The news release focuses on a small, short-term study of healthy women that found consuming two cups of mango a day was associated with reduced systolic blood pressure. However, it is not clear how much the systolic blood pressure was reduced or how the researchers accounted for normal, daily variations in blood pressure. The release also neglects to note how mango consumption would fit into other approaches that can be taken by healthy adults to maintain healthy blood pressure.
Without a control group in the study to prove otherwise, it’s possible the consumption of two cups of any fruit, or even any food, may affect systolic blood pressure. And the phenomenon of post prandial (after eating) drops in blood pressure are very real and affect a significant percentage of the population, especially the elderly. Consequently, it would be quite important to see the impact of consumption of two cups of anything on systolic blood pressure before concluding that it was the mangoes.
This was a small, preliminary study and — as the release itself notes — “mangos may be a heart-healthy fruit” and longer-term studies are needed before drawing any firm conclusions. Given the vague nature of the reported findings, the fact that the relevant research paper is not publicly available (at the time of this review) and the preliminary nature of the study, the question becomes: why issue a news release on this now? After all, if the researchers think mangos may be a heart-healthy fruit, that means the researchers also believe they may not.
Cost is not addressed. That said, if one has access to mangoes, their cost is likely comparable to many other fruits in some parts of the country and higher in others. This raises the question of cost and access to fresh fruits and vegetables — which is a significant problem in many parts of the U.S. — but which is beyond the scope of what we can expect to be addressed in a news release. Taking all of this into account, we’ll mark this as “not applicable.”
The release doesn’t quantify the benefits, instead noting that “once mango was consumed, systolic blood pressure was significantly lower two hours after mango intake compared to baseline values.” The release described benefits — all surrogate markers for health — in a similar way for reduced pulse pressure and reduced methane levels in the breath of three of the six patients who produced methane. What does “significantly lower” mean? And since all of the patients were described as healthy, do the reductions actually matter?
Mangoes are a fruit. Eating fruit is generally a good idea — as long as it is part of a balanced diet. The “balanced diet” part is missing from the release. Mangos are not inherently unhealthy, but they do contain a significant amount of sugar. So, if one is going to increase one’s mango consumption, that should be offset by reducing other sources of sugar in the diet. Adding two cups of mangoes a day at 214 calories is not insignificant unless calories are cut back elsewhere in the diet. To be clear, we don’t think mangoes need a warning label — but a simple note that mango consumption should be incorporated into a balanced diet would have been valuable.
The release did a fairly good job of describing the number of study participants, as well as their age, sex and health status. However, the release doesn’t address a key point that’s relevant to any study of blood pressure: how did they account for normal changes in blood pressure? In general, blood pressure follows a daily pattern: it’s lower at night, rising during the course of the day until afternoon, then lowering again from the late afternoon into the evening. That means that it’s important to understand how the study accounted for this normal variation. The release states that “systolic blood pressure was significantly lower two hours after mango intake compared to baseline values.” Okay, but how did they establish the baseline? And when did patients eat the mango? For example, if they consumed the mango at lunchtime, their blood pressure would likely have been lower two hours later anyway.
And as noted above, post prandial (after eating) drops in blood pressure affect a significant percentage of the population, especially the elderly. The study should have compared the impact of consuming two cups of any foods on systolic blood pressure before concluding that the mangoes were responsible for the drop.
The release states that “two cups of mangos a day had beneficial effects on systolic blood pressure among healthy postmenopausal women.” However, if the women had healthy blood pressure levels already (as the release indicates), they didn’t need to lower their systolic blood pressure. Treating blood pressure as something that is inherently bad is misleading. High blood pressure can be dangerous. So can low blood pressure. It’s maintaining a healthy blood pressure that is important.
The release clearly notes that the research was partially funded by the National Mango Board. We were unable to access the published study to check whether any conflicts of interest were disclosed.
There are a host of options for patients who would like to lower their blood pressure — including a number of pharmaceutical interventions for patients who have high blood pressure. This study focused on healthy adults, so the pharmaceutical interventions are likely not relevant. But there are also a host of lifestyle-oriented options for people who are at risk of high blood pressure or who want to ensure they maintain a healthy blood pressure. These choices include things like reducing sodium intake, being physically active, and maintaining a healthy body weight. None of these things are mentioned in the release. It would have been good to see a reference to incorporating mango consumption into a broader effort involving a healthy diet and lifestyle choices — rather than treating mango consumption as a stand-alone intervention.
The release doesn’t mention this, but presumably people know that mangoes are already available to the public. We’ll rate this not applicable.
The release states that “This is the first study to demonstrate positive vascular effects of mango intake in humans.” The question is whether the study actually does demonstrate these effects. Given the lack of controls, we can’t be certain. This concern is addressed under “quality of evidence.”
The headline states that “mangoes helped improve cardiovascular…health in women.” But the release doesn’t support that. The release tells us that healthy women who ate mango had reduced systolic blood pressure two hours after eating mango. It doesn’t tell us how much of a reduction there was. It doesn’t tell us whether the same result might occur with a different type of food. And it’s not clear that reducing the blood pressure of women who had healthy blood pressure is necessarily an improvement of cardiovascular health.
Systematic, Criteria-Driven
Monday at #ADA2021, an infectious disease epidemiologist, a journalist, and a researcher shared perspectives on communication of risk in the era of COVID-19: http://ow.ly/ROfR30rMeE7 @AstleyCM @garyschwitzer @berthahidalgo @ADA_DiabetesPro
Shoutouts to @susan_bewley @drkevinknopf @MichaelBaum11 in this call for more than fawning coverage from press releases for these kinds of stories.
Also, linked history inside goes back 5 years just on Grail apparently trying to become Holy Grail. https://twitter.com/garyschwitzer/status/1408849696416841731
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