any doctor here for a vitamin D test and they will respond, why test, everybody has low levels of vitamin D in Canada. As for the other 30% they say you get from diet, I don’t see that the majority of people eat large amounts of  “foods such as fatty fish (salmon, tuna), cod-liver oil, and eggs.”  And what is too much vitamin D, the average person can produce 20,000 IU in 10 minutes of sun exposure (in the SUMMER for Canadians) The accepted “too much” vitamin D is 150 nmol/litre which can only be determined by a blood test which is hard to have done in Canada. So my guess is that you would have to swallow a whole lot of vitamin D tablets (at 1000 IU each) to have “too much” vitamin D.The RDA is 600 IU which will prevent Rickets, which by the way is actually making a reappearance in North America along with Scurvy. Is it any wonder when we get advice like this discouraging Canadians from supplementing with vitamin D. Which industry makes the most money by keeping us sick?

  12. The reason I and my children take vitamin D is not due to the lack of sun exposure we receive up here, it’s to benefit our immune system.  I found this out during the whole H1N1 scare.  It’s also been shown that people who develop MS symptoms have lower amounts of vitamin D, not to mention how it helps people who get S.A.D. (seasonal affective disorder). 

    • “It’s also been shown that people who develop MS symptoms have lower amounts of vitamin D’

      No. It hasn’t.

      “not to mention how it helps people who get S.A.D. (seasonal affective disorder)”

      No, it doesn’t.

  13. Pregnant women SHOULD take D-vitamin every day. Newborns show much better bone development and research shows that after 8 years they are born, children  have a more developed bone and teeth structure if their mother took this vitamin while they were pregnant. In addition, many child disease can be prevented too with vitamin D.
    Just do the research on this topic and you’ll find out how necessary it is to take vitamin D when pregnant.

  14. If you see a study done by a person which name start with Dr. you may be misled . They try to keep you away from vitamin D . If every adult person will take 10,000 I.U daily the Hospitals will be for Emergency purpose only . The harmful dose of the Vit. D is 50,000 I.U. daily . U.S . and Canadian governments ordered studies on vitamin D to scare people and keep them away of the miracle vitamin . You realize , all the money they get (not taxes) from the pharmaceutical companies aka drug dealers and medical equipment makers gone just because people take vitamin D .

    • If Vit D was the miracle cure yousuggest, a Government could save 30 to 40 percent of their spending, which would more than make up for any corporate/pharma kickbacks.

      Your logic is faulty.

      • Unless its not about the total income of the government to be used on the people themselves but instead perhaps the people in government have a relationship to those in the pharmaceutical industry and receive money/perks, much like how doctors often get paid vacations at high class resorts paid for by the same pharmaceutical companies to promote their new drugs. The logic is sound.

        • Well, in Ontario, docs don’t get those perks anymore. The legislation changed about 10 years ago, and the drug companies have sucked it up and put the moey into advertising.

          Your facts are wrong. Thus, your logic is faulty.

  15. Somebody needs to call Steve Gibson @ GRC..

    • You can find a podcast on Vitamin D here..

  16. I’ve had the blood tests done, on my own accord, and found I’m deficient. Pale skinned, red hair, don’t get a lot of sun though I am out and about in the summer. So I just negated all of the supposed “expert” comments in this article. And the last “thank you” is garbage as well. The supplements are required to negate all the junk corporate America/Canada is putting into the food chain. HFCS is a prime example. A properly functioning FDA wouldn’t allow half the additives corporations put into processed food, but their bought by large corporates.

    So offer the people like myself a way to pay for the test (at a reasonable cost) instead of billing the health system. The system is not set up to allow that.

    BTW, if you take D supplements, make sure they are D3 !

  17. I rather take vitamins than taking expensive allopathic horse medecins and other drug products and guessing how many side effects will affect me or even create another illness in the process to be treated with another drug with countless side effects ad nauseam. Of course drug companies prefer we debate publically and negatively about natural products and homeopathy rather than the population start a serious discussion about our use andd misuse of allopathic horse medecins and their list of side effects. 

  18. This article is just not true. Patients are being cured from multiple sclerosis taking vit d3 (which isn’t an actual vitamin, the author forgot to say). Want to prevent blood calcification? Please take vit k2 with d3. Please dear author get informed. Some doctors I don’t understand why they get so much prestige and trust just for being a doctor. People assume because they’re doctors they are above others and must know best, but the truth is that in biology and health a lot of things don’t have only one absolute answer. They’re just like any other professional / human being subject to failing and imperfections and sometimes you’re just better off doing your own research.