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Dark Chocolate May Lower Stroke Risk


3 Star

Dark Chocolate May Lower Stroke Risk

Our Review Summary

Three best practices on reporting on research were violated in this story: 

  1. The limitations of observational studies were not explained adequately so that readers could understand. 
  2. The story is based on an abstract of a talk that won’t even be given for two months yet so true peer review hasn’t taken place.
  3. Only relative risk reduction data – not absolute risk reduction figures – were provided. 


Why This Matters

This is the kind of science story that helps science and journalism fall out of favor with the public.  These chocolate and Valentine’s Day stories are predictable on the calendar – and predictable in content and delivery. If the science behind it were more fully explained, it would be sweet.  This wasn’t.


Does the story adequately discuss the costs of the intervention?

Not Applicable

The cost of chocolate is not in question.

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

Not Satisfactory

Used only relative risk reduction, not absolute. We have a primer on this as well. So when it talked about 22% lower stroke rate or a 46% lower stroke death rate, we’re not told 22% of what?  Or 46% of what? 

Later there’s mention of chocolate helping to reduce blood pressure or increase blood flow but no data are provided.

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


The story did discuss the possible harms of higher LDL cholesterol "or perhaps higher incidence of cardiovascular disease" from chocolate. But it didn’t provide any evidence.  Nonethless we’ll give it the benefit of the doubt.

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

Not Satisfactory

This story swings wildly back and forth, saying dark chocolate may lower stroke risk but then saying the findings aren’t conclusive. It said that the findings don’t prove that chocolate is good for your heart (heart?  The headline and lede said this was about stroke!).  And then it confusingly dropped in the researcher’s quote, "I’d definitely go with the dark chocolate" over white or mik chocolate.  For what?  Taste?  Or for benefit? And if so based on what data?

What the story didn’t explain is why using any language about lowering stroke risk is inappropriate, since such an observational study can’t prove cause-and-effect.  We’ve just added a new guide for journalists about why the language of association versus causation is so important.

Does the story commit disease-mongering?

Not Applicable

The story didn’t tell us anything about stroke, so it couldn’t commit disease-mongering.

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


 A dietitian and a nutrition researcher – both apparently unaffiliated with the research – were quoted.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

No explanation was given for the researcher’s recommendation of dark chocolate over milk or white chocolate, and no reasons were given for why "dark chocolate in particular" – as the story states – may have health benefits.

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

Not Applicable

The availability of chocolate is not in question.

Does the story establish the true novelty of the approach?


The story explained this study was a review of existing studies.

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


Since several sources were quoted, it does not appear that the story relied solely on a news release.

Total Score: 4 of 7 Satisfactory


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