This news report describes a study which suggests that dark chocolate might be healthy for the heart. It provides some background on flavonols, the constituent in dark chocolate that might be beneficial, notes some of the potential harms associated with this "chocolate therapy," and includes interviews with three experts who are mostly enthusiastic about the study’s findings. Yet the story fails to examine the rigor of the new evidence.
The researchers enrolled 39 people. Were there enough subjects to muster the statistical power needed to answer their question? Could the improvements in blood flow be the result of chance? Did the researchers account for other factors that might affect arterial blood flow? What are the true benefits of improvements in blood flow to an arm? Is there research to suggest that they correspond to any outcome of clinical significance, such as rates of heart attack, stroke, or death? What else could patients do to derive the same apparent benefit without the fat and calories of chocolate? Could they take a low-cost, fat-free, calorie-burning walk once a day? The story answers none of these.
The study appears to be one small, preliminary step in the investigation of a scientific hypothesis. Readers should not be left with the impression that consuming chocolate every six hours is a sound, scientifically proven, good idea.
Thought there was no discussion of cost, most people have a general idea how much cocoa costs.
The story fails to describe the improvement in blood flow in absolute terms, instead noting only relative or percent improvement (e.g. 37% compared to baseline for consumption of artificially sweetened cocoa). The reported 37% improvement is much greater than that reported in a press release from the American College of Cardiology (2.4% over baseline); the reason for the discrepancy is unclear.
The story notes that chocolate is laden with fat and calories, potentially harmful in people who are already overweight or obese.
This story is based on the preliminary results of a small, unpublished study presented at a national cardiology meeting. The researchers fed three different foods (two types of chocolate and a placebo whey powder) to 39 people during three separate 6-week trials, and then after each trial used ultrasound to measure arterial blood flow in the arms of their subjects, a test that purportedly “corresponds well to heart disease.” Unfortunately, the story says little about the methodological shortcomings inherent in such a research design. Are there enough subjects in the study to muster the statistical power to answer the question being asked—or could the improvements in blood flow be the result of chance? Did the researchers account for other factors that might affect arterial blood flow, such as exercise routines? Is there research to suggest that the observed differences in arterial blood flow correspond to any outcome of clinical significance, such as rates of heart attack, stroke, or death? This news report says nothing about such potential limitations. We suspect many observers would say that this study simply raises an interesting question, but certainly doesn’t answer it. Despite the researcher’s assertion–"This tells you that it (cocoa) is cardio-protective"–the data seem only to show that cocoa simply relaxes smooth muscle in the arm.
The story contains no obvious elements of disease-mongering.
The report cites three sources and their credentials, but mentions a potential conflict of interest for only the lead author, who received funding from Hershey and the CDC. It is impossible to judge the independence of the other sources. Nonethless, we'll give the story the benefit of the doubt.
The report neglects to mention “treatments” other than chocolate that might improve the endothelial function of these subjects. Among these is low-cost, fat-free, calorie-burning exercise.
Though it would seem reasonable to think that the Hershey’s cocoa mixes used in this study are available on grocery store shelves, it’s impossible to know. (It’s not readily clear from Hershey’s web site either.) Nonethless, we'll give the story the benefit of the doubt on this criterion.
The story says this is the “latest in a growing number” of studies in this area.
The report includes some information that was widely available in press releases, but also additional information that goes beyond the press releases.
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
Comments
Please note, comments are no longer published through this website. All previously made comments are still archived and available for viewing through select posts.
Our Comments Policy
But before leaving a comment, please review these notes about our policy.
You are responsible for any comments you leave on this site.
This site is primarily a forum for discussion about the quality (or lack thereof) in journalism or other media messages (advertising, marketing, public relations, medical journals, etc.) It is not intended to be a forum for definitive discussions about medicine or science.
We will delete comments that include personal attacks, unfounded allegations, unverified claims, product pitches, profanity or any from anyone who does not list a full name and a functioning email address. We will also end any thread of repetitive comments. We don”t give medical advice so we won”t respond to questions asking for it.
We don”t have sufficient staffing to contact each commenter who left such a message. If you have a question about why your comment was edited or removed, you can email us at feedback@healthnewsreview.org.
There has been a recent burst of attention to troubles with many comments left on science and science news/communication websites. Read “Online science comments: trolls, trash and treasure.”
The authors of the Retraction Watch comments policy urge commenters:
We”re also concerned about anonymous comments. We ask that all commenters leave their full name and provide an actual email address in case we feel we need to contact them. We may delete any comment left by someone who does not leave their name and a legitimate email address.
And, as noted, product pitches of any sort – pushing treatments, tests, products, procedures, physicians, medical centers, books, websites – are likely to be deleted. We don”t accept advertising on this site and are not going to give it away free.
The ability to leave comments expires after a certain period of time. So you may find that you’re unable to leave a comment on an article that is more than a few months old.
You might also like