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Nuanced portrait of evidence on prevention benefits of vitamin D

Vitamin D supplements: Panacea, placebo or something in between?

Our Review Summary

vitamin DThis story examines the history of controversy over whether vitamin D has any preventive role in a laundry list of conditions including diabetes, depression and multiple sclerosis. There’s no controversy over its role in bone health. Different studies have reached different conclusions, and the story predicts that large randomized studies might help resolve these disputes a few years from now.

The coverage is exemplary in many ways. It delves deeply into the evidence on this topic and helps readers understand the strengths and limitations of existing studies. It features numerous expert perspectives from leaders in the field who provide a strong critical evaluation of the evidence. We were pleased to see the Institute of Medicine’s (IOM) conclusions on vitamin D featured prominently. The IOM found that the evidence on vitamin D outside of bone health is “inconsistent, inconclusive as to causality, and insufficient to inform nutritional requirements.”


Why This Matters

Because many Americans love the idea that a pill will improve their health, we are again faced with a ‘wonder vitamin’ situation where the public believes the conclusions of select limited studies rather than comprehensive assessments of the evidence. Stories like this one have an important role to play in educating the public about evidence quality and informing decision-making about supplement use.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

A brief mention of cost would have improved an already strong article. While it can be argued that most people have a rough idea of the price of vitamin D supplements, a quick word on the monthly cost of supplements, or the potential cost-effectiveness of supplementation as a prevention strategy, would have been welcome.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?


The story begins from a baseline context of controversy and uncertainty, rather than one of assumed benefit — an approach that frames the issue appropriately in our view. There is detailed discussion of research showing benefits, and research NOT showing benefits. In the absence of definitive large trials, the benefits accepted by the Institute of Medicine are limited to bone health.

The story quotes the Institute of Medicine, which concludes that vitamin D and calcium are “necessary for bone health” but that as for preventing cancer, heart disease, diabetes and autoiummune disorders, the evidence was insufficient.

Does the story adequately explain/quantify the harms of the intervention?


Research has shown risks from high levels of vitamin D. We were glad the story included the following:

“A 2014 study, for instance, found that people with the highest levels of vitamin D in their blood (more than 60 nanograms per milliliter) were significantly more likely to die in the three months following a hospitalization as were people whose levels were between 30 and 49.9 ng/mL.”

Another possible harm that the story could have examined is people downing pills and thinking they have “prevented” some future problem. Does taking a vitamin pill reassure them and delay or forestall established preventive measures such as diet and exercise, known to help prevent type 2 diabetes and heart disease?

Does the story seem to grasp the quality of the evidence?


The story does an exemplary job exploring this issue and the reporting could serve as a model for others exploring areas with uncertain evidence. Beyond the extensive interviews with experts, the story deftly points out that correlation between two things does not mean that one causes the other. It also notes that benefits shown in early studies of other vitamins has later been contradicted by large trials — and that the same thing could happen with vitamin D.

Does the story commit disease-mongering?


The story does not succumb to mongering.

Does the story use independent sources and identify conflicts of interest?


The experts cited are leaders in the field. (Well done on the part of the story to entice these folks to comment.) There do not appear to be any major conflicts among the sources quoted.

Does the story compare the new approach with existing alternatives?


The alternative here is to obtain vitamin D from foods, or not to supplement at all. The study covers both these options when it outlines the Institute of Medicine recommendations.

Does the story establish the availability of the treatment/test/product/procedure?


It’s clear from the story that vitamin D is widely available from food and supplements.

Does the story establish the true novelty of the approach?


Although there’s nothing novel about vitamin D, the story makes it clear that there is old evidence, new evidence, and more research findings to be expected in the coming years.

Does the story appear to rely solely or largely on a news release?


The story clearly goes beyond any news release.

Total Score: 9 of 10 Satisfactory

Comments (2)

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Dr Carl

September 18, 2015 at 1:28 am

What is missing is that sunlight produces a long list of critical hormones and peptides along with D. You cannot replace the sun with a pill. They are not close to the same thing.


Aleta Kerrick

September 21, 2015 at 4:16 pm

I was very surprised to read the unequivocal 2nd sentence of this post: “There’s no controversy over [Vitamin D’s] role in bone health.”
That immediately called to mind Health News Review’s July 22 post titled “Wrong forces drive osteoporosis treatment – despite evidence of lack of benefit.” In it, Gary Schwitzer called attention to an “important” BMJ Analysis article which asserts that calcium and vitamin D “supplements do not reduce the risk of fracture and may result in harm.” Gary’s post (at links to the BMJ article.