Here is the full transcript of nutritionist Ruairi Robertson’s TEDx Talk presentation: How Your Belly Controls Your Brain at TEDxFulbrightSantaMonica conference.
Listen to the MP3 Audio: How your belly controls your brain by Ruairi Robertson at TEDxFulbrightSantaMonica
Ruairi Robertson – Author at Authority Nutrition
Imagine this: You have just won $10 million in the lottery. Congratulations.
You have just eaten the most delicious, warm, chocolate brownie that has ever been baked.
You have just had sex.
And you have just done all three at the same time. Congratulations to you, too.
In these situations, our brains produce chemicals called neurotransmitters which give us these great feelings of energy, excitement and happiness. And without such chemicals inside of us, we wouldn’t feel such emotions during such pleasant circumstances.
So instead, imagine this: You’ve just been fired. You’re about to sit an exam. You have depression. In these situations, our brains, instead, produce different chemicals, making us feel stressed and anxious.
The highs and lows of life are controlled by our emotions and these chemicals in our brains. This vital organ inside all of us that controls everything that we feel, think and do. However, as a biologist, I’ve always found it strange to comprehend that every feeling, thought, and action that we have is controlled by a three-pound, soggy lump of cells inside of our heads, until I discovered that this might not be the case.
The story I want to share with you today unfolds a fascinating new revelation in our understanding of human physiology, that we each have a second brain — another organ in our body which controls as much of our physical and mental functions as the brain in our heads, and which may be the key link between modern disease epidemics, globally, from obesity to cardiovascular disease, maybe even to mental health.
But first, to give you a little introduction to this story, I want to tell you a little bit about my background.
I was brought up in a family of psychologists. My mom is a clinical psychologist; my dad a professor of psychology in a university; my sister even has a PhD in psychology. So when it came to me going to university, I wanted to study something different. I’d heard enough about the brain and how it worked at home, so I wanted to study something new.
I considered what I was interested in, and I figured out that from a very early age, I’d had a big interest in food. I loved eating food. And so, I decided to study human nutrition. And this was great because I got to study food, how it affected our bodies, how it could contribute to disease, and more importantly, how we could use it to fight and prevent disease.
This story begins back in 1845 with the birth of a curious young boy in Russia who became an incredible man, but who was forgotten by history and medicine. Ilya Mechnikov was fascinated by everything in nature, and by the age of eight, he was taking notes on all the living things in his vibrant back garden. He became so good at science that he discovered the role of phagocytes, some crucial cells in our immune systems, for which he won the Nobel Prize in 1908.
But it was his science after winning the Nobel Prize that was even more crucial to our understanding of human health, through a tale of discovery, death, and self-experimentation.
See, everyone in this room has something in common. We all spent the first nine months of our existence inside our mothers’ wombs. And this was essentially a sterile environment where no other living things existed, just you. But as you emerged into this world, you were smothered in an invisible coating of microbes, friendly microbes from your mother’s birth canal. And these bacteria grew to form what is now a three-pound invisible organ inside your large intestine, the same weight as your brain, and which has become known as our microbiota, or microbiome.
And this invisible organ has grown so much, in fact, that right now, 90% of the cells in your body are bacterial cells; only 10% are your own human cells. So you are more bacteria than you are human.
This ecosystem of microbes in your gut is as diverse as the Amazon rainforest. Thousands of species all with different functions. And your health is incredibly dependent upon the life and vibrancy of this rainforest. Your gut bacteria digest certain foods, produce essential vitamins and hormones, respond to medicine and infections, control your blood sugar and blood cholesterol levels.
Meaning the types of bacteria in your intestines can significantly control your risk of certain diseases from obesity to diabetes, maybe even osteoporosis. They’re involved in just about every process in your body. They function almost as a second brain.
Well, Ilya Mechnikov [also written as: Élie Metchnikoff] may have figured this out himself in 1892. He lived in France, in Paris at the time, where a deadly cholera epidemic had broken out with thousands of deaths. Naturally, as a scientist, he decided the best way to study this was to drink a broth of cholera himself. Remarkably, he didn’t get sick.
So again, as a true scientist, he needed to increase his sample size, so he recruited a colleague to do the same thing. This guy didn’t get sick either. But when he recruited another colleague to do the same, this poor guy got critically ill and very nearly died.
By studying cholera under the microscope, Mechnikov found that certain species of bacteria from the human intestines supported and stimulated cholera’s growth, while other species prevented it. He subsequently claimed that our gut microbiota, or our gut bacteria, were essential for human health, and that the right balance of microbes inside of us could help stave off disease.
However, popular understanding at the time, was that the human gut was a noxious reservoir of toxins. Surgeons had even begun removing entire sections of human intestines in patients with gut discomfort. Mechnikov’s death in 1916 meant that his ideas that our gut bacteria were good for us were forgotten.
A decade later, antibiotics were discovered, and drastically became overused. C-sections became common. Diets became Westernized. A war was waged on microbes and we spent a century trying to kill them, which turned our intestinal rainforests into barren wastelands. This Nobel Prize winner’s ideas were lost in time.
Some of the implications of this were identified recently. See, right now, one in three children in America are born by C-section, meaning they don’t get this initial inoculum or coating of bacteria that’s been designed by evolution to be in the mother’s birth canal. Instead, they’re first coated with other bacteria on the skin or in the hospital environment which has contributed to up to a 25% increased risk of obesity, asthma, immune deficiencies and inflammatory bowel disease in later life.
Fortunately, in recent times, we’ve realized we must restore our relationship with gut microbes for our own physical health. However yet, we’ve still completely underestimated their role as our second brains. And this is something that I’m researching.
And I learned this first through the intriguing story of a mouse. If mice become colonized by the microbe Toxoplasma gondii, an intriguing thing happens: they lose their fear of cats. In fact, they become attracted to cats. In essence, they go a bit mad, and unfortunately for them, usually end up as dinner for cats. So, this microbe ingested by this animal takes control of its brain, and changes the way that it thinks and behaves.
So, by delving deep inside the intestinal jungle of bacteria in our intestines, we’ve begun to find some incredible discoveries that are changing our appreciation for bacteria forever.