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Making a better home for our microbes – the relationship between the microbiome and disease, including cancer


To celebrate Darwin Day, The Institute of Cancer Research, London, invited Professor Martin Blaser to deliver its annual Darwin Lecture on the importance of microbes in a healthy life for humans. Professor Blaser took time to chat with the ICR’s Mark Jones ahead of the lecture.

Posted on 09 February, 2024 by Mark Jones

Profile picture of Martin Blaser.

Image: Professor Martin Blaser. Credit: Rutgers Center for Advanced Biotechnology and Medicine.

Although most of us will know about bacteria and how they can make us unwell, there is much more to microbes and how we depend on them. A physician and microbiologist, Professor Martin Blaser has been studying the relationships we have with our persistently colonising bacteria for more than 30 years.

In that time, he has focused on Campylobacter species and Helicobacter pylori, which are also model systems for helping us to understand the interactions between bacteria and the hosts on which they live. Now, as Henry Rutgers Chair of the Human Microbiome and Director of the Center for Advanced Biotechnology and Medicine, both at Rutgers University he is exploring how these relationships can impact on the health of the host, which includes us – people.

As well as having a role in making us sick, microbes can help us to keep well. But what functions do microbes perform and how do they help us stay healthy and ward off disease? 

“The microbes that live in and on us, called the human microbiome, are essential for healthy life,” explains Professor Blaser. “They help digest our food, they provide vitamins, they train our immune system, interact with the brain, and importantly help defend against invading organisms. Human life  – and all animal life – is the result of the partnership between us and our residential microbes.”

The impact of modern life on our microbiome

But that partnership between us and our microbes has changed over time – as our lives have dramatically changed and largely improved, the microbes’ living arrangements have become completely different, and not necessarily in a good way, for us.

“Numerous aspects of modern life are upsetting the balance between us and our microbes that has evolved over the millennia. One important aspect is the use of antibiotics. These are drugs that are designed to inhibit and kill microbes,” says Professor Blaser.

“Antibiotics have tremendous use in medicine, but we have only recently recognised that they have important side effects, based on their collateral damage to our microbiome. This was never on the radar screen before.”

He feels we “over-estimate the benefits of antibiotics” – for example, we’re using them to treat minor infections which often aren’t even caused by bacteria, which are the microbes that antibiotics target. And Professor Blaser thinks we have only recently recognised the costs that antibiotics inflict.

“Our diets also include anti-bacterial agents that we ingest every day and they are low in certain nutrients, such as fibre, that sustain our microbes,” he explains. “Birth via caesarean-section deprives a baby of the normal acquisition of the microbes transferred from the mother via normal delivery. Our microbiome is under siege!”

What’s the link between the microbiome and cancer?

Professor Blaser’s work, and the work of many others, he says, links changes in the microbiome to diseases that have become more common in recent decades – including asthma, allergies, obesity, diabetes, and neurodevelopmental problems, like autism spectrum disorder, and learning disabilities. But he says there have been links with cancers as well, especially colon cancer since so many bacteria live in our gut.

At the ICR, our researchers have studied how the mix of bacteria in the gut can indicate how susceptible individual cancer patients are to gut damage caused by radiotherapy for prostate and gynaecological cancers. More recently, our researchers found that bacteria commonly found in the gut can fuel the growth of prostate cancers and allow them to evade the effects of treatment.

Researchers like Professor Blaser think that maintaining the health and variety of our bacteria is important for us to stay healthy and ward off disease.

How do we preserve our microbiome?

“This is a critical problem,” says Professor Blaser. “Comparisons with human populations who have not benefitted from modern society suggest that we, in the industrialised nations, have already lost about half of all the microbial species that our ancestors might have had.”

“It is a crisis in our ‘microecology’ comparable to the well-recognized crisis in our ‘macroecology’ that we call climate change.”

But what can we do when we’re faced with a collapse in our bacterial biodiversity of such scale? Much like with tackling climate change, Professor Blaser thinks it’s not too late to act.

“First, we must become aware that this is happening. Then we must seek ways to diminish the on-going damage, through reduced reliance on technologies that are injuring the microbiome. Finally, we must identify the key organisms and plan approaches for restoring them across the broader population.”

“These are big challenges over the next 20 years or more, but the sooner we start, the less we will have to dig ourselves out of the hole from these unintended effects of medical and societal progress.”

Hopefully we can make a better home for our microbes – our health depends upon it.

Professor Martin Blaser was invited to give the seventh annual Darwin Lecture by Professor Sir Mel Greaves, Founding Director of the ICR’s Centre for Evolution and Cancer, who hosts the lecture to mark Darwin Day.


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