Go With Your Gut

The human intestine contains more than 1,000 species of microorganisms that comprise the 100 trillion “good bacteria” that keep our bodies healthy and our digestive systems functioning properly. The profile of the microbes present in each individual varies on the basis of age, sex, diet and lifestyle, but, together, these bacteria help maintain overall health. And not just digestive health. New evidence suggests strong links between gut microbiota and mental health.

Recently, much attention has been paid to the connections between the brain and the intestines. The so-called brain-gut axis facilitates communication between the brain and the digestive system via neural, endocrine, and immune pathways. This communication likely involves intestinal microbiota that activate immune and signaling molecules that regulate cognition and behavior. Therefore, altering the natural gut flora through probiotic supplementation is a potential strategy for modulating cognition and mood.

A new study published in Brain, Behavior, and Immunity reports that probiotic supplementation reduced cognitive reactivity to sad moods.

The research team included 40 healthy participants in a 4-week study of probiotic supplementation. The participants were young adults and most were female. Twenty of the participants received a daily multispecies probiotic supplement and 20 participants received a placebo. Reactivity to sad mood was assessed through self-reporting before and after the interventions and participants who received the probiotic supplement showed a significant reduction in reactivity to sad mood after 4 weeks. Specifically, the subscales of rumination and aggressive thoughts showed the most substantial decreases. Overall, the study authors concluded that probiotic supplementation could reduce negative thoughts associated with sad mood, which could lead to a decreased risk of depression and other mood disorders.

Probiotics – bacteria and other microorganisms that are ingested for health benefits – are available in food products such as yogurt and as capsules for supplementation. Probiotics have been used to treat a variety of gastrointestinal-related conditions including diarrhea associated with antibiotic use and inflammatory bowel disease. Probiotics have also been shown to improve metabolic profiles, markers of inflammation, and oxidative stress. And, in addition to the current investigations into mood disorders, probiotic supplementation is believed to have potential benefits in anxiety, autism, and Parkinson’s disease, as well as dermatologic conditions and allergies.

There is a lack of evidence regarding the safety of probiotics and adverse event reports related to probiotics are scarce. However, available evidence does suggest that probiotics do not confer an increased safety risk in healthy individuals.

Mental health is closely association with physical health, and new evidence relating bacteria in the human digestive tract to mood and cognition offers confirmation that you should always trust your gut. The symbiotic relationship between our bodies and bacteria has a long evolutionary history, and, in a beautiful example of a mutually beneficial partnership, if we keep our guts happy, our guts will keep us happy.


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Image via Juan Gaertner / Shutterstock.

Jennifer Gibson, PharmD

Jennifer Gibson, PharmD, is a practicing clinical pharmacist and medical writer/editor with experience in researching and preparing scientific publications, developing public relations materials, creating educational resources and presentations, and editing technical manuscripts. She is the owner of Excalibur Scientific, LLC.
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