Have you ever followed your ‘gut feeling’? Whatever your gut tells you is obviously computed in your brain. Rigorous science has established that in fact your gut ‘talks’ to your brain. The vice-versa is also true of course. You may recall an instance when you experienced an upset stomach while being nervous or anxious? Or does ‘butterflies in your stomach’ ring any bells? The bidirectional communication between the gut and the brain (Figure 1) is too often underrated and neglected especially by the food industry that caters more to our hunger pangs than to our body’s nutritional requirements.
Scientific research has shown that there is in fact a ‘second brain’ in our gut. The gut has a mass of neuronal tissue filled with neurotransmitters that relay information to our brain primarily via the Vagus nerve. Therefore, what we eat, how it affects our gut lining as well as how it is digested and absorbed can affect brain function that in turn controls our mood and anxiety levels.
Furthermore, our gut houses what is known as the ‘gut microbiome’. The latter consists of trillions of bacteria that have a huge potential to influence health and disease. In fact, the hormonal and neural signaling relayed between the brain and the gut microbiome via blood (systemic communication) and/or nerves (neural communication) is very robust. This is substantiated by a vast body of scientific literature that shows physical and psychological stress affects the metabolism of gut bacteria and determines how many good (bacteria aiding digestion and absorption of food) or bad bacteria (disease causing bacteria) reside in our gut. In turn, changes in gut microbiota profoundly affect emotional behavior and may be one of the many factors that underlie disease states such as depression, anxiety and autism spectrum disorders, to name a few.
Figure 1: Bidirectional communication channels between the gut, gut microbiome and brain. The hormonal signals and inflammation –related signals from the gut affect the brain. In turn the brain can influence the gut function and microbial composition through neural and hormonal signals. Adapted from Mayer et al 2014, Journal of Neuroscience.
Unfortunately, the effect of diet on mental health is much-to-often neglected by conventional psychiatry. For example, typically the first line of medication for patients that complain of depression are SSRIs (selective serotonin reuptake inhibitors, example Prozac) that alter brain neurochemistry and whose long-term use (and often short-term use as well) induces a host of side-effects affecting the individual’s productivity. Given that depression is a disease which is rapidly becoming an epidemic due to stressful life conditions, a vast majority of depressed individuals rely on long-term medications rather than improving their diet. “We are indeed what we eat”. Scientific literature as well as holistic psychiatric practice has shown that making drastic changes towards a healthy diet can reverse much of the symptoms associated with mental disorders.
We must realize that our lifestyle and our modern diets have evolved much faster than our physiology. The sugary, gluten-containing food which has become staple diet in the urbanized world wreaks havoc in our gut epithelial lining, breaks into our blood stream where it is (still) recognized as foreign. This can induce immune responses manifesting as undetectable inflammation or allergic reactions in the extreme case. We are all aware of rising numbers of gluten induced celiac disease patients leading to the burst of gluten-free products in the market. Flour-based gluten-containing foods, processed and artificial sugars, as well as certain proteins present in dairy products insult the single-cell epithelial lining in the gut and threaten the population of good bacteria in our gut.
On the other hand, our modern diet includes very little essential fats and fat-soluble vitamins that are derived by fish oils, red meat, nuts, seeds as well as ghee and lard. Roughly 80% of the brain is made up of fat (lipid). Therefore, it is essential to complement our diet with healthy fats. Even cholesterol that is infamous for blocking arteries and causing heart attacks, is extremely essential so we should not be depleting our diets of cholesterol. This small molecule is not just critical for maintaining the integrity of neuronal cell membranes but is also the precursor of several steroid-based hormones such as estrogen, testosterone and the famous stress hormone - cortisol. There is tremendous cross-talk between these various hormones in our body that governs much of our body’s functioning with respect to metabolism, homeostasis, cognition and behavior.
Health and wellness experts as well the organic food advocates have long championed the cause of fresh fruits, vegetables, pastured meats, nuts and seeds. Conversely, sugary food leads to a spike in insulin levels in the blood, that ultimately results in a temporary crash in blood sugar levels. This contributes to drowsiness, fatigue and headache following a binge on cookies, for example. These low energy levels lead to us craving for more energy rich, sugary food yet again. It is high time we break this vicious cycle. For the sake of our mental and physical health, let’s trash the burgers and welcome the oranges.
- Dr. Avani Shukla, Molecular Neurobiology,
International Max Planck Research School,