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Some evidence vitamin D might fight colds


4 Star

Some evidence vitamin D might fight colds

Our Review Summary

The story points out that the results of the study provided only weak support for the idea that vitamin D has a protective effect and that in fact for the main outcome of this trial there was no statistically significant difference between the participants given vitamin D and those who took placebo pills. It almost feels as if the writer or editor wondered why they were doing the story at all and then decided to gussy up the headline and lead in order to justify running the piece. After all, a headline saying “Study unable to tell whether or not vitamin D helps fight colds” isn’t likely to attract as many readers.

One alternative approach to the story might have been to focus on what this trial adds to the body of evidence suggesting that the winter dips in vitamin D levels (because people don’t get as much sunlight) may help explain why colds and flu are more common in the winter. That story frame could have attracted interest without hyping the trial results.

In sum, this is a careful story undone a bit by a careless head.


Why This Matters

When trial results are not statistically significant, headlines shouldn’t tease readers. And – as always – we wish there had been an independent expert voice offering perspective on this study.


Does the story adequately discuss the costs of the intervention?

Not Satisfactory

This story does not mention cost. Sure, vitamin pills cost only pennies a day, but treating everyone would cost billions of dollars a year.

Assuming just a nickel a day for 400 IU of vitamin D (the dose used in this study), the cost of treating everyone in the U.S. would exceed $5 billion a year. That bill has to be compared to the expected benefits of supplements given to healthy people, which in this trial were not statistically significant, so those billions might just be flushed down the drain.

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


As noted above, the body of the story makes clear that the results of this trial did not show a clear benefit from taking 400 IU daily. However, the headline and lead sentence both state that vitamin D might fight colds, something this trial failed to clearly demonstrate. We’ll give the story the benefit of the doubt for what’s in the middle, not at the top.

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


The story cautions that vitamin D can cause problems including nausea, vomiting, constipation, poor appetite, weight loss and even higher blood pressure or heart rhythm abnormalities.

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


This rating is a close call. The story notes the limitations of the study of vitamin D and winter colds, including the fact that there was no statistically significant difference in the main outcome measure between the treatment and placebo groups, that the study was small, and that the extent of any benefit was not clear. The story also does a nice job of providing readers with some background, including results of other recent trials, as well as recommendations and opinions of health agencies and experts.

However, the cautionary notes in the body of the story are drowned out by the headline and the lead sentence that tout potential cold-fighting properties of vitamin D. Also, while the story says that 164 men took part in the trial, it fails to tell readers that 60 of them dropped out before the study was done and that the high number of drop-outs made it impossible for the researchers to determine if there was a statistically significant difference in absenteeism between the treatment and placebo groups.

We’ve made our point about the headline and lead, so we won’t ding the story for that again in this criterion. But the grade could have gone either way for reasons noted.

Does the story commit disease-mongering?


This story does not exaggerate the effects of common winter colds.

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

Not Satisfactory

Although this story refers to the findings of other studies and the recommendations of health agencies and experts, there is no identified independent source to comment on the trial.

In their journal article, the researchers reported no potential conflicts of interest. It would have been helpful to tell readers that the trial was funded by the Medical Research Fund of Finnish Defence Forces, in order to distinguish this trial from studies funded by supplement manufacturers or others with a vested interest in the results.

Does the story compare the new approach with existing alternatives?


The story points out that experts generally recommend supplements only when people aren’t getting enough vitamin D from their diet or sunlight. And as noted above, the story points out that supplements expose people to some risks of vitamin D toxicity.

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

Not Applicable

The availability of vitamin D supplementation is really not in question.

Does the story establish the true novelty of the approach?

Not Applicable

There was no claim that there is anything new about tests of vitamin D for prevention of respiratory illness.

This story missed the opportunity to explain what was different about this trial. In their article in the Journal of Infectious Diseases, the researchers pointed out that by studying military conscripts much of the variability that complicates population studies was filtered out. All the participants were from a narrow age group, had passed the same entry physical examination, lived in the same military housing, ate the same food, followed the same daily routines and so on. Also, the classification of their daily status (healthy or ill) was more uniform than would be expected in a study of people in varied civilian occupations. The strengths of the study would be expected to filter out much of the background noise that fogs typical population studies. It is notable that despite those features, this trial failed to reach statistically significant results (partly because of the high drop out rate, which the story should have mentioned.)

One word usage nit: the story refers to military “recruits,” but the study participants were not recruited to join the military, they were performing mandatory service.

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


The story quotes an e-mail exchange with the lead researcher, so it’s clear it didn’t rely solely on a news release.

Total Score: 6 of 8 Satisfactory


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