Prebiotic supplements could boost seniors’ brain health, trial suggests 

Writing in Nature Communications, the research took an innovative approach in its methodology, with the UK-based team conducting the study on a 100% remote basis.

Led by senior author Claire Steves, professor of ageing and health at King’s College London (KCL), the team said this approach illustrates the feasibility of remotely delivered trials for older people, which could reduce under-representation of this demographic in clinical trials.

Fibre supplement appeared to boost numbers of beneficial bacteria

Findings from the PRebiotic and prOtein on Muscle in Older Twins (PROMOTe) randomised controlled trial revealed that a fibre supplement led to significant changes in gut microbiome composition, particularly an increase in the beneficial bacteria Bifidobacterium.

“These plant fibres, which are cheap and available over the counter, could benefit a wide group of people in these cash-strapped times,” said Steves.

“They are safe and acceptable, too. Our next task is to see whether these effects are sustained over longer periods and in larger groups of people.”

The study, which also looked at how inducing gut microbiota changes could possibly alter muscle physiology and function, found the prebiotic supplements had no effect on muscle strength over the 12-week period.

The team attributed this finding to the timeframe, which may have been insufficient for muscle remodelling to take place.

They added that it was possible that a longer intervention period may have been needed to appreciate the influence of gut microbiome modulation on muscle health.

Unlocking the secrets of the gut-brain axis

As populations age globally, the prevalence of age-related conditions such as cognitive decline and muscle loss is on the rise, with the prevalence of dementia growing globally. As the population ages, recognition of cognitive changes that can happen as part of healthy ageing will become increasingly crucial for researchers and clinicians working with older people.

“We are excited to see these changes in just 12 weeks,” said first author Dr Mary Ni Lochlainn, from KCL’s Department of Twin Research.

“This holds huge promise for enhancing brain health and memory in our ageing population. Unlocking the secrets of the gut-brain axis could offer new approaches for living more healthily for longer.”

Could differences between treatment and placebo be due to chance?

However, the study attracted some criticism.

Commenting on the findings, David Curtis, honorary professor at University College London’s Genetics Institute, was critical of the methodology, highlighting the failure to find any effect on the main strength outcome and cognitive function.

“The differences they found between the treatment and placebo group could easily have occurred by chance,” he said. “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. 

“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.

“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.”

Glenn Gibson, professor of food microbiology at the University of Reading, pointed out that the volunteers participated remotely so more direct measures on muscle effects could well have been positive. 

He added: “Nevertheless, because gut microbiota mediated influences upon health were seen in terms of cognitive aspects, this is a very important study from the Twins cohort research at KCL.”