Written by Aiman Khan

Thumbnail Photo by Maëliss Demaison on Unsplash

We are not alone in our bodies, but rather we coexist with a multitude of different organisms that can affect what we eat and how we feel. In essence, our bodies are an ecosystem.

We might have all heard about the microorganisms living on our skin. Fortunately for us, these tiny organisms ward off harmful pathogens all while taking care of our old skin cells so we don’t have to. The skin may be our largest organ, but each internal organ in our bodies has its own mutually beneficial relationships with other bacteria and fungi. Increasingly over the past few decades, the spotlight has been turned on the gut and its microbiome, and the effects it can have on health and disease. Understanding the role they play in our bodies may help us to better understand ourselves.

What is the gut microbiome?

The gut microbiome refers to microscopic organisms like bacteria, viruses, fungi, and yeast that live inside our gut. Of all these organisms, bacteria have garnered the most interest from researchers and scientists. This makes sense considering the sheer number of bacterial cells in our bodies – over 10 million more than our own human cells, contributing to 4 pounds of our body weight (more than the weight of our brains!) Some might say, we are more bacteria than human beings.

Gut microbiomes differ among people and there are up to 1,000 different species of bacteria in our guts. Both quantity and quality matter here. It has been shown that the higher the diversity of bacteria in your microbiome, the better it is for your body and that healthier individuals have a higher diversity of microbiome than their less healthy counterparts. While some of these microorganisms are our friends, others can cause serious diseases like cancer, obesity and diabetes. Conversely, they also play a significant role in regulating energy metabolism and insulin resistance.

Interestingly, we are not completely genetically predestined to have the microbiome that we do. Lifestyle factors like what we eat contribute to whether or not you have friends or foes in your gut. This was shown in several well-known studies on identical twins. Results found that mice who received microbiota from obese twins gained more weight than the control mice, despite them being on the same diet.

The role of the gut microbiome on brain health is also considerable. Studies have shown that people with different psychological disorders may have different species of bacteria in their guts compared to healthy individuals. Moreover, certain probiotics like probiotic yogurt have also been shown to have an effect on improving symptoms of depression (but don’t throw out your antidepressants just yet!).

Our Second Brain

The gut is lined with upwards of 100 million nerve cells, leading some to call it our “second brain.” These cells carry instructions to the brain about how hungry we are, when to stop eating, and even what kind of foods we should eat. You may have intuited the connection between your gut and mind without prior scientific knowledge. After all, at one point or another, we’ve all experienced butterflies in our stomach before an exciting trip or date, or the feeling of dread before a big presentation.

But did you know that your gut also produces neurotransmitters like your brain – 30 different ones, in fact. And maybe most surprising of all, some evidence shows that as much as 95% of your ‘happy neurotransmitter serotonin is stored and produced in the gut.

The vagus nerve, a thick bundle of neurons at the base of the brain, serves as your bi-directional highway from the gut and brain. You might think that most of the signalling happens in your brain and is then sent into the gut to be carried out. In actuality, 90% of the neurons in the vagus nerve carry information to the brain from the signals produced by our tiny gut microbes.

What does this mean for our health? Inflammation has been shown to be associated with mental illness with recent studies reporting a large number of patients with inflammatory bowel disease also suffering from depression and anxiety. This has led some researchers to even go as far as to suggest that stimulating our vagus nerve might serve as a drug-free antidepressant.

Researchers have also found that changing the ratio of beneficial and pathological bacteria in an animal’s gut can cause changes in its brain chemistry, ultimately leading it to become either bolder or more anxious, respectively. In one study, a lab-manufactured strain of mice that are typically timid were put on a diet of antibiotics that changed their gut bacteria. As a result, their behaviour was completely altered and emboldened. In the words of gastroenterologist Emeran Mayer, director of the Center for Neurobiology of Stress at the University of California, “It’s almost unthinkable that the gut is not playing a critical role in mind states.”

The implications of the gut microbiome in our mood regulation and brain processes are still a relatively new scene of discovery for neuroscience. At the moment, most of the studies on gut science have been conducted on our furry friends, and are themselves at their infancy. Only further scientific exploration can tell us how far our gut-brain connections go. However, the findings thus far are clear: what you eat can have a large impact on your mental health and behavior.

Eating Your Way to a Better Gut

So, how can you improve your gut microbiome? Here are some ways you can increase the number of beneficial bacteria in your gut and decrease the quantities that are associated with diseases.

·Eat a diverse range of foods – the more diverse your microbiome, the healthier is your gut. This is because different species of bacteria can afford you different benefits. Include more varieties of whole foods in your diet, and cut back on the unhealthy fats and sugar.
Eat Prebiotic food (fibres from carbs that your microbiota digests) – some examples would be cocoa, berries, apples, flaxseed, garlic, tomatoes, oats, and legumes.
Eat foods rich in polyphenols (micronutrients we get from plant-based foods) – This should be an easy step to implement. Foods like dark chocolate, grape skins, red wine, green tea, blueberries, broccoli, and even onions contain polyphenols.
Eat fermented foods –products like yogurt, kefir, sauerkraut and kombucha.

We’re all prone to eating fast food when we’re on the go. But the effects of eating fast food can be devastating to your gut. A professor of genetic epidemiology at King’s College in London had his son eat only McDonald’s for ten days straight. The resulting impact on his microbiome was shocking: he lost almost 40% of the total bacterial variety in his gut – which even after two weeks of returning to a normal diet was not recovered According to the professor, “the loss of diversity is a universal signal of ill health.”

Although the science on this is still in its infancy, our gut is a fascinatingly complex system that deserves more careful consideration in what we put in it. If you’re on a journey to better your mental and physical health this year, you can start with your gut. Try to improve your diet and lifestyle if you want to train your second brain.

Our Second Brain: Gut Feelings and Microbiome

FOLLOW US