New Research Confirms: Eating Fermented Foods Reduces Stress

A new study from APC Microbiome Ireland has found that consuming fermented foods helps reduce perceived stress levels. The research is published in Molecular Psychiatry.

The question of diet and its effects on human health has fascinated scientists for centuries. It is now widely accepted that diet plays a critical role in overall well-being. Conversely, poor nutrition contributes to an astonishing number of chronic health conditions, including obesity, diabetes, heart disease, cancer, and cognitive decline.

As science advances, there has been growing interest in the role of the gut microbiome in human health. This complex and fascinating collection of trillions of bacteria, viruses, and other microbes lives in the digestive system, helping to metabolize food, synthesize nutrients, and protect against infection. These microbes also produce metabolites that can influence mood and behavior.

Scientists are still working to understand the full extent of the gut microbiome's role in human health, but it's clear that this tiny ecosystem is essential for keeping you healthy.

More recently, research has begun to explore the link between diet and mental health, and there’s been increasing interest in the 'gut-brain axis' — the link between the brain and the digestive system. Numerous studies have suggested a connection between what you eat and how you feel.

Now, new research published in the journal Molecular Psychiatry has suggested that eating a diet rich in prebiotic and fermented foods can help reduce stress.

Diet and stress

Stress is a ubiquitous and essential part of human life. It's a normal physiological response that helps you deal with challenging situations. But long-term stress takes a toll on your physical and mental health. It's been linked to numerous health problems, including heart disease, diabetes, obesity, depression, anxiety, and sleep disorders. Therefore, finding ways to reduce stress is critical for overall health and well-being.

Exercise, hobbies, and mindfulness practices like yoga and tai chi are frequently touted as effective stress busters. Now, it seems that diet may also play a role.

The research team behind the new study has been investigating the association between stress and the gut microbiome for over a decade. Initially, they discovered that when young animals experienced stress, it impacted their microbiome later in life.

Research from 2017 showed that the microbiome impacts stress and behavior. However, it left scientists questioning if changing the microbiome through diet could affect stress levels. The latest study shows that consuming more fermented foods and fiber for just 4 weeks significantly lowered perceived stress levels.

The microbiome

The microbiome is part of your ecosystem. It comprises a community of microorganisms, including 'good' bacteria and disease-causing pathogenic microorganisms. If the balance of these microbes is disturbed, it can lead to health issues.

The digestive system has a nervous system — the enteric nervous system that's embedded in its lining. It can operate independently of the brain and spinal cord but relies on interaction with the autonomic nervous system through the vagus nerve, which extends from the brainstem to the abdomen. This communication occurs in both directions, meaning that the microbiome can influence brain function and vice versa. This is the basis of the gut-brain axis.

Should the vagus nerve become damaged, it can slow stomach emptying, which impacts digestion. This explains why stress can often contribute to digestive issues. For example, research has linked depression and anxiety to irritable bowel syndrome.

A psychobiotic diet

In the study, participants ate prebiotic and fermented foods. The researchers refer to this as a 'psychobiotic' diet, which contains foods that target the microbiome and aim to support mental health.

The 45 participants aged 18 to 59 years were randomized to two groups. The control group ate according to the food pyramid, meaning they consumed a diet high in carbohydrates, low in fat, and moderate in protein.

The participants in the psychobiotic diet ate 2 to 3 daily servings of fermented foods, including sauerkraut, kefir, or kombucha. Saurkraut is a type of fermented cabbage, while kefir is a fermented milk drink and kombucha is a fermented black or green tea. They also ate large amounts of fruits and vegetables high in prebiotic fibers, such as leeks, onions, cabbage, apples, and bananas. Both groups also had counseling from a registered dietician.

The volunteers followed the diet for 4 weeks, and then the researchers evaluated their stress levels and gut microbiota.

Reduced stress

The scientists used questionnaires to assess the stress levels of the participants. They found that those in the psychobiotic diet group had significantly lower perceived stress scores. Additionally, the more committed the participants were to the psychobiotic diet, the less stressed they felt.

The scientists were unsure if the short intervention would be enough to have an effect, but they found that even 4 weeks was enough to change the way participants felt.

The psychobiotic diet includes both probiotics or 'good' bacteria and fiber-rich foods, high in prebiotics that feed the microbes. Because the diet promotes gut health, which links to the stress response, and could help with stress management.

Increased sleep quality

The authors also noted that sleep quality improved in all volunteers. This could be due to several factors. Gut bacteria produce about 95% of the body's serotonin, which influences mood and is a precursor for melatonin, the hormone that regulates circadian rhythm and sleep.

The gut microbiome also contributes to gamma-aminobutyric acid (GABA) production, which promotes calm and helps with sleep.

Therefore, consuming a diet that nourishes the gut microbiome also provides the building blocks for critical sleep-promoting substances.

Diet influences health, and a new study has shown that a psychobiotic diet can help reduce stress. The diet comprises fermented foods, such as sauerkraut, kefir, and kombucha, as well as prebiotic-rich fruits and vegetables. The 4-week intervention was enough to change the way participants felt and improve sleep quality.

While more research is needed to understand how long these effects last and whether the diet can help with other mental health conditions, the findings suggest that the foods you eat can play an important role in stress management.