Gut Bacteria and Mental Health: How Food Affects Mood

August 2, 2022
Reviewed by Sonja Schoonenberg, RDN, CDE
Gut Health

If you’re like most people, chances are you’ve experienced some lethargy after a heavy meal. It is a commonly known fact that the more food you consume, the more likely you are to feel lethargic afterwards ¹. However, something that fewer people are aware of is that the types of food you consume can also have a significant effect on your mental health.

In this post, I examine the relationship between gut bacteria and mental health, as well as how you can improve your diet to benefit your mental health and general well-being.

What is Gut Bacteria?

Gut bacteria is a general term that commonly refers to the trillions of microbes, fungi, viruses, and other microscopic creatures that populate the gastrointestinal tracts of every human being. Collectively, these gut bacteria and microbes constitute what is known as the gut microbiome.

Studies have shown that the health of a person’s gut microbiome can have an effect on their immune system, metabolic function and even their basic physiologic functions ².

The Gut-Brain Connection

At this point, you might be wondering: how exactly is the digestive system linked to the brain?

In short, the vagus nerve is one of the body’s longest nerves systems and the brain uses this neural pathway to control many of the body’s involuntary functions, including digestion, heart rate and muscle function ³. This is also known as the gut-brain connection, and it is through this pathway that gut bacteria is able to affect your mental health.

The Relationship Between Your Gut Microbiome & Mental Health

Scientists have studied the connection between gut microbiomes and physiological conditions such as obesity for decades. The gut microbiome is widely accepted as one of the key risk factors that can contribute to obesity ⁴.

However, the link between gut bacteria and mental conditions such as depression or anxiety is a one that has only been established in recent years.

Gut Bacteria and Depression

Recent studies have shown that gut bacteria can send signals to the brain via the gut-brain barrier ⁵. As a result, changes in gut microbiome compositions have also been linked to changes in mood.

Some bacteria such as butyrate-producing Faecalibacterium and Coprococcus have been shown to increase the quality of life experienced by their hosts ⁶. Conversely, a lower population of these bacteria could result in depression and a lower quality of life.

Gut Bacteria and Anxiety

If you find that you’re often feeling anxious or panicky, chances are that your gut health might also be one of the factors causing you to feel that way.

As with depression, gut bacteria can send signals to the brain via the gut-brain barrier, affecting neurological functions such as mood regulation ⁷. Imbalances in gut bacteria, also known as dysbiosis or dysbacteriosis, have also been shown to cause stress and stress-related behaviors such as anxiety.

Gut Health and Mental Health: Changing Your Diet to Improve Your Mood

The composition of an individual’s gut microbiome can be affected by a variety of different factors such as genetics and even their method of delivery at birth ⁸. The gut microbiome is generally resilient to external influences and short-term dietary changes typically have limited effect on the composition of one’s gut bacteria composition and gut health. However, recent studies have shown that long-term dietary patterns can have a significant impact on an individual’s gut microbiome ⁹.

Thus, changing your diet can be a good first step to improving your gut health and consequently, your mental health. Here are some changes you can make to your diet dietary habits to improve your mental health:

Consume More Probiotic-Rich Foods

Commonly touted as health foods that can contribute to weight loss, probiotic-rich foods can also do wonders for your mental health. Probiotics is a term that generally refers to a family of gut-friendly bacteria and yeasts that are beneficial for your gastrointestinal health when consumed regularly. Some of the most commonly available probiotic-rich foods that you can get include yogurts and soft cheeses.

Studies have shown that probiotics can help to prevent dysbiosis, enabling you to maintain a healthier gut microbiome ¹⁰. This can in turn have mood-regulating effects, helping you to improve your mental health and mitigate your risk factors for depression and anxiety. Moreover, you can also enjoy the added benefit of lowered obesity risk when you consume probiotic-rich foods as part of your regular diet.

Consume More Fermented Foods

While it may not seem immediately obvious to most people, there is actually an abundance of health benefits that you can enjoy from consuming fermented foods. The process of fermentation introduces bacteria into foods such as kimchi, miso, kombucha, sauerkraut, and even beer ¹¹. If done right, the fermentation process can be hugely beneficial and can help to introduce beneficial bacteria into your gut microbiome when you consume them.

Consequently, fermented foods can bring with them significant health benefits such as lowered blood pressure, reduced cancer risk and antioxidant effects ¹². They also contribute to healthier guts and improved mental health.

Consume More Fiber-Rich Foods

Like all living organisms, gut bacteria require nutrients to survive. Foods that are rich in dietary fibers have been found to promote gut health and contribute to the growth of beneficial bacteria in the gut ¹³. Thus, you can also consider adding more fiber-rich foods to your diets such as fruits, vegetables, legumes and cereals.

Foods with high fat and sugar content can also be detrimental to your gut health and you should avoid consuming these in excessive quantities. Studies have found that individuals who regularly consumed foods with high fat and sugar contents often experienced dysbiosis ¹⁴.

Apart from negative impacts on their cognitive and behavioral functions, such individuals typically also had higher risk factors for various metabolic disorders such as type 2 diabetes, irritable bowel syndrome and colorectal cancer ¹⁴. Thus, while the occasional fast food treat be too detrimental to your mental health, it would be advisable to avoid making these foods a part of your daily routine.