It is the year 2036. A patient struggling with depression and anxiety is referred to her local psychobiotics clinic where the consultant prescribes a course of personalised pills to improve her symptoms. But rather than acting on her own cells, let alone those in her brain, the pills work by administering specific strains of microbes in her gut.

This future vision of doctors tweaking the contents of your digestive tract to improve complex and hard-to-treat psychological disorders might seem far-fetched. But research over the past couple of decades has revealed the far-reaching impact of the ecosystem of bacteria, fungi, viruses and other microbes that lives within us. Perhaps most surprising has been the associations scientists have discovered between the gut microbiome and our mental health. Now they are exploring whether harnessing this intricate ecosystem could help people feel better.

Growing evidence

The notion that your 鈥済ut feeling鈥� connects with your psychological experience of the world is well established in popular imagination. But until recently, scientists were deeply sceptical鈥攑articularly of the notion that the multitude of microbial cells inside us could have an impact on mental health. 鈥淔ifteen years ago, there was sniggering at the back of the seminar room when people presented their research,鈥� says Professor Phil Burnet, a neuroscientist at the University of Oxford, UK.

But the field of microbial neuroscience has accelerated rapidly over the past decade, thanks to an explosion of lab studies and trials in humans that involve microbiota. Some explore live beneficial microbes known as probiotics, others formulations of microbe food, or prebiotics, to fertilise specific bacterial strains. Meanwhile, heat-treated microbes, or postbiotics, are also being developed.

Together, these studies paint a picture of deep and important connections between the 鈥� from as many as 5000 different species 鈥� in your digestive tract and your physical and mental health. 鈥淗ow can we use this to maintain wellbeing or treat brain disorders?鈥� asks Burnet. 鈥淲ithin the gut-brain circuit, the gut microbiome is the most accessible component.鈥�

What happens in vagus

The neurons that operate the gut are sometimes referred to as our 鈥渟econd brain鈥�. Known as the enteric nervous system, in humans it contains an estimated 500 million neurons, more than . It operates autonomously to control digestion but is also in constant bidirectional communication with the brain via the vagus nerve.

This second brain and its connection with the one inside your skull is one way that gut microbes can affect mental health. There are others too:聽via metabolites they produce passing into the blood and crossing the blood-brain barrier, by impacting gut hormones and by stimulating the immune system.

鈥淭he microbiome is endlessly complicated, and what I suspect is that there is more than one mechanism for the clinical effects that we see,鈥� says Dr Richard Day, V.P. Medical Affairs and Clinical Development within R&D at ADM, a company that researches and markets pre-, pro-, and postbiotics. 鈥淲e鈥檙e still on that journey to unpick the mechanisms of action.鈥�

The fact that the gut microbiome is capable of impacting the brain is, however, clear.

Some of the strongest evidence comes from research into mood disorders, with studies showing associations with gut microbiome composition. Now, scientists are moving beyond these observational studies to experimental interventions to find out more.

A mechanistic study led by the University of Oxford, for example, found that giving participants a probiotic had measurable effects on their cognitive and emotional processing.聽 Other studies are exploring the gut-brain axis in clinical populations. In 2023, for example, researchers at King鈥檚 College London and ADM published a study in JAMA Psychiatry, exploring the effects of a probiotic in people with major depression. 鈥淭ogether, these studies paint an increasingly compelling picture of the gut-brain connection,鈥� says Dr Malwina Naghibi, Head of Clinical Development at ADM.

A two-way street

This connection works both ways: mental health can affect digestive health and vice versa. Irritable bowel syndrome (IBS), for example, has an established relationship with anxiety, and this link is being actively explored. In , ADM鈥檚 researchers gave adults with IBS either a live or a heat-treated strain of gut bacteria. Both produced similar results in patients, providing researchers with vital clues on how bacteria鈥攁live or dead鈥攊nteract with the gut and nervous system (see Box, right).

scientists are relishing the challenge of exploring this new frontier

These studies are typical of a proliferation of mostly small, but rigorous clinical trials testing the impact of the gut microbiome on , (ADHD) and . There is even into whether it plays a role in Alzheimer鈥檚 disease.

What鈥檚 needed now are larger studies over longer periods that can show how robust any impacts really are. 鈥淭here is just this explosion of research at the moment,鈥� says Naghibi.

The sniggering at the back of seminar rooms has gone quiet, but there is still a long way to go. Microbial neuroscience is a field in its infancy, psychobiotics even more so. Yet scientists are relishing the challenge of exploring this new frontier. 鈥淚 think this is the most exciting part,鈥� says Naghibi.

MICROBIAL AFTERLIVES鈥擳HE SCIENCE OF POSTBIOTICS

The new kid on the block in microbiome research is postbiotics. Unlike probiotics (live microbes) or prebiotics (microbe nutrients), these are preparations of microbes inactivated by heat or other methods, sometimes also together with the soup of cell fragments and metabolites they produce (see graphic). Even though the microbes are no longer alive, they can still exert biological effects. ADM scientists, for example, have shown that heat-treated bacteria produce to live ones in people who have IBS.

These effects can be rapid. A of postbiotics and the gut-brain axis noted physiological changes within an hour of administration. And findings from other trials suggest that the effects of postbiotics wear off when participants stop taking them. This suggests a direct effect rather than a permanent change to the microbiota, though much more research on mechanisms is needed.

Meanwhile, postbiotics are being investigated in a wide range of conditions. The ADM team, for example, has conducted a trial of 72 people exploring whether postbiotics can reduce the symptoms of allergic rhinitis.
The advantage of postbiotics over probiotics is that they don鈥檛 need to be kept alive, meaning they can be added to foods or drinks. Why swallow a pill if you could take postbiotics in the milk on your cereal?聽

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April is said to be the cruellest month, as the poem goes, 鈥渕ixing memory with desire鈥�. And this is oddly reflected in some of the non-fiction books we鈥檝e rounded up for you this month. There鈥檚 the life spent largely in a log cabin, often with only trees and other non-human life for company. Then there鈥檚 the problem of reconciling science with life鈥檚 toughest questions 鈥� and lived experience. Or how about an inspiring journey though the moon鈥檚 history, in the month we actually head back to it for the first time in 50 years? Perhaps you should really go for it and share one researcher鈥檚 tough quest to end violence, and another鈥檚 to future-proof our brains for the 21^st century. Buckle up for some bumpy emotions this month.

by Bernd Heinrich

One for naturalists who like spending a lot of time out in the woods. This, say his publishers, is the life of Bernd Heinrich 鈥� a former professor of entomology, a biologist, a naturalist and runner 鈥� who, for much of the year, lives in the cabin he built amid a 鈥渧ast sea of spruce, fir and larch in the mountains of western Maine鈥�. He鈥檚 been doing this on and off for some 40 years, facing, with the rest of the life around him, vast changes in the landscape as it is covered in snow, gives way to summer heat and sometimes is beset by fire, drought and flood. The 鈥渃ommon uncommon鈥� of the title reflects the characteristics of the spiders, ants, chestnut trees, porcupines, owls and mice in the woods near him. It鈥檚 聽鈥渁 narrative of small surprises in nature, some delightful and some 鈥� brought on by climate change 鈥� devastating, all seen through the sharp eye of a world-renowned naturalist鈥�.聽 Apart from the climate change, it sounds like Heinrich is a bit of a modern-day Thoreau, and his log cabin a stand-in for that occupied by the 19th-century writer, who isolated himself with nature in Walden, Massachusetts 鈥� albeit just for two years.

by Gary Slutkin

Gary Slutkin is a man on a very big mission. Here, he sets out his big idea: we can end violence by recasting it as an epidemic which can be interrupted, controlled and ultimately eliminated. Slutkin is an epidemiologist who earned his spurs tackling the spread of TB in San Francisco in the early 1980s, then moving on to work on cholera and TB in Somalia. From 1987, he worked at the World Health Organization on HIV and AIDS epidemics in Africa. Back in the US, two killings by 12-year-olds prompted him to look closely at violence, where he found the greatest predictor of a shooting is a prior shooting 鈥� like an infectious disease, exposure is crucial and so is social acceptance within a group. Slutkin set up Cure Violence Global, and his programmes to 鈥渃ure鈥� violence look to have been successful where they鈥檝e been applied, so his book should make a fascinating and rewarding read.

The best new popular science books of 2026

Clear out your shelves for a bumper new crop of books by authors including Naomi Klein, Rebecca Solnit and Xand Van Tulleken, says culture editor Alison Flood

by Vincenzo Levizzani

Just imagine being a professor of cloud physics. That鈥檚 Vincenzo Levizzani鈥檚 job and by the sound of his book, his vocation too. In The Book of Clouds: How to read the sky, he sets out to get us all to pay more than aesthetic attention to clouds by replacing our ignorance with what looks to be a very decent grounding. And yes, he cites lots of art and cultural cloud references, from chunks of Shelley鈥檚 poem The Cloud (Prometheus Unbound) to Cesare Pavese鈥檚 Grappa in September (Hard Labor). But if you want to recognise those clouds, find out how they form and create rain (among other aspects of their behaviour) and, of course, discover how climate change is affecting them, then this is for you. There are wonderful graphics and photos 鈥� and a glossary so you know a dropsonde from a graupel.

by Richard Elwes

Googology has everything to do with huge numbers 鈥� and nothing at all to do with a certain search engine. Those huge numbers are the stuff (and title) of a new book by Elwes, a mathematician and presenter of Numberphile (a YouTube channel 鈥� come on, keep up at the back). According to its publishers, Huge Numbers shows how counting has shaped human thought. Elwes himself describes it all as a 鈥渉uman story鈥�, stretching from the distant past to the far future. There are two main strands here.Firstly, he asks how big are the numbers people need and which ones mark our world鈥檚 outer limits? Secondly, what systems do we use for describing or processing these numbers? What are the biggest values they can cope with before they break down? Can you even name the largest number? I defy you not to laugh out loud at least twice.

by Hannah Critchlow

We live in supercharged, hyper-connected, thrilling yet downright scary times, as wave after wave of unprecedented change fuelled by AI and other forces crash over us. Is this, as some thinkers argue, a full-on major evolutionary transition? Will we have to rethink the nature of the biology of human intelligence, identity and individuality, as culture becomes the dominant driving force? What will we become? In The 21st Century Brain, neuroscientist Hannah Critchlow, an academic at the University of Cambridge and a public intellectual, takes all of this on 鈥� and according to her publisher, emerges with hopes that we can future-proof our brains. Her optimism looks to be based on humans drawing on innate capacities, skills and virtues, such as problem-solving, flexibility, curiosity, creativity, courage, empathy and communication. Given the widespread fear of governance by algorithm, of information distortion or hijack, not to mention of the power of social media to destroy childhoods and calls to ban smart phones for under-16s, let鈥檚 fervently hope she is right.

by Nobuko Nakano

Now here鈥檚 a topic guaranteed to entice and enrage in equal measure: the nature of luck and what we can learn from people who call themselves 鈥渓ucky鈥�. A sneak-peek at Nobuko Nakano鈥檚 Lucky People 鈥� a bestseller in Japan 鈥� shows that it aims to both deconstruct the idea that luck is random and encourage us to think that lucky people are, for all sorts of reasons, running different 鈥渘eurological software鈥� from the unlucky ones 鈥� software that can be installed. Among the things shaping this lucky personality that we can cultivate, Nakano says, are the brain changes that happen when we shift perception from detecting threats to seeing opportunities. Then there is possessing a positive self-image and generosity toward other people, and regular sleeping and rising habits 鈥� preferably early bird rather than night owl. Prayer is also in the mix. Fascinating stuff.

by Kathryn Paige Harden

Original Sin by Kathryn Paige Harden definitely needs its subtitle to reassure readers that we haven鈥檛 suddenly retitled the magazine New Theologist. So here it is: The genetics of wrongdoing, the problem of blame and the future of forgiveness. Harden, director of the developmental behaviour genetic lab at the University of Texas, studies some of the most important questions in modern life: how do we take responsibility for the people we become, knowing how we are shaped by both biology and experience? And what should we do when people hurt each other 鈥� or themselves? And has science made guilt obsolete? These are the ancient tensions between nature and nurture, freedom and constraint, the desire to punish and the longing to forgive. Let鈥檚 hope it delivers on such rare promise.

by Guilia Enders

Author and doctor Giulia Enders鈥檚 Gut was a bestseller, taking us on an unexpectedly fascinating voyage of the complex digestive system and covering the vital gut-brain connection, the importance of the microbiome and the impact of gut health on mental health. She is back with a new offering, Organ Speak: What it really means to listen to our bodies, which has already spent over six weeks at the top of the German bestseller list, say its publishers. This one could be even more surprising, with its message to look inside to better understand life outside. We can expect to be guided through our inner landscape and meet 鈥渢he unseen heroes of our bodies鈥�, as Enders explains how our organs have responded to challenges with astonishing intelligence 鈥� and just how much they have to teach us. What, for example, can the immune system tell us about our need to feel safe? And how does the process of wound-healing mirror emotional recovery? The bottom line is: what do we truly need to thrive? Definitely another one to watch out for 鈥� oh, and celebrity epidemiologist Tim Spector calls it a 鈥渢hrilling journey through health and disease 鈥� seen through the secret lives of our cells and organs鈥�.

by Christopher Cokinos

The moon is definitely back on the agenda with the launch of NASA鈥檚 Artemis II mission around the moon, sending four astronauts on a 10-day flight. The publication of Still as Bright: An illuminating history of the moon, from antiquity to tomorrow could hardly be better timed. Writer Christopher Cokinos tells the story of the moon over time and space, describing its role in the beliefs of ancient cultures and the science of Galileo鈥檚 telescopic discoveries, from the obsessions of 19th-century 鈥渟elenographers鈥� to the astronauts of Apollo, and now, Artemis II. The book also tracks Cokinos鈥檚 own lunar adventures as he explores the surface of the Moon using only his backyard telescope. The publishers call it a 鈥渃ultural and scientific history, as well as memoir鈥� a thoughtful, deeply moving, evergreen natural history鈥�. For all sorts of reasons, readers will never look at the moon the same way again.

by Lucy Rogers

We all scan the skies for signs of rain or sun, or just to look at the delightful clouds that change shape as they speed by. Then there鈥檚 the birds, effortlessly soaring, swooping or creating spectacularly improbable formations. Lucy Rogers鈥檚 book Up: A scientist鈥檚 guide to the magic above us, explores 鈥渢he beauty, science, and surprises of the world above鈥� as she travels the world: stopping off at a kite market in India, at the Borneo jungle to see bats as they pour out of a cave at dusk, and in Mexico to witness a total solar eclipse. Up聽definitely sounds like it鈥檚 one for all of us who crave a glimpse of the aurora borealis or marvel at the ingenuity of flight. Rogers is an engineer (she鈥檚 worked on space-debris-mitigation technologies, and you might have seen her as a judge in the BBC TV show聽Robot Wars) so the sense of wonder and quest for marvels will be well grounded. Looking forward to it.

by Ijeoma Uchegbu

Where would we be without chemistry quietly holding our chaotic world together? Every aspect of life is chemically mediated: from our DNA, resting tightly within our cells, to how we treat illnesses and physically build our world, to the chemical makeup of PFAs 鈥� the 鈥渇orever chemicals鈥� that are so terrifyingly good at sticking around. In her book, Chain Reaction, Ijeoma Uchegbu, professor of pharmaceutical nanoscience at University College London, reminds us of this science we take for granted and tells us about the chemistry which has shaped her own life.

The best new popular science books of March 2026

A new book from Rebecca Solnit, promising to bring us hope in these 鈥渄ifficult times鈥�, is among our pick of popular science titles out this month 鈥� along with a guide on how to talk to AI, and a look at modern warfare

by Helen Pearson

Helen Pearson is a seasoned editor at one of the world鈥檚 leading science journals so it seems fitting that she should tell the extraordinary story of how evidence, rather than opinion, is now seen as the only way to guide human decisions. This 鈥渆vidence revolution鈥�, say the publishers of her new book Beyond Belief, is a global effort to science-ify policy. This involves using data and scientific methods to discover what really works for questions such as: if police patrols reduce crime, are performance appraisals effective in actually boosting performance? Or can evidence show whether smaller classes help students 鈥� and, currently, shed light on whether smartphones really harm teenagers? Policy has always suffered from problems with evidence 鈥� possibly because it wasn鈥檛 available, or wasn鈥檛 in an accessible, timely form. Even medicine has had to creep forward, often relying on doctors鈥� opinions and conventional wisdom, rather than solid science. Looking forward to the nuts and bolts of this read.

Madeline Lancaster first created brain organoids back in 2013, they have become widely used for brain research around the world. But what exactly are they? Are they effectively miniature brains in dishes? Could implanting them in animals create super-smart mice? How close are we to crossing ethical lines?