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expert reaction to study looking at a daily fibre supplement and muscle function and cognition in over-60s

A study published in Nature Communications looks at fibre supplements, muscle function and cognition in over 60s.


Prof David Curtis, Honorary Professor, UCL Genetics Institute, UCL, said:

“I don’t think this study does provide evidence that supplements affect brain function.  The authors failed to find any effect on the main strength outcome and tested a number of other things, including cognitive function, but the differences they found between the treatment and placebo group could easily have occurred by chance.”

“There are mistakes in the table which provides the results so it is difficult to understand exactly what the findings are.  However the main issue is that they say that there was an improvement in the cognitive first-factor score with a p value of 0.014.  However this was not the only thing they tested.  They also tested other items including strength, appetite and metabolism.  It would be standard practice to correct the p value obtained by multiplying by the number of tests performed, termed a Bonferroni correction for multiple testing.  If they had done this, as they should have done, the results for cognitive first-factor would not meet conventional criteria for statistical significance.  Hence, they cannot claim that there is evidence that this dietary supplement influences cognitive function.”


Prof Glenn Gibson, Professor of Food Microbiology, University of Reading, said:

“This is a very well designed and reported study that addresses health parameters of gut microbiota modulation.  The authors used sophisticated analyses of the microbiome to confirm that the supplement had a prebiotic effect.  The authors also reported that they measured a positive influence on cognitive function, which is an important observation.  They also measured muscle integrity (by looking at the time it takes to rise from a chair) – but this didn’t differ between test and placebo groups.  This could have been due to trial duration.  The volunteers participated remotely so more direct measures on muscle effects could well have been positive.  Nevertheless, because gut microbiota mediated influences upon health were seen in terms of cognitive aspects, this is a very important study and another great output from the world class Twins cohort research at KCL.”



‘Effect of gut microbiome modulation onmuscle function and cognition: thePROMOTe randomised controlled trial’ by Mary Ni Lochlainn et al. was published in Nature Communications on 29 February 2024.


DOI: 10.1038/s41467-024-46116-y



Declared interests

Prof David Curtis: “I declare no conflict of interest.”

Prof Glenn Gibson: “None.”

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