To its credit, the story included some excellent balancing quotes from independent sources.
However, there was no discussion of the fact that the blood pressure drop was small and the participants had pre-hypertension, not hypertension. The story does not make this distinction or provide information about it, though it is readily available.
This is some of what we get in the flood of stories based on some of the countless papers presented at a huge conference such as the American Heart Association’s Scientific Sessions.
Woloshin and Schwartz of Dartmouth and the VA have written about “Media Coverage of Scientific Meetings: Too Much Too Soon?” Excerpt:
“Although they are preliminary and have undergone only limited peer review, research abstracts at scientific meetings may receive prominent attention in the news media.”
If it’s preliminary, and if the story advises readers to be cautious about eating the amount of kiwis consumed by subjects in the study, then why – of all the research presented at the AHA meeting – is this newsworthy?
Not applicable. No discussion of costs. Shoppers probably have a ballpark idea.
The story quantified the benefits but didn’t put them in any meaningful perspective. What difference does it make to lower systolic blood pressure by 3.6 points?
Is this truly newsworthy?
Enough to raise the question in the story, “So is kiwi the new ‘wonder’ fruit?”
There’s an odd cautionary quote that even 3 kiwis a day “doesn’t sound like moderation and I would caution against eating that much.” But the story never explains why. Is there a harm? This point was just left hanging unexplained.
Here’s some of the explanation that could have been given. Kiwi is rich in potassium, which may be one of the ways it helps lower blood pressure. People with kidney disease or other metabolic disorders predisposing them to high potassium could get into trouble with high intake of the fruit (theoretically). See Medlineplus for information about potassium-rich diets.
The story never commented on the clinical significance of a 3.6 point drop in the subjects’ systolic blood pressure. Is that meaningful? If you accept that a BP of 128/85 is mildly elevated (which some may not), then a 3.6 point drop in the systolic still doesn’t bring it under the stated “ideal” of 120/80.
And, while the story said the subjects didn’t change anything else in their diets, what else might have accounted for the drop?
What is the strength of the evidence for lutein (the hypothesized responsible agent in kiwis) lowering blood pressure?
The story dropped the ball on this criterion.
We’re going to rule this one unsatisfactory because this was a study of pre-hypertension – a set of blood pressure readings that not all are convinced merits treatment. The story should have made that distinction.
Several independent sources were quoted.
We’ll give the story the benefit of the doubt because it at least mentioned the DASH diet, which is the main dietary intervention recommended in primary care for prehypertension and mild hypertension. The DASH diet is only a little more efficacious than the reported kiwi intervention. (for nonhypertensive patients, the DASH diet lowers the systolic BP 7.1 mm Hg).
The story noted that kiwis “are not easy to find”
We’re not given any context about past research looking at kiwis or lutein for blood pressure. We’re also not sure why lutein was highlighted as the potential active agent, instead of potassium, for which there is solidl understanding of how it lowers blood pressure.
Why was the study design set up as apples versus kiwis? No explanation given. Is this based on a research track record?
It does not appear that the story relied on a news release.