Blueberries are a healthy alternative to many foods that Americans consume, but are they a potential alternative to drug therapy for individuals with hypertension? That’s the message readers may take away from this New York Times brief, which suggests — based on a study of people with high blood pressure — that blueberries could help “keep the doctor away.”
In truth, we really can’t tell much of anything from a study that included a mere 40 people who took blueberry powder for only 8 weeks. So we think the story should have been more circumspect about what conclusions we might be able to take away from this research.
Don’t misunderstand us: we realize that briefs like this aren’t always going to merit a 5-star rating on our reviews (although many shorter stories have done so). But we do hope that they’ll use language that reflects the quality of evidence being reported on. Maybe there is “something very special about the composition of blueberries,” as the quoted researcher suggests, but we’d like to see more proof before canceling our next doctor’s appointment.
According to the CDC, nearly 67 million Americans have high blood pressure, and controlling hypertension costs roughly $47.5 billion every year. Hypertension is also directly associated with the risks for heart attack, stroke, chronic heart failure, and kidney disease. If blueberries really could rein in the profoundly negative health and social effects of high blood pressure, that would certainly be important news for American health care consumers (and blueberry lovers!).
Blueberries are expensive, and the featured study utilizes “freeze-dried blueberry powder,” which is more of a supplement than something you’d find in a grocery store. Some back-of-the-envelope calculations based on prices from this supplier suggest that the daily powdered blueberry regimen could cost as much as $50 a month.
The story uses percentages to describe the reductions in blood pressure. But percentages of what? Without the baseline values, it’s impossible to know what these percentages mean. What’s more, the actual blood pressure reductions observed (7 mm Hg systolic and 5 mm Hg diastolic) were easy to find in the abstract, and most Americans are accustomed to looking at actual blood pressure numbers. A few small changes in language would have earned the story a satisfactory here.
The story does not mention or discuss the potential harms of consuming a daily portion of blueberries or blueberry product. But since it’s difficult to imagine what these would be, we’ll rule this not applicable.
The story includes reasonable details about who was studied and how, but it includes no language that would clue readers into the significant limitations of this study, particularly the fact that it was very small, of short duration, and looked at a surrogate marker of heart disease risk. It would also have been nice to include some discussion of what the reported reduction in blood pressure might mean in terms of someone’s overall cardiovasular risk.
High blood pressure affects the health of millions of Americans and people around the globe. No disease mongering here.
The story does not utilize any independent sources or expert analysis, something that might have clued readers into the study’s limitations. In addition, there was no direct mention or description of any potential conflict of interest in the story. The study was partly funded by the US Highbush Blueberry Council, and it stands to reason that they are very interested in increased blueberry sales as a result of greater health benefits.
We give the story credit for noting that the reductions in blood pressure were “modest” compared with those achievable through drugs, and that “other fruits and plant extracts have not produced the same result.” Nevertheless, the story fails to consider the most obvious comparison: a diet high in fresh fruits and vegetables and low in processed foods and salt (such as DASH), which is associated with reductions in BP that were similar to those reported in the study. We’ll call this a borderline satisfactory.
The story does not discuss or mention the availability of blueberries or blueberry products. Since the investigators were studying a freeze-dried blueberry powder that may be harder to find than typical grocery store blueberries, we would expect the story to look for and comment on the availability of this product.
The story does not mention or discuss the novelty of the research or the health claims associated with blueberries. The study upon which the story is based references several prior studies of blueberries, or a plant-rich diet, and hypertension.
Since the story includes comments from an interview with the lead researcher, we can be sure it wasn’t based entirely on a press release.