probiotics and gut health


In pursuing a happier, healthier life, our exploration can include various avenues: nutrition, exercise, and mindfulness practices. Yet, an unseen factor may hold the key to optimal mental health—an intricate ecosystem of microorganisms in our digestive tracts. These minuscule inhabitants, collectively known as the gut microbiota, have emerged as unsung heroes in the complex relationship between our guts and brains, offering new hope for a brighter outlook through the power of probiotics. As we delve into the intricate world of the gut-brain axis, this blog will unravel the fascinating connections between probiotics and mental health.


The Probiotic Journey: Unveiling the Microbial Marvels Transforming Gut Health

Deep within our bodies, the gut microbiota resembles a bustling metropolis populated by trillions of diverse microbial species. Recent scientific revelations have illuminated a previously overlooked link between this thriving community and our mental well-being. Once regarded as mysterious, the gut-brain connection is now a focal point in scientific research, shedding light on the profound impact of gut health on our emotional and psychological balance.

Intriguingly, probiotics—beneficial live bacteria and yeasts—have emerged as change agents in this complex picture. Known for their ability to promote digestive health, these microorganisms may also play a remarkable role in nurturing our mental well-being.

The Food and Agriculture Organization of the United Nations and the World Health Organization defines probiotics as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host” [1]. While scientific interest in probiotics has surged, challenges arising from the popularity of the term have led to confusion and skepticism on a global scale.

Precision in probiotic research is now a necessity for credibility. Misinterpretations serve as cautionary tales, emphasizing the importance of stringent testing, adherence to clinical guidelines, and precision in research to prevent unwarranted damage to probiotics’ reputation [1]. The minimal requirements for an effective probiotic include live microorganisms, genetic identification of strains, appropriately designed studies, and specificity for each intended application.

As the field of microbiome science progresses, there is a growing call for physicians to critically evaluate microbial preparations, considering evidence from randomized, controlled human trials, viability, and whole-genome strain characterization [1]. This underscores the rapid progress in microbiome research and the potential therapeutic benefits of manipulating microbial ecosystems.

Our digestive system is a hidden world teeming with life and vitality, orchestrating a symphony of interactions that intricately weaves together our physical and mental well-being.

Understanding Gut Microbiota: Guardians of Digestive and Mental Health

The connection between mental and physical health is inseparable. Inflammation serves as the fundamental catalyst for conditions such as anxiety, depression, cognitive fog, and fatigue. Various factors contribute to this inflammatory response, including hormones, gut health, nutritional gaps, environmental pollutants, persistent stress, and unresolved trauma. It is crucial to recognize that our innate state is not fundamentally flawed, and significant healing is entirely achievable.

Nestled within the depths of our digestive system is a dynamic microcosm—a hidden world teeming with life and vitality, orchestrating a symphony of interactions that intricately weaves together our physical and mental well-being. In this intimate ecosystem, the inseparable connection between our mental and physical health comes to life, influencing and shaping our overall sense of wellness. This intricate web of microorganisms, collectively known as the gut microbiota, is a diverse community comprising bacteria, viruses, fungi, and other microscopic entities [2].

The gut microbiota, often called the “forgotten organ,” is pivotal in maintaining a delicate balance within our bodies. Envision the gut microbiota as a complex ecosystem, where each member plays a distinct role in maintaining the balance of digestive processes, crucial for nutrient absorption and immune response [2].

As we delve into the captivating realm of the gut microbiota, we uncover intricate connections between these microscopic inhabitants and our overall well-being. This exploration extends beyond traditional perspectives on digestive health, guiding us into the exciting domain of probiotics and their potential impact on mental health—a frontier gaining increasing attention in scientific research.


Navigating the Microbiota-Gut-Brain Axis: A Bidirectional Communication System

The gut microbiota and probiotics operate as guardians of gut balance through various mechanisms, promoting a symbiotic relationship with the host [2]. These mechanisms include competitive exclusion, where probiotics outcompete pathogenic bacteria for resources and adhesion sites, thereby preventing their colonization.

Additionally, probiotics produce antimicrobial substances, such as bacteriocins, that inhibit the growth of harmful microorganisms. Furthermore, they modulate the host’s immune system, enhancing its ability to respond to challenges while maintaining tolerance to commensal microbes.

This journey through the microbial landscape reveals the profound implications of nurturing our gut for a healthier and happier life.


Scientific Validation: Probiotics as Catalysts for Mental Well-Being

In a randomized, double-blind, placebo-controlled trial involving 70 human participants, the effects of probiotic yogurt and multispecies probiotic capsule supplementation on mental health and the hypothalamic–pituitary–adrenal axis were investigated.

Participants were divided into three groups, each receiving a specific intervention for six weeks. Both probiotic yogurt and probiotic capsule groups significantly improved mental health parameters, as measured by the general health questionnaire (GHQ) and depression anxiety and stress scale (DASS) scores. In contrast, the conventional yogurt group exhibited no significant changes. The study suggests that consuming probiotic yogurt or a multispecies probiotic capsule positively affects mental health [3].

In another clinical trial, different probiotic strains were tested on various groups of people, from healthy volunteers to those with conditions like depression or autism. The results showed promising effects on mental well-being [4]. For example, some strains were linked to reduced anxiety and depression behaviors, improved mood, and even lower levels of negative thoughts. In patients with major depressive disorder, certain probiotics led to a decrease in depression scores and an increase in a marker associated with antioxidant activity. 

In children with abdominal pain, a probiotic reduced the severity and frequency of pain [4]. Another study on autistic children found improvements in autism severity after a probiotic intervention. Interestingly, a probiotic was also associated with reduced stress and anxiety during exam periods for students. However, not all studies showed significant changes, emphasizing the need for more research. These findings suggest a potential link between probiotics and mental health benefits in various populations, showing promise for further exploration.

Probiotics in human mental health and diseases
Sivamaruthi BS, Prasanth MI, Kesika P, Chaiyasut C. Probiotics in human mental health and diseases – A minireview. Tropical Journal of Pharmaceutical Research. 2019;18(4):29. doi:10.4314/tjpr.v18i4.29.

Exploring the Impact: Probiotics and Mechanisms

Due to factors such as malnutrition, decreased gut motility, and polypharmacy, older adults can experience a shift in the microbiome, leading to gut dysbiosis and microbial imbalance [5]. Alterations in the gut microbiota, referred to as gut dysbiosis or microbial dysbiosis, can impact microbial populations and their by-products, including short-chain fatty acids (SCFA) and neurotransmitters, affecting the brain through the microbiota-gut-brain axis [6].

The microbiota-gut-brain axis is a bidirectional communication system involving the gut microbiota and the human host, influencing the brain and impacting mood and behavior through various mechanisms [7]. These mechanisms include immune and inflammatory pathways, neurotransmitters, microbial by-products, neuroendocrine and enteroendocrine signaling, the stress response, and the vagus nerve [7]. The gut microbiota considered a functional organ, consists of various microorganisms, including bacteria, viruses, fungi, archaea, and protozoa, with an intricate balance influenced by lifestyle, age, body composition, diet, and antibiotic use [8].

Dietary habits, such as those associated with the Western and Mediterranean Diets, can significantly influence the gut microbiota composition [9]. A high intake of ultra-processed foods, refined sugars, and low dietary fiber typically characterizes the Western Diet. This diet is associated with reduced diversity and abundance of beneficial bacteria in the gut. The lack of fiber means fewer substrates (complex carbohydrates) available for beneficial bacteria to feed on, leading to a less diverse microbiota. In contrast, the Mediterranean diet is rich in fruits, vegetables, whole grains, and legumes, providing a higher dietary fiber intake. Fiber acts as a prebiotic, promoting the growth of beneficial bacteria in the gut. This can contribute to a more diverse and robust microbiota.

Under normal physiological conditions, the gut microbiota stimulates the release of cytokines and chemokines, regulating bacterial populations in the gut and maintaining homeostasis [10]. However, increased inflammation, as seen in stress, can compromise the intestinal barrier, leading to a “leaky gut” and bacterial infiltration, resulting in elevated plasma lipopolysaccharide (LPS) levels [10]. This bacterial translocation can trigger a neuroinflammatory response, affecting the Hypothalamic-Pituitary-Adrenal (HPA) axis and influencing the brain through various pathways [10].

Bacteria within the gut microbiota produce neurotransmitters, including GABA, norepinephrine, dopamine, acetylcholine, and serotonin, which play crucial roles in mental health and neurocognitive function [11]. Additionally, microbial by-products such as bacteriocins, bile acids, choline, and short-chain fatty acids contribute to gut-brain communication [11]. The gut microbiota also communicates with the central nervous system through gut endocrine cells, releasing neuropeptides and hormones that influence behavior and mood [11].

gut health
Ghasemian Sorboni S, Shakeri Moghaddam H, Jafarzadeh-Esfehani R, Soleimanpour S. A Comprehensive Review on the Role of the Gut Microbiome in Human Neurological Disorders. Antimicrob Chemother. Published online January 5, 2022. doi:10.1128/CMR.00338-20.


Probiotics and Mental Health Disorders

In the realm of neurocognitive and mental health disorders, gut dysbiosis is a recurring observation, extending its influence to various conditions, including dementia. Pathological proteins like amyloid and tau contribute to neuroinflammation in dementia, and the gut microbiome is implicated in the progression of Alzheimer’s dementia. Recent reviews have succinctly summarized data on alterations in gut microbiota composition in Alzheimer’s patients, underscoring the potential link between gut dysbiosis and dementia pathology [12]. Moreover, behavioral and psychological symptoms associated with dementia, characterized by disturbed perceptions and behaviors, may be influenced by the gut-brain axis, thereby opening avenues for dietary and nutritional interventions.

Depression, a prevalent condition marked by mood dysregulation, sleep disturbances, and appetite changes, has also been associated with shifts in the gut microbiota. Research in both animals and humans has demonstrated a connection between microbial dysbiosis and major depression, with specific bacterial phyla showing altered abundance. Additionally, certain antidepressant medications, like fluoxetine and sertraline, may contribute to gut dysbiosis through their antimicrobial effects [12]. Encouragingly, probiotics, whether administered independently or as adjunct therapy with antidepressants, have exhibited promise in mitigating depression symptoms [12,13].

Obsessive-compulsive disorder (OCD), characterized by intrusive thoughts and ritualistic behaviors, is another psychiatric illness where the gut microbiome may play a role. Both animal and human studies suggest that specific gut bacteria can influence neurotransmitter levels and the HPA axis, potentially impacting OCD-like behaviors [14]. Although limited, existing studies indicate a reduction in OCD-like behavior with the administration of probiotics, emphasizing the need for further research into the gut-brain connection in OCD.

Anxiety, a condition with notable effects on gastrointestinal function and gut microbiota, displays a correlation between chronic stress, microbial populations, and altered gut metabolites [15]. Mouse models and human studies indicate that disruptions in the gut microbiota are associated with anxiety-like behaviors. Promisingly, probiotics have demonstrated efficacy in reducing anxiety symptoms, presenting a potential avenue for treatment [15].

Bipolar disorder (BP), characterized by recurrent mood and energy changes, showcases alterations in gut microbiota composition in affected individuals [16]. Studies highlight changes in specific bacterial populations, including Faecalibacterium, Flavonifractor, and Actinobacteria, in patients with BP. Preliminary evidence from small randomized controlled trials suggests the therapeutic potential of probiotics in BP [16].

Schizophrenia, a mental disorder characterized by psychosis, reveals alterations in the gut microbiota in affected individuals [17]. Both animal and human studies demonstrate associations between specific bacterial populations and schizophrenia-related behaviors. Furthermore, medications used to treat psychiatric conditions, such as risperidone and olanzapine, have been linked to altered gut microbiota levels [17].


A Holistic Approach to Mental Well-Being


As we navigate the captivating realm of probiotics and their profound influence on mental health, we stand at the intersection of scientific discovery and holistic well-being. The bidirectional communication of the microbiota-gut-brain axis has unveiled a promising frontier for those seeking innovative strategies to nurture emotional resilience and maintain mental balance.

In the pursuit of mental wellness, integrating probiotics into our diets offers a compelling avenue. The symbiotic relationship between our gut and mind allows for a more comprehensive and enlightened approach to mental health. The impact of dietary habits, the microbiome’s role in the release of neurotransmitters, and the potential therapeutic benefits of probiotics provide a multifaceted view of mental well-being.

However, it is crucial to approach these findings with a discerning eye. The complexity of mental health conditions calls for ongoing rigorous research. Precision in probiotic research is necessary for credibility, emphasizing the importance of stringent testing, adherence to clinical guidelines, and precision in research to prevent unwarranted damage to probiotics’ reputation.

The journey into the microbial world of probiotics and the gut-brain connection is not just a scientific exploration but a call to action. By understanding and embracing the relationship between our gut and mind, we embark on a path toward a more resilient and harmonious state of mental health. As we stand on the threshold of this new frontier, let curiosity, scientific inquiry, and a commitment to well-being guide us toward a future where mental wellness is cultivated through a profound understanding of the intricate dance between our gut and brain. The key lies in combining scientific rigor with the potential benefits of probiotics, recognizing that this journey is ongoing and holds promise for those seeking novel and integrative strategies for mental well-being.

At Wise Mind Nutrition, we are committed to helping you take steps to move toward optimal gut health. Please reach out if you want to learn how to incorporate probiotics into your daily diet!


Blog Contributor:

Persefone Pappas


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Having Trouble Finding Balance?

We are behavioral health nutritionists, recognizing the challenges faced when attempting to make lasting health changes.  If you struggle with food and/or body image, Nutrition in Recovery is the program for you. We will show you how to navigate the tricky food terrain with confidence. There is no “one size fits all” approach to recovery.

Dr. David Wiss became a Registered Dietitian Nutritionist (RDN) in 2013 and founded Nutrition in Recovery, a group practice of RDNs specializing in treating eating and substance use disorders. In 2017, David received the “Excellence in Practice” award at the National Food and Nutrition Conference and Expo. The California Academy of Nutrition and Dietetics awarded him the “Emerging Dietetic Leader Award” in 2020. He earned his Ph.D. from UCLA’s Fielding School of Public Health in the Community Health Sciences department (with a minor in Health Psychology) by investigating the links between adverse childhood experiences and various mental health outcomes among socially disadvantaged men. His treatment philosophy is based on a biopsychosocial model which incorporates an understanding of biological mechanisms, psychological underpinnings, and contextual factors that integrate the social determinants of health. Wise Mind Nutrition is an app-based interactive treatment program available for download now -

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