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Berries May Ward Off Parkinson’s Disease


1 Star


Berries May Ward Off Parkinson’s Disease

Our Review Summary

One of our reviewers, Andrew Holtz, has quipped that “alarm clocks may cause the sun to rise” is an example of the flawed logic behind news stories that confuse association with causation.

This story committed that oft-repeated sin, spinning an observational study that pointed to an association into a story about how berries may “ward off” Parkinson’s disease.

And why just berries in the headline?

Flavonoids, the story tells us, are found in apples, tea, red wine, chocolate and citrus fruits as well.


Why This Matters

Andrew Holtz, mentioned above, also wrote about reporters and observational study limitations: “If including caveats, context and explanation make a story too weak, there is a simple solution: don’t run it. One reason people feel so overwhelmed by apparently contradictory reporting on health science is that there are too many stories that sacrifice the (complicated and nuanced) truth in order to create a punchy lead and headline.”


Does the story adequately discuss the costs of the intervention?

Not Applicable

Not applicable. The costs of the flavonoid-containing foods mentioned in the story is not in question.

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

Not Satisfactory

Inadequate.  The story consistently used only relative risk reduction estimates – 35% lower risk or 22% lower risk.

But 35% or 22% of what?  How many people in either arm of the study developed Parkinson’s?  Why not spell it out in absolute terms?  Again, we urge WebMD to read another of our primers, “Absolute vs. Relative Risk.”

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

Not Applicable

Not applicable.  Harms aren’t discussed but we don’t know what they’d be.

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

Not Satisfactory

The story simply failed on this criterion – as so many such stories do.

The story never discussed the limitations of such observational studies.  The story quotes the researcher on “the association” between flavonoids and risk of developing Parkinson’s disease.   But that researcher isn’t quoted saying anything about how the substances “may ward off Parkinson’s disease” (as the headline states), or “may pay off by reducing the risk” as the first sentence states.

You can’t establish cause and effect from such observational studies and the story should have said do.  Association does not equal causation.  So it is simply wrong to use active, causal terms like “ward off” or “pay off by reducing the risk” when that can’t be proven from such a study.

We urge WebMD to distribute our primer, “Does the Language Fit the Evidence? Association Versus Causation,” to all of their writers and editors.

In addition, the story was based on a study that won’t even be presented in a meeting for two more months – much less published anywhere.
The brief caveat at the end of the story is appreciated, but it doesn’t go far enough in countering the headline and first sentence of the story.

Does the story commit disease-mongering?


There was no overt disease-mongering about Parkinson’s disease in the story.

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

Not Satisfactory

The only quote comes from the researcher from a news release.  No independent perspective appears in the story.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

There’s not even a line about other research looking at other factors to lower Parkinson’s risk.  There’s also no discussion of other research looking at potential benefits of flavonoids.

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

Not Applicable

Not applicable. The availability of the flavonoid-containing foods mentioned in the story is not in question.

Does the story establish the true novelty of the approach?

Not Satisfactory

The story allows the researcher to claim that “this is the first study in humans to examine” this association.  We don’t know whether that’s true or not.  And the story didn’t provide any independent perspective to reflect on whether this is novel or not. But there’s been a lot of other flavonoid research which the story could have at least mentioned.  From this story, one might assume that this is the first study that’s ever recognized flavonoids.

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

Not Satisfactory

The story discloses that its only quote comes from a news release.

Total Score: 1 of 7 Satisfactory


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