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Vitamin D: Breast Cancer’s Wonder Drug?


4 Star

Vitamin D: Breast Cancer’s Wonder Drug?

Our Review Summary

This segment reports on a study that describes a link between low vitamin D levels and increased risk of breast cancer and poor outcomes. It is a good example of how a study with narrow implications can be used to discuss the limits of current scientific knowledge and treatment recommendations. It’s also an illustration of a reporter resisting the urge to exaggerate the importance of the findings. 

The segment does several things well:

  • It acknowledges the controversies and uncertainties about vitamin D and cancer.
  • It (therefore) declines to make specific recommendations.
  • It makes clear the possible risks of excessive doses of vitamin D supplements and sunlight. 

The segment has two signficant weaknesses: It uses only one source, the program’s physician/reporter; and it fails to help women understand the size of the underlying risk of breast cancer spreading and killing.


Does the story adequately discuss the costs of the intervention?

Not Applicable

Because the segment does not make specific treatment recommendations, cost is not an issue.

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

Not Satisfactory

The segment reports that women with lower levels of vitamin D in their blood were 94 percent more likely to have their cancer spread and 73 percent more likely to die.

But it faiils to report the underlying incidence of metastasis or death, making it difficult for viewers to understand true magnitude of the risk.

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


The segment warns against the possible harms of high doses of vitamin supplements and overexposure to the sun.

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


The segment is based on a study to be presented at a medical meeting and published in a major journal. It’s a small, observational study that links low blood levels of vitamin D to higher risk and worse outcomes for breast cancer.

The segment is careful not to overstate the implications of the study and does not invite viewers to overrespond to the findings.

Does the story commit disease-mongering?


The story does not exaggerate the findings of the study or the benefits of treatment.

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

Not Satisfactory

The segment relies on only one source–the correspondent described as "our doctor."

While she does a good job of explaining that the implications of the study are unclear and the science in the area of vitamin D is controversial, one source isn’t sufficient to provide context and balance.  

Does the story compare the new approach with existing alternatives?


Because the segment carefully refrains from recommending treatments, it isn’t necessary for it to provide alternative ways of lowering breast cancer risk.

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

Not Applicable

Vitamin D supplements, sunshine and foods with vitamin D are easily available enough that this report does not need to specify.

Does the story establish the true novelty of the approach?


The segment does not suggest that boosting vitamin D intake with supplements, food or sunshine is novel. 

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


There is no evidence that the segment draws excessively on a press release.

Total Score: 6 of 8 Satisfactory


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