‘We were a society dying, said Aunt Lydia, of too much choice.’
Margaret Atwood. The Handmaid’s Tale.
Books can change you. They can change how you think, about relationships, about love, about toasting and grinding your own spices – all the important stuff. The most rewarding books, I think, are those which most give us pause for thought. Books with nothing to teach us are boring. We crave knowledge.
Lots of people read Margaret Atwood’s The Handmaid’s Tale last year. It’s a book that has been a catalyst in a chain reaction leading to a dramatic shift of attitudes. Usually though, the changes made by books are relatively small and incremental. We gather ideas and opinions and slowly alter our way of being.

In her book, Transformative Experience, Philosopher L.A. Paul writes about the occasions in our lives when we face a life-changing choice. You know, those times you review with hindsight and remark that you were a different person then. Becoming a mother is something many women feel is a transformative experience. Paul’s thesis is that you can’t know, before the transformation, who the new you will be after it. So, you can’t rationally choose to have a baby. You, the new mother, might feel completely differently about the whole idea to you who hasn’t had a baby.
Paul gives another great example. Imagine for a moment that I am outrageously attractive and charismatic, and a vampire. Imagine also that I like you and I offer you a one-time-only opportunity to become a vampire. It will only hurt for a second and then you will be gorgeous and powerful, just like me. Vampires have that kind of sexy thing going on and there’s the promise of immortality of course so you might say yes. But, imagine then that you discover you can’t stand the taste of blood, can’t stomach even a slice of black pudding, and the biting thing is less erotic than advertised. You’ve made a terrible mistake. Or, then again, you might love it. You might ROCK as a vampire for all eternity. The thing is you can’t know ahead of the choice- it’s simply not possible. Becoming a vampire will teach you things that you can’t learn without becoming a vampire, and you will experience a new way of being you which is difficult to even imagine beforehand.
You don’t make a decision on whether or not being a vampire is going to work out for you. What you really decide is whether you want to find out what it’s like to be a vampire. Or, what it’s like to be a mother, or perhaps an emigrant, or a priest, or an astronaut, or even a Martian, or a human Earthling with a fully functional microbiome. A what? I’ll come back to that.
Think about books again. Do you think a book could change you so much that you could call it transformative? To begin with, as the adage goes, you can’t judge a book by its cover. Well, we do, but it doesn’t get you far. You can’t know until you read the book if it will change you. You can’t even know if you will like it, no matter how much I tell you that you will. I know that I have ended reviews with a line about how whichever book will make you think differently about whatever subject but I don’t think I’ve ever thought for a moment that a single book could fundamentally change who you are.
I’ve spent January reading, re-reading and mulling over The Psychobiotic Revolution, published this month by National Geographic, written by Scott C. Anderson and based on the research of John F. Cryan and Ted Dinan at the APC Microbiome Institute here in Cork. John Cryan is a neuroscientist while Ted Dinan is a psychiatrist. Together with other APC researchers, they are the cutting edge.
Probiotics, as you are probably aware, are live micro-organisms introduced to the body for their beneficial effects. Psychobiotics, as defined by Cryan and Dinan, are a subclass of probiotics which, when ingested in large amounts, produce beneficial effects psychologically.
Their work is built upon several decades of research into the human microbiome, that is the vast and various community of microscopic organisms living on, and in, you.
The latest ballpark estimate figures that you have something in the region of 30 trillion human cells in your body. You also carry about 39 trillion microbial cells, give or take a billion. There are more bacteria in your gut, Anderson writes, than stars in our galaxy. The microbes in your gut, taken all together, weigh more than your brain. There could easily be a thousand different species of bacteria inside you alone which is a lot when you consider that fewer than 100 species of bacteria have ever been identified as disease-causing in humans. Fewer than one hundred- that’s nothing in the vast scheme of bacterial existence. What’s even more fascinating is that some of those species inside you live nowhere but inside the human gut. You probably even have a species or two which are uniquely yours. The continuation of their kind is completely dependent on your survival. They need you, and you need them too. That’s what they call symbiosis.
And now for the truly mind-blowing statistic: Your human cells carry between 20 and 25 thousand genes but your microbial buddies can beat that number 500 times over. The organisms of your microbiome are busily expressing their genes inside your body and affecting, in the most fundamental way imaginable, what it means to be you. Those genes code for proteins that affect your nutrition, your energy levels and the strength of your immune system. They affect how you smell, how you taste (back to the vampire thing) and who you fancy. They affect the progression of disorders coded by your human genes. They affect your sleep patterns and your appetite. They give you cravings. They affect your mood. They can make you feel anxious or aroused, deflated, depressed, stimulated or scared stiff. They affect the growth and repair of your brain cells. They affect how you think. A significant alteration to your microbiome, then, would make you a different person. No? Yes?

When I was in college, all the buzz was about HUGO, the project to sequence the human genome. Every week, it seemed, molecular biologists identified a new gene associated with one disease or another. We were confronted with the idea of genetic testing – that a simple blood test might tell us how we would die. Genetic sequencing was a revolution in science. It changed everything. But it also gave the impression of being pretty cut and dried. If you have this gene, you’ll die of that disorder. Environmental factors were bound to have an effect but the genetic contribution of the human microbiome was not, as far as I can recall, ever mentioned.
Now, the human microbiome is the hottest of topics. It’s scorching. Microbiologists all over the world are savouring their newly found cachet as they publish paper after paper and find themselves listed as some of the world’s most influential minds.
Cryan and Dinan’s work focuses on the communication between your gut flora and your brain, something they call the gut-brain axis.
Let me give you just one example. Bifidobacteria are what is known as a keystone species in your gut. They make up a relatively small percentage, about 2%, of your gut flora but they exert a lot of influence. Anderson suggests you think of them as being like lions on the savannah. If they are wiped out, the whole ecosystem is out of whack. Bifidobacteria have a dietary preference for a soluble fibre called inulin which you source by eating lots of plant material. Bifidobacteria digest that inulin, assuming you’ve been eating your veggies, and they produce a fatty acid called buyrate. Butryate does a whole stack of stuff. Butyrate feeds the cells which make up the lining of your gut wall. It dampens inflammation and heals damage. Butyrate also melts through the gut wall, enters your bloodstream and travels to your brain where it stimulates the production of dopamine making you feel chilled out and happy. Butyrate also encourages the growth of brain cells. It makes you think more clearly. Butyrate makes you feel and think better and it makes you crave more of that fine inulin substance and so begins a self-perpetuating cycle of good form and good health.
Crave fibre, you scoff, who am I kidding? Anderson points out that craving sugar is a reliable clue that your gut flora is not what it ought to be. The term for a faulty microbiota, a failure in the symbiotic relationship, is dysbiosis. Other signals of dysbiosis include, but are not confined to, asthma, allergies, autism, IBS, gluten intolerance, lactose intolerance, persistent diarrhoea, constipation or flatulence, diabetes, lack of drive, lack of focus, anxiety, panic attacks, withdrawal from society or depression. Anderson lists some possible causes of dysbiosis: infection, inflammation, chronic stress, overuse of painkillers, overuse of antibiotics, excessive alcohol, autoimmune disorders, radiation therapy, chemotherapy, over-eating, poor diet and lack of exercise.
Anderson enthusiastically explores the butyrate cycle as well as providing an overview of some of the other ways your gut flora communicates with your brain. It’s scientifically detailed but never less than fascinating. He describes the development of your microbiome from conception all the way through to the moments following your demise. He describes the variations in your microbiome in the different parts of your body and along the length of your digestive sytem, from your gum line to your rear end. He explains why your microbiome is largely inherited from your mother making this a matrilineal society. He details the incredible advantages bestowed upon breast-fed babies and why the diet of a toddler up to the age of two is of crucial importance. He explains why so many people eating a ‘western’ diet of junk food, loaded with sugar, feel sluggish, sick, anxious or depressed. He explores the effectiveness of probiotic supplements on the market today, offers some advice on which brands have potential for alleviating which digestive disorders and which may have psychobiotic effects. He provides guidelines on which foods are most effective in nurturing a healthy, balanced, physically beneficial and mood-enhancing gut flora, foods termed prebiotics. He does all this in an accessible and entertaining style.
Your microbiome has a remarkable and, until now, sorely underestimated degree of control over your mind. But ultimately, you are the boss of them. You control what you eat and what you eat changes everything. As Anderson puts it, you can change your microbiome overnight, just by changing what you eat.
If you imagine your self to be a bundle of expressed genes, and accept that you can alter a significant portion of that bundle, you might just be holding the key to a fundamentally transformative experience. Once you read Anderson’s book, you will have information which you can’t really get anywhere else (unless you feel like ploughing through 400 scientific publications), information which could radically alter your life, information which could change you to such a degree that you will, with hindsight, look back and say that you were a different person before you read this book.
Because, you see, once you have that information, it’s difficult to ignore it, which brings me full circle.
‘Ignoring isn’t the same as ignorance, you have to work at it.’
Margaret Atwood. The Handmaid’s Tale.
If Atwood’s book could change how you think about the experience of being a woman, and Laurie Paul’s book could change how you think about change, The Psychobiotic Revolution could change how you think.
The only problem is that you can’t know until you read it how it is going to change you, regardless of how much I try to convince you. You have to decide whether you want to find out what it might be like to be that human with a microscopic, symbiotic army marching to your tune. There can be no going back.
Let me know what you decide.
Full disclosure:
I am a graduate of the Microbiology Department of UCC.
Prof. Ted Dinan sent me an e-copy of The Psychobiotic Revolution in anticipation of an honest review.
Prof. Laurie Paul is my friend.