Fermented Foods Improve Brain Health: Study

Another study adds to findings that bacteria-rich foods can help us preserve mental and neurological health

Fermented foods have many reported benefits, including improved cognition and brain health, according to preliminary findings in a new study. zarzamora/Shutterstock

Fermented foods, which we all know are good for the gut, are also beneficial for our brains, preliminary findings from a new study out of Ireland suggest.

Foods can significantly impact our mental health, and certain foods in particular can positively affect the brain.

For example, according to a review published in Preventive Nutrition and Food Science, fermented foods may improve cognitive function by modulating the release of neurotransmitters like brain-derived neurotrophic factor (BDNF), glutamate, gamma-aminobutyric acid (GABA), and serotonin, which are involved in learning and memory.

Sauerkraut, a type of fermented cabbage, contains choline, an amino acid essential for the production of acetylcholine. Acetylcholine is a neurotransmitter involved in muscle control, circadian rhythm, and memory, and research shows it may have a protective effect against Alzheimer’s disease.

Fermented foods are also a source of tryptophan—an important amino acid. The body can use tryptophan to make the hormone melatonin (which regulates our sleep-wake cycles).

Tryptophan is present in milk, tuna, and many types of meat, such as turkey.

Tryptophan is also an essential precursor for serotonin, a neurotransmitter that influences a huge variety of brain functions, including mood.

Research has also shown that eating fermented foods may have long- and short-term impacts on brain function, resulting in improved mood and reduced stress.

Researchers from APC Microbiome, University College Cork, and Teagasc (Ireland’s Agriculture and Food Development Authority) in Moorepark, Cork, Ireland, are conducting a large study to figure out which fermented foods are best for the brain. The research team is comparing data from more than 200 foods from all over the world in search of a variety of metabolites that are known to be beneficial for brain health.

Fermented Foods for Brain Health

Although the study is still in its preliminary stages, researchers have been surprised and delighted at the results thus far.

“I expected only a few fermented foods would show up, but out of 200 fermented foods [tested], almost all of them showed the ability to exert some sort of potential to improve gut and brain health,” Ramya Balasubramanian, one of the study authors, said.

More research is needed to determine which foods have the most significant impact on brain health, but a couple already stand out.

“Fermented sugar-based products and fermented vegetable-based products are like winning the lottery when it comes to gut and brain health,” Ramya said.

“For all that we see on sugar-based products being demonised, fermented sugar takes the raw sugar substrate, and it converts it into a plethora of metabolites that can have a beneficial effect on the host. So even though it has the name ‘sugar’ in it, if you do a final metabolomic screen, the sugar gets used by the microbial community that’s present in the food, and they get converted into these beautiful metabolites that are ready to be cherry-picked by us for further studies.”

Fermented sugars can include those found in fruit, many vegetables, other carbohydrates, and the lactose found in dairy products.

As the study moves forward, Ramya said she hopes the public can use their preliminary results and consider including fermented foods in their diet to support their mental health and general well-being.

How the Gut Affects Mental Health

The microbiome is the collection of all the microorganisms, such as viruses, bacteria, and fungi, that live in a particular environment, such as in a human body. The gut is the most populated residence of the human microbiome. The gut microbiome helps with digestion, destroys harmful bacteria, protects against pathogens, and produces countless important metabolites.

In recent years, there has been considerable interest in the gut microbiome, and scientists are learning that it affects an enormous number of health issues. Our understanding of mental illness is also evolving based on new studies involving the microbiome. Rather than seeing mental health as localized to the brain, research demonstrates that our gut plays an active role in affecting mood and behavior through the microbiome-gut-brain axis.

A research article published in Microbial Ecology in Health and Disease discusses how research into the gut microbiome is disrupting the long-held assumptions in disciplines such as psychiatry.

“Research into the active role that the microbiome-gut-brain axis plays in affecting mood and behaviour may lead to the conclusion that mental health is more than an internalized problem of individual brains,” it notes.

One example is how studies have linked a disruption of the gut microbiome (dysbiosis) with stress, anxiety, and depression.

In a research review published in Clinics and Practice, the researchers from Texas Tech University note that the two-way communication between the central nervous system and gut microbiota, referred to as the microbiome-gut-brain axis, has been of significant interest in recent years.

“Dysbiosis and inflammation of the gut have been linked to causing several mental illnesses including anxiety and depression, which are prevalent in society today,” they note.

The researchers also note that probiotics can restore normal microbial balance, giving these foods and supplements a potential role in preventing and treating mental disorders.

Fermented Foods for Mental Health

Foods are fermented by bacteria that can then continue living in foods as long as they aren’t killed off by additional processing, a common occurrence with many foods, such as lower-end yogurts. Fermented foods with live bacteria are called probiotics and they are a simple, cost-effective way to improve digestion, mood, and brain health.

While the findings from the Irish study above may provide a wider scope of insight into the brain-boosting metabolites in fermented foods, other studies have also explored the benefits of eating fermented foods on cognitive function and brain health.

Much research has focused on the role of strains of Lactobacillus (L.) bacteria that break down sugars, including those in milk.

A study involving older adults aged 60 to 75 who ate Lactobacillus helveticus in the form of mediated fermented milk found that the fermented milk improved the subjects’ cognitive function.

In healthy middle-aged adults in Japan, a study found that participants who consumed probiotic milk (L. helveticus CM4) also had improved cognitive performance.

In a study of 60 Alzheimer’s patients aged 60 to 95 in Iran, participants consumed probiotic fermented milk (Bifidobacterium bifidum, L. casei, L. fermentum, L. acidophilus). The study concluded that the patients who drank the probiotic milk had improved cognitive abilities.

A review in Clinical Nutrition and Metabolic Care published in 2022 states that dietary changes to the microbiome impact brain health and behavior but that this knowledge is seldom incorporated into clinical practice.

That means that even though researchers have proven the therapeutic benefits of these foods, that information isn’t being acted upon by doctors. The result is that our medical treatments rarely reflect the impact food has on our overall health. Current and future research into the microbiome will inevitably give us more details about fermented foods and how they improve the health of the body, including the brain.

For now, adding fermented foods such as yogurt, kimchi, miso, and sauerkraut to your diet is an excellent way to enhance your gut microbiome and improve brain health.