The microbiome is such a hot topic of research at the moment, being linked to all things health – from weight, mood and mental health, to type 2 diabetes and cardiovascular disease. And we’re just starting to understand the link between our microbiome and healthy ageing.

In this article, I focus on the link between ageing and changes in the gut microbiome. But before we delve into the science, let’s cover some basics!

What is the microbiome and the microbiota?

Your body houses a large number of microorganisms, which live both on the inside and out. The mix of bacteria, viruses, fungi and other microbes are called the human microbiota. The terms microbiota and microbiome are usually used interchangeably, but strictly speaking, your body’s microbiome is the genes of all your microbiota. 

One of the most interesting microbiomes in the body is the gut microbiome. It plays an important role in the functioning in our bodies. It contributes to processing food, storing fat, producing vitamins and maintaining the intestinal barrier. In addition to metabolism, it has an influence on your immune system, body weight, tendency for illness, appetite and your mood.  

Age-linked changes in the microbiome

The microbes in your gut don’t age in themselves, but health problems linked to the microbiota tend to increase as you get older. Although it’s difficult to say if changes in the microbiome are a cause or a consequence of the ageing process.

Your gut microbiome constantly evolves throughout your life, in response to genetic and environmental factors. But what we now know is that the gut microbiome can become significantly different as you age. In fact, one of the main differences found when comparing the microbiomes of young and older people in clinical studies, is the lack of microbial diversity in the older population. This shift can be due to changes in diet, increased use of medicines and reduced mobility. A lower microbiota diversity has been linked to ill-health in older people and the development of age-related disease, like type 1 diabetes and rheumatoid arthritis. 

The reduced microbiota diversity is an important feature in the imbalance seen in what’s called age-onset dysbiosis. There’s less of the beneficial microbes, like bifidobacteria and lactobacilli which help protect against harmful bacteria and inflammatory factors in the gut. Other bacteria which produce certain beneficial substances, like butyrates (a short chain fatty acid which stimulates the formation of new neurons) also decline in number and in activity. Whereas, there’s an increase in the levels of opportunistic bacteria involved in gut inflammation, like enterobacteria.

The richer and more diverse your gut microbiota is, the lower your risk of disease and allergies. And if your gut is healthy, then your microbiota exists in a state of balance. So, it makes sense to target a more balanced microbiota to support a longer healthspan.

Longevity and the microbiome

What’s really interesting is that the lack of microbiota diversity generally seen in older people, isn’t a feature in centenarians’ microbiomes. Centenarians seem to have a high level of bacteria linked to good health, like Bifidobacteria, Akkermansia and Christensenella.  And contrary to the drop in butyrates levels which happens in older adults, centenarians have a rearrangement in the population of bacteria responsible for producing butyrates.

As it happens, the microbiome can directly influence lifespan too! At least, this can be true in fish! A fascinating study on African turquoise killifish has shown that when the gut of middle-aged fish received a microbiota transplant from younger fish, to older fish lived longer and were more active during their later life. How amazing is that!

There’s still more research to be done in humans. But a more recent study published in “Microbiome” journal showed that a faecal transplant from older to younger mice changed their gut microbiome, which in turn affected their spatial learning and memory. To be honest, I’m not sure why the researchers didn’t try this experiment the other way around and check if this would improve the cognitive function of the older mice! But at least, this shows the potential that microbiome manipulation has in terms of helping us age healthily.

Is there anything I can do to optimise my microbiome?

Yes, a few things in fact! There are many factors which can contribute to building up your good gut bacteria, like your diet and exposure to certain environments. Diet in particular is a major force in shaping the makeup of your microbiome.  So, here are a few diet tips to give your little gut friends a healthy boost:

Eat a variety of fruits and veg. The more diverse your diet, the more diverse your gut flora. And remember, a rich microbiota is better for you and your health.

Include high fibre vegetables. Artichoke, green beans, onions, leeks, carrots, broccoli are all good examples. They contain a high level of inulin – a prebiotic fibre which supports useful microbes.

Have more fibre in your diet. Try and have at least 30g of fibre a day. Good sources include beans and pulses, nuts, seeds, fruits and veg and starchy foods like wholemeal or wholegrain bread or pasta, porridge and oat bran.

Include some fermented foods in your diet. Although the clinical evidence for their benefits is somewhat limited, it’s still worth including some of these into your diet. Things like natural yogurt, kefir (fermented milk), sauerkraut (fermented cabbage) not only taste good, but may give your gut a healthy dose of probiotics – the microbes themselves which are thought to be beneficial for your health. 

What’s next?

Analysing and measuring your gut bacteria is likely to become common practice in future medicine. The same as taking a blood test to diagnose a particular condition or investigate your symptoms.

In the future, it may be possible to treat certain conditions -or better still ageing- by using interventions which change the makeup of your gut bacteria. In the meantime, make sure you look after your friendly bacteria, so it looks after you!