Tuesday, November 30, 2010

Vitamin D in the news

The report from the National Academies (it's behind a paywall, so I'm not going to waste your time by linking to it) on vitamin D and calcium has been in the news today.

What's surprising is that the headlines are so very different.  Okay, that's not really surprising, given the poor quality of writing, reading, and investigation that passes for journalism in this country.

WaPo:  New vitamin D recommendations

Bloomberg: Vitamin D, Calcium Supplements Are Unnecessary, Study Finds

WSJ: Triple That Vitamin D Intake, Panel Prescribes

AP: Report: A bit more vitamin D is good, not too much

NPR: Medical Panel: Don't Go Overboard On Vitamin D

USA Today: Most getting enough calcium, vitamin D, report says

Science News: Vitamin D targets increased

NYTimes: Report Questions Need for 2 Diet Supplements

WebMD: Guidelines Call for Increase in Vitamin D

What's going on?

Well, as I said, not very many of these reporters seem to be reading their scientific sources very well.

At the bottom is the actual news release from the National Academies.  I was able to find a poor-quality scan of the report that isn't behind a paywall.  There is also a report brief here.

From that, here's the table for recommended total calcium and vitamin D intake:




To be honest, about all the news organizations had to report to do a good job was the new recommended intake for both calcium and vitamin D and the fact that girls 14-18 are not getting enough calcium.  Instead, most of them misinterpreted the report or the NAS news release in favor of some over-the-top scare headlines.

Grades:
WaPo:  C- (missed the conclusion that girls 14-18 are not getting enough calcium)
Bloomberg: D- (misinterpreted the report and concluded that people should stop taking supplements)
WSJ: (Headline is misleading, reports that infants should be receiving 600 IUs, ignored calcium)
AP: C- (Headline is appropriate, missed some important conclusions, ignored calcium)
NPR: C- (Appropriate headline, ignored calcium, missed important conclusions)
USAToday: B- (hit the highlights, gave too much voice to people who advocate way too much D)
Science News: D- (fine headline, but then spent most of the article quoting people who advocate too much D, ignored calcium)
NYTimes: F I can't read the article because of their registration wall.  Their headline is flat-out wrong.
WEbMD: B (hit the highlights, decent headline)




News from the National Academies
Nov. 30, 2010

FOR IMMEDIATE RELEASE

IOM Report Sets New Dietary Intake Levels for Calcium and Vitamin D To Maintain Health and Avoid Risks Associated With Excess

WASHINGTON — Most Americans and Canadians up to age 70 need no more than 600 international units (IUs) of vitamin D per day to maintain health, and those 71 and older may need as much as 800 IUs, says a new report from the Institute of Medicine.  The amount of calcium needed ranges, based on age, from 700 to 1,300 milligrams per day, according to the report, which updates the nutritional reference values known as Dietary Reference Intakes (DRIs) for these interrelated nutrients. 

The report's recommendations take into account nearly 1,000 published studies as well as testimony from scientists and stakeholders.  A large amount of evidence, which formed the basis of the new intake values, confirms the roles of calcium and vitamin D in promoting skeletal growth and maintenance and the amounts needed to avoid poor bone health.  The committee that wrote the report also reviewed hundreds of studies and reports on other possible health effects of vitamin D, such as protection against cancer, heart disease, autoimmune diseases, and diabetes.  While these studies point to possibilities that warrant further investigation, they have yielded conflicting and mixed results and do not offer the evidence needed to confirm that vitamin D has these effects.  Rigorous trials that yield consistent results are vital for reaching conclusions, as past experiences have shown.  Vitamin E, for example, was believed to protect against heart disease before further studies disproved it.

"There is abundant science to confidently state how much vitamin D and calcium people need," said committee chair Catharine Ross, professor and Dorothy Foehr Huck Chair, department of nutritional sciences, Pennsylvania State University, University Park.  "We scrutinized the evidence, looking for indications of beneficial effects at all levels of intake.  Amounts higher than those specified in this report are not necessary to maintain bone health." 

The science on calcium's role in bone health shows that 700 milligrams per day meets the needs of almost all children ages 1 through 3, and 1,000 milligrams daily is appropriate for almost all children ages 4 through 8. Adolescents ages 9 through 18 require no more than 1,300 milligrams per day.  For practically all adults ages 19 through 50 and for men until age 71, 1,000 milligrams covers daily calcium needs.  Women starting at age 51 and both men and women age 71 and older need no more than 1,200 milligrams per day. 

As for vitamin D, 600 IUs daily meets the needs of almost everyone in the United States and Canada, although people 71 and older may require as much as 800 IUs per day because of potential physical and behavioral changes related to aging. 

The majority of Americans and Canadians are getting enough vitamin D and calcium, the committee determined from reviewing national surveys of blood levels.  Some adolescent girls may not get quite enough calcium, and there is a greater chance that elderly individuals may fall short of the necessary amounts of calcium and vitamin D.  These individuals should increase their intake of foods containing these nutrients and possibly take a supplement.

Confusion about the amount of vitamin D necessary to ward off deficiency has arisen in recent years as tests that measure levels in patients' blood have become widely used.  The measurements of sufficiency and deficiency — the cutpoints — that clinical laboratories use to report test results have not been based on rigorous scientific studies and are not standardized.  This lack of agreement means the same individual could be declared deficient or sufficient depending on which laboratory reads the test.  There may be an overestimation of the number of people with vitamin D deficiency because many labs appear to be using cutpoints that are higher than the evidence indicates are appropriate.  Based on available data, almost all individuals get sufficient vitamin D when their blood levels are at or above 20 nanograms per milliliter as it is measured in America, or 50 nanomoles per liter as measured in Canada

Although sunlight triggers the natural production of vitamin D in skin and contributes to people's vitamin D levels, individuals' sun exposure varies greatly and many people are told to minimize their exposure, so the committee assumed minimal sun exposure to establish the DRIs.  The new intake levels for vitamin D cover the needs of individuals who get little sun. 

Greater amounts of food fortification and rising rates of supplement use have increased the chances that people consume high amounts of these nutrients.  Getting too much calcium from dietary supplements has been associated with kidney stones, while excessive vitamin D can damage the kidneys and heart.  Evidence about other possible risks associated with routine vitamin D supplementation is still tentative, and most studies have focused on very high doses taken short term rather than on routine, long-term consumption of large amounts.  However, some signals suggest there are greater risks of death and chronic disease associated with long-term high vitamin D intake, which informed the committee's conclusions about levels that consumers should not exceed. 

Upper intake levels represent the upper safe boundary and should not be misunderstood as amounts people need or should strive to consume.  The upper intake levels for vitamin D are 2,500 IUs per day for children ages 1 through 3; 3,000 IUs daily for children 4 through 8 years old; and 4,000 IUs daily for all others.  The upper intake levels for calcium are 2,500 milligrams per day from age 1 through 8; 3,000 milligrams daily from age 9 through 18; 2,500 milligrams daily from age 19 through 50; and 2,000 milligrams per day for all other age groups. 

"While it is too early to make definitive statements about the risks associated with routine high doses of vitamin D and calcium, people don't need more than the amounts established in this report," Ross said.  "Past cases such as hormone replacement therapy and high doses of beta carotene remind us that some therapies that seemed to show promise for treating or preventing health problems ultimately did not work out and even caused harm.  This is why it is appropriate to approach emerging evidence about an intervention cautiously, but with an open mind."

The new DRIs are based on much more information and higher-quality study results than were available when the DRIs for these nutrients were first set in 1997.  At that time, limitations in the evidence resulted in intake levels called Adequate Intakes, which are rougher estimations of people's requirements than the new values.  The old and new DRIs reflect different calculations and are not directly comparable.

The study was sponsored by the U.S. Department of Health and Human Services, U.S. Department of Agriculture, U.S. Department of Defense, and Health Canada.  Established in 1970 under the charter of the National Academy of Sciences, the Institute of Medicine provides independent, objective, evidence-based advice to policymakers, health professionals, the private sector, and the public.  The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies.  For more information, visit http://national-academies.org.  A committee roster follows.

Contacts: 
Christine Stencel, Senior Media Relations Officer
Christopher White, Media Relations Assistant
Office of News and Public Information
202-334-2138; e-mail news@nas.edu

3 comments:

Kerry said...

But, saying "most people get enough vitamin D and calcium in their diet" is not nearly as exciting as saying "YOU'RE GOING TO DIE FROM TOO MUCH VITAMIN D!!!!!!"

Jennifer said...

The way things are reported are getting out of hand! Eat this, no wait, now that will kill you, don't eat it anymore. Eat this other thing over here instead and it'll cure the damage we did by telling you to eat that first thing.

I'm a little biased because my 2 years of education in nutrition was heavily swayed towards the "government has no clue what they're talking about and should butt the hell out" opinion. Since Americans rarely see the sun nowadays, and when we do we've been told we MUST wear sunscreen or die, serum levels of Vit D are dangerously low. Personally, I take 2000iu a day and there is extensive research on cultures who consume over 10,000iu with no ill effects.

I am Moses. said...

Jennifer, I find your comments very interesting.

On the one hand, you admit bias against "the government," which is a little nebulous, but I'll let it go.

On the other hand, you mention "extensive research..." that supports your view.

Well, NONE of the participants in the study works for what I would characterize as "the government." The study itself was simply a review of peer-reviewed research articles, though it was commissioned by the government, probably at the behest of a number of experts in the field.

"Government" is just taking what the scientists discover and making broad policy recommendations based on that knowledge, but tempered by politics and reality. I'm more willing to trust that system than the one based on greed and "free market."

So, I guess I don't see how you can accept the research from one group as valid but not accept a compilation of that same and much more research. All of the research that supports your view, the research that doesn't, and the compilation were probably paid for through grants from NIH.

As a counter-anecdote to yours: I don't take any supplements, I don't drink much milk, I don't drink much juice, I don't specifically check for Vitamin D fortification in any of my food, but I doubt that much of it is supplemented. I'm not running around outside, naked all day (any day). In general, the most time I spend outside, during the week, is walking from my office to my vehicle. I'm not experiencing any ill effects of my "dangerously low" serum 25(OH)D levels. I don't even know what that concentration is, but I'm willing to bet that it's around 20 ng/mL, and possibly lower. For both of our cases, the suggested upper limit for daily intake is 4,000 iu. I know I'm not getting anywhere near that, and I'm probably not getting anywhere near the recommended daily intake either.

10,000 iu is equivalent to spending all day outside,naked, at the equator. I'm perfectly willing to believe that there are cultures who consume that much (or acquire that much through exposure) with relatively minor ill effects from the vitamin D. I'm also perfectly willing to believe there cultures (mediterranean, for example) who smoke from age <15 to 90 and seem to suffer no ill effects. In neither of those cases am I willing to go to such an extreme and follow their example. I don't particularly care to increase my odds of getting cancer.

My point on the reporting was that the reporters never bothered to do anything other than pull one or two scary-sounding words from the press release and/or the report itself and then come out with a doomsday headline. The reporters themselves are more at fault than the researchers. Scientists never get to see the final copy. In fact, we rarely get to see ANY copy of what is printed until it's printed, so we never have a chance to correct misinformation before it's already out there and then the best we can hope for is some amount of damage control.


Here's a list of institutions that the study members work for:

Pennsylvania State University
Baylor College of Medicine
State University of New York
Cornell University
Ohio State University
Loyola University Chicago
Creighton University Medical Center
University of California
Queen’s University
Memorial University of Newfoundland
Harvard Medical School
Yale Comprehensive Cancer Center
Maine Medical Center Research Institute
Rutgers University