This tiny, industry-sponsored study of how the polyphenols found in Montmorency tart cherries might impact gut bacteria adds to a growing list of similar industry-sponsored studies investigating a wide range of possible health benefits of this domestic cherry.
This study did not show that Montmorency tart cherries may enhance gut health, and this news release did not even explain that there’s no scientific consensus on what defines “good” bacteria, “bad” bacteria, or a “healthy” gut.
The combination of unjustified language and lack of supportive data is a major weakness of this news release. Yes, the industry sponsorship and limited sample size (9 human subjects) is acknowledged, but other key limitations (lack of control group; reliance on subjects completing diet questionnaires) are not, and the end result is a news release with an arguably promotional tone.
The microbiome has become an important line of research into human health but this research is preliminary, at best. So what’s the harm in promoting preliminary research?
Check out this customer review of a Walmart tart cherry juice product:
It was recommenced that I try this because of an awful gout condition. I bought a few bottles and had them on hand for the next flare up. Well that happened yesterday and I took my cholchicine but drank the entire 32 oz bottle and this morning I am basically pain free!
We’re hoping this person wasn’t diabetic. We share this because it shows that plenty of people (there were similar comments related to a host of touted health benefits) will act on unproven nutritional studies that are funded by the companies selling the product, and are brought to the public’s attention (as in this case) by public relation firms whose primary motivation is promotional, not educational.
The cost of Montmorency tart cherry juice is not mentioned.
Walmart sells a quart of concentrate for about $16.
The lead author of the study is quoted as saying:
Our results suggest that the unique polyphenol mixture in tart cherries may help positively shape the gut microbiome, which could potentially have far-reaching health implications.
What are the “far-reaching health implications”? They’re not specified. Nor are any specific benefits described. The release says the researchers analyzed study participants’ stool samples but offers readers no glimpse into the findings or what was measured.
Harms are not mentioned.
Several tart cherry juices on the market contain substantial amounts of sugar. This is germane since — among the host of diseases cherry juice is claimed to be good for — there are claims that tart cherry juice is actually “good for diabetes.”
Although the amounts used in this study were modest, it’s worth noting that some readers might think “more is better” and drink enough to substantially elevate their blood sugar.
Further, most physicians do not recommend juice as a source of nutrition, but rather the whole fruit.
The research is poorly described and it’s unclear from the release what the primary findings were. We’re told the study had 2 arms:
The release also tells us that in the human trial, “the microbiome was positively altered (primarily measured by the increase in good bacteria).” Which bacteria are “good” and why they’re “good” is not explained. And data are not provided.
It’s suggested human subjects that ate a more Western diet (“low in fruit, vegetables, and fiber”) … “potentially had a lower ability to metabolize polyphenols” … while those who ate a more plant-based diet (“with a higher intake of carbohydrates and fiber”) responded with an increase in Bacteroides and Bifidobacterium ( 2 types of bacteria).
We were glad to see the news release mention that further and larger studies are needed, but it should have mentioned two other key limitations: this study had no control group and it relied on diet questionnaires completed by the subjects. Therefore, it’s quite possible the observed results can be attributed to many factors other than the chemical characteristics of the tart cherries.
The significance of this is not explained; rather, we’re offered this conclusion without context or explanation:
The results help build the foundation for future research and suggest Montmorency tart cherries can play a role in positively shaping the microbiome and maintaining gut health.
The release doesn’t engage in disease-mongering. It also doesn’t provide any context for the type or extent of the problem the intervention (cherry consumption) is intended to help.
It’s mentioned that The Cherry Marketing Institute “provided financial support for the study.”
It’s not clear if any of the researchers involved have financial ties to the institute.
What’s not made clear to readers is that dozens (perhaps hundreds) of foods and beverages are rich sources of polyphenols.
We can presume that tart cherry juice is widely available, and the news release does mention that Montmorency cherries are a common domestic variety “available year-round in dried, frozen, canned, and juice forms.”
The news release mentions the study is “a first-of-its-kind trial” of humans combined with a parallel laboratory study.
It’s mentioned in the published study that, to the authors’ knowledge, this is the “first microbiota/metabolome investigation of the impact and fate of tart cherries and their polyphenols in the human colon.”
The use of repeated phrases such as: “enhance gut health … gut-friendly foods … good bacteria … shaping the microbiome” perpetuates and reinforces the erroneous notion that scientists have definitively determined which bacteria are good vs bad, and that we can dictate the “health” of our microbiome by our food choices. To date, there is no research that can unequivocally support these notions.
This study does not support such cause-and-effect language or the over-reaching news release headline.