Appetite linked to healthier gut bacteria and better muscle function in over-60s

15th February 2021 – by Paz García

Pizza cut into slices

Over-60s with a good appetite have more diverse and different communities of microbes in their gut than those with a poor appetite, according to a new study from King’s College London and the University of Southampton.

The study, published in the Journal of Cachexia, Sarcopenia and Muscle, is the first to identify differences in gut bacteria based on appetite between otherwise healthy older adults.

In addition, the researchers found that lower appetite was associated with reduced muscle strength and function, with gut bacteria as a potential link between the two.

Co-first author Dr Ruth Bowyer, Research Associate at TwinsUK, King’s College London, said:

“Loss of appetite is very common in older people, and this can have serious consequences including loss of muscle mass and function. Our research is the first to explore the links between appetite and gut bacteria, and how this may be related to muscle strength.”

The team used appetite questionnaire answers to identify 102 twins who had small appetites and 102 twins who had greater appetites, and compared their gut bacteria. The two groups of twins were otherwise as similar as possible in terms of age, body mass index, calorie consumption, antibiotic use and other factors that could impact gut bacteria.

The researchers found that twins with a poor appetite had less variety in their gut bacteria than twins with a good appetite. They also found that twins with healthy appetites were more likely to have microbes associated with diets high in vegetables and fibre.

The team then looked at participants’ muscle strength, based on previous muscle strength assessments completed during clinic visits, and found that twins with a lower appetite had reduced muscle strength compared to twins with a good appetite.

Co-first author Dr Natalie Cox, Clinical Research Fellow at the University of Southampton, explained:

“A lower appetite can lead to undernutrition, which in turn can lead to loss of muscle mass and so reduced muscle strength. We know from previous research however that a poor appetite is also linked to loss of muscle strength independent of overall weight loss.

“We now need studies to understand how exactly appetite, gut bacteria and muscle function affect each other and in what order. This could inform the development of treatments in the future to preserve muscle mass and function, to improve health in older age.”

What does tap water mean for our gut bacteria? Dr Ruth Bowyer explains in this blog

17th July 2020 – Dr Ruth Bowyer

The global improvement to tap water quality worldwide has been a public health success, with access to clean water for drinking, food preparation and cleaning being essential for health.

It’s understood that where there are contamination events – for example, pollutants entering water bodies that feed into tap water treatment works – drinking water can affect human health. How badly this might affect an individual might in part be due to their microbiome.

Microbiome and health

Whilst diet is frequently researched, drinking water, and its ability to alter gut bacteria, has been surprisingly overlooked. So that’s what we set out to do.

We asked 90 of our amazing twins who have lived in the same house since they donated their microbiome samples to supply a much easier to acquire sample – tap water! We then looked for any associations between the tap water and the microbiota.

Because drinking water in the UK is extremely regulated, we were not looking to see if there was a health effect of the water. Unless there are very old pipes, it is not only safe to drink but indeed essential to drink tap water regularly.

What we found instead was that molecules that are commonly found in water (for example, minerals that are dissolved in the water), but differ from tap to tap and region to region, did associate with microbiome composition.

This was a small, preliminary study, and further work and experiments are needed to confirm our findings, but it does suggest that tap water could influence the microbiome.

This means that where there is a contamination event, one of the ways it might harm us is via the microbiome, and that in areas where this happens frequently, treatments targeted at the microbiome it might be one way of lessening its impact.

Thank you to our twins

We’d really like to thank the twins who participated in this project, who were extremely patient, engaged and a joy to speak to for the questionnaire part of the data collection. Every project is a constant reminder that all of the research we do would be impossible without our dedicated volunteers!

Bowyer et al. Associations between UK tap water and gut microbiota composition suggest the gut microbiome as a potential mediator of health differences linked to water quality. Science of The Total Environment, 2020.

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