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BOOSTING VITAMIN D: Not enough or too much?

Article / Review by on January 10, 2012 – 8:00 pmNo Comments

BOOSTING VITAMIN D: Not enough or too much?

Highlights: Boosting Vitamin D: Not Enough or Too Much?
Presented in Collaboration with Reuters. Part of the Andelot Series on Current Science Controversies. /Video from March 29, 2011. …



BOOSTING VITAMIN D Not enough or too much? Presented in Collaboration with Reuters

March 29, 2011

The nutrients calcium and vitamin D are essential to build and maintain healthy bones. Yet determining the optimum effective and safe daily allowances have proven to be a challenge. In part this is due to inherent limitations of many studies, the needs of different groups within the population, and changes in methods for measuring blood levels. In addition, vitamin D status depends on a complex interaction of dietary and supplemental sources and environmental factors such as sun exposure.

Against this backdrop, the United States and Canadian governments asked the federal Institute of Medicine (IOM) to review the evidence and, if necessary, revise the Dietary Reference Intake amounts for Vitamin D and calcium. An IOM committee evaluated 1,000 scientific studies and heard testimony from researchers and stakeholders before releasing a report in November 2010 calling for slight increases in the DRIs. (See )


  • Walter Willett – Chair, Department of Nutrition, Harvard School of Public Health, and Fredrick John Stare Professor of Epidemiology and Nutrition
  • JoAnn Manson – Chief, Division of Preventive Medicine, Brigham and Women’s Hospital; Professor of Medicine, Harvard Medical School; and Member of the IOM Committee to Review Dietary Reference Intakes for Vitamin D and Calcium
  • Patsy Brannon – Member of the IOM Committee to Review Dietary Reference Intakes for Vitamin D and Calcium, and Professor, Division of Nutritional Sciences, Cornell University
  • Bess Dawson-Hughes – Senior Scientist and Director, Bone Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University; Professor, Tufts University School of Medicine; and Past President and Trustee, National Osteoporosis Foundation


Boosting Vitamin D: Not Enough or Too Much?

Event held 3.29.11. A long-awaited report from the Institute of Medicine (IOM), “Dietary Reference Intakes for Calcium and Vitamin D,” calls for increasing daily vitamin D intake. Yet some experts say these new recommendations are still too low in vitamin D. Why do these nutrition specialists disagree? This Forum webcast examined the question, “Boosting Vitamin D: Not enough or too much?”


• The scientific evidence to support specific intake amounts of vitamin D is conflicting and hotly debated, especially since the Institute of Medicine (IOM) issued new recommendations of 600 IU daily for people between the ages of 1 and 70 (an increase from the former recommendation of 400 IU) and of 800 IU daily for people older than 70 years. More research is needed.• With a graying population led by a health-conscious cohort of aging baby boomers, increasing concerns about vitamin D deficiency in North America have fueled a demand for blood level tests and large doses of supplements whose effectiveness and safety are uncertain.

• New guidelines from the IOM for daily vitamin D intake are based primarily on bone health because the IOM panel says that it did not find sufficient evidence linking vitamin D to non-skeletal disorders such as cancer, heart disease and diabetes.

• Communication by the IOM that levels of vitamin D beyond the new increased recommendations are not beneficial may have been too definitive. There is evidence supporting benefits to higher levels.

• When it comes to assessing vitamin D needs, policymakers may want to consider an approach that differentiates between average-risk and high-risk groups. People at high risk include individuals who are obese, have darkly-pigmented skin, or have problems absorbing the vitamin in their bodies.

The IOM set the vitamin D recommended daily intake at 600 International Units (IU) for people ages 1 to 70; 800 IU for ages above 70. These amounts, according to the report, are believed to be sufficient for at least 97.5 percent of the U.S. and Canadian populations.

The report immediately prompted strong criticism from some bone metabolism and nutritional experts and advocacy groups. The continuing debate has left the public unsure about whether their intake levels are optimal yet safe, and what, if any, action they should take.


At least three issues in the IOM report have generated disagreement and questions:

• Should the recommended blood levels and dietary allowances for vitamin D have been set even higher by the IOM? Or, do concerns about safety at higher doses outweigh calls for higher levels?

• Does the daily allowance of dietary and supplemental vitamin D recommended by the IOM actually provide – as the report says – sufficient amounts to assure bone health for 97.5 percent of the population. Critics point to evidence that this is a significantly flawed assumption.

• How can these population-wide recommendations be reconciled with the needs to test high-risk groups to reduce bone fracture risks? If screening the entire population is unnecessary and not cost-effective, then who should be screened?

Two types of measurements are used in the discussion. One is the amount of vitamin D (in the form of a metabolite) in a person’s blood. It is expressed in nanograms per milliliter (ng/mL). On the intake side, vitamin D in the diet and nutritional supplements is measured in International Units (IU). The relationship between intake and blood levels is difficult to predict.

One of The Forum expert participants, Bess Dawson-Hughes, director of the Bone Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, takes issue with the IOM’s choice of 20 ng/mL as an appropriate target for vitamin D blood levels. She argues that, for many people, this amount is too low to maintain strong bones and prevent fractures. “I believe that the evidence supports, very strongly, a higher figure of 30 nanograms per mL, based on the amount of [vitamin] D needed, and the circulating level needed, to lower risk of hip fracture, which is, of course, the main endpoint that everyone agrees with in the report,” Dawson-Hughes asserted. Walter Willett, chair of the Department of Nutrition at Harvard School of Public Health, agreed, and added, “There is definite evidence confirmed in other systematic reviews that falls are reduced by vitamin D supplements. And that takes levels getting up to levels above 20 nanograms per mL.”

Patsy Brannon, a nutritional scientist at Cornell University and an IOM panel member, said that although some studies do show additional benefit at levels higher than 20 ng/mL, others find evidence of benefit at much less than 20 ng/mL.

“So the difficulty is trying to take the totality of the evidence and look to see what it means, in terms of population distribution needs,” she said. “And that was a challenge, particularly for vitamin D, because it’s very clear, from the data, that there is an interrelationship between the amount [of] vitamin D that one is consuming, and the amount of calcium that one is consuming, in terms of bone health and perhaps other non-skeletal health outcomes.”


Even if the IOM panelists had been inclined to raise the target blood level to 30 mg, they would have hesitated because of studies that suggest adverse health outcomes with higher intakes.

“The committee definitely had wanted to propose a higher intake if we felt that that was safe for the population,” said JoAnn Manson, professor of medicine at Harvard Medical School, chief of preventive medicine at Brigham and Women’s Hospital, and a member of the IOM panel. “But you have, when you’re talking about public health recommendations that are long-term, chronic, 20, 30 years potentially, the level of evidence for the safety of long-term intake of very high dose vitamin D, or even maintaining a blood level at 30 nanograms or 40 nanograms, the evidence was just not there.” The IOM panel suggested that the tolerable upper intake level of daily vitamin D is 4,000 IUs.

Willett, on the other hand, contended, “There’s no question you can overdo vitamin D. But, the levels, blood levels that we’re talking about, 30 or even 40 nanograms per mL, that there is no evidence of harm there.”


Some Forum expert participants and attendees found fault with the way the IOM findings were communicated. Media reports emphasized the report’s assertion that most people are getting enough calcium and vitamin D and that taking extra large doses of vitamin D confer little extra benefit and may be dangerous.

According to Dawson-Hughes, “The hitch comes in the IOM’s conclusion that 97.5 percent of the population will be served by 600 to 800 units, when the proportion of the population that is at high risk for low [vitamin] D levels is far greater than 2.5 percent.” She added, “We’re talking about a large segment of the population.”

Dawson-Hughes cited results from the National Health and Nutrition Examination Survey (NHANES) from 2000 to 2004 indicating that 30 percent of adults would fall below the 20 ng/mL point. And if the bar were raised to 30 ng/mL, which Dawson-Hughes said is necessary to lower the risk of hip fractures, then 70 percent of adults would be deficient.

She and other critics contend that the IOM failed to emphasize in its public messaging the needs of this high-risk subpopulation. People at risk for vitamin D deficiency include individuals who are obese, have darkly pigmented skin, habitually wear protective clothing and sunscreen, or have chronic malabsorption problems.

Willett agreed, saying that there are, “tens of millions of Americans below that level [of 20 ng/mL] and to ignore them and say it’s no problem is a big mistake.”

In response, Manson pointed out that the IOM committee was charged with making public health, not “clinical decision-making” recommendations, for the entire population. She asserted that the IOM guidelines were not neglecting any segment of the population. “I think that is extremely reasonable for patients who are a higher risk, individuals in the population who have a number of risk factors for vitamin D deficiency, to be screened by their clinicians, to be treated with high dose vitamin D, to be monitored closely,” she said.


Given the incomplete state of evidence on health risks associated with larger doses, but in light of the IOM committee’s stated concerns, it may be up to individuals and clinicians to decide how aggressively to supplement their diet.

Dawson-Hughes’ advice to clinicians is this: “If you identify someone as being at high risk or at reasonably increased risk, I think it’s reasonable to measure their 25-hydroxy D level to supplement with the dose that you can estimate — we can talk about the formula —but you can estimate how much they will need, replete them with that, wait three months with them on that dose, and then repeat the measure to ensure that you have achieved your goal.”

In the meantime, some of the differences expressed by The Forum expert participants can be bridged with consensus on these points: • Like the IOM committee, The Forum experts agreed that population-wide screening for vitamin D levels is unnecessary and not cost-effective. • It’s reasonable for children to take a vitamin D supplement and to eat fortified food to boost their levels. • More research is needed.




IVAN ORANSKY, EXECUTIVE EDITOR, REUTERS HEALTH: Okay. Welcome everyone. This is not a difficult crowd to quiet down, so I won’t have to spend any time doing that. Thank you all for your attention, for coming. And welcome. Welcome to The Forum, I should say, at Harvard School of Public Health. This event is in collaboration with Reuters today. I’m Ivan Oransky. I’m the Executive Editor of Reuters Health in New York. And today’s topic, as I think all of you know, is Boosting Vitamin D: Not Enough or Too Much. In a minute, I’ll introduce our expert participants. There are four of them who will actually be guiding us through a discussion of what I’m sure will be a very compelling and– and inter­esting subject for us to think about today.

But, just very briefly, I wanted to set the stage a little bit. As I’m sure you all know, the Institute of Medicine came out with a report which included some guidelines for vitamin D consumption last year. Two of our panelists were actually on that committee, and they’re going to talk about that. The guidelines were slightly higher. And I’m really oversimplifying here, which is why I’m glad we have real experts.

The guidelines were slightly higher than the previous sort of reference standards that had come out. But they weren’t dramatically higher. And I think we can all sort of agree on that. But of course, again, there are experts here who will say far more, in far more detail. And, where there was a lot of agreement, by my read of the report, and by many people’s read, was on bone health: osteoporosis. What can we say about vitamin D and that relationship?

Where there was less agreement, and where I think that there’s still a lot of discussion going on, is on sort of non-bone health issues, whether that’s heart disease, whether it’s cancer, etcetera. As we all know, you get vitamin D more or less from three sources, if I may: food, supplements, as well as the sun. This not being the sun, but lights otherwise.

So, how do you put all that together? When there’s conflicting or unclear evidence, how do you actually decide what guidelines to have? This is a national report. It has some– Obviously, it has a lot of impact on a lot of people. So, how do you do that? And, once you do that, how do you implement that report? How do you implement those guidelines? So those are the kinds of questions we’re going to be discussing today, as well as those from the audience, and, as well, from some online questions through as well as through The Forum’s own site.

So, without any further adieu, let me introduce our four expert participants today. On my right, on video today, joining us from Ithaca, New York at Cornell is Patsy Brannon. Patsy is [a] professor in the Division of Nutritional Sciences at Cor­nell. She was a member of that Institute of Medicine IOM Committee that I mentioned, that reviewed dietary reference intakes for vitamin D and calcium. Welcome to Patsy.


IVAN ORANSKY: Thank you for joining us. And I want to mention one thing, and I’ve mentioned this to our panelists. I’m going to ask them, when they make some brief introductory remarks, just to let us know whether or not there are any conflicts of interest. I’m a journalist. I have to think about these things, because I also happen to think they’re important. And these, I’m really talking about financial conflicts of interest. And I think we all are comfortable with that, but I just wanted to make sure that we’ll just introduce that very briefly.

To my left is JoAnn Manson, who is a professor in the Department of Epidemiology here at the Harvard School of Public Health. She’s also Chief of the Division of Preventive Medicine at Brigham and Women’s Hospital. And she was also a member of that IOM Committee that I mentioned.

To JoAnn’s left is Bess Dawson-Hughes, who is a senior scientist and the Director of the Bone Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. She is a professor at Tufts and is also past President Trustee of the National Osteoporosis Foundation.

And finally, Walter Willett, who is Chair of the Department of Nutrition here at the Harvard School of Public Health, also the Fredrick John Stare Professor of Epidemiology and Nutrition. And I did want to mention that Dr. Willett has done a number of studies, as I’m sure we all know, and particularly the Nurses’ Health Studies, looking at dietary assessments, and obviously brings a great deal in that regard.



IVAN ORANSKY: So, welcome to our panelists. I wanted to start, Dr. Manson, if you could, with some remarks on your sense of the report, having taken part in it and in that committee, and where we are now, and your thoughts.

JOANN MANSON, PROFESSOR OF MEDICINE, HARVARD MEDICAL SCHOOL AND MEMBER OF THE IOM COMMITTEE: First I’d like to add my words of welcome, and thank The Forum organizers for inviting me to be here. I think it’s very important for everyone to understand that the Institute of Medicine Committee did a comprehensive and rigorous review of the evidence for both bone health and non-skeletal outcomes, the relationship to vitamin D.

We looked at a number of non-skeletal outcomes, including cancer, cardiovascular disease, diabetes, autoimmune diseases. Close to a thousand studies were evaluated. And the committee did conclude that there was compelling evidence that vitamin D has a role in maintaining bone health. And the recommended dietary allowances were based primarily on bone health. The recommendation for 600 IUs a day for ages one to 70 [years], 800 IUs a day for ages above 70 [years], are believed to cover the requirements for vitamin D, for bone health purposes, for at least 97.5 per­cent of the U.S. and Canadian population.

But, for non-skeletal outcomes, the types of outcomes that I mentioned, the evidence was found by the committee to be inconsistent, inconclusive, and not yet of enough– high enough quality to really inform the nutritional requirements for vitamin D. And I don’t have any financial conflicts of interest. I do have NIH funding to conduct vitamin D research.

IVAN ORANSKY: Great. Thanks Dr. Manson, setting the stage a little bit, in terms of what the guidelines say, what the report said. Dr. Dawson-Hughes, you were also part of that committee. Tell me about– Excuse me, you were not part of the committee. My mistake, in fact kicking myself as we speak, as we do at Reuters. Tell me, from your own work, your take on the guidelines.

BESS DAWSON-HUGHES, DIRECTOR, BONE METABOLISM LABORATORY, USDA HUMAN NUTRITION RESEARCH CENTER ON AGING AT TUFTS UNIVERSITY: Okay. Well, I believe there are many strong and positive features to the IOM report. I do take issue with several of the key tenets put forward in the report, specifically the choice of 20 nanograms per mL as the blood level of vitamin D that is associated with the optimum intake.

I believe that the evidence supports, very strongly, a higher figure of 30 nanograms per mL, based on the amount of [vitamin] D needed, and the circulating level needed, to lower risk of hip fracture, which is, of course, the main endpoint that everyone agrees with in the report.

There are a couple of other areas of substantial departure. One is the conclusion that– that there is little [vitamin] D deficiency, if any, in the United States, and that, therefore, supplements are not needed. If you use the lower cut point of 20 nanograms per mL as put forward by the IOM, the NHANES [National Health and Nutrition Examination Survey] report covering the period of 2000 to 2004 indicates that 30 percent of adults would meet– would be insufficient. If you used the, in my opinion, preferred 30 nanogram cut, then 70 percent would fall below that, okay.

The NHANES estimates include the use of supplements. And, since about a third of the population was using supple­ments at that time, were they, upon recommendation of the IOM, to stop taking them because they didn’t need them, then we would have a much higher prevalence of levels below both 20 and 30. So I see no safety issues. The IOM was perfectly on target, I thought, with raising the safety upper level from 2000 to 4000. So I think what I would put forward, if anyone were interested in later in this discussion, an approach that might marry the two strategies here, one for average-risk individuals, and another approach, a more measured approach, for individuals who are at high risk for having low vitamin D levels.

IVAN ORANSKY: Very good. And I wanted to ask Dr. Willett for his take in a moment. I just want to pull back one second and just sort of point out that, what we’re hearing is some of the, I think, very difficult work that the committee had to do, in terms of looking, not only at– you can’t simply come up with a recommendation based on, “This is how much everyone should have.” You actually have to decide what a low level is. What is deficiency? What is insufficiency?

And so, there are actually– You know, already we have two axes and a third, sort of, layer, if you will, of healthy people who are at risk, healthy people who are not at risk, and every permutation of that. So I just want to just sort of seed that a little bit, to, you know, make everyone understand just the difficulty that the committee had, and some of the issues we were grappling with. So Dr. Willett, your take.

WALTER WILLETT, CHAIR, DEPARTMENT OF NUTRITION, HARVARD SCHOOL OF PUBLIC HEALTH: Sure, thanks. And again, I have no conflicts. And I do appreciate the daunting task this committee had. There is a huge lit­erature on this that’s complicated. And probably what most people don’t appreciate, these committee members put in many evenings, many weekends, all for no pay. So there is a lot of–

IVAN ORANSKY: — It’s a reverse conflict of interest.

WALTER WILLETT: Right, yes. A lot of work that goes into this. And it’s a huge job, and gets bigger every year as the literature gets larger. I again totally agree that the raising of the so-called upper limit of safety, doubling that to 4000 IUs a day, was a good move in the right direction. And the committee acknowledged that even up to 10,000, there’s actually no evidence of any harm. And 4000 was being super safety, super safe.

I also, though, agree with Dr. Dawson-Hughes, that this adequate limit amount of 20 nanograms per mL is– is a low limit, and that the evidence actually supports that people would be better off with a higher blood level. Even if we fo­cused, just specifically, on bone health, as Dr. Dawson-Hughes said, the evidence is to get the– from randomized trials, to get the reduction in fractures with vitamin D, you need to get up to 30 mLs in the randomized trials. And people who took lower amounts of vitamin D, 400 or 600 IUs per day, did not have a reduction in fracture risk. And their level did not get up to 30 mLs.

And also, the committee was really pretty schizophrenic in using data from the National Survey of Vitamin D and Bone Mineral Density to set part of the– justify the calcium intake. But they totally ignored the much stronger, much more robust across all ages, all ethnic groups, and men and women, that people with blood levels of vitamin D well above 20, even above 30 nanograms per milliliter had better bone marrow density than people with 20 nanograms per mL. There is also the issue of other end points besides bone health. There is definite evidence confirmed in other systematic reviews that falls are reduced by vitamin D supplements. And that takes levels getting up to levels above 20 nanograms per mL.

And then, there is all this evidence, a huge body of evidence, that I agree with Dr. Manson, has not been confirmed by randomized double-blind trials. But, for colon cancer, for example, many very consistent studies showing about 50 percent lower risk of colorectal cancer with higher blood levels of vitamin D.

And, you know, I think it’s fair for the committee to say– I don’t agree with it– that you require randomized trials to make a recommendation. But a lot of confusion would have been avoided if the committee had, in their conclusions, had said something like, “There is a substantial amount of suggestive evidence of benefit with higher blood vitamin D levels. But it hasn’t been confirmed in randomized trials– not because the trials showed no benefit, because it hadn’t been done.”

And that’s a description of the evidence. Not that there’s no benefit, which sort of a reasonable person would assume that many studies have been done and showed no benefit. In fact, many studies have been done that have showed ben­efit, actually, but not by the randomized double-blind trials haven’t been done. So, I think that caused a lot of confusion.

And very often, in medicine and policy, we’re in situations where we don’t have all the final evidence. The studies that we’d really like to have sometimes are just not possible. Sometimes they may be many years in coming. And so, we’re almost always in a situation of operating on the best available evidence, not the perfect evidence.

And I think, if you look at the data, most reasonable people would conclude they’d want to have a blood level of 30 nanograms per mL when they look at mortality, when they look at fractures, when they look at colon cancer, many other conditions, rather than 20 nanograms per mL. I think we all agree more research needs to be done. But here today, we have to operate on the best available evidence.

IVAN ORANSKY: Thank you, Dr. Willett. And again, just to interject a tiny bit here, I want to pick up on a couple things that Dr. Willett was talking about, that I think will sort of– I want to percolate throughout the room, and throughout the panel as we continue talking today, sources of evidence, sources of data. Where are you finding the actual information that you’re basing results on? But also, the kinds of studies that were actually done.

We all can be comfortable with observational studies showing that there is a link, that there is a tie, that there is some­thing going on, we’re not quite sure what it is. We can’t prove, as Dr. Willett was suggesting, we can’t prove a cause/effect relationship, you know, comfortably, scientifically, until we’ve done that randomized control clinical trial. We’ve given some people vitamin D, various doses; other people don’t get it, etcetera. And again, that’s oversimplified. But, you know, what are we looking at? And where can we justifiably, and reasonably, come up with guidelines as the com­mittee did?

And finally, but certainly not least, I’m going to be looking at, here, Dr. Brannon, tell us your thoughts. And I understand that you’re involved particularly in implementation. But feel free to tell us your thoughts on the report.

PATSY BRANNON, MEMBER OF THE IOM COMMITTEE AND PROFESSOR, DIVISION OF NUTRITIONAL SCIENCES, CORNELL UNIVERSITY: Thank you. And I’d like to echo some of the comments that have been made, and make a couple of points that maybe haven’t been discussed yet. The first is that it’s true that you can find evidence in some studies of some benefit at levels higher than 20. You also can find evidence of benefit in some studies at con­siderably lower levels than 20.

So the difficulty is trying to take the totality of the evidence and look to see what it means, in terms of population distri­bution needs. And that was a challenge, particularly for vitamin D, because it’s very clear, from the data, that there is an interrelationship between the amount vitamin D that one is consuming, and the amount of calcium that one is consum­ing, in terms of bone health and perhaps other non-skeletal health outcomes.

So that you can find people that have very high levels of circulating vitamin D who have rickets. And you can find evi­dence of individuals with very low levels of circulating vitamin D who don’t have rickets. And what is likely the case is that that those with higher vitamin D are consuming inadequate amounts of calcium. And those with lower vitamin D are consuming maybe adequate- to above-adequate levels of calcium.

And, when you look at the studies, many of the studies don’t just give vitamin D alone. They give vitamin D with calcium. So, determining the independent effects of vitamin D and calcium are quite difficult. And I think that contributes, then, to what judgments one makes when one looks at the evidence. So that’s one point that I wanted to make.

In looking at bone health, we actually did an integrated bone health outcome. And we looked at a wide variety of evi­dence. And fracture risk was mentioned. Once you have evidence of causality, we looked at the observational studies, as well, to determine dose response. Because many times, randomized clinical trials do not give us sufficient evidence for dose response. They use a single dose, typically. And so, observational studies can be quite useful in that regard.

And again, when you look at observational studies for fracture risk, they vary from a level as low as 14 or 15 nanograms per mL to as high as above 35 nanograms per mL. So again, it’s difficult to determine that dose response.

And I’d like to make just a few comments about how much is too much. Because one of the real concerns that emerged, as we looked at relatively new evidence that suggested that there’s not just risk of harm at low levels of 25-hydroxy D, there is also risk of harm at higher levels. And this includes, for outcomes such as all-cause mortality, certain kinds of cancers, including colorectal cancer, and pancreatic cancer and prostate cancer, cardiovascular disease, and a number of other outcomes.

And one concern the committee had was an analysis that we did of the NHANES data. And we had data more recent than the data that was mentioned before by Dr. Dawson-Hughes. We had 2003-2006 data that had been corrected for the recognized technical difficulties in measuring 25-hydroxy D. And in those data, we looked at all-cause mortality in African Americans. And there, there was, again, evidence of this emerging U-shaped risk, as it’s been called. But the inflection point was actually below 30 nanograms per mL in that population. So again, there is reason to be concerned about where we set the level and how we make this determination among what is admittedly quite a range of evidence.


IVAN ORANSKY: Great. Thank you very much, Dr. Brannon. I think that’s a great introduction. If I can just pull– not so much, necessarily, the highlight of what you were saying, but one of the things that is difficult that has been coming up a little bit is that we are looking, not just at vitamin D, we’re looking at calcium. And obviously, we’re looking at all sorts of things. People who have high/low levels of vitamin D, there’s probably something else that they’re doing or not doing that is associated with that. Similarly calcium, I think, in broad strokes, we can sort of agree on that.

And so, calcium. Got to think about that as well. So, I see a lot of issues for discussion in the– in the time we have today. Vitamin D and calcium. Should people be getting tested for levels? In other words, if we’re talking about guidelines for how much to consume or get from the sun, etcetera, should we be starting by testing levels? I think there are– Actu­ally, I know that there are a number of internists who do that, of primary care physicians who do that. Should people be doing that? How much should people be eating? What kinds of sources should they be getting their vitamin D from? All kinds of issues.

Let’s maybe start with, should people be getting tested? We have some disagreement over whether it should be 20 nanograms, right, or 30 nanograms. But, if we can agree for a moment that there is a number, should people be getting tested? Or, do we have to agree, first, that there is a number?

JOANN MANSON: First, partially in response to that, I do want to make the point that the RDAs are population, public health recommendations, which is very different from a medical model of whether a clinician would decide that they want to test an individual patient’s vitamin D level. They have risk factors, clear risk factor[s] for vitamin D deficiency. They may have malabsorption syndrome. They may already have osteoporosis and many clinical conditions, where very close monitoring would be indicated.

On a population-wide basis, even though it really wasn’t the charge of the IOM Committee to make recommendations about screening, it was the view that wide-scale screening really was not indicated. That, depending on what you con­sider to be vitamin D deficiency versus insufficiency, we did not agree with many of the cut points that were being used by clinical labs. We did not consider them evidence-based.

The view was that vitamin D sufficiency or adequacy was at a level of 20 nanograms. And that’s what the committee decided, based on a very large amount of evidence, looked very, very closely at several studies. And there was not this clear dose response, where suddenly, when you get to 30 nanograms, you start to see benefit.

Many of the studies suggested a threshold at around 20 nanograms, where there was not only no greater benefit, in terms of bone health or other outcomes, some of the non-skeletal outcomes, there was no greater reduction and risk as you got above 20 nanograms. But, as Dr. Brannon mentioned, you began to see a suggestion of a U-shaped curve, where there was actually an indication of increased risk.

So the committee definitely ha[d] wanted to propose a higher intake if we felt that that was safe for the population. But you have, when you’re talking about public health recommendations that are long-term, chronic, 20, 30 years potentially, the level of evidence for the safety of long-term intake of very high dose vitamin D, or even maintaining a blood level at 30 nanograms or 40 nanograms, the evidence was just not there.

Yet, the evidence was quite strong that, at 20 nanograms, you had bone health, an evidence of a plateau, even in terms of the PTH level. There was a suggestion that the level–

IVAN ORANSKY: PTH? Parathyroid–

JOANN MANSON: The parathyroid hormone, which is often used as a guide to what is the optimal 25-hydroxyvitamin D level for bone health, where you start to see no further decline in the PTH level as you increase vitamin D. We saw the plateau of the PTH level across a very broad range, including many studies were showing the PTH level plateaued at below 15 nanograms. A large number plateaued below 20 nanograms, and some higher. But it was not consistent.

So the evidence was really quite inconsistent that getting above 20 nanograms would confer greater benefits for either bone health or falls. In fact, a recent study suggested that frailty risk increases as you get above 30 nanograms at the optimal level for frailty, was 25-hydroxyvitamin D, between 20 and 29 nanograms.

The evidence was actually quite inconsistent. And the committee looked very, very carefully. And we certainly would have been more than happy to have recommended a cut point of 30 nanograms if we thought that that was safe and evidence-based for the population as a whole, and that we could, at this point in time, say that the population can go ahead, get their– strive for a level of 30 nanograms, take 2000, 3000, maybe even 4000 IUs a day, which many people in the general population would require to get to that threshold of 30 nanograms.

Because there is actually an enormous difference between the amount of vitamin D required to get to 20 nanograms and the amount required to get to 30 nanograms. There’s almost a physiological response, where you very quickly, with even a relatively small amount of vitamin D, will get up to the 20 nanograms. But to get to 30 nanograms, you may require well above 2000 or 3000. We did not think that there was enough evidence for safety to recommend that, long-term.

BESS DAWSON-HUGHES, PAST PRESIDENT AND TRUSTEE, NATIONAL OSTEOPOROSIS FOUNDATION: The issue of the 20 versus 30, I mean, we could go on almost indefinitely on that. I think that a practical and reasonable approach, U.S., should people be measured, etcetera, I would approach that as follows: If you are at average risk for having a low 25-hydroxy D level, then take 800 units or 1000 or some number that is reasonable, no need to measure.


IVAN ORANSKY: And sorry to interrupt, but how would you know– how would a particular person know or population know that they were at risk?

BESS DAWSON-HUGHES: Right. If you’re at high risk, there is another approach. Now, who are the high-risk people? That would be people who are obese, people with very dark skin, people who do not spend regular time out of doors, in the sun, individuals who habitually wear sunscreen before they go out, those who are dressed in protective clothing, individuals with osteoporosis, those with malabsorption, individuals taking medications for seizure disorders, which accelerate the metabolism. So that’s an example of people who would be at higher risk for having a low 25-hy­droxy D level. And, when you think about it, that’s a large segment of the U.S. population.

IVAN ORANSKY: So you’re talking about, sort of almost dividing the population.

BESS DAWSON-HUGHES: Right. And you can make that clinical assessment as an individual or as a healthcare provider. If you identify someone as being at high risk or at reasonably increased risk, I think it’s reasonable to measure their 25-hydroxy D level to supplement with the dose that you can estimate– we can talk about the formula– but you can estimate how much they will need, replete them with that, wait three months with them on that dose, and then repeat the measure to ensure that you have achieved your goal, whether your goal be 20, 25, 30, or 40.

So, I think restricting the measurements to the high-risk people is appropriate. And I think it’s good use of healthcare resources, because of the very high potential for benefit in correcting D insufficiency.

WALTER WILLETT: Yeah, I think that’s a very reasonable approach. And I would just add that Dr. Dawson-Hughes was, I believe, part of a committee from [the] National Osteoporosis Foundation that looked at this, had very extensive discussions about an approach, which I think is reasonable.

But, and I’d like to point out that, even if you take the IOM very low bar, which I disagree with, of 20, there is still, in that report, 11 percent of the European-American population, 54 percent of the African-American population, below that level. And that’s tens of millions of Americans below that level. And, to ignore them and say it’s no problem is a big mistake.

And you would want to know if you are below that level, or do something about it. And I think this strategy of– I don’t– I agree, also, that going out and blood testing everybody will add a whole lot to medical care cost, and I think is not necessary. Which is why I think, sort of, separating the population into two components is a reasonable way to go. And those numbers, again, of 11 percent of European-Americans, 54 percent of African Americans, is very low. The more recent data show 30 percent of Americans below that level.

I’d also like to point out that the statistical method used by the committee was completely flawed in determining the dose. Because they plotted it all on a figure, fit some fancy curves through it. But those data points were for population means, not for individuals. So, even if the population mean is at a– you would attain, on average, with a certain dose, still 50 percent of the population is going to have a blood level lower than that average. And that really needs to be considered carefully. There is a big spread, as I think several people have pointed out, for any given dose, a big spread in the blood levels that you’ll find if you actually measure them.

IVAN ORANSKY: Dr. Manson, I saw you–

JOANN MANSON: Yes. I think a really key point is that the IOM guidelines, these public health recommendations do not preclude the clinical decision-making based on risk factors. As both of you have mentioned, I think that is extremely reasonable for patients who are a higher risk, individuals in the population who have a number of risk factors for vitamin D deficiency, to be screened by their clinicians, to be treated with high dose vitamin D, to be monitored closely.

But the charge of the IOM Committee was the public health recommendations. And these are two very different models, the medical model and the public health guideline model. But they are compatible with one another. So I don’t think that the IOM guidelines were neglecting any segment of the population. In fact, we were quite concerned about the seg­ments of the population that might have vitamin D deficiency. And a large percentage of the report is dedicated to risk factors for vitamin D deficiency, what to do in terms of people who have these risk factors. And it was certainly consis­tent with screening members of the population who were at high risk. It was just not a population-wide recommendation.

IVAN ORANSKY: Dr. Bess Dawson, I just want to mention that we will be taking questions. [simultaneous conversation]

JOANN MANSON: And I think Dr. Brannon, also.

IVAN ORANSKY: Dr. Brannon’s got something else, so I’m going to– Dr. Bess Dawson[-Hughes], then Dr. Brannon.

BESS DAWSON-HUGHES: The hitch comes in the IOM’s conclusion that 97.5 percent of the population will be served by 600 to 800 units, when the proportion of the population that is at high risk for low D levels is far greater than two and a half percent, as you would know if you looked down a list of [at-risk groups, such as those who are] obese, dark skinned, etcetera. We’re talking about a large segment of the population.

IVAN ORANSKY: Okay. Dr. Brannon.

PATSY BRANNON: Yes. And I would like to comment on that, and clarify some aspects of how we approached doing our simulated dose-response that address a few of the concerns that have been raised. First of all, we assumed minimal sun exposure. We had the benefit of several studies that were done in the winter at extreme northern latitudes, or in Antarctica.

Under those conditions, one can assume that very little vitamin D is being endogenously produced. And, therefore, our recommendations are fully applicable to individuals in the population, irrespective of their skin color and pigmentation.

WALTER WILLETT: That’s misleading. That wasn’t individuals, that was population averages that were used in that analysis.

PATSY BRANNON: It was population averages. And I would like to address that and explain how we did it. Because we actually used our simulated dose-response curves quite conservatively. And, if you’ll look, you’ll see that we chose to “overshoot” the achieved levels. And we did that because of the variability and because we did not have the same kind of population estimates.

These were all randomized clinical trials and, in most cases, were quite small numbers of individuals in the randomized clinical trials that we used for the simulated dose response. The issue then came that some gave us means, some gave us medians. And a number of the studies did not give a kind of estimate of the variance that would have allowed us. If they’d all given us standard deviation, we could have addressed your specific concern somewhat more to our liking, as well. But we were able– They were the data that we had, and the only data that we had available to us, that allowed us to simulate the dose response.

We therefore overestimated, because we knew there was a hint in the data that we had, which was limited, that there might be more variability in older individuals. And so, at the level of 600 and 800 international units, it actually achieves, at the lower predicted confidence intervals, serum 25-hydroxy D levels that are closer to 25 nanograms per mL, rather than 20 nanograms per mL. And we did that because we’re cognizant of the need to protect the public health.


IVAN ORANSKY: Thank you Dr. Brannon. I want to take some questions, now, from the audience. And I believe we have our first question. And please introduce yourself and just let us know who you are when you speak. And there is a mic circulating for those of you who may not have lavalieres, which I think is most of you. So please make sure to identify yourself, and we’ll get to you.

LILIAN CHEUNG: I’m Lillian Chung, editorial director of the Nutrition Source, Harvard School of Public Health nutri­tion website. And thank you, all the experts, for this very important discussion. And my question to you is, if you were in charge of implementing public health policies in school districts, what is one message that you should be giving to the schools and to parents about vitamin D?

JOANN MANSON: Well first, I think it’s very important to understand the dietary sources of vitamin D. So the key di­etary sources would be the fortified dairy products, fortified cereals and juices, and fatty fish. There is some vitamin D in eggs. But those are the main dietary sources. Also mushrooms, some forms of mushrooms.

IVAN ORANSKY: Kids probably won’t be getting much from the mushrooms. [laughter]

JOANN MANSON: Right, right, exactly. So, I think that that’s very important. And also, as Dr. Brannon was mention­ing, that we’re not recommending increasing sun exposure for the purpose of getting adequate vitamin D, because for someone who doesn’t get enough, it is possible to take a supplement without the risk of skin cancer. However, younger, you know, children do get much more sun exposure than adults, in general. So they’re more likely to have that endog­enous component if they are outdoors.

So, I think that it is very important to consider the dietary sources and to ensure that the school lunch programs and, you know, the diets of children do have adequate vitamin D intake through these sources. And I think an increasing number of foods will be fortified with vitamin D. The labels have to be read, and children aren’t likely to do that.

IVAN ORANSKY: Dr. Brannon.

PATSY BRANNON: Yes. And I’d like to follow up on Dr. Manson’s comments, because if a child is following the recommendations in my pyramid and the dietary guidelines, especially with the new recommendations for seafood consumption twice a week, and that seafood is either salmon or tuna, and up to one ounce a day of their grains is be­ing consumed from a fortified grain, it’s actually possible to get very close to the 600 international units that are being recommended.

WALTER WILLETT: Although grain is not fortified, routinely at present. And the actual survey data show that almost no Americans get up to 600 IUs of vitamin D per day. And kids are, if you look at the national data, coming nowhere close to my pyramid. And they’re not going to, in my lifetime, just given that we’ve worked hard and made almost no change over the last 30 years.

So, I think it’s totally reasonable for children to take a supplement of vitamin D. At the– not a mega dose, just at the level of 600 IUs per day, which–

IVAN ORANSKY: It looks like there’s some agreement on that, more or less.

PATSY BRANNON: And actually, the American Academy of Pediatrics recommends 400 international units a day of supplemental vitamin D for all children through age 18.

WALTER WILLETT: Yeah, I think it’s a good recommendation.

BESS DAWSON-HUGHES: Just a technicality regarding fatty fish. And that is that farm-raised salmon are not feeding on planktons, which are the source of vitamin D in wild salmon. And so, you will not actually see a whole lot of vitamin D unless they start fortifying the salmon food. Now that would be an idea.

IVAN ORANSKY: I think we can have another panel on the fortification of the salmon. But that’s a good point and thank you.


IVAN ORANSKY: Questions? I believe there is one in the back.

PAT SKERRETT: Hi, my name is Pat Skerrett. I’m the editor of the Harvard Heart Letter and an occasional writer about nutrition. Something that several of the panelists and other nutrition experts stress is the importance of food. You can’t get your vitamins from a vitamin bottle because we don’t know all the vitamins that are in food and how they interact and how they work together. How does that apply to sunlight and vitamin D? We talk about fortification. Is there any evidence, at all, that when your body is converting– using sunlight to make vitamin D, it’s doing other things that may also be contributing to the healthful pathways?

JOANN MANSON: We actually looked at that question. There was some interest in whether results would be different according to the source of the vitamin D, endogenously synthesized versus exogenously taken supplements or through food. And we really could not find any clear evidence that there was a distinction, though it is an important issue.

And there are some studies suggesting that sun exposure may have some effects on the immune system that may be of relevance. But it was certainly not evidence to the point where we could make a recommendation to increase sun exposure, which is classified as a carcinogen, has been linked to an increased risk of skin cancer, and to go that route rather than trying to get the vitamin D through foods or supplements.

IVAN ORANSKY: Other thoughts on that?

PATSY BRANNON: And if I could comment, as well, I think it’s clear, from the latest NHANES data, the 2003-2006 data, as Dr. Willett said, most Americans aren’t consuming the recommended dietary allowance of 600 or 800 inter­national units. And yet, they are achieving the 25-hydroxy D levels linked to those consumptions. And the inference is, quite strongly, that they are getting incidental sun exposure despite our recommendations that everyone use sunscreen and avoid sun exposure.

So that’s a piece that we really thought needed much more research. And we really do need to understand the poten­tial benefit of sun exposure. And the question really is, is there [an] amount of sun exposure that will provide sufficient amounts of vitamin D and not increase the risk for skin cancer? And we really don’t have data to answer that question.

IVAN ORANSKY: I believe we have another question. Here.

JAY WINSTEN: Hi, Jay Winsten from the School of Public Health. A question for Dr. Manson, kind of having to do, re­ally, with the philosophical underpinning and approach of the IOM’s recommendation and the charge to the committee. Earlier in your remarks, you made a clear distinction between the public health model and public health recommenda­tion, on the one hand, and clinical medical approach on the other.

But, wouldn’t a population-wide recommendation for a high-risk population be a public health recommendation? And, why would you think of that as outside the domain of public health? Just because we’re not talking about the means? Couldn’t the charge to your committee be a public health recommendation for the mean, and then for the high risk?

JOANN MANSON: Well, we did include, in the public health recommendations, chronic conditions that were very prev­alent in the population. So our public health recommendations do apply to overweight and obese individuals, though there certainly will be some individuals, a clinician will make a decision, you know, to screen for vitamin D and treat with higher doses. But, we did not exclude overweight or obese individuals from our recommendations.

And, as Dr. Brannon mentioned, because we had the assumption of minimal sun exposure, the skin pigmentation issue, living at higher latitudes, winter months, were not key factors in the amount of vitamin D recommended, because we were already addressing that there would be very minimal endogenous vitamin D synthesis.

So, we did believe that the recommendations of the 20 nanogram cut point, and then 600 to 800 IUs a day, would cover the needs for a large swath of the entire U.S. and Canadian population. But again, this still allows for clinical judgment and the discretion of the clinician in making decisions on a case-by-case basis.

IVAN ORANSKY: We have more questions from the audience.


WALTER WILLETT: Just maybe while we’re waiting, I wanted to come back to that safety issue, that of course, Dr. Brannon raised, that you can take too much of virtually any vitamin or any mineral, and you’ll get toxicity. So there’s no question you can overdo vitamin D. But, the levels, blood levels that we’re talking about, 30 or even 40 nanograms per mL, that there is no evidence of harm there. Or again, the vitamin amounts that we’re talking about are well within the upper limit of 4000. Even 4000 is safe And, if you look at the– I think the committee really overblew the safety issue, in an imbalanced way. Of course, we wanted to pay lots of attention– We have to be double careful about that. But the same study that was quoted, the NHANES study, is suggesting a U-shape. In fact, it wasn’t a U-shape. It was a big inverse relationship with higher blood vitamin D level and lower mortality, a little tiny blip at the end, maybe, that wasn’t even statistically significant.

But, if you take that same data, people with 40 nanograms per mL or 30 nanograms per mL have substantially lower total mortality than people with 20. It was a direct linear relationship overall, wide part of the dose response curve. And, you know, we should pay attention to the very high end. I agree with that. But again, the levels that we’re talking about, intake, are well within the range of safety.


JOANN MANSON: Yes. There were a number of studies that suggested a U-shaped curve and some concern. It was not just the NHANES study. There was also a bone health study from the Women’s Health Initiative, looking at African-American and white women, where there was a suggestion that the optimal 25-hydroxy D level for the African-American women was at a lower level, and a significant increase in the risk of fracture at levels getting above that 20 nanogram cut point. That was one thing.

There was some evidence for pancreatic cancer of increased risk in some studies at higher levels, even though that has been controversial. Some other studies have not shown that. There was concern about aortic vascular calcification at higher blood levels of 25-hydroxy D. There was another all-cause mortality study beyond the NHANES one, suggesting this inflection and some increased risk.

IVAN ORANSKY: What is that, sort of, point that you’re talking about? And they may not have been consistent.

JOANN MANSON: Yeah. As you got– with some of these other studies, it was even at 20-25 nanograms.

IVAN ORANSKY: So we’re not talking about– [simultaneous conversation]

WALTER WILLETT: I disagree. I would have to go over that. It was much higher, up by 40 or 50. [simultaneous con­versation] And virtually all the other literature, too.

JOANN MANSON: NHANES? Yeah. That’s the NHANES all-cause mortality. That was at a higher level. But there were other studies, including the bone health, the pancreatic cancer. We looked very, very carefully. This was one of the reasons why we didn’t just decide, “Go with 30 nanograms because there is no increased risk that we can identify. And it would cover those people who might otherwise not get enough at 20 nanograms.” There was concern that, if you make a public health recommendation, get 30 nanograms, there might actually be some segment of the population at increased risk at that level.

BESS DAWSON-HUGHES: With all these concerns, I would rather wonder why 4000 units was considered safe.

JOANN MANSON: 4000 units is not a target level. And it’s really important to understand that the RDA and the toler­able upper limit, upper intake level, do not provide a range of safe intake. The point is that, at 4000 IUs a day, or at a level of 50 nanograms, there was already evidence of adverse events. There was already evidence in the literature of the adverse events. And, there is very little research; there is very little literature about the long-term safety of levels that are above the RDA in that range of the RDA to the tolerable upper intake level. And so, we do not recommend that you just take up to the tolerable upper intake level or use that as a target level.

WALTER WILLETT: That’s not what I read in the report, that it said there was no evidence of 4000, even no evidence up to 10,000.

JOANN MANSON: We’re talking about acute toxicity. Acute toxicity is very different from the long-term– [simultane­ous conversation]

IVAN ORANSKY: I think we can agree that there is some disagreement. [laughter] I know we have a couple questions, at least a few questions, several questions from online people who couldn’t be in the room with us. And I want to just get to a couple of those.


ROBIN HERMAN: Hi, I’m Robin Herman. I’m the director of The Forum. And we’ve got a slew of questions from our online audience. And, as you would expect, a number of people are asking how does this information apply to me? They’re concerned whether they’re in a risk group. So I’m just going to read you three questions, and maybe you could answer for each of these people, even though it’s been touched on, maybe they didn’t catch that.

One question is from Kristine Niles, who is at the University of Alaska in Fairbanks. And she is saying, “Please address vitamin D requirements in far northern regions, where there are very cold climates and not much opportunity for sun­shine for approximately six months of the year.”

IVAN ORANSKY: Even further north than Ithaca, Dr. Brannon.

ROBIN HERMAN: Right. And then, here is one from Julie Smith in Nova Scotia. She is a junior high school teacher. She said, “Last year a student who was working on a vitamin D study asked whether wearing sunblock would prevent skin’s absorption of the vitamin D that naturally occurs in sunlight. I still remain stumped.” So I think you can help her there.

And then, lastly, another question. Many women who observe modest dress and keep themselves covered, what kind of vitamin D should they add to their diet?

IVAN ORANSKY: So sort of, if you will, places or people who are not getting the kind of sun that, even again in Boston or New York, where I am, you’re getting. Recommendations? Suggestions?

JOANN MANSON: Well sunscreen does– [simultaneous conversation]

PATSY BRANNON: So I might feel that the recommended dietary allowance of 600 to 800 covers those individu­als, even in Alaska, because the studies that we looked at were at very high northern latitudes, 50 degrees north or in Antarctica, in full darkness. And the same would be true for clothing.

The issue of sunscreen is a very good issue. We don’t have a lot of data. There is at least one study that was done in Australia that suggests that, with appropriate amounts and repeated application of sunscreen, that there could be some endogenously synthesized vitamin D. But we really don’t know enough about that to say anything conclusively right now. It’s one of the areas where we need further research.


BESS DAWSON-HUGHES: There were several questions related to, how can I, as an individual, categorize myself or classify myself in terms of risk? And I think it’s worth maybe repeating some of those risk factors. One is being overweight or obese. These individuals will have ambient lower levels and will have smaller increments in response to supplementation. Dark-skinned individuals will produce less vitamin D in their skin with sun exposure of a fixed amount of time. And so, they tend to be lower. Individuals with ineffective sun exposure– that is, the sunscreen users, the people out with protective clothing, etcetera. Individuals with malabsorption. Those on–

IVAN ORANSKY: Malabsorption, I should have got this earlier, but just maybe explain.

BESS DAWSON-HUGHES: Expand a little bit on that. That would be, for example, individuals with celiac sprue that’s not well controlled, individuals with inflammatory bowel disease who may have had much of their distal small bowel removed. That’s where much of the vitamin D is absorbed. So they would be tending to malabsorb vitamin D.

IVAN ORANSKY: So, these are people who would be eating a lot– taking a lot of this in–

BESS DAWSON-HUGHES: — and not getting appropriate step-up in the blood level. Individuals on anti-seizure medications, which causes the liver to metabolize vitamin D more rapidly and, therefore, lowers the level. Individuals with osteoporosis. In our osteoporosis clinic, we will see, almost uniformly across these patients, low initial 25-hydroxy D levels. So that’s kind of a starting list. And you can self-identify using most of those.

IVAN ORANSKY: You know, I still remember working on a story, a number of years ago, now, the Orthodox Jewish Community in Brooklyn, where children were actually developing rickets. This is a disease that we supposedly don’t know from anymore. And yet, there they were. And there was a pediatrician in the community who was working with families to try and– Obviously, this was a sun exposure problem, very modest dress in particular.


IVAN ORANSKY: Were there other questions from the audience?

EKATARINA MOSLOVA: Hi, I’m Ekatarina Moslova. I’m a doctoral student in the Department of Nutrition. And this is a question for Drs. Willett and Dawson-Hughes. How you would have approached this problem if you were on the com­mittee, in terms of focus, emphasis, or analytical strategy. [laughter]

JOANN MANSON: Thank you for the question. [laughter]

BESS DAWSON-HUGHES: You’ll find yourself on the committee, the next one. [laughter]

WALTER WILLETT: Well, maybe I’ll have to buy some drug company stock and keep myself off the committee. [laugh­ter] But it is a challenge. I think a lot of this is how the findings were communicated. I think if there had just been a more straightforward description of the conclusions, it would have solved a lot of the– avoided a lot of the confusion.

Again, you know, we can look at the evidence. Different people can interpret it different ways. I think there were some serious flaws in the report, including the estimation of the required dose, even to get you to 20 nanograms per mL. But I think, again, even [if] you accepted the bar was at 20 nanograms per mL, I think expressing the– instead of concluding that there was no benefit with higher amounts, that honest and, I think, accurate description is there is lots of evidence of benefits with higher blood level of vitamin D. Those haven’t been proven by randomized control trial. We clearly need more research in that area. I think everybody agrees with the need for more research.

But it was expressed as sort of a cut-and-dry issue. And, in reality, there is a lot of uncertainty. And people can make different individual choices based on whether they want to wait for randomized double-blind control trial, or go with the best available evidence.

IVAN ORANSKY: And this is something that– we’ll get Dr. [Dawson-]Hughes in a second– Something that has come up before in the presentation of the guidelines, if you will, the communication of them, I know that there was a Forum event in the fall about mammography, breast cancer screening, which one of my former colleagues took part in.* And that, again, a lot of the criticism was about– There was plenty of criticism about the report. A lot of the criticism, however, was about the communication of those guidelines. So, I think that’s something to thread here, that maybe we should pay attention to.

*[Editor’s Note: The Forum event, Mammograms: Who in the world are they good for?, took place on March 8, 2011, and can be watched at The Forum event, The Impact of the 2010 Elections on U.S. Healthcare Reform, was presented in collaboration with Reuters on November 5, 2010. The on-demand video is at Maggie Fox, who was a health and science editor at Reuters, moderated that event.]

BESS DAWSON-HUGHES: Yeah, I agree. And I think it was categorical in the intakes required for 97.5 percent of the population, when a large proportion of our population is at risk for low levels. So, I think more careful attention to that allowance would have been a favorable approach.


IVAN ORANSKY: Other questions from the audience? I believe we have one in the front here who’s going to wait one moment while the mic gets to you, if you wouldn’t mind.

MEIR STAMPFER: Meir Stampfer, Department of Epidemiology here at Harvard School of Public Health. I’ve read the same papers and come to a pretty different conclusion from the IOM, which leads me to take 3000 IU per day. But I wanted to push Dr. Brannon, and maybe JoAnn a bit, on this risk side of the equation. Would you feel that, if you found yourself with a level above 20, that you should take measures to lower your vitamin D level? Are people putting themselves at risk if they, for whatever reason, metabolism, or being out in the sun, they have a level of 30, should they take action to put themselves at the lower level?

IVAN ORANSKY: Dr. Brannon?

PATSY BRANNON: Well, I would say that, when we looked at this emerging evidence, although there is a range of lev­els of 25-hydroxy D, at which this emerging risk at the higher levels is seen, the concordance of, albeit limited evidence right now, is around 50 nanograms per mL. And that’s the level that we linked the tolerable upper levels.

So I would say to somebody, if your level is between 20 and 49, I don’t think that I would particularly worry about that myself very much. Although there were 14 of us on the committee. And, I think if you asked each one of us, you would get a different answer. And that’s a segue to hear Dr. Manson’s answer. [laughter]

JOANN MANSON: Well, I do think many members of the committee would have disagreed, because the point was made, very clearly, that it was not a range of intake that would be considered recommended, anywhere between 20 and 49. But rather, once many of the studies were suggesting that, even once getting to 30 nanograms, there were a few outcomes that looked like an increased risk. And then, there was no consistent evidence of greater benefit between 20 and 30 nanogram.

So I would say, if you are taking 3000 IUs a day, or 4000 IUs a day, and your blood level is 40 nanograms, that you may want to just be aware of the evidence, the conclusion of the Institute of Medicine Committee, that there was not consistent evidence of greater benefit above 20 nanograms. And there were concerns about some risk for a number of outcomes even in that range of 20 to 49. And then, once you get to 50 nanograms, some real concern about adverse events. So, I would leave it at that.

IVAN ORANSKY: Other questions from the audience? Well, thank you all very much. I want to thank our panelists, who are terrific and really, certainly, a spirited debate which I expected and appreciated. Dr. Patsy Brannon, Dr. JoAnn Manson, Dr. Bess Dawson-Hughes, and Dr. Walter Willett, please a round of applause for them.


IVAN ORANSKY: That concludes today’s Forum, Harvard School of Public Health Forum, in collaboration with Reuters on Boosting Vitamin D. Thanks very much for those of you who have been paying attention at home, watching us, and will hopefully watch us in the archive. And thanks very much. Take care.



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‘Universities nurture the hopes of the world: in solving challenges that cross borders; in unlocking and harnessing new knowledge; in building cultural and political understanding; and in modeling environments that promote dialogue and debate… The ideal and breadth of liberal education that embraces the humanities and arts as well as the social and natural sciences is at the core of Harvard’s philosophy. ’/ Drew Gilpin Faust

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* The above story is adapted from materials provided by Harvard University

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