Scientists are discovering links between gut health, the gut microbiome, and the central nervous system, that may have effects on our mood, behaviors, and thought processes. The health of the gut flora and its effect on mental and physical well-being is referred to as the gut-brain axis.
Research suggests that an imbalance of gut flora may negatively affect overall health and influence mood. Made up of over 100 million neurons, the digestive system has its own nervous system and is referred to as the “second brain.” What you feel in your gut is often connected to what you feel in your brain. This connection supports the findings that digestive discomfort may impair both physical and psychological well-being.1
There is also research to suggest that there is an association between the digestive system, and thinking and memory.1
Research Suggests There Are Links Between Digestion, Health, And Mood.
Researchers are uncovering evidence to suggest that irritation of the gastrointestinal tract may send signals to the central nervous system that trigger changes in mood.1 The enteric nervous system (ENS) is made up of over 100 million nerve cells that line the gastrointestinal tract.1 The ENS may “trigger big emotional shifts” in people dealing with digestive discomfort.
Emerging Evidence Suggests Two-Way Communication Between The Gut Microbiome And The Brain.
It is known that psychological and physical stressors can affect the gut. There is emerging research to suggest that the reverse is also true. Ongoing, large-scale population-based studies are looking at how experimental changes to the gut microbiome may affect how the brain responds to stimuli targeted at the brain regions involved in emotional response.2
Two recent studies investigated this concept: one study looked at the effect of probiotic yogurt consumption on the regions of the brain that control emotion and the other study looked at links between specific clusters of gut microbiota and the bacteria’s impact on subjects’ behavioral characteristics.
Consumption Of A Probiotic Yogurt May Affect Brain Regions That Control Emotion And Sensation.
Foster, et al., regard the diet as one of the most important modifying factors of the gut-brain axis as the microbiota has emerged as a key player in the control of the gut-brain axis.3
A double-blind, controlled, parallel study looked at the effect of consumption of a probiotic-infused yogurt on brain regions involved in stress and emotion.4 For four weeks, healthy female subjects consumed yogurt (twice per day) with a probiotic (Bifidobacterium animalis subsp lactis CNCM I-2494) and four strains of bacteria5:
- Streptococcus thermophilus CNCM I-1630
- Lactobacillus bulgaricus CNCM I-1632
- Lactobacillus bulgaricus CNCM I-1519
- Lactococcus lactis subsp lactis CNCM I-1631
Four-week intake of the probiotic yogurt resulted in a muted response from the areas of the brain that control emotion and sensation.4 This altered brain function was observed “both while in a resting state and in response to an emotion-recognition task.”6
These results suggest that gut-brain communication is not only a two-way street but also modifiable.4,6 The authors also claim it is the first study to show the effect of a fermented milk product with a probiotic on gut-brain communication in humans.4
A New Study Supports This Concept Of Brain-Gut-Microbiota Interactions In Healthy Humans.
A more recent study identified associations between the gut microbiota, and brain and behavioral characteristics, by looking at fecal samples of healthy female subjects.7 Among the samples, two clusters of bacterial prevalence were found: one group with a greater amount of the Bacteroides genus, and another with a greater amount of the Prevotella genus.7 The findings of this study provide additional support for the concept of a mind-gut connection.
Subjects with more of the Bacteroides bacteria showed greater thickness of brain regions involved with complex processing of information and a larger volume of brain regions involved in memory processing.8
Subjects with more of the Prevotella bacteria had more connections between brain regions dealing with emotion, attention, and sensation.8 “They also rated higher levels of negative feelings such as anxiety, distress and irritability after looking at photos with negative images than did the Bacteroides group.”8
Even though researchers don’t yet understand the reasons for, and causes of, these differences, this study supports the concept of brain-gut-microbiota interactions in healthy humans.
Include Fermented Foods And Probiotics In Your Diet And Recommend Them To Your Patients.
Researchers are still uncovering new relationship and communication pathways between the brain and the gut, but you can start adding fermented foods and probiotics to your diet now and recommend them to your patients.
Emeran Mayer, MD, PhD, author of The Mind-Gut Connection, explains that regularly including fermented foods and probiotics as part of your diet helps to maintain a diverse gut microbiome, especially during stress, antibiotic treatment, and old age.9 In addition, some fermented foods even provide prebiotics (food for probiotics) for your own gut microbiota.9
Here Are Some Tips For Adding Probiotics And Fermented Foods To Your Diet.
- Consume probiotic yogurt
- Try kefir with probiotic strains
- Look for dried fruits and juices with probiotics added
- Read labels for common species of probiotics:
- Lactobacillus (examples: L. plantarum, L. casei, L. reuteri, L. acidophilus)
- Bifidobacterium (examples: B. bifidum, B. lactis, B. animalis, B. longum)
- Some of the studied probiotic strains are:
- Lactobacillus casei DN-114 001
- Bifidobacterium animalis lactis DN-173 010/CNCM I-2494
- Bifidobacterium animalis lactis DSM 25954 (BB-12®)
- Bacillus coagulans GBI-30, 6086 (GanedenBC30®)
- Lactobacillus rhamnosus GG (LGG®)
Including fermented foods and probiotics in your diet can help to promote and support a diverse gut microbiome. Recommending probiotic foods to your patients is an easy way you can help support their overall well-being.
- Healthy Aging: The Brain-Gut Connection. Johns Hopkins Medicine. The Johns Hopkins University. Available at: www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-brain-gut-.... Accessed March 29, 2018.
- Mayer EA, Knight R, Mazmanian SK, Cryan JF, Tillisch K. Gut Microbes and the Brain: Paradigm Shift in Neuroscience. J Neurosci. 2014;34(46):15490–15496.
- Foster JA, Rinamin L, Cryan JF. Stress & the gut-brain axis: Regulation by the microbiome. Neurobiol Stress. 2017;7:124–136.
- Petrochko C. Probiotic Gut Effects May Alter Brain Activity. MedPage Today. 2012. Available at: https://www.medpagetoday.com/meetingcoverage/ddw/32944. Accessed March 29, 2018.
- Tillisch K, et al. Consumption of Fermented Milk Product with Probiotic Modulates Brain Activity. Gastroenterology. 2013;144(7): 10.1053/j.gastro.2013.02.043.
- Champeau R. Changing gut bacteria through diet affects brain function, UCLA study shows. UCLA Newsroom. 2013. Available at: http://newsroom.ucla.edu/releases/changing-gut-bacteria-through-245617. Accessed March 29, 2018.
- Tillisch K, et al. Brain Structure and Response to Emotional Stimuli as Related to Gut Microbial Profiles in Healthy Women. Psychosom Med. 2017;79(8):905-913.
- Rivero E. Research suggests association between gut bacteria and emotion. UCLA Newsroom. 2017. Available at: http://newsroom.ucla.edu/releases/research-suggests-association-between-.... Accessed April 19, 2018.
- Mayer, MD E. The Mind-Gut Connection: How The Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, And Our Overall Health. HarperCollins Publishers; 2016:277-278.