How microbes affect you from brain to bowel

From Cosmos Magazine, September 5-9, 2016. (Photo: Lactobacillus casei by AJC1 via Flickr)

Not a day goes by without some new study proclaiming the importance of our microbes to our health. It’s hard to keep up, and hard to sort the wheat from the chaff, the mildly interesting association from the water-tight causal link. I recently wrote a five part series that looks at the current state of microbiota research – what evidence is solid, and what needs further investigation.

Microbes and you: a partnership millions of years old

We are not alone. Our bodies are teeming metropolises of microscopic life – and the microbes that call us home influence everything from bowel to brain.

Over the past decade, technological advances in the lab have allowed us to take a census of our microbial entourage – known as the microbiota – like never before. Instead of seeing only the small fraction of microbes from our skin or poo that blossom on a petri dish, we can now blend, extract and read the genetic essence – the DNA – of all microbes, called the microbiome, to get a better idea of who’s there.

The picture that has emerged is one of staggering complexity. Read more…

How bugs in your gut can make you fat (or thin)

Tinkering with gut microbes causes more than a tummy ache. They can wring more calories from food and boost fat cell production – all from day one.

By far the majority of our companion microbes, weighing an impressive 1.5 kilograms and containing more than 1,000 species, reside in our gut, mostly in the large intestine.

As soon as a baby is born – and perhaps even before – microbes move in. Many are seeded from bacteria in the mother’s birth canal if it’s a vaginal birth or from her skin if it’s a caesarean birth. Read more…

Microbe tenants help – and hinder – your immune system

Obesity isn’t the only condition linked to imbalanced gut microflora. A host of autoimmune and inflammatory conditions – inflammatory bowel disease, coeliac disease, multiple sclerosis, rheumatoid arthritis and lupus – are also associated with changes to gut microbial ecosystems.

(Indeed, obesity is often described as an inflammatory condition for the widespread immune reaction that accompanies excess weight.)

Connecting the dots between altered gut microbes and disease is a lively area of research. Scientists are working on the ‘chicken or egg’ problem: does disrupting the gut microflora cause the disease, or does having the disease lead to changes in gut microflora?

In many cases, it is likely that a complex interplay between genetics and environmental triggers – including the microbes in our guts – is involved. Read more…

Mood, mind and memory – can gut bacteria meddle with the brain?

The microbes in your gut may be tiny, but their influence appears to extend as far as the brain, affecting mental health, stress levels, memory and cognitive abilities. Yet many of the most compelling results illustrating the microbiota-gut-brain axis, as it has become known, have only been seen in animals.

The potential for gut microbes to affect mood is probably best illustrated by an experiment conducted at McMaster University in Canada. Mice devoid of a microbiota were effectively given ‘personality make-overs’ via poo transplants. Timid mice became more brazen, and once daring mice retreated into shyness, taking on the anxiety profiles of their donors.

Human-to-rodent poo transplants also work. Read more…

Bugs as drugs – medicine’s next frontier

Microbiome research is providing tantalising clues about how we might change our microbiota to improve our health. But translating findings from the lab into clinical treatments is a slow and arduous process.

The most dramatic illustration of how our microbiota can be used in the clinic is the case of the poo transplant, also known as faecal microbiota transplantation. Read more…


Gut harmony: Why the right mix of microbes is important to our health

We are not alone. Each of us is teeming with bacteria and other microbes. From the soles of our feet to the follicles on our head — and every crevice in between — trillions of microbes form specialized ecosystems collectively known as our microbiota. The microbes that live on and in us outnumber our own cells by more than ten to one.

Far from being mere freeloaders, many of our microscopic passengers are essential residents — friendly bacteria that help us to digest our food, synthesize vital nutrients such as vitamins, and keep pathogens at bay. The rapidly growing field of microbiota research is starting to generate some tantilising results, linking our microbiota to everything from our weight, to our moods and behaviour.

But how is it that our microbes influence our health? How does our own behaviour — our diet and lifestyle — change our microbial ecosystems? And could we one day start to treat illnesses by manipulating our microbial communities?

In the latest episode of Up Close I spoke with a world expert in the field of microbial ecology. Professor Rob Knight is from the Department of Chemistry and Biochemistry, the BioFrontiers Institute, and the Howard Hughes Medical Institute, all at the University of Colorado, Boulder. Listen to the podcast or download the transcript here.

Speaking from the gut for immune health

B0007180 Villi from the small intestine
Villi from the small intestine (Photo credit: wellcome images)

Intestinal cells communicate with probiotic gut microbes for a healthy immune system

The human body is swarming with bacteria and other microbes that outnumber our own cells by more than ten to one. From the soles of our feet to the follicles on our head and every crevice in between, trillions of microbes form specialized ecosystems collectively known as our microbiota. Far from being mere freeloaders, many of our microbial ecosystems are comprised of essential residents – friendly bacteria called commensals. In the gut, these microbial allies help us to digest our food, synthesize vital nutrients such as vitamins, and keep pathogens at bay.

They also speak to us. By listening to the chemical chatter of our microbial lodgers, epithelial cells that line the inner surface of our gut can distinguish friend from foe.

Learning to decipher the chemical cacophony is critical to the development of a healthy immune system, and when the system breaks down, debilitating conditions like inflammatory bowel disease can take hold.

It turns out that our microbes are listening to us, just as much as we are listening to them. And according to a team of Finnish researchers, the dialogue between us and our microbes changes the way that both of us behave. Continue reading “Speaking from the gut for immune health”

Probiotic yoghurt counteracts fast food diet

Beneficial gut bacteria boost the immune system to prevent obesity in mice, regardless of diet.

The Western lifestyle, with its abundant fast food, is wreaking havoc with our waistlines and sending many of us to early graves. A high fat, high salt, low-cost diet has been fuelling an obesity epidemic in industrialised nations and, increasingly, in developing countries. While the consequences of obesity, such as an increased risk of developing type 2 diabetes, cardiovascular disease, fatty liver, arthritis and cancer are well-known, public health solutions are thin on the ground.

A team of researchers from the Massachusetts Institute of Technology and the Aristotle University of Thessaloniki in Greece now believe that probiotic bacteria – such as you might find in yoghurt – could be the answer.  Continue reading “Probiotic yoghurt counteracts fast food diet”