Decoding gut-brain connections may help people live longer and healthier
Prebiotics are simple fibres that encourage healthy bacteria to flourish in the gut and are available aplenty
We estimate that the costs of taking this kind of supplement are pittance. They are safe and easy to take. They could benefit a large group of people and the research team plans to further test whether these results are sustained over longer periods
In just 12 weeks, a daily fibre supplement improved brain function in twins over the age of 65. Could the microbes in our gut hold the key to preventing cognitive decline in our ageing population?
The study my colleagues and I conducted showed that this simple and cheap food supplement can improve performance in memory tests – tests that are used to spot early signs of Alzheimer's disease. As populations age globally, and prevalence of age-related conditions such as declining brain and muscle function is on the rise, we need innovative ways to slow and prevent this. The number of gut microbiome studies has increased exponentially over the past 15 years.
Researchers are recognising the huge potential of this under-explored facet of human health. We know that the gut microbiome can be influenced and changed from the outside, for example, using a prebiotic supplement. Prebiotics are simple fibres that encourage healthy bacteria to flourish in the gut. They are already widely available to buy.
With this new study, we sought to understand how targeting the microbiota, the diverse community of microorganisms residing in our guts, using two cheap, commercially available plant fibre supplements, inulin and FOS, could affect both brain function and muscle health.
The study comprised 36 twin pairs, with one twin randomly allocated to receive a placebo and the other randomly allocated to receive a prebiotic fibre supplement. The treatments (prebiotic or placebo) were taken every day for three months and none of the participants knew which of them they were receiving – in other words, the study was “blinded”. To improve muscle function, all the participants also did resistance exercises and took a daily protein supplement. We monitored participants remotely via video calls, online questionnaires, and online tests of memory and thinking.
Beneficial bacteria: When we tested participants' stool samples, we found the fibre supplement led to significant changes in their gut microbiome composition. In particular, there was an increase in beneficial bacteria, such as Bifidobacterium. While there was no significant difference in muscle strength between the groups, the one receiving the fibre supplement performed better in tests assessing memory and thinking, including the Paired Associates Learning Test.
This test is able to detect early signs of Alzheimer's disease. Those who received the prebiotic had half the number of errors on this test compared with the group that received a placebo. Seeing this positive result in just 12 weeks holds huge promise for enhancing brain health and memory in our ageing population.
We hope that further understanding of the gut-brain connections may unlock new approaches for helping people live more healthily for longer. For example, preventing or delaying frailty and ultimately keeping our ageing population independent and well for as long as possible.
Innovative trial: Another novel aspect of the study was its remote design, which showed the feasibility of conducting trials in older adults without the need for extensive travel or hospital visits, which could be delivered in many settings globally. Such trial designs aim to improve the representation of older people in research. We acknowledge that challenges to this type of study design exist, including access to the internet and computers, and we aim to address these in future large-scale projects. Ultimately, the aim is to enhance the quality of life for ageing populations worldwide.
We estimate that the costs of taking this kind of supplement are pittance. They are safe and easy to take. They could benefit a large group of people and the research team plans to further test whether these results are sustained over longer periods and in larger groups of people.
Our findings show that targeting the gut bacteria with simple interventions can have significant effects on human function. So how else can we target these microbes to enhance wellbeing as the population gets older?
We are planning to carry out further trials, exploring the huge potential of this important question.
(The writer is associated with King's College, London)
