Vitamin D: Cutting Through the Confusion & Controversy

By Andrew Moseman | December 1, 2010 2:36 pm

vitamins and mineralsAfter two years of work developing new guidelines to tell us how much vitamin D and calcium is enough, the Institute of Medicine released its report this week with the basic message: Relax, you’re all doing pretty well.

Yet confusion still reigns in headlines about the report, as there are several different facets to the new standards (and the reaction to them). The new report also seem to contradict earlier, alarming studies that found vitamin D deficiencies in most Americans. So, what’s going on?

Most people are doing just fine

IOM looked at both Vitamin D and calcium intake for different age groups, and slogged through hundreds of studies of the levels of those nutrients versus health. The only group that was found deficient was adolescent girls, whom the researchers said should intake a little bit more calcium.

The panel said its findings challenged the notion that, when it comes to dietary nutrients, “more is better” — a belief that has inspired a multibillion-dollar market for dietary supplements in the United States. Americans spent $1.2 billion last year on calcium supplements and $430 million on pills containing vitamin D, according to the Nutrition Business Journal. [Los Angeles Times]

Ohio State oncologist Steven K. Clinton, a coauthor of the report, says most people have enough variety in their normal diet to get adequate amounts of both nutrients.

New findings? Not convincing enough

The reason that gigantic supplement market exists is that a number of studies have suggested vitamin D—found in some foods but mostly produced in your skin by the action of ultraviolet radiation—could help to prevent diseases like cancer, heart disease, diabetes, and more. But in its meta-review of vitamin D studies, IOM wasn’t convinced. Its report reinforced the traditional wisdom that vitamin D is crucial for skeletal health, but wouldn’t go further in determining healthy levels.

“We had to look at the totality of the evidence,” says Patsy Brannon, a molecular nutritionist at Cornell University, who served on the panel making the new recommendations. The panel scoured studies showing vitamin D’s effects on other health problems. “For each of those other health indicators,” Brannon says, “we found very limited randomized control trials.” … The trials they did find didn’t establish cause and effect or clarify beneficial doses for other conditions, she says. [Science News]

That doesn’t mean Vitamin D can’t help against those other health problems. It means one or two studies don’t prove the case, and Clinton says the connections between vitamin D and fighting those other problems were much more tenuous than he imagined going in:

“What we have are intriguing other areas that warrant research,” he said. “Yet the data at the moment is insufficient with regards to defining an appropriate intake. Bone health is the primary outcome.” [HealthDay News]

The numbers, and the testing, are confusing

Figuring out vitamin D levels is confusing for several reasons. First, the IOM’s new standards don’t even match up to their old ones in what they’re telling you:

The updated daily recommendations are not directly comparable to previous sets, which were established in 1997 and are based on “adequate intakes” rather than on the newer recommended dietary allowance and estimate average requirement. Catharine Ross, chair of the IOM’s review committee and a professor of nutrition at Pennsylvania State University, noted in a Tuesday press briefing that the two values are “like comparing apples to pears.” (The previous adequate intake recommendations were 200 IU per day for infants through age 50, 400 IU/day for ages 51 to 70, and 600 IU/day for those 71 and older.) [Scientific American]

The new report states that 400 international units (IU) of vitamin D daily is sufficient for most people, but the recommended intake stands at 600 IU for people from ages 9 to 70 and 800 IU for people over 70.

IOM itself admits that even the tests to determine your vitamin D levels can be misleading:

Confusion about the amount of vitamin D necessary to ward off deficiency has arisen in recent years as tests that measure levels in patients’ blood have become widely used. The measurements of sufficiency and deficiency — the cutpoints — that clinical laboratories use to report test results have not been based on rigorous scientific studies and are not standardized. This lack of agreement means the same individual could be declared deficient or sufficient depending on which laboratory reads the test. There may be an overestimation of the number of people with vitamin D deficiency because many labs appear to be using cutpoints that are higher than the evidence indicates are appropriate. [press release]

Keep on dosing?

If you, dear reader, don’t agree with the IOM’s conservative approach, there is good news for you: Though the new recommended intake stands at 600 IU for people from ages 9 to 70, the IOM standards also upped the maximum daily amount to 4,000 IU.

Supplement trade groups and doctors doing the vitamin D research have proposed 2,000 IU as a daily standard—though it should be noted that the trade group has a vested interest in selling you more supplements, and the doctors a vested interest in being right. IOM warns that taking a huge excess of either calcium or vitamin D could result in kidney or heart damage, which is why the 4,000 IU figure is still a tad cautious.

But this is far from the final word on how much is enough. Many doctors, like Boston University Medical Center’s Michael Holick, say the IOM is far too conservative on vitamin D.

Holick believes that most people should be taking vitamin D supplements. “I think there is no downside to people increasing their vitamin D intake,” he said. “I personally get 3,000 IU of vitamin D a day. I have most of my patients on 3,000 IU a day and they are all in good shape.” This level of vitamin D will maximize bone health and not be toxic in any way and “may have some additional benefits,” Holick said. [HealthDay News]

Fourteen scientists sat on the IOM panel, which was sponsored by several agencies under the government of the U.S. and Canada.

Related Content:
80beats: A Sunbath a Day Keeps the Grim Reaper Away
80beats: To Protect Against Colds and the Flu, Take Regular Doses of Sunshine
80beats: Sweet, Sweet Sunshine Helps Your Heart (and Practically Everything Else)
80beats: Many Toddlers Lack the “Sunshine Vitamin”

Image: iStockphoto

CATEGORIZED UNDER: Health & Medicine, Top Posts
  • Charles

    Well that’s just confusing. I was told to take Vitamin D in the winter because my blood calcium was low. Maybe I’ll just take weaker Vitamin D pills (I don’t take any other vitamins nor drugs except the occasional ibuprofen). I do get enough calcium through my regular diet.

    And what does “you’re all doing pretty well” mean, anyway? Since I’m actually basing my blood calcium levels based on blood tests (as well as the fact that during the winter I never actually go out into the sun) mean I should continue? bah.

  • Wiglaf

    You say, “the doctors [have] a vested interest in being right.”

    Doctors sometimes seem to like to do what Big Pharma is wiling to pay for. The doctors have all kinds of vested interests; money, association, reputation, job, fame, grants, funding, appearance, etc. It’s very simplistic to say that their only interest is in “being right.” In addition, Vitamin D is not a patentable product. Any nutrition company can manufacture it. SO, at least vitamin D is subject to competition for quality and value. The IOM/FNB is a somewhat monopolistic board supported by government money. Perhaps such a board would have an “interest” in presenting findings that would encourage more funding for more reports and studies. I’ll read between the lines myself. I don’t trust the surface conclusions or implications.

    This study doesn’t stress the importance of testing your D levels if you’re concerned about whether or not you’re deficient. Why not?

  • ChrisMavo

    First off, vitamin D is not even a vitamin! It was misidenified as one when it was discovered about 80 years ago. In reality what we call vitamin D is actually a form of steroid precursor! And I doubt that most medical experts would recommend anyone to supplement with any kind of steroid!

    I supplemented with vitamin D for years because I too bought into the hype surrounding “vitamin D”! And after years of supplementation and a 25(OH)D level of 50 … I was diagnosed last year with ALS or Lou Gehrig’s disease! Now there is certainly no proof this supplementation caused my ALS illness. But, I certainly would exercise the utmost caution before supplementing with vitamin D in any form. Just eat a good balanced diet and your body will produce enough vitamin D on it’s own!

  • Wiglaf

    ChrisMavo, your body won’t produce vitamin D without the right kind of light exposure; typically sunlight.

  • The taipan

    Anybody REALLY looking out FOR our health out there?
    Sounds very blase’ / pessimistic but this is the hard question that we are afraid to ask!
    It’s our HEALTH at risk, WHY is there no one to speak for the PEOPLE?
    There are LOBBYSTS who lobby for big corporations and convince the government to pass certain laws that they (the lobbyists and their bosses, the big corporations) think will be good for the public(?)
    We the PEOPLE just passively go on with our lives and grumble and mutter all we want and NOBODY (government and all) gives a hoot!
    This is not been written to attract any argument, it’s just my take on the whole situation!

  • Birgit Calhoun

    Originally the Vitamin D level was established by seeing how much supplementation it took to keep children from getting rickets.

    Science has come a long way since then. Experts now understand that Vitamin D receptors exist in many parts of the body. That means Vitamin D is necessary for organs other than bones.

    The blanket statement that most people get enough Vitamin D is not backed by any research that I have seen.

    Two years ago I started taking 1000 IU a day of Vitamin D. At the same time I went out into the sun at noon for about 30 minutes every day, religiously. My bone density was ok. But when I got tested my 25 (OH) D3 was very low: 14ng. I got therapeutic doses of 50,000 for 6 weeks (twice), then 100,000 IU for 8 weeks. Finally my level came up to 32 ng. I have been taking 4,000 IU since then. The joints in my fingers are not as painful and my general constitution is much better.

    I would not have known to get tested if it hadn’t been for my son who has extreme osteopenia. He has had about 100 broken bones in his body. Over 10 years ago he was tested as having 11ng. At that time the orthopedic surgeon and a second opinion told me that that was within the normal range. The x-rays looked as if my son had rickets. They stated he did not have rickets. My son would not be in a wheelchair if he had received a proper diagnosis. It turns out he had osteomalacia. Rickets is the same as osteomalacia. Except osteomalacia happens in adults. How many doctors check the parathyroid level when testing Vitamin D? It’s an impotent factor. Why is that not being addressed in the report. And yes, the kidney makes the active form of Vitamin D. So if you have kidney disease you might want to check that.

    Here is my question: Why were the experts not involved is this study. The experts I know of are Cedric Garland, Reinhold Vieth. Dr. Holick. Dr. Hollis, Dr. Cannell. They have good arguments in favor of a much higher dose of Vitamin D than what this panel came up with.

    How much conflict of interest is involved choosing the panel members and the type of reporting we see? The difference between just The Wall Street Journal and The New York Times is stunning.

  • Marianne Buchwalder Antezzo

    The panel which came up with the negative conclusions on D3 did not do any testing of their own. They just examined the reports of studies done on D3, and concluded that the performed tests were flawed in some way. Essentially this panel said…you haven’t proved it, according to us, and so it’s not true. This panel has done no research. How they decided to even minimally increase recommended D3 consumption was not explained, and seems as if they just winged it. Experts in the field of D3 were consulted (on some level), and wrote rebuttals to the panel’s conclusions. Their rebuttals were excluded from the report. A group is trying through FOI to gain access to the experts’ comments on the panel’s report.
    I hope the experts’ rebuttals will be published and given the same extensive media coverage as has this dubious report.

  • Brian

    I don’t believe 3000IU would hurt, do you? I’m tempted to jump my intake to 4000IU, now.

  • Saibal Mitra

    One can also ask why animals would have evolved to make bone health dependend on the Sun being high in the sky. Note that vitamin D itself does not get the calcium from food into bones, this is done by other compounds that some genes code for; those genes are switched on in response to vitamin D.

    Vitamin D being involved in only bone health does not make a lot of sense. But if we take serious the evidence of it being involved also in modulating the immune system, then things become more clear. Animals may have evolved to use vitamin D to modulate processes that use a lot of energy, like the immune system. When the Sun is no longer high in the sky, that signals a coming Winter, and it makes sense to let such processes run in a more energy efficient way, so that fat reserves can be built up more easily.

    The less fat an animal has to begin with the sooner its vitamin D levels will drop, as vitamin D is stored in body fat. So, this is consistent with vitamin D being used to implement an optimal strategy to make it through Winter. As vitamin D levels drop to ever lower values as Winter progresses, more energy saving measures are taken.

    Getting calcium from food costs energy, due to the low concentration of calcium in food. It costs far less energy to maintain the necessary calcium levels in the blood from getting it from our bones, because the concentration of calcium there is much higher. However, this comes at the expense of maintaining the bones. If this situation lasts for a few weeks, it is not going to do significant damage; the benefits of spending less energy to digest food are much greater for animals that have to survive in nature.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.

See More

Collapse bottom bar