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Newsweek overlooks key limitation of study on vitamin D and childhood obesity


2 Star



Our Review Summary

Newsweek covers the results of a preliminary study that suggest a weekly dose of vitamin D might help children with obesity.

While the story provides important context to the issue, identifies some caveats, and includes the voice of an outside expert, some key details weren’t included. The study did not appear to control for things like daily activity levels (which can positively influence many aspects of health), and it covered a small population size with a limited geographic scope.


Why This Matters

Childhood obesity is a real problem, as the story points out, and a big one that affects more than 40 million kids under the age of 5 years. Life is short on simple and readily available fixes to major problems, so it makes for a compelling health story when scientific results hint at such a fix. But media outlets must be careful in covering rudimentary results, even if their competitors are doing so with abandon and generating great attention as a result.

With this study, the results may or may not pan out after larger, longer, and more detailed studies are completed. And while taking vitamin D supplements on a weekly basis may seem innocuous, there are some risks. It’s also not hard to imagine that some readers may try to substitute it for more provably effective (yet more difficult) interventions — perhaps leading to secondary harm.


Does the story adequately discuss the costs of the intervention?

Not Applicable

The cost of Vitamin D is not mentioned, but the cost is so low we’ll rate this N/A. (The study says about 100 of the 200 participants were given 50,000 IU of the vitamin per week, which works out to about 20 cents per month.)

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

Not Satisfactory

We’re told kids who took vitamin D “had a significantly lower BMI” and “lower body fat, as well as healthier cholesterol levels.” But this is not adequate. How much did BMI appear to improve for the kids who took vitamin D? How much fat did they appear to lose relative to kids who didn’t take vitamin D? And just how much better were their cholesterol levels? We don’t know, because those numbers are not included.

The story hints that researchers didn’t provide this information, via this quote: “Although the effect sizes are not given, these outcomes are certainly positive.” Lay readers may not understand what “effect sizes” mean and why they matter.

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

Not Satisfactory

The possible harms of taking too much vitamin D are fairly well-known for adults, less is known about how it affects kids. Nevertheless the harms are numerous and significant. At least a small sample of those risks should have been included in the story, e.g. putting too much calcium in the blood, a greater risk of forming kidney stones, and a greater risk of developing kidney diseases.

The story did at least point out “there remains a lack of evidence on the safety and long-term effects of supplementation, particularly if there is no vitamin D deficiency.”

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

Not Satisfactory

The story notes the small study size and some caveats, but it should have pointed out that major factors like physical activity levels and diet were not controlled for. Thus it’s possible (if not likely) that any effect might be the result of those proven means of improving health outcomes for children with obesity.

Newsweek acknowledges the study is “set to be presented at the 57th Annual European Society for Pediatric Endocrinology Meeting, and have therefore not yet been reviewed.” The story would have been stronger if it had explained why this matters: Many findings presented in medical meetings are never published, mostly because they fail to stand up to scrutiny when other doctors look at the details.

Does the story commit disease-mongering?


We didn’t see any sensationalized or disturbing language in this story.

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


There appears to be at least one expert, Mary Fewtrell (of the Royal College of Paediatrics and Child Health), who comments on the study yet is not involved in the research.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

Alternatives to taking vitamin D to head off some of the symptoms of obesity are noticeably absent. Why aren’t diet or exercise mentioned, at a minimum?

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

Not Applicable

Vitamin D is easy to find and used pervasively, so we’ll mark this N/A.

Does the story establish the true novelty of the approach?

Not Satisfactory

The story highlights recent research into vitamin D and belly fat levels in adults, but claims the study is the first to “investigate the links between vitamin D supplementation and the weight and health of obese children and adolescents.” But this is not accurate. In 2017, the authors of an ongoing study published partial results that echo the ones of the latest study.

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

Not Satisfactory

Some quotes used in the story match word-for-word what we found in a press release published by the European Society for Pediatric Endocrinology. Although there was outside expert commentary woven into the story, not mentioning or even linking to the release is a no-no if you are trying to be transparent about sourcing and helpful to readers.

For example, this quote appears in the Newsweek story, and is not attributed to the news release:

“These findings suggest that simple vitamin D supplementation may reduce the risk of overweight and obese children developing serious heart and metabolic complications in later life.”

Total Score: 2 of 8 Satisfactory


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