The gut, food, mood connection
Ever have to run to the bathroom every time you’re anxious or stressed?
Do you get butterflies in your stomach when you’re nervous?
The connection between our mood and digestive symptoms is due to what’s called the gut-brain axis.
The key to your mental health could lie in your gut.
What is the gut-brain axis?
Exciting new studies in the field of gut microbiome research have shown that the trillions of microbes that reside in our intestines affect our mood and vice versa in what’s now called the gut-brain axis.
This two-way communication occurs via the vagus nerve, which runs from the brain stem down throughout our digestive system. This communication primarily travels from the gut up to the brain.
Within our gut, intestinal microbes, hormones, immune cells, and a substance produced by good gut bacteria called butyrate that communicate with the central nervous system which controls our hunger, food preferences, satiety, and hunger. There is also an association between our microbes and many psychological conditions and illnesses such as anxiety, schizophrenia, autism, Alzheimer’s disease, and Parkinson’s disease.
Microbes affect our mood
An imbalanced gut microbiota composition has been associated with increased stress, depression, and anxiety.
Interestingly, several intestinal microbes can produce neurotransmitters, or brain chemicals, such as dopamine, serotonin, norepinephrine, and gamma-aminobutyric acid (GABA). An estimated 95% of serotonin is produced in our intestines.
Stress and our gut
Not surprisingly, new evidence shows that stress negatively affects the gut-brain axis. When we experience physical and mental stress, the gastrointestinal tract releases brain chemicals like the calming neurotransmitters GABA and dopamine, which make us feel motivated, and can also affect digestive functions of the immune system.
IBS patients, who frequently suffer from anxiety and stress, have been found to have an unhealthy gut microbiome and increased intestinal inflammation which reaches the central nervous system. The stress experienced by these patients has also been found to alter the gut microbiota composition.
Experiencing stress and the consequent release of the neurotransmitter norepinephrine can also increase susceptibility to suffering a pathogenic infection like Salmonella enterica.
Stress may also affect brain development in fetuses and teenagers. Pregnant women who experience stress during critical times of fetal development can cause alterations in the gut-brain communication of their babies. Teens going through puberty may experience sex-specific stress that alters the gut microbiota composition which consequently alters hormone levels and neurotransmitter production.
Inflammation in the gut
Gut microbiota-related inflammation can consequently cause brain inflammation which has been observed in Alzheimer’s and Parkinson’s disease patients. Targeting the gut microbiota through diet and supplements is now becoming a therapeutic target in treating neurological disorders associated with an underlying cause of inflammation such as anxiety, depression, schizophrenia, autism, and Alzheimer’s disease.
Good bugs for good moods
Anxiety and depression are becoming more prevalent and are a global health concern. Although few studies have been performed on humans, research has shown that certain probiotics may improve neuropsychiatric or neurodegenerative disorders, making them a promising therapeutic approach for improving mood with little side effects. For example, probiotics like Bifidobacteria and Lactobacillus strains have been effective in treating depression, anxiety, autism spectrum disorders and improving Alzheimer’s disease symptoms.
On the other hand, taking antibiotics which indiscriminately get rid of the good and the bad bacteria in our intestines, has been shown to negatively impact behavior through various mechanisms like altering serotonin production.
Food and your mood
Long-term adherence to a diet seems to have the greatest impact on the gut microbiota composition, although certain nutrients have also been shown to affect the gut-brain axis.
Mediterranean diet: Following a Mediterranean diet has been shown to decrease inflammation and the risk for depression possibly due to its positive effects on the gut-brain axis.
Western diet: Following a Western diet which is high in fat, protein, and processed foods may increase stress because it’s pro-inflammatory and has negative effects on the gut microbiome.
Ketogenic diet: This very low carbohydrate diet increases the level of ketones in the blood, which are chemicals the liver produces in response to low glucose intake, which has been found to reduce neurodegeneration. This diet may also decrease inflammation and alter the gut microbiota composition in a way that’s protective against epilepsy, autism, and schizophrenia.
Fibre: Eating a high fiber diet, especially foods like tubers, bananas, and asparagus, has been shown to increase the production of the anti-inflammatory substance butyrate in the colon, which may have therapeutic effects for neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Polyphenols naturally occur in colorful plant-based foods ranging from tea to cacao and can be protective against a wide range of diseases. Their anti-inflammatory and antioxidant properties have been shown to reduce oxidative stress in various psychiatric disorders and have a positive effect on the central nervous system.
Vitamin D: Deficiency has been associated with multiple sclerosis, autism, Alzheimer’s disease and depression due to its anti-inflammatory properties and ability to alter the gut microbiota composition.
Vitamin B12: The gut microbiota can synthesize B12 and affect its absorption in the intestines which consequently influences neurological health.
Omega 3: The omega 3 fatty acids DHA and EPA appear to improve depression, schizophrenia, age-related cognitive decline, overall mental health, and possibly Alzheimer’s disease. Omega 3 fatty acids also influence the gut microbiota composition.
Avoid food additives that are inflammatory and can hurt the gut microbiome.
In conclusion, gut health greatly affects our mental health through various mechanisms. On the other hand, high-stress levels, inflammation, and antibiotics can harm the gut microbiome and consequently neurotransmitter production and overall mental health and mood. Luckily more studies are emerging that show that adhering to a whole foods anti-inflammatory diet like the Mediterranean diet and supplements like probiotics can support and even improve mood and cognitive health.
***Note: This article was written for Wellness Journey.
References
Dinan, Timothy G.a; Cryan, John F.b The impact of gut microbiota on brain and behaviour, Current Opinion in Clinical Nutrition and Metabolic Care: November 2015 - Volume 18 - Issue 6 - p 552-558 doi: 10.1097/MCO.0000000000000221
Cryan JF, et al. The Microbiota-Gut-Brain Axis. Physiol Rev. 2019 Oct 1;99(4):1877-2013. doi: 10.1152/physrev.00018.2018. PMID: 31460832.
Kim, Y. K., & Shin, C. (2018). The Microbiota-Gut-Brain Axis in Neuropsychiatric Disorders: Pathophysiological Mechanisms and Novel Treatments. Current neuropharmacology, 16(5), 559–573. https://doi.org/10.2174/1570159X15666170915141036
Mukhtar, K., Nawaz, H., & Abid, S. (2019). Functional gastrointestinal disorders and gut-brain axis: What does the future hold?. World journal of gastroenterology, 25(5), 552–566. https://doi.org/10.3748/wjg.v25.i5.552
