There was enough effort here to earn a 5-star score: plenty of original reporting and critical evaluation of the study. The deficiencies have to do with how the results were reported–language that wasn’t quite careful or detailed enough to convey the findings accurately.
This story correctly pointed out that association (a link) is not equivalent to causation, but fails to give absolute risk.
And if you’re going to pull a quote from a press release, be transparent about it and let readers know that you didn’t actually talk to the source.
For years we’ve been hearing about the benefits of this or that “superfood” with the most antioxidants. But the reality is that there’s no strong evidence to support the health benefits of any particular fruit or vegetable over any other. All fruits and vegetables contain antioxidants and other nutrients that are important for health, and it’s the combination of fruits and vegetables in a healthy diet that seems to offer the most benefit for preventing chronic diseases. Anyone who says otherwise is probably either: a) trying to get a study published, or b) trying to sell you something, or c) both.
Readers should be skeptical of reports such as these because dietary studies are so difficult to interpret. Clear reporting is necessary to give any idea of whether the findings merit a change in their eating habits.
The cost of tomatoes, or other sources of lycopene, is not in question.
The story provides relative risk numbers, not absolute comparisons. Please read our primer on why that’s an important issue.
We’re not aware of any harms from eating tomatoes.
Of the three stories we reviewed on this same study, this was the only one to point out that the researchers measured lycopene levels in the blood, not tomato intake. That’s important, because we don’t know exactly why the men in this study may have had more or less lycopene in their blood. It’s therefore problematic to suggest that tomatoes were responsible for any potential benefits.
We’ll score one for WebMD for making this important distinction, but we’re confused as to why the story seems to ignore the implications in its own headline (“Tomatoes may lower your risk for stroke.”) The story also rightly points out that this observational study “just showed a link. It was not designed to say whether or not eating more tomatoes can lower stroke risk.” So again, why does the headline incorrectly suggest that “Tomatoes may lower your risk for stroke”?
Overall, there was a strong effort to critically evaluate the results of the study, but the story didn’t apply the same rigor to the language it used to communicate the findings.
Because we want to encourage – and because we at least saw an attempt to address the limitations of an observational study, we’ll give the story the benefit of the doubt. But it certainly had room for improvement.
The sourcing was strong. We hear from three different experts on stroke, who add some valuable context.
The story notes that tomatoes aren’t the only sources of lycopene. It also included a recommendation for a diet rich in fruits and vegetables, adequate exercise, and quitting smoking, as steps that may be beneficial for stroke prevention.
The availability of tomatoes isn’t in question.
The story alludes to previous research suggesting that lycopene levels may be linked to cancer risk, and that fruits and vegetables are protective against stroke.
The story pulls some text and a quote directly from a press release without acknowledging the source. Here’s the comparison:
Story:
The new study included slightly more than 1,000 men from Finland aged 46 to 65. Researchers measured the level of lycopene in their blood when the study began and followed the men for about 12 years. During that time, 67 men had a stroke.
“This study adds to the evidence that a diet high in fruits and vegetables is associated with a lower risk of stroke,” says researcher Jouni Karppi, PhD, of the University of Eastern Finland in Kuopio. “The results support the recommendation that people get more than five servings of fruits and vegetables a day, which would likely lead to a major reduction in the number of strokes worldwide, according to previous research.”
Press release:
The study involved 1,031 men in Finland between the ages of 46 and 65. The level of lycopene in their blood was tested at the start of the study and they were followed for an average of 12 years. During that time, 67 men had a stroke.
Among the men with the lowest levels of lycopene, 25 of 258 men had a stroke. Among those with the highest levels of lycopene, 11 of 259 men had a stroke. When researchers looked at just strokes due to blood clots, the results were even stronger. Those with the highest levels of lycopene were 59 percent less likely to have a stroke than those with the lowest levels.
“This study adds to the evidence that a diet high in fruits and vegetables is associated with a lower risk of stroke,” said study author Jouni Karppi, PhD, of the University of Eastern Finland in Kuopio. “The results support the recommendation that people get more than five servings of fruits and vegetables a day, which would likely lead to a major reduction in the number of strokes worldwide, according to previous research.”
Systematic, Criteria-Driven
The tale of two “negative” studies. Or, how spin is applied to make research findings look more impressive. A must read. https://johnmandrola.substack.com/p/the-tale-of-two-negative-studies
The @nytimes chose to interview one of the editors of the @AnnalsofIM (publisher of this paper) who "gushed with extraordinary glee: It’s huge! There are very few things that reduce your mortality by 30%."
Turns out coffee is not one of those few things despite all that glee. https://twitter.com/garyschwitzer/status/1533202075928215558
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