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Ever felt butterflies in your stomach when nervous or lost your appetite during stressful times? It’s a clue to the amazing connection between your gut and brain!

Recent research has found a complex two-way communication network between our digestive system and the central nervous system. The trillions of microbes in our gut, known as the microbiome, play a big part in this.

How the Gut and Brain Communicate: Understanding the Gut-Brain Axis

The gut-brain axis is a two-way communication highway between the central nervous system and the gut. This communication happens through the immune system, neurological pathways, and hormonal signals. 

The ENS is a complex network embedded in the gut lining with 200-600 million neurons. This neural system runs from the esophagus to the rectum and looks very similar to the brain. So, essentially, our central nervous system (CNS), which includes the brain and spinal cord, talks to the enteric nervous system (ENS) in the gut, which is often referred to as our second brain.

The two-way nature of this communication allows the brain to influence gut function and vice versa. For example, stress or mood changes can change gut motility and microbiome composition, while gut bacteria can produce neurotransmitters and short-chain fatty acids that affect brain function.

The Vagus Nerve and Neurotransmitters

The vagus nerve, the 10th cranial nerve, is key to the gut-brain axis. This nerve is the main communication highway between the brain and the gut, transmitting sensory and motor signals.

The vagus nerve is important in relaying information about the gut environment to the brain (Breit et al. 2018). Neurotransmitters are also part of this communication network. The gut microbiota can produce neurotransmitters like serotonin and dopamine, which affect mood, stress response, and cognitive function. In fact, 90% of the body’s serotonin is produced in the gut!

A study in mice published in the Proceedings of the National Academy of Sciences (Bravo et al 2011) found that probiotic consumption reduced stress hormone levels in the blood. But when the vagus nerve was cut, the probiotic had no effect, showing the vagus nerve is key to gut-brain communication.

How Gut Bacteria Affect Mood and Cognition

Gut bacteria produce neurotransmitters like serotonin, dopamine, and GABA, which regulate emotions and cognitive functions. They also synthesize short-chain fatty acids that affect brain health and behavior.

The gut microbiome also affects the hypothalamic-pituitary-adrenal (HPA) axis, which regulates stress responses. A balanced microbiome helps to keep the HPA axis in check, which can reduce anxiety and depression. Gut bacteria also modulate inflammation, which can impact cognitive function and mental health.

Research shows that certain probiotic strains can improve cognitive function and reduce symptoms of depression and anxiety. For example, Boehme et al. (2023) found that taking Bifidobacterium longum NCC3001 for 6 weeks reduced people’s perceived stress and improved subjective sleep quality.

The Impact of Dysbiosis on Mental Health

Dysbiosis, an imbalance in the gut microbiome, is associated with many mental health conditions.

Various studies show:

1. People with irritable bowel syndrome (IBS) are more likely to have anxiety and depression.
2. People with diverse gut microbiomes are less likely to develop psychiatric disorders.
3. Probiotic and prebiotic interventions to improve gut health show promising results in reducing symptoms of depression and anxiety.

Practical Steps to Make for Better Mental Health

1. Take it slow

Start with small, manageable changes to your eating habits to increase the chances of long-term success. For example, a wellbeing solution HeyWellness can help you gradually introduce healthy habits into your life by preparing personalized daily plans for your sound mental state. 

So, swap one processed snack for a piece of fruit a day or add a new veg to your meals each week. By taking it slow, you give your taste buds and gut microbiome time to adapt, making the transition smoother for your mental health.

2. Eat more fermented foods

Fermented foods like yogurt, kefir, kimchi, and sauerkraut are gut superfoods, full of good bacteria that support the gut-brain axis. 

The study by Wallace and Milev (2017) found that eating probiotics for 4 weeks reduced depressive symptoms, so try to include at least one serving of fermented foods in your daily diet to become mentally resilient.

3. Eat more plant-based meals

Plant-based meals are high in prebiotic fiber that feeds gut bacteria and promotes a healthy microbiome. People who followed a plant-based diet had higher levels of good gut bacteria compared to those on an omnivorous diet (Tomova et al. 2019) , while Psaltopoulou et al. (2013) found that a Mediterranean diet, which is known for being plant-based, was associated with a 30% reduced risk of depression.

4. Cut out processed foods and added sugars

Processed foods and added sugars can harm gut health and therefore mental wellbeing. A study by Akbaraly et al. (2009) in the British Journal of Psychiatry found that people who ate more processed foods had a higher risk of depression compared to those who ate mostly whole foods. 

So, swap sugary snacks for fresh fruit and whole grains for refined carbs, and read food labels carefully to identify and avoid hidden added sugars in packaged products.

5. Hydration and mood

Even mild dehydration can affect mood, cognitive function, and energy (Zhang et al., 2019). Aim for at least 8 glasses (64 oz) of water a day and set reminders or use a water tracking app to help you reach your hydration goals. Remember, staying hydrated supports optimal gut function and better mental health!

Conclusion

By understanding the gut and brain relationship, we can make informed choices to support our psychological well-being through nutrition. We believe that small, consistent changes in our eating habits can lead to significant improvements in our mental health. 

As research in this field continues to evolve, we’re excited about the potential for dietary interventions to complement traditional mental health treatments, offering a holistic approach to well-being.

References

• Breit S, Kupferberg A, Rogler G, Hasler G. Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Front Psychiatry. 2018 Mar 13;9:44.
• Bravo JA, Forsythe P, Chew MV, Escaravage E, Savignac HM, Dinan TG, Bienenstock J, Cryan JF. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. Proc Natl Acad Sci U S A. 2011 Sep 20;108(38):16050-5.
• Boehme M, Rémond-Derbez N, Lerond C, Lavalle L, Keddani S, Steinmann M, Rytz A, Dalile B, Verbeke K, Van Oudenhove L, Steiner P, Berger B, Vicario M, Bergonzelli G, Colombo Mottaz S, Hudry J. Bifidobacterium longum subsp. longum Reduces Perceived Psychological Stress in Healthy Adults: An Exploratory Clinical Trial. Nutrients. 2023 Jul 13;15(14):3122.
• Wallace CJK, Milev R. The effects of probiotics on depressive symptoms in humans: a systematic review. Ann Gen Psychiatry. 2017 Feb 20;16:14.
• Tomova A, Bukovsky I, Rembert E, Yonas W, Alwarith J, Barnard ND, Kahleova H. The Effects of Vegetarian and Vegan Diets on Gut Microbiota. Front Nutr. 2019 Apr 17;6:47.
• Psaltopoulou T, Sergentanis TN, Panagiotakos DB, Sergentanis IN, Kosti R, Scarmeas N. Mediterranean diet, stroke, cognitive impairment, and depression: A meta-analysis. Ann Neurol. 2013 Oct;74(4):580-91.
• Akbaraly TN, Brunner EJ, Ferrie JE, Marmot MG, Kivimaki M, Singh-Manoux A. Dietary pattern and depressive symptoms in middle age. Br J Psychiatry. 2009 Nov;195(5):408-13.
• Zhang N, Du SM, Zhang JF, Ma GS. Effects of Dehydration and Rehydration on Cognitive Performance and Mood among Male College Students in Cangzhou, China: A Self-Controlled Trial. Int J Environ Res Public Health. 2019 May 29;16(11):1891.

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