The benefits of probiotics for stress, depression, anxiety, and cognition

On the surface, the digestive system seems pretty simple: one opening where things go in, a long tube winding its way through your body, and another opening where things come out.

Talk to a doctor or a scientist twenty years ago and this is basically how they would have described it to you.

Then, a bunch of scientists got together and decided to make things a lot more complicated (as they usually tend to do). They began asking what all those tiny microorganisms in the digestive tract are doing.

A whole new world of discovery emerged.

They realized what goes on in the gut is more complex and important than anyone could have imagined.

The bacteria, bacteriophages, viruses, fungi, protozoa, and archaea living in the digestive tract are collectively referred to as the “gut microbiome”.

A typical person has about 300 to 500 different species of bacteria living in their digestive tract. Some are harmful. Some are helpful. Some are even necessary for basic health.

The particular makeup of bacteria living in your intestines and whether it is positively influencing your health or negatively influencing your health is referred to as your “gut health”.

Researchers have noticed that gut health is linked to basically every part of the body. It influences the immune system, your mood, your mental health, autoimmune diseases, endocrine disorders, skin conditions, and even cancer.

The digestive system is a pretty direct link to the outside world. That means what we do and what we eat can have a substantial impact on the bacteria that reside in the digestive system and, in turn, all the facets of health that the gut microbiome impacts.

Things like high stress, not enough sleep, eating processed and high-sugar foods, and taking antibiotics all alter the gut microbiome in a negative way.

Healthy foods and probiotic supplements, on the other hand, can alter the gut microbiome in a positive way.

This article is going to focus on the positive impact probiotics have on brain function. Specifically, we’re going to touch on research linking probiotic supplementation to an improved stress response, less depression and anxiety, and improved cognition.

There are a ton of links to the original studies at the bottom of the page. Please check them out!

What are probiotics?

Probiotics are live bacteria and yeasts. The good and helpful kind that help keep your gut healthy.

Exactly how probiotics work isn’t completely understood. However, it is thought to have something to do with replacing good bacteria that have been lost and/or by balancing the amounts of good bacteria and bad bacteria in the gut.

Most probiotics come from two groups of bacteria: Lactobacillus and Bifidobacterium.

Lactobacillus is a type of “good” bacteria normally found in our digestive, urinary, and genital systems. It is also found in some fermented foods like yogurt and in many probiotic supplements.

Bifidobacterium are also “good” bacteria commonly found in the intestines. They belong to a group of bacteria called lactic acid bacteria, which are found in fermented foods like yogurt and cheese. This type of bacteria is also commonly found in probiotic supplements.

The positive effects of probiotics on the stress response

Most of the people you talk to are stressed out. Work, family, and financial woes can bring anyone to the brink of insanity.

If you feel this way, you’re not alone: 77% of people experience physical symptoms caused by stress. 73% regularly experience psychological symptoms caused by stress.

While probiotics can’t remove stressors from your life, they may be able to help regulate your response to them.

It turns out the gut microbiome plays a role in this physical and psychological response to stress. Mainly by regulating the HPA axis.

Animal experiments suggest bacteria in the gut have a positive influence on the stress response. Mice raised in conditions where they lack bacteria in the digestive tract have an exaggerated stress response.

This exaggerated response can be reversed when the animals are given probiotics.

Another study in animals showed that probiotics normalize stress hormones.

In humans, probiotics dampen the stress response and alter the activity of brain regions responsible for controlling the processing of emotion and sensation.

The positive effects of probiotics in depression and anxiety

Depression and anxiety affect over 100 million people all over the world.

As a result of an increased understanding of the link between the gut microbiome and mood, neuroscientists have become increasingly interested in using compounds, like probiotics, to treat depression and anxiety.

Animal models tell us that probiotic treatment moderate anxiety and antidepressant-related behavior. We know from studies in people that probiotic consumption is linked to better scores on depression and anxiety scales, improved mood status, and improved clinical signs of depression.

Probiotics may be working to produce these beneficial effects by elevating blood tryptophan concentrations, modulating serotonin levels in the frontal cortex, modulating dopamine metabolites in the cortex, and altering the expression of certain receptors for neurotransmitters.

The positive effects of probiotics on cognition

Cognition is a catch-all term used to describe many intellectual functions and processes our brains perform. These include things like attention, the formation of knowledge, memory and working memory, judgement and evaluation, reasoning and computation, problem solving, decision making, comprehension, and the production of language.

Cognitive function decreases with age and is drastically diminished in neurodegenerative disorders like Alzheimer’s disease.

In healthy people, probiotics improve scores on cognitive fatigue tests and modulates brain activity during emotional attention tests.

Probiotic supplementation also improves cognitive function in patients with Alzheimer’s disease.

Conclusion

Good gut health is essential for good overall health.

Probiotic supplementation is a good way to make sure your gut microbiome is functioning optimally. There are a lot of good options out there. If you’d like help picking a good one, please contact me. I’d love to help you out.

Sources and further reading

Postnatal microbial colonization programs the hypothalamic-pituitary-adrenal system for stress response in mice

Probiotic treatment of rat pups normalises corticosterone release and ameliorates colonic dysfunction induced by maternal separation.

Bifidobacterium longum 1714 as a translational psychobiotic: modulation of stress, electrophysiology and neurocognition in healthy volunteers.

Consumption of fermented milk product with probiotic modulates brain activity.

The effects of probiotics on mental health and hypothalamic-pituitary-adrenal axis: A randomized, double-blind, placebo-controlled trial in petrochemical workers.

Impact of consuming a milk drink containing a probiotic on mood and cognition.

Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial.

Fermented milk of Lactobacillus helveticus IDCC3801 improves cognitive functioning during cognitive fatigue tests in healthy older adults.

Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer’s Disease: A Randomized, Double-Blind and Controlled Trial.

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