Why your gut microbiome might be important for your mental wellbeing

Your mental wellbeing is nourished by several things, including exercise, sleep, and social connection. In recent years, researchers are proposing that our gut health, particularly the gut microbiome, also affects our mental wellbeing.

What is the gut microbiome?

The gut microbiome refers to the trillions of bacteria that live in your gut. These bacteria are involved in digesting and extracting nutrients from the food you eat and regulating your immune system. A balanced and diverse microbiome is considered to be better for your health.

Why might the gut microbiome be important for your mental health?

Your gut and brain communicate to each other through your nervous system, immune system, and hormones. In recent years, scientists are becoming more interested in the role of the bacteria taking up residence in your gut. They are discovering that what goes on in the microbiome appears to affect your central nervous system, the system that governs what happens in your body and mind.¹

This may have implications for your mood and ability to cope with the stresses of life. Here are some ways your gut microbiome may play a role in your mental health:

it may affect the function of a system that helps your body respond to stress, called the hypothalamic-pituitary-adrenal (HPA) axis.2 An HPA axis that isn’t operating well has been linked to depression³
it can produce signaling molecules that control feelings and emotions, like serotonin and dopamine⁴
it produces short-chain fatty acids (SCFAs), which are molecules that impact your brain function¹
it influences your immune system and the inflammation that happens in your body. An unbalanced gut microbiome triggers molecules that promote inflammation, while a healthy gut microbiome produces SCFAs which decrease inflammation. Ongoing inflammation has been associated with depression.^4,5

When you experience stress, this can result in a gut microbiome that is out of balance.

Have there been research studies investigating this further?

There sure have, and the results prove to be exciting. Here’s what the latest research is showing.

The gut microbiome may be linked to depression or anxiety

In several studies, researchers have observed that people experiencing major depressive disorder seem to have lower numbers of certain gut bacteria than people who are not experiencing depression.^6,7

A 2021 review of 26 studies appears to support this, suggesting that there may be less SCFA-producing bacteria and more bacteria that promote inflammation in people experiencing anxiety and depression.⁸

Probiotics seem to alter mental health symptoms

Probiotics is the name given to live bacteria that are good for your gut. When probiotics are given to people experiencing depression or anxiety, this appears to improve their symptoms.^6,9,10

While this sounds like good news, don’t rush out yet to purchase probiotic supplements. According to Michelle Theodosi, an accredited practising dietitian based in Sydney, NSW, probiotic research is still in its early stages.

“We still can’t say specifically that ‘this strain of bacteria is what we need more of to reduce levels of anxiety’ and link each different strain to a specific mental health condition,” explains Theodosi. “But the science is moving that way.”

Diet changes that influence the gut microbiome also appear to influence mental health

The Mediterranean diet is a dietary pattern high in plant-based foods, lower in meat and dairy, and rich in healthy fats and oils, says Eleni Georgiou, an accredited practising dietitian based in Woolloongabba, Queensland.

This eating style has been associated with a healthy gut microbiome.^11,12,13 One possible explanation for this is that the gut microbiome seems to grow more types of SCFA-producing bacteria when people eat many different kinds of plant-based foods and fibre.¹⁴

In a 2017 study, researchers at Deakin University in Victoria found that study participants who adopted a Mediterranean diet finished the 12-week trial with greater improvement in depression symptoms, compared with participants who regularly attended a type of counselling.¹⁵

While the researchers did not specifically look into the microbiome in this paper, it may not be too far-fetched to wonder whether it has contributed to this fascinating result.

What can you do to nurture a healthy gut microbiome?

Knowing the promising link between your gut microbiome and mental wellbeing, here are five ways to give your gut bacteria the care they need to thrive.

Prioritise plant-based foods

Theodosi says the first thing to aim for is to eat as many different kinds of plant-based foods as you can, with the research showing over 30 types are better for the gut microbiome.¹⁴

What does this look like? “If you’re having oats with strawberries in the morning, this would give you two types, but if you want to boost that up, you might sprinkle a mix of nuts and seeds, and instead of just strawberries you might have mixed berries, so now you're getting six, seven, or eight types instead of one or two,” Theodosi says.

Mix up your fibres

As you gradually get into the swing of things, you can start looking at diversifying your fibres.

Different bacteria feed on different types of fibre, so don’t limit yourself to fruits and vegetables, but feel free to go nuts on chickpeas, lentils, beans, wholegrain breads, oats, brown rice, nuts and seeds!

Theodosi also encourages foods containing resistant starch, a type of fibre that feeds good gut bacteria in the last part of your digestive tract. These include bananas that are less ripe, and cooked potato and rice that is left to cool down first before you eat it.

Put in probiotics

After you’ve started feeding your gut bacteria the food it needs, you can introduce probiotic-rich foods like sauerkraut, kimchi, and kombucha.

“What these foods are doing is they're introducing new bacteria into the gut, which is great, but if we don't feed the existing bacteria, it's like planting a bunch of seeds in a barren desert that you haven't worked on or fertilised to make it an environment that can actually allow these seeds to thrive,” Theodosi explains.

Other sources of probiotics include yoghurt, cheese, olives, and fermented milk drinks.

Adopt Mediterranean-style eating

Finally, you can choose foods that lower inflammation through applying Mediterranean diet principles, says Georgiou. One key way to start is by having more healthy fats, like olive oil, nuts, seeds, avocado, and fatty fish like salmon.

A higher amount of healthy fats reduces inflammation in the body, says Georgiou, and less inflammation is linked to a healthy and balanced gut microbiome.

Embrace stress-relieving habits

We’ve been talking a lot about how your gut affects your mental health, but did you know it goes the other way? When you experience stress, this can result in a gut microbiome that is out of balance.¹⁶

Lowering stress is important when it comes to a healthy gut microbiome. You may already know what helps you relieve stress when things get overwhelming. If not, you may like to experiment with a couple of activities to see which ones help you most. Some activities to try include exercising, writing all your thoughts and tasks down, doing a breathing exercise, meditation, and taking some time to practice self-care or do what you enjoy.¹⁷

If you’re working in an office team environment, you might like to take it a step further and suggest some stress-relieving activities your colleagues can take part in during their breaks. This might include a quick walk around the block or journal whenever they feel snowed under, so they do not feel guilty or restrained from engaging in self-care at work.

En Masse offers a 1-hour seminar/webinar, The Right Mix, exploring the connection between healthy lifestyle habits and mental health, with some tips and goal setting aimed at adopting healthy behaviours. Contact us today to discuss a program tailored to your audience.

References

Almeida C, Oliveira R, Soares R, Barata P. Influence of gut microbiota dysbiosis on brain function: a systematic review. Porto Biomed J. 2020;5(2):1-8. doi:10.1097/j.pbj.0000000000000059
Rea K, Dinan TG, Cryan JF. The microbiome: A key regulator of stress and neuroinflammation. Neurobiol Stress. 2016;4:23-33. doi:10.1016/j.ynstr.2016.03.001
Belvederi Murri M, Pariante C, Mondelli V, et al. HPA axis and aging in depression: systematic review and meta-analysis. Psychoneuroendocrinology. 2014;41:46-62. doi:10.1016/j.psyneuen.2013.12.004
Butler MI, Mörkl S, Sandhu KV, Cryan JF, Dinan TG. The Gut Microbiome and Mental Health: What Should We Tell Our Patients?: Le microbiote Intestinal et la Santé Mentale : que Devrions-Nous dire à nos Patients? Canadian J Psychiat. 2019;64(11):747-760. doi:10.1177/0706743719874168
Milaneschi, Y., Kappelmann, N., Ye, Z. et al. Association of inflammation with depression and anxiety: evidence for symptom-specificity and potential causality from UK Biobank and NESDA cohorts. Mol Psychiatry. 2021. doi: https://doi.org/10.1038/s41380-021-01188-w
Sanada K, Nakajima S, Kurokawa S, et al. Gut microbiota and major depressive disorder: A systematic review and meta-analysis. J Affect Disord. 2020;266:1-13. doi:10.1016/j.jad.2020.01.102
Valles-Colomer M, Falony G, Darzi Y, et al. The neuroactive potential of the human gut microbiota in quality of life and depression. Nat Microbiol. 2019;4(4):623-632. doi:10.1038/s41564-018-0337-x
Simpson CA, Diaz-Arteche C, Eliby D, Schwartz OS, Simmons JG, Cowan CSM. The gut microbiota in anxiety and depression - A systematic review. Clin Psychol Rev. 2021;83:101943. doi:10.1016/j.cpr.2020.101943
Yang B, Wei J, Ju P, Chen J. Effects of regulating intestinal microbiota on anxiety symptoms: A systematic review. Gen Psychiatr. 2019;32(2):e100056. doi:10.1136/gpsych-2019-100056
Wallace CJK, Milev R. The effects of probiotics on depressive symptoms in humans: a systematic review [published correction appears in Ann Gen Psychiatry. 2017 Mar 7;16:18]. Ann Gen Psychiatry. 2017;16:14. doi:10.1186/s12991-017-0138-2
De Filippis F, Pellegrini N, Vannini L, et al. High-level adherence to a Mediterranean diet beneficially impacts the gut microbiota and associated metabolome. Gut. 2016;65(11):1812-1821. doi:10.1136/gutjnl-2015-309957
Mitsou EK, Kakali A, Antonopoulou S, et al. Adherence to the Mediterranean diet is associated with the gut microbiota pattern and gastrointestinal characteristics in an adult population. Br. J. Nutr. 2017;117(12):1645-1655. doi:10.1017/S0007114517001593
Ghosh TS, Rampelli S, Jeffery IB, Santoro A, Neto M, Capri M, Giampieri E, Jennings A, Candela M, Turroni S et al. Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries. Gut. 2020;69(7):1218–28. doi: 10.1136/gutjnl-2019-319654
McDonald D, Hyde E, Debelius JW, et al. American Gut: an Open Platform for Citizen Science Microbiome Research. mSystems. 2018;3(3):e00031-18. doi:10.1128/mSystems.00031-18
Jacka FN, O'Neil A, Opie R, et al. A randomised controlled trial of dietary improvement for adults with major depression (the 'SMILES' trial) [published correction appears in BMC Med. 2018 Dec 28;16(1):236]. BMC Med. 2017;15(1):23. doi:10.1186/s12916-017-0791-y
De Palma G, Collins SM, Bercik P, Verdu EF. The microbiota-gut-brain axis in gastrointestinal disorders: stressed bugs, stressed brain or both?. J Physiol. 2014;592(14):2989-2997. doi:10.1113/jphysiol.2014.273995
Queensland Government. 5 ways to reduce stress right now. Queensland Health. Updated October, 2020. https://www.health.qld.gov.au/news-events/news/how-to-reduce-stress-right-now