New Recommendations for Calcium and Vitamin D Intake

 A Walmart ad in my local newspaper trumpets “75% of all Americans don’t get enough Vitamin D” and offers to sell me Maximum Strength Vitamin D3, 5000 IU capsules to “promote bone, colon and breast health.” Meanwhile, the Institute of Medicine (IOM) tells me that “the majority of Americans and Canadians are receiving adequate amounts of … vitamin D” and that no one should take more than 4000 IU a day.  Apparently Walmart and the IOM aren’t talking to each other.

The media have been giving the impression that vitamin D is a new wonder drug. They have told us that we aren’t getting enough sunlight, that a large percentage of us suffer from vitamin D deficiency, and that low levels of vitamin D are associated with cancer, multiple sclerosis, peripheral vascular disease, diabetes, rheumatoid arthritis, Parkinson’s and Alzheimer’s disease, and other conditions. Low levels of vitamin D have been linked to higher overall mortality (but so have high levels of vitamin D!). The anti-vaccine folks have been telling us (without any controlled studies) that vitamin D supplements are better than vaccines for preventing influenza. There’s no good evidence that raising vitamin D levels with supplements actually prevents any of these conditions, but many people think it should, and doctors have increasingly been measuring blood levels and prescribing high dose supplements. Is this just another passing fad like the enthusiasm for vitamin C, or are we belatedly recognizing a serious deficiency problem?

I’ve had a lot of inquiries about “is this information trustworthy?” and “how much vitamin D should I be taking?” I’ve been telling people that I didn’t know, that recent findings will soon result in new recommendations, and I’ve been eagerly awaiting the new guidelines. Now we have them, thanks to the IOM. They are not what most of us anticipated. Since so many doctors had been advocating higher levels to prevent things like cancer, I thought official recommended intake levels would go up; instead, they went down.


The IOM was asked by the US and Canadian governments to assess the current data on health outcomes associated with calcium and vitamin D. They formed a committee of experts who did an exhaustive review of over 1000 studies and listened to testimony from scientists and stakeholders. Their report, issued on 11/30/2010, concluded that the evidence supported a role for these nutrients in bone health but not in other health conditions, that the majority of the American and Canadian population is getting enough of both vitamin D and calcium, and that there is emerging evidence that an excess of these nutrients may be harmful. Based on that evidence, they established new Dietary Reference Intakes (DRIs) for vitamin D and calcium. They acknowledged exceptions and areas of uncertainty.

A couple of my correspondents have been screening their patients for vitamin D deficiency and they report that at least half fall in the “very low” category <20ng/mL. Doctors are giving large doses (often a weekly 50,000 IU pill for several weeks) to quickly get their patients back into the “normal” range. Then a 2000 IU or even a 5000 IU daily dose can be necessary to keep them at that level. Are they treating a true deficiency? Or are they uselessly trying to move people from one side of a normal bell curve to the other? When half of our patients fall into the “abnormal” category, it bothers me.

The IOM report explains

the measurements, or cut-points, of sufficiency and deficiency used by laboratories to report results have not been set based on rigorous scientific studies, and no central authority has determined which cut-points to use. A single individual might be deemed deficient or sufficient, depending on the laboratory where the blood is tested. The number of people with vitamin D deficiency in North America may be overestimated because many laboratories appear to be using cut-points that are much higher than the committee suggests is appropriate.

There can be too much of a good thing. Gary Null inadvertently sounded a note of caution when he managed to poison himself with one of his own products.  The manufacturer of Null’s Ultimate Power Meal supplement got the math wrong (by a factor of a thousand, no less!) and overloaded the supplement with 2,000,000 IU of vitamin D instead of 2000 IU. Null nearly died. The IOM recommends an upper limit of 4000 IU a day.

Calcium supplements, long recommended to prevent osteoporosis, have been associated with heart attacks in postmenopausal women, but only in those who took it without the recommended addition of vitamin D. There are concerns that excess calcium might cause kidney stones and other adverse effects. The IOM found that most people get enough calcium from their diet, with the exception of girls ages 9-18, and that postmenopausal women who take supplements may be getting too much calcium. Once intakes exceed 2000 mg a day, the risk for harm increases.

This table shows the new recommendations for calcium and vitamin D for different age groups. 

As we continue to learn more about nutrition, the DRIs will continue to change. Science is a work in progress. The IOM has not given us a final answer, but it has offered reasonable science-based interim guidance. I’ll take its advice over that of Walmart any day!

Posted in: Nutrition

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54 thoughts on “New Recommendations for Calcium and Vitamin D Intake

  1. dougsmith says:

    Thanks, Harriet, for the informative and balanced report. I was unsure about this point you made: “I thought official recommended intake levels would go up; instead, they went down.”

    I believe the recommended intake levels went up. They used to be 200 IU/day up to age 50, now are 600 IU/day, a tripling.

    Also the safe upper bound basically doubled from 2,000 IU/day to 4,000 for most age groups.

  2. dlpfc says:

    Ah, I’ve been eagerly awaiting SBM’s take on that report. One thing the vitamin D supplementation (in reasonable quantities, mind you) has going for it is biological plausibility. Our caveman – or cave-person – ancestors had a lot less shelter and got a lot more sun than we do, so probably would have had far higher levels. Basically all the other micronutrients come from a balanced diet, but unless you happen to be eating a lot of fish liver (ew) you’re probably not getting a whole lot of Vitamin D from diet. As is the mantra of science, Further Research is Needed.

  3. dr.cosa says:

    Pointing out the extreme opposite side of the argument can misrepresent the issue in my mind.

    Mr. Nulll’s 2 million IU overdose was well beyond any sort of debate in the vitamin d dosage issue. I know it wasnt SBM’s intention to sensationalize but I only say this because his close call was constantly flouted as a sign of over zealous and misdirected attempts to boost vitamin d levels in the mass media.

    These sort of singular events are constantly brought up as if they are in some way relevant to the issue but they arent. Inserting them in the story only serves to make it appear that vitamin d dosing is this delicate event where the results could be toxic and life threatening. several thousand units in either direction and any possible side effects are vastly different than several million. especially in light of the fact that we can absorb several thousand units of vitamin d via sunlight during relatively moderate stretches outside in the summer.

    several million units of virtually any supplement could yield dangerous results, this is akin to suggesting that a drawback of asprin is that it can be deadly if you ingest 1000 of them at one time.

  4. WilliamLawrenceUtridge says:


    One reason why Null’s OD and the near-lethal consequences are pointed out is that supplements are often treated as panaceas – able to cure everything and anything while presenting no risk at all. That’s not the case. There is an obvious acute risk (for which Null is now a posterboy) and it’s a good starting point towards a discussion of chronic risks.

    It also illustrates the fact that supplements are essentially unregulated, uncontrolled, untested and therefore present dangers that are not present (or at least are mitigated through stringent quality-control and testing processes) in modern pharmaceutical manufacturing. Say what you want about Big Pharma, but they put a lot of effort into making sure the dose you’re getting is a reasonable approximation of what it says on the box (in part at least due to the FDA’s oversight – which supplements do not have). Your comparison to aspirin is close, but not quite correct. It’s more akin to taking a single aspirin that has 1000 times the does per pill than what is written on the box. Again, that’s prevented by mandatory manufacturing standards overseen by the FDA – standards and oversight that are lacking for supplements.

  5. Scott says:

    Dr. Cosa does, however, have a good point in that Null’s experience does not provide evidence that the doses in supplements without such a manufacturing error are hazardous.

    For the general principle that there IS a toxic dose, certainly. So it’s a good illustration of the fact that the simplistic “more is better” is not an appropriate principle to follow with supplementation. And as I read the post, that’s the context in which Dr. Hall was invoking it.

    So it’s reasonable as used here, but shouldn’t be taken too far.

  6. Ash says:

    Thanks for this nice summary. I have to admit I do take a vitamin D supplement in the winter, mostly because I rarely see the sun (I live far enough north that I am often at work before sunrise and don’t leave until after sunset). At least with a new recommendation from a credible agency it helps me make sure I take the right dose (looks like a 400 IU vitamin would be plenty). I’ve never considered 5000 IU as necessary though and certainly wouldn’t take Walmart’s word for the right dose.

  7. Robin says:

    So, they gave recommended intake guidelines for supplements but didn’t specify a cut-point blood level for deficiencies and insufficiencies? Did I miss something?

  8. Harriet Hall says:

    I said “I thought official recommended intake levels would go up; instead, they went down.”

    The IOM recommendations are a little higher than the previous RDA, but many experts had been recommending doses higher than the RDA. I was thinking of them. The way I used the word “official” was probably misleading.

    Based on everything I had read, I had been taking 800 IU of vitamin D a day (I’m 65) and had been wondering if I should up the dose. The IOM report convinced me not to.

  9. Harriet Hall says:

    @ Robin,

    “didn’t specify a cut-point blood level for deficiencies and insufficiencies”

    No, they didn’t. They made the point that we don’t have a reliable evidence-based cut-point.

  10. CarolM says:

    Thanks for this article. I fell prey to a hysterical “warning” about D deficiency last year and promptly bought some D3 at – you guessed it – Wal Mart!

    What no one seems to mention is whether the D supplementation in milk and other dairy is good enough. I’m relying mostly on that for my D and calcium both. Could you OD on that??

  11. Jeff says:

    WilliamLawrenceUtridge states,

    Again, that’s prevented by mandatory manufacturing standards overseen by the FDA – standards and oversight that are lacking for supplements.

    Of course the supplement industry is governed by the FDA’s stringent GMP regulations, for which full compliance is now mandatory.

    The FDA has estimated that 25% of all supplement companies will be forced out of business due to the high cost of GMP compliance.

  12. lillym says:

    My mother was diagnosed with vitamin D deficiency after having all kinds of aches and pains. The doctor ordered blood tests that looked for various things including her levels of D.

    At first she was put on a higher dose of D for a short period of time, then more blood tests, and finally put on a maintenance dose. She goes back for regular blood tests to make sure her levels are okay. right now she takes 1 supplement twice a day.

    But a few months ago she started having really bad stomach pains and finally went to the doctor for that. While she was there they discussed all her meds and even looked at the bottles.

    Turns out Mom had bought a different brand of D and didn’t look at the dose – each pill was twice as much as the other brand. After that she has been really careful about reading labels, also she had been taking a lot of different supplments that were not doctor recommended and she finally talked to her doctor and stopped taking most of them. Accidentally over dosing on D made her concerned that the other stuff she was taking may not be helping and might even be hurting her. Nothing really was but she decided to only take supplements on the advise of her doctor.

  13. dr.cosa says:


    point well taken,

    though again the intent of a 2 million IU dose is far and away what is being discussed (differences between 850 IU’s a day and say 2000-5000)

    again if the debate were for something even more benign like water and when discussing if 8 glasses a day is required, the story posts a cautionary “but you can have too much of a good thing, a minesota woman recently died after having drank 120 glasses of water in a single sitting”… these are sensationalist stories that do nothing to add real meaning to the debate.

    i agree that the issue of manufacturing safety should be considered but once again, is the issue that doctors are concerned about patients being accidentally poisoned by a 1 million UI doe of Vitamin D? is this fear in line with other risks to buying supplements like the threat of car accidents on the way to the pharmacy? blah!!! lets be serious here!

    of course portraying supplements in the extremes is always going to win you points among skeptics, portraying people who take triple the recommended alongside people who believe vitamin d will cure anything and everything is specious reasoning.

    humans absorb several thousand units of vitamin D just sitting out in the sun during the summer, does anyone really believe they are being administered a toxic dose?

  14. Always Curious says:

    Check your milk jug, but I think milk is fortified to approximately 200 IU/ 8oz glas of milk (depending on company & country?). When I last worked it out (can’t find my calculations now), drinking three glasses of milk per day was approximately enough to meet the old standard. Unless you have some other health concerns, you’d be hard pressed to consume enough dairy to overdose of Vitamin D.

    Also note that the recommended intake assumes zero sun exposure, so depending on your outdoor habits & latitude, you might not need any nutritional supplementation at all.

  15. Joe says:

    @Jeff on 07 Dec 2010 at 11:43 am wrote “… The FDA has estimated that 25% of all supplement companies will be forced out of business due to the high cost of GMP compliance.

    Well, that’s a good start! Still, a lot of hooligans will be left.

  16. oderb says:

    Simple question. I’d like to know why the IOM report should be given any greater credence than consensus statements developed by eminent and pioneering Vitamin D researchers such as Dr Hollick, Dr. Hollis and Dr Hearney, among others.

    Here is a consensus statement from 12 such researchers and practitioners made last year.

    It recommends testing to insure levels of 40 to 60 ng/ml and a daily intake of 2,000 iu, and more for certain subgroups.

    Are the IOM panel members more qualified than these 12? Hardly.

  17. mark says:

    @ Harriet Hall

    “Based on everything I had read, I had been taking 800 IU of vitamin D a day (I’m 65) and had been wondering if I should up the dose. The IOM report convinced me not to.”

    Did they convince you to stop the supplements though? The IOM says most people don’t need them. They say the only good evidence for beneficial effects of vitamin D is in bone health, but the only trials that show vitamin D prevents fractures were 2 trials of frail, elderly, institutionalized women who were very vitamin D deficient. They also took calcium supplements (and who would take calcium if it might increase the risk of heart attacks?). The results for fracture prevention have not been replicated in community-dwelling individuals.

    Following the IOM report should lead you to stop taking vitamin D, shouldn’t it? Or is the situation- if you are already taking supplements, don’t stop, but if you are not taking supplements, don’t start? Pragmatic but somewhat illogical.

  18. mark says:


    “Our caveman – or cave-person – ancestors had a lot less shelter and got a lot more sun than we do, so probably would have had far higher levels.”

    Really? Why would they have had less shelter? Plenty of caves and trees around. But seriously, people living today in undeveloped tropical countries don’t have particularly high vitamin D levels. Why should we assume our ancestors would?

  19. Scotty B says:

    Hello all,

    I shared this SBM post on Facebook and received the following responses from a cousin of mine:

    According to Dr. Robert Heaney humans utilize approximately 4000 IUs of vitamin D3 per day. Heaney et al. 2003 Human serum 25 hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am. J Clin. Nutr. 77: 204-210. Dr. J…ohn Cannell MD, the Executive Director of the Vitamin D council stated in a recent Vitamin D Council on-line newsletter http:// entitled ‘The Truth About Vitamin D Toxicity’ that there is no evidence anywhere in the published literature that even 10,000 IUs per day of vitamin D is toxic to humans and that human toxicity does likely not occur until over 40,000 IUs of daily consumption. “Vieth reports human toxicity probably begins to occur after chronic daily consumption of approximately 40,000 IU/day (100 of the 400 IU capsules).” He goes on to state that “Physician ignorance about vitamin D toxicity is widespread” and concludes by stating that “In fact, living in America today while worrying about vitamin D toxicity is like dying of thirst in the desert while worrying about drowning.” In other words any danger associated with vitamin D is from deficiency NOT toxicity.

    As I am no doctor, I was wondering if you could address any of these points for me.

    Scotty B

  20. WilliamLawrenceUtridge says:

    “The FDA has estimated that 25% of all supplement companies will be forced out of business due to the high cost of GMP compliance.”

    How can I do anything but celebrate?

    @dr.cosa again

    I believe the ability to produce vitamin D via sunlight has feedback controls that prevent acute overdosing. Certainly over the long term via increased melanin deposition (i.e. tanning).

    Also, the concern for me is less about acute overdosing – it’s more about chronic toxicity. Few are likely to take 2,000,000 iu at once, but many could take 5,000 iu a day for years and there could be health consequences. Witness vitamin E. Promoted for years as a possibly beneficial then it turns out to be associated with increased risk of heart failure. Skeptics should certainly point to Null’s experience and the lessons drawn from it, as well as the general idea of the benefit of “nutritional insurance”. Eating a healthy diet is probably a better idea than a multivitamin, which could either be a waste of money or actively dangerous depending on dose and the person taking it. I’ve always liked Quackwatch’s take on the matter.

  21. dlpfc says:

    “Really? Why would they have had less shelter? Plenty of caves and trees around. But seriously, people living today in undeveloped tropical countries don’t have particularly high vitamin D levels. Why should we assume our ancestors would?”

    They may have had caves and trees, but they had to leave them frequently to forage and hunt. They didn’t have cars, air-conditioned buildings, office jobs, or sunscreen. They also tended not to live very long, so diseases of aging (such as osteoporosis) were less likely to be an issue. Most people living in underdeveloped tropical countries have dark skin – one would expect them to produce less.

    I’m not arguing that Vitamin D supplements are necessary – the IOM report does an excellent job of outlining the fact that there’s simply not enough evidence for that position. I’m simply saying that, unlike for most supplements, there is some biological plausibility to oral Vitamin D in modest amounts. This need not come from pills, mind you, but simply from supplemented milk. However, lactose tolerance is, worldwide, not as common as you’d think and is mostly found among light-skinned Europeans, meaning that people with darker skin – who need more oral intake – are less likely to be able to get it from milk.

  22. mark says:


    Sure- I’ve heard this argument a lot before but there’s too many assumptions for me personally. That often seems to be a problem with biological plausibility for many contentious issues. What one person/expert thinks is highly plausible, the next person/expert thinks is tenuous. I suppose that is why the issues are contentious.

  23. dr.cosa says:

    another twist to the story:

    Milk as a vitamin d source may not be idea as it has been supplemented with Vitamin D2 which appears to less desirable than D3:


    The relative potencies of vitamins D2 and D3 were evaluated by administering single doses of 50,000 IU of the respective calciferols to 20 healthy male volunteers, following the time course of serum vitamin D and 25-hydroxyvitamin D (25OHD) over a period of 28 d and measuring the area under the curve of the rise in 25OHD above baseline.

    The two calciferols produced similar rises in serum concentration of the administered vitamin, indicating equivalent absorption. Both produced similar initial rises in serum 25OHD over the first 3 d, but 25OHD continued to rise in the D3-treated subjects, peaking at 14 d, whereas serum 25OHD fell rapidly in the D2-treated subjects and was not different from baseline at 14 d. Area under the curve (AUC) to d 28 was 60.2 ng·d/ml (150.5 nmol·d/liter) for vitamin D2 and 204.7 (511.8) for vitamin D3 (P < 0.002). Calculated AUC{infty} indicated an even greater differential, with the relative potencies for D3:D2 being 9.5:1.

    Vitamin D2 potency is less than one third that of vitamin D3. Physicians resorting to use of vitamin D2 should be aware of its markedly lower potency and shorter duration of action relative to vitamin D3.

  24. TimonT says:


    “Here is a consensus statement from 12 such researchers and practitioners made last year.

    I’d be interested in the comments of you SBM foks on that letter. No reference is given so it’s not clear where it originally came from or whether it was peer-reviewed.

    What about the Vit. D/cancer prevention connection. Is there anything to it?

  25. Angora Rabbit says:

    Oderb asked:
    “Simple question. I’d like to know why the IOM report should be given any greater credence than consensus statements developed by eminent and pioneering Vitamin D researchers such as Dr Hollick, Dr. Hollis and Dr Hearney, among others. ”

    Simple answer: I don’t see any references cited in their claims. It’s mere opinion. Take a read at the IOM report. It is a book with mountains of citations which the committee actually took the time to read. The press release is just that, an opinion piece.

    Haven’t been able to post on this today with a progress report due. But Dr. Hall, wonderful summary!

  26. Angora Rabbit says:

    Oh, yeah, and their opinion piece is also over 2 yrs old, whereas IOM has been meeting for months-plus and reviewing literature up to the last minute.

  27. Fifi says:

    TimonT – Whether you’ll need vitamin D supplementation (due to deficiency) depends on where you live, how much sun you’re exposed to, what you eat and what time of the year it is.

    Some of the first research that pointed to vitamin d deficiency contributing to (if I remember correctly) colorectal cancer in men was done in Canada. What was found was that men who went on a two week vacation in the sun during the winter had lower rates of cancer. The Canadian cancer society does recommend vitamin d supplementation because most Canadians (and other people who live in areas of the planet where you don’t get sufficient sunlight in winter and what sun you do get is less effective for producing vitamin d) are deficient in the winter (unless they holiday in the sun to up their natural vitamin d production).

    Traditionally, Canadians and other northern people ate foods (fish) that were rich in vitamin d (cod liver oil was commonly given to children to prevent rickets, which is caused by a vitamin d deficiency). Cod liver oil is notoriously disgusting (and very high in vitamin A) so most people these days prefer to take a pill. As someone mentioned, vitamin D2 isn’t nearly as easily metabolized as D3.

    You don’t need much sun at the right latitude to naturally generate vitamin D but if someone wears sunscreen all the time and works indoors, they may become deficient. Vitamin D, along with calcium and magnesium, is important for healthy bones (though it’s about the balance between the three). It’s also important for immune functioning.

    Dark skinned people living in northern climes are even more likely to be deficient, according to studies (and people of African and Asian descent are also more often lactose intolerant so unlikely to get it from milk supplemented with vitamin D). So, there are lots of factors that may or may not contribute to needing vitamin D supplementation. It’s not a panacea but it is much more important than originally thought. It’s about getting enough, not mega-dosing.

    Most of the research done on vitamin D in Canada is public science (not corporate science). You could get tested but a basic understanding of what causes deficiency – where you live, what your habits are, etc – will probably give you a pretty good indication of if it’s something you should look into (or get tested for).

  28. Fifi says:

    The Canadian Cancer Society recommends 1, 000 IU a day for Canadians during the fall and winter months.

    The studies being done in Canada are mainly being done by public/academic researchers and obviously, because we have a universal healthcare system, there’s a stronger interest in preventative medicine here.

  29. KGelling says:

    The panel’s recommendations do not stack up.

    Why 400 IU/d for children but only 600 IU/d for adults who may be 3 or 4 times heavier? Why no mention of skin tone, season, latitude (Canada should ask for its money back) or obesity? It a good thing that the max limit was raised but why choose 4,000 IU/d?

  30. Fifi says:

    I’m sure everyone in Canada would be happy to get vitamin D via the “natural” route of two weeks in the sun in Cuba every so often during the winter. However, that’s not particularly realistic for a lot of people.

  31. LovleAnjel says:

    “Really? Why would they have had less shelter? Plenty of caves and trees around.”

    Plus they had wicked home theater set-ups.

    As to toxicity:

    Vitamin D is fat-soluble, meaning any excess taken remains in the body. It would be easier than one might think to build up a toxic level.

  32. vicki says:


    I am not a doctor, but the recommendations for children are often different from those for adults in ways that don’t scale with body weight, because children are growing. There’s a difference between growing bones and keeping already-grown bones healthy.

    (The problem with Canada asking for its money back is that they’d have to chase down the Hudson’s Bay Company for part of the west, and an assortment of creditors, some of them no longer extant, for Newfoundland. And most of it wasn’t bought, it was stolen: Elizabeth II is officially Queen of Canada by right of conquest.)

  33. Jeff says:

    “How can I do anything but celebrate”

    I too would celebrate if the FDA ever gets serious about using the enforcement provisions of DSHEA – the agency could rid the marketplace of those companies making shoddy or adulterated products. But it is incorrect to state that supplements are an unregulated industry. Not only does the FDA have the GMP regs, but these important provisions:

    1. The New Dietary Ingredient Regulations, whereby the FDA has pre-market approval over any new supplement ingredient.

    2. Mandatory reporting of serious adverse events (exactly the same as for OTC drugs).

    If the Food Safety Bill ever passes, the FDA will finally have mandatory recall authority over supplements. Now if only the agency had MRA over drugs!

  34. Always Curious says:

    I doubt it would be hard to find other possible explanations for differences in cancer rates between Canadians who take vacations during the winter time and those who don’t.

    @Dr Cosa The differences between Vitamin D2 & Vitamin D3 appear immaterial in the current context. The recommendations are for daily dosages, not for one-time acute intake. At 50,000 IU, there is indeed a difference, but is that significant if you’re taking closer 800 IU at a time?

    And beings the paper clearly demonstrates both provide a boost to active 25-OH-D in the bloodstream for at least 3 days, by tomorrow, it won’t matter too much which provides a more stable long-term profile.

  35. KGelling says:

    The IOM report is essentially an evidence based meta-analysis and as SBM have pointed out, in so many words, meta-analysis studies come with baggage.

    I had hoped that the SBM blog would have provided an authorative analysis of what the report did well but also where it may have tripped up, but instead it’s a couple of straw men (Walmart and Gary Null) and an “I told you so” which is disappointing

  36. Harriet Hall says:

    @ KGelling,
    First, there is a difference between a meta-analysis and a systematic review. The IOM report is not a meta-analysis. It systematically reviewed the evidence, but is not just a typical systematic review and is more than a systematic review. I am not an authority and can’t produce an “authoritative analysis,” but I can judge that what they did well was to look at all the published data, to consider the quality of the research, to consult many experts, and to apply common sense and good judgment to the available evidence. Baggage? I didn’t see any evidence of bias. I didn’t see anywhere that they tripped up, but I did try to explain that theirs is not a final definitive answer. My mention of Gary Null was not a straw man, just a vivid reminder of how there can be too much of a good thing; and I don’t see where I said anything that could be construed as “I told you so.” In fact, I said just the opposite: that I had considered raising my own intake and that I had decided not to based on the IOM report. I’m sorry you were disappointed in my post; other commenters were not.

  37. Angora Rabbit says:

    Dr. Hall, you are absolutely right; it’s not a meta-analysis. I’ve had a ringside seat to these reviews, and in general an IOM study sits down and physically reads the published literature, both covered in the previous report (dates to roughly 1998, don’t have the book in front of me) and literature published since that date. What’s great is that, in addition to the reading, they often take expert testimony as well as solicit input from stakeholders ranging from physicians to researchers to the general public. The final report will include the list of people who testified as well as the publications and date reviewed; it’s a wholly transparent review. And the report isn’t buried but will be published by the National Academy of Sciences and anyone can buy it – I’ve already ordered my copy. It will be mandatory reading for my grad students next semester, and the writing is fairly accessible. I really recommend it for anyone who wants to understand more about how requirements are set.

    In response to GKelling’s questions, a basic principle is that one does not scale dose based on weight. Children and adults have many metabolic differences including differences in absorption efficiency, metabolism, storage capacity, and clearance. Linear scale-ups seldom happen (I can’t actually think of one). Similarly, skin tone, climate etc don’t affect the requirement. What they do affect is how much VD one needs to obtain from the diet as opposed to obtaining through skin synthesis. That is not requirement but source and is a very different thing.

    Regarding D2 vs. D3, this is why the dose is expressed as IUs rather than by weight (mg). This allows us to correct for the differential metabolism between the isoforms. There’s a similar expression for vitamin E intake, which has 6 common isoforms with different activity.

    Regarding toxicity, there are case reports of clear toxicity, pretty painful because you get calcified tissue among other problems. There was a situation about 20 yrs ago in New England, where the dose in milk was miscalculated (oversupplemented) and several children experienced toxicity. VD is one of the few vitamins where I really worry about toxicity and am careful about intake.

  38. cloudskimmer says:

    Thanks for the great post, Dr. Hall. Is it possible to read the entire report (you link only to the report brief) without paying a large fee?

    Are the recommendations for supplementation, or should one estimate dietary vitamin D and then supplement enough to get to the total recommended, or should the entire recommendation be taken as a supplement?

    I was baffled by Jeff’s comments; I thought DSHEA meant the FDA couldn’t ban a supplement until it killed someone, or caused severe harm, and I certainly didn’t think it gave them authority for prior approval.. so what is true?

    In general it seems that one should eat a healthful diet; supplements don’t seem to do much good, and seem more and more to be causing harm.

  39. From the IOM press release:
    “Vitamin D levels in the body may come from not only vitamin D in the diet but also from synthesis in the skin through sunlight exposure. The amount of sun exposure one receives varies greatly from person to person, and people are advised against sun exposure to reduce the risk of skin cancer. Therefore, the committee assumed minimal sun exposure when establishing the DRIs for vitamin D, and it determined that North Americans need on average 400 International Units (IUs) of vitamin D per day (see table for the Recommended Dietary Allowances — values sufficient to meet the needs of virtually all persons).”

    They assumed minimal sun exposure because we’re talking about recommendations, and the recommendation is to stay out of the sun.

    Also we are talking about DRIs and RDAs, which are recommendations for governments when thinking about their populations. If a body is going to mandate minimum amounts of vitamins D and A in milk, or set standards for school lunches, then they should have an understanding of how much is appropriate when trying to feed a very mixed population.

    Ideally, an RDA or DRI is an amount that if everyone gets it, then nobody should be deficient and nobody should be intoxicated. It’s NOT about ensuring that you personally have an optimum amount of Vitamin D in your body (something that we have no idea how to establish) but of making sure that the bell curve of the populations of Canada and the US is between deficient and toxic.

    If the RDA for your demographic chunk is 600 IU, then it’s unlikely to make any difference if you’re getting 400 IU (the estimated daily requirement) or 1000 IU.

    Note that even though the estimated daily requirement is 400 IU, governments target 600 IU because not everyone drinks all their recommended milk/ eats liver etc. So if regulatory bodies overshoot a little that helps compensate for the fact that some people are hard to reach with regulations.

  40. Solandra says:

    I take abour 3,000 IU’s of vitamin D a day on the recommendation of my doctor. Living in Oregon and working in an office, blood tests showed me to be below 20. It seems to help, I don’t have the SAD I used to have, but it could be placebo. I would like to see more tests.

  41. KGelling says:

    @ AngoraRabbit

    But the evidence suggests that vitamin D dosage needs to be linked to weight (1) and this is appears to be particularly important if BMI is high

    1. van Groningen, L. et al. Cholecalciferol loading dose guideline for vitamin D deficient adults. European journal of endocrinology / European Federation of Endocrine Societies (2010).

  42. KGelling,

    Variations in BMI are presumably yet another reason to set the DRI for middle-aged adults at 600 IU when their estimated daily requirement is only 400 IU.

    Remember that the DRI is for a population. It’s not intended to be personalized. Fortunately it doesn’t need to be because the committee has thought of all these exceptions and variations and taken them into account when choosing a DRI.

  43. Joe says:

    @cloudskimmer on 09 Dec 2010 at 12:02 am wrote “… I was baffled by Jeff’s comments; I thought DSHEA meant the FDA couldn’t ban a supplement until it killed someone, or caused severe harm, and I certainly didn’t think it gave them authority for prior approval.. so what is true?

    Read “Natural Causes” by Dan Hurley (Broadway Books, 2006) it explains DSHEA very well. You are correct that the FDA can ban a product after they amass enough evidence of harm. They also have the ability to ban “new” ingredients; but it depends on how you define “new.” It seems to mean newly synthesized material, not new shrubbery that will be marketed to cure something.

    The September 2010 issue of Consumer Reports has a list of 12 products that should not be sold; but are because the FDA has not banned them yet.

  44. KGelling says:


    I must apologise for my previous troll post (but it worked though ;-).

    With any review of this nature, there is always baggage – preconceptions lead to cognitive dissonance, conflicts of interest create personal agendas, committees result in group-think. Also because the review is evidence-based it, by definition, may not give enough weight to plausibility.

    I thought that this is where SBM steps in – science-based medicine considers the plausibility that is missing from EBM.

    With vitamin D there is evolution (skin tone lightened with latitude), genetics (associated with 200 genes), lab trials (calcitriol shown to regulate many important pathways), epidemiology (latitude, season, race) and all of those “disease X is linked to vitamin D defiency” studies (yes I know, correlation is not causation).

    The committee’s conclusions raise a lot of questions, I was just hoping that SBM could provide some answers:

    Why only bone health? What about infections (SBM’s Mark Crislip MD recommends vitamin D sufficiency for all of his patients), auto-immune diseases, inflammation, hypertension and cancer?

    Why was 20ng/ml used as the cut-off for bone health, when at least 30 ng/ml is needed to stablise PTH levels?

    How is it possible to evaluate vitamin D levels without considering sun exposure? Just a few minutes of strong sunlight produces vitamin D well in excess of 4000 IU, the new maximum limit. If you like in Florida you’ll get this exposure every day.

    Why did they not consider latitude? Many Canadians will experience a 10-15 ng/ml drop in vitamin D levels between October and March but 600 IU/d, the new DRI, will only increase levels by about 6 ng/ml.

  45. KGelling says:


    RE: Gary Null

    Null’s toxicity was due to industry contamination and the cause was probably lax supplement regulation. It had nothing to do with overdosing with correctly labelled vitamin D supplementation.

    Vitamin D toxicity is accepted (except by the ‘woo’est of the woo), it just very hard to achieve it by taking supplements.

    Of more concern is the U-shaped risk of cancer – when vitamin D levels increase above 60 ng/ml the cancer risk appears to rise.

  46. KGelling says:

    @Alison Cummins

    “Remember that the DRI is for a population.”

    Like I said – Canada should ask for its money back

  47. The committee assumed minimal exposure to sunlight when selecting a DRI. That covers Canadians.

    If someone is absorbing 5000 UI of Vitamin D daily due to sunlight exposure, the difference between a DRI of 400 IU and 600 IU is not going to make much difference. That’s why they chose a DRI of 600 IU instead of splitting the difference between 4000 IU and 400 IU to get 2200 IU. 2200 IU *could* make a difference to that person.

    This is not about optimizing an individual’s bloodstream Vitamin D. We don’t even know what that would look like.

  48. rmgw says:

    Several commentators here mention their work (“getting there before sunrise and leaving after sunset”; “working in an office” etc), apparently generating a need for supplementation.
    Doesn’t this strike anyone else as something “Human Resource” people should be addressing?

  49. lou33 says:

    Does anyone find it strange that one of members on IOM owns a company that is working on an analog of vitamin D to treat cancer? You’d need a lot of vitamin D for immune system to fight cancer more effectively (probably in the range of 8,000-10,000 IU to see therapeutic effect). 600 IU DRI isn’t very much. If you want to prevent cold/flu, it’d be a lot more like 5000 IU a day for adults during the winter. Too many people saw that it worked against them so it can’t be ignored. No difference than spending time outside at the pool without sunblock which can offer as much as 20,000 IU or more.

    Back in the old days of 1930s, scientists were experimenting with vitamin D to treat asthma and allergies. They number in the tens of thousands of IU a day. It worked very well. Not sure where it went wrong. It’s like we went into dark age in vitamin D and pretty much forgotten about it.

    It’s a shame that we have bad science in the papers that some people use to justify the reasoning of low amount even though other people can’t produce consistent numbers in the latter studies.

  50. lou33 says:

    No good evidence that vitamin D prevents flu?

    You didn’t say how much vitamin D that can cause death which can take a ridiculous amount over a period of time. You can’t just say that without providing numbers or links to that. That makes you an hypocrite. – RCT study showed that vitamin D indeed do a job of preventing flu.

    Throw in thousands of people seeing the same effect as well. Like me, they tried everything but never worked out to prevent flu and cold until we tried vitamin D at higher dosage often at 5000 IU a day during the winter.

    I can say it’s working after 2 years. I used to get several cold and perhaps a flu along with hated sinus infection that took forever to get over but nothing since then.


  51. Chris says:

    lou33, unless you are getting your Vitamin D from sitting in the sun as much as possible, then you are supporting Big Pharma. Who do you think owns all of the supplement companies?

    And Lew Rockwell is not an expert.

  52. Harriet Hall says:

    lou33 says “I can say it’s working after 2 years…

    1. You can say it’s working. You can say anything. But anecdotes are not persuasive and the scientific evidence simply isn’t there. Did you read the details of the article you linked to? This recent systematic review did not conclude that vitamin D was effective for infectious diseases: it only recommended further study.

    2. Trying something yourself is not a reliable way to determine effectiveness. That’s why we have to do science.

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