This story did a good job of delivering the right take-home messages about this study: Basically, that the research should be considered trustworthy, but that the benefits seen were so small as to raise doubts about their importance. The story could have emphasized this point even further by explaining what the 8% reduction in cancer means in absolute terms for participants in the study. It would also have done well to compare multivitamins with other approaches to cancer prevention, such as exercise, a healthy diet, and smoking cessation.
Even on a number of criteria for which we judged this story to be satisfactory (read below), we also point out how the AP story was “more” satisfactory.
Current evidence is unclear as to whether vitamin supplements help prevent chronic diseases, and they’ve been shown to cause harm in some cases. That’s why, with the exception of people suffering from a vitamin deficiency, most of us are advised to get our vitamins from food instead of supplements. The current consensus, however, is based on studies that typically used high doses of a single vitamin. The low-dose multivitamin used here doesn’t seem to cause the same problems seen in other research, and may even offer a benefit for men similar to those in this study. That’s good news, of course, but it’s hard to get too excited considering the very small size of the reduction, which is barely outside of the range that would be considered statistical noise. It’s the kind of finding that could easily be reversed when the next study comes around–and readers should be warned accordingly.
Multivitamin use is widespread and reporting on this major trial needs to be accurate as it could make an enormous impact on public behavior for years to come.
Not applicable. The story didn’t mention costs, but most people know that a daily multivitamin isn’t very expensive.
The benefits were reasonably framed using words like “modest” and “small.” But the only hard numbers provided pertain to the relative risk of cancer in the multivitamin group compared with placebo. And it can be difficult to judge exactly what this 8% reduction in cancer cases looks like without more detail. As the competing AP coverage explains, the benefit worked out to about one fewer cancer per thousand men each year. In the AP’s words: “For every 1,000 men per year in the study, there were 17 cancers among multivitamin users and more than 18 among those taking the placebo pills.” That’s a much more informative way to describe things than simply calling it an 8% reduction, as Reuters did. The absolute risk reduction was clearly stated in the abstract and did not even require digging into the tables of the published manuscript.
The story said that taking a multivitamin “appears to have no dangerous side-effects,” which we’ll call good enough for a satisfactory. In addition, it describes the results of previous studies that have suggested harm from other vitamin formulations. However, it didn’t emphasize that the study was conducted in relatively healthy non-smoking men, and that certain vitamins may cause problems for people who smoke or who are taking medications. The AP explained this nuance.
The story notes some differences between the current study and previous research, which was often questionnaire-based or used high doses of a single vitamin. It gives the correct impression that this was a high-quality study whose results can be viewed with confidence.
We’ll award a satisfactory here, but note that the AP took things a bit further by explaining that these results in and of themselves do not justify a broad recommendation to take a multivitamin. “…the results need to be confirmed by another study before recommending multivitamins to the public,” the AP noted. The AP was also a bit clearer on the fact that questionnaire-based studies (observational studies) are generally considered less reliable than the trial being reported on here.
The story points out that the participants were healthy middle-aged men. There was no disease-mongering of cancer.
The story includes comments from two experts not involved with the research, but its explanation of the funding was not quite as thorough as the competing AP piece. Reuters says that the study was sponsored by NIH, which is true, but it didn’t note that Pfizer supplied its Centrum multivitamin free of charge. Since we’re talking about 15,000 men taking pills for 10 years, that’s more than pocket change–and worth pointing out to readers.
This is a grey area. Explicitly pointing out the role Pfizer played in the study is important for readers to know.
The story doesn’t compare multivitamins with other steps that may be helpful for preventing cancer, such as a healthy diet, exercise, and not smoking. The AP made these comparisons.
The availability of multivitamins isn’t an issue.
The story states that this was the first large-scale randomized study of multivitamins to prevent cancer. That’s accurate.
There’s enough original reporting that we can be sure it wasn’t based on a press release.
Systematic, Criteria-Driven
We wrote only about efforts that label themselves as “fact-checking” projects. You’ll see that if you read the piece.
“Not everything published in a medical journal is newsworthy, proven, or even important.” https://t.co/J37btponS6
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