Following a very small study of 26 people, scientists at the University of Exeter claimed that drinking about two tablespoons of blueberry juice concentrate improved the brain function of 12 adults, partially based on magnetic resonance imaging (MRI) function tests. The study lasted only 12 weeks.
The news release exaggerates the importance of such a brief limited study, and it doesn’t include any numbers that would help readers understand any changes that were observed. On the plus side, the release does disclose that the study received financial support and samples from a blueberry supplement manufacturer.
The volume of nutrition advice hitting the daily news cycle is overwhelming readers’ capacity to keep up and sort the evidence-based news from the purely promotional. News releases like this tend to straddle both the good and the bad.
While fruits and vegetables are uniformly considered healthful, this claim of brain changes from a few tablespoons of blueberry concentrate is backed by very thin “evidence” from a very preliminary and limited study. We wish the release had explained the limitations of small, short duration studies.
We’ve seen this before and described some of the problems in a blog post on why readers need to be skeptical about nutrition claims relating to brain health — and how you can’t eat your away out of dementia risk.
Moreover, these sorts of releases and news stories further perpetuate the notion that supplements provide remarkable and clinically meaningful health benefits despite the fact that with almost no exceptions, the research has not borne this hope out.
There is no mention of the cost of this blueberry concentrate. According to the manufacturer’s website, a 473ml bottle of BlueberryActive Concentrate sells for £17.99 British pounds, or $21.85 in US dollars. Thirty blueberry capsules cost $13.35 in US dollars.
The release gives us the broadest brush about benefits, but does not provide numbers or quantify how much improvement occurred.
It states that “brain blood flow, brain activation and some aspects of working memory were improved in this group of healthy older adults” and “Compared to the placebo group, those who took the blueberry supplement showed significant increases in brain activity in brain areas related to the tests.”
How much improvement was there? How did brain activity change before and after taking the supplement?
But even with those numbers, brain activity is not a clinically meaningful measure. It’s a surrogate end point, not a measurable clinical benefit.
There was no statement about harms, not even a statement declaring there are none.
The study from the get-go wasn’t sufficiently powered (meaning it didn’t have enough study volunteers) to detect changes in cognitive performance. The published report notes that: “Cognitive function was assessed, as a secondary outcome, although the study was not sufficiently powered to detect changes in cognitive performance.”
How many more people would have been required to provide sufficient power? What limited the researchers from taking the time to recruit them?
The release included the important fact that a commercial enterprise selling blueberry juice concentrate and blueberry capsules provided the samples and some of the funding for the study.
The published paper states the authors declared they had no conflicts of interest.
The release could have included some of the other factors that are known to reduce risk of dementia including exercise, maintaining a healthy weight, and moderating any alcohol use.
We know blueberry juice is widely available but what about the concentrated blueberry juice used in the study?
The study does not make a claim of novelty, and includes this statement about previous research:
“Previous research has shown that risk of dementia is reduced by higher fruit and vegetable intake, and cognitive function is better preserved in healthy older adults with a diet rich in plant-based foods.”
We think the headline is not justified by the evidence presented.
“Blueberry concentrate improves brain function in older people.”
The statement makes it sound as if this single study of 12 people proves a functional improvement that is permanent, and that is not proven by the limited 12-week study. We also question whether the markers that were used — blood flow and brain activity during tests — can be reliably linked to a permanent change in the individual’s cognitive ability.
Systematic, Criteria-Driven
Puleeeeease... this 'game changer' weight loss drug causes more nausea and vomiting than a placebo. Some game, some change. My friend Gary would spank you for using the eighth word medical reporters should never, ever use. @garyschwitzer @thackerpd
https://www.healthnewsreview.org/toolkit/just-journalists-writing-tips-case-studies/7-words-and-more-you-shouldnt-use-in-medical-news/ https://twitter.com/OttawaCitizen/status/1361426796126830597
A scary @statnews Op-Ed warns that govt attempts to rein in Pharma may cut off access to "life-changing" drugs.
It takes @garyschwitzer to let us know: the author spent 10 years as Pfizer's public-policy chief. https://twitter.com/garyschwitzer/status/1360325022578053123
.@TranspariMED criticizes STAT op-ed for not disclosing pharma funding of author’s institute - similar to criticism we’ve made of STAT op-eds in the past. @transparify @ThinkTankWatch @icer_review https://www.healthnewsreview.org/2021/02/transparency-watchdog-criticizes-stats-non-disclosure-on-pro-pharma-op-ed/
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