Tuesday, August 14, 2018

Study Finds Giving Prebiotics To Kids Doesn't Change Their Energy Intake And Ups A Major Hunger Hormone Yet Still Concludes Prebiotics Have Potential To Help With Childhood Obesity?

Today will be discussing a study that had kids randomly assigned to taking either 8g oligofructose enriched inulin (prebiotic) per day or placebo (maltodextrin) for 16 weeks.

The study's pre-registered primary outcome measure, as recorded in ClinicalTrials.gov, was change in baseline fat mass at 16 weeks.

Secondary outcome measures (as recorded) were changes in baseline appetite at 16 weeks (assessed with visual analog scales and an eating behavior questionnaire), and objective appetite measures including a weighed breakfast buffet, weighted 3-day food records, and serum satiety hormone levels.

(Not preregistered as an outcome of interest? Body weight change or BMIz score.)

Outcome wise, here's a snapshot of the study's abstract:
Reading through the study, here's what I found as outcomes:
  • According to their 3 day food diaries (but be aware, food diaries are notoriously inaccurate), there was no difference in 3 day energy intake between the prebiotic and placebo arms.
  • When all ages were included in the analysis, there was no difference in all-you-can-eat breakfast buffet energy intake between the probiotic and placebo arms, BUT, by dividing the kids into those between the ages of 7-10 and 11-12, suddenly, but only in the older group, kids ate less breakfast in the prebiotic arm, while in the younger group, they ate more.
  • The hunger hormone ghrelin was found to be significantly elevated in those taking the prebiotic (an increase of 28%) from baseline, whereas placebo was not demonstrably different from baseline (an increase of 8%).
  • There was no difference reported in subjective post-breakfast buffet hunger in either group
  • There was no difference reported in subjective eating behavior questionnaires between groups, but parents reported improvements in fullness, but equally in both prebiotic and placebo groups.
  • The primary outcome of change in baseline fat mass was not mentioned anywhere in the study.
The authors' conclusions about a prebiotic supplement that was shown to markedly increase hunger hormone levels, that didn't decrease 3 day food diary energy intake, that didn't change all-you-can-eat breakfast buffet energy intake (unless you arbitrarily after the fact divided up the kids into those aged 7-10 and 11-12), and where the study's registered primary outcome wasn't mentioned in the study itself sure look differently than what you might expect, with their concluding sentence being,
"This simple dietary change has the potential to help with appetite regulation in children with obesity"
I also found it surprising that the study was free to read, and given the incredibly unexciting findings, it's more difficult to imagine the authors paying for its open access. Easier to imagine the company that makes the prebiotic that a randomized controlled trial published in an impactful journal explicitly concluded, "has the potential to help with appetite regulation in children with obesity" (even though it didn't), paying the extra fees as open access articles generally gather more citations.

As to what Beneo, the manufacturer of the prebiotic used in this study had to say, I found these quotes in an article published on the trade-zine Nutraingredients at the time of the study's publication,
"Beneo regards this research of highest importance",
and despite the study not even remotely coming to this conclusion also added,
"The intake of 8g of prebiotic inulin (Orafti Synergy 1) in a glass of water prior to dinner is a simple dietary intervention that supports children in their weight management efforts. The results show that they were naturally eating less (YF: no they didn't) than the control group having maltodextrin"
Beneo also put out an excited press release to publicize the study.

And you can bet your bottom dollar, it's studies and conclusions like this one that supplement companies use to suggest great benefits to their products, and it's also studies like this one where I wish the journal employed open peer review as I can't fathom how this one got through as is.

Lastly, while the authors didn't report any conflicts of interest with this particular study, the supplements and placebos were provided by Beneo, and it was noted that one of the authors had previously enjoyed funding from Beneo. Unfortunately there is no mention as to who paid for this study's open access.

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