It seems improbable: how could bacteria, which are often associated with disease and infections, be used to defeat depression? Scientists have been exploring this phenomenon, and their findings have uncovered a potentially new treatment option for this common mental issue.
Depression is a serious health problem. Nearly 13 percent of adults in Canada meet the criteria for a mood disorder at some time during their lives, according to Statistics Canada’s 2012 Canadian Community Health Survey on Mental Health. Close to 5 percent of the Canadian population aged 15 years and older reported symptoms for major depression within the previous 12 months.
Although every person is unique, there are some common symptoms of depression:
• Depressed mood
• Loss of interest or joy in activities usually enjoyed
• Changes in appetite and/or weight
• Feelings of helplessness, hopelessness, guilt, or worthlessness
• Lack of energy or fatigue
• Problems with sleep
• Thoughts of death or suicide
• Difficulty making decisions and/or concentrating
Among the many treatments available for depression, including medications, body therapies (e.g., acupuncture), natural supplements, and various talk and behavioral approaches, probiotics have emerged as a possibility. The connection between good bacteria (aka, friendly bacteria) in the intestinal tract and the central nervous system (CNS) occurs along the gut-brain axis, a “super highway” in the body. Rather than an actual roadway, the gut-brain axis consists of two-way signaling communication between the CNS and the enteric nervous system (gastrointestinal system).
Do Probiotics Work for Depression?
It’s been shown that the microorganisms (microbiota) in the intestinal tract have a significant impact on the function of the central nervous system, which led to the hypothesis that taking probiotics can have a positive on psychological symptoms such as depression. Here’s some of what researchers have discovered thus far about how probiotics may help us defeat depression.
In a recent meta-analysis from Australia that looked at seven studies, the authors found that use of probiotic supplements resulted in “significant improvement in psychological symptoms,” including depression, anxiety, and perceived stress, when compared with placebo.
Another recent meta-analysis found that use of probiotics significantly reduced scores on depression scales and that the beneficial bacteria were effective in both healthy individuals as well as those with major depressive disorder. Age did seem to matter, however, as probiotics were benefical for people younger than 60 and not for those older than 65.
Not every study of probiotics and depression have yielded findings that shed a positive light on beneficial organisms for this treatment option, however. Another recent study, for example, did not find any benefit from taking two probiotics (Lactobacillus helveticus and Bifidobacterium longum) versus placebo for 8 weeks among 79 individuals with moderate scores on mood factors. A much larger study (18,019 subjects) considered the impact of probiotics in this population, of which 14.11 percent said they had used probiotics or consumed probiotic foods. The authors found that use of probiotics was not associated with lower depression rates.
Which Probiotics Work for Depression?
Researchers have identified some probiotics that have an ability to enhance mood and cognitive function while also reducing anxiety and stress. These probiotics are sometimes referred to as psychobiotics and include L. acidophilus, L. casei, B. bifidum, L. helveticus R0052, and B. longum R0175. Note that the latter two probiotic species are more specific than the two mentioned in an earlier study, which may explain the difference in findings.
In general, probiotics have been found to be helpful for a variety of gastrointestinal problems while their benefit for psychological disorders, such as depression, may be less clear. However, use of probiotics is safe and associated with virtually little to no side effects, although some people do experience mild gas or bloating.
Therefore, trying probiotics for depression may be something you should consider and talk about with your doctor.
Written by Deborah Mitchell. Deborah Mitchell is passionate about personal health and the well-being of animals and the planet. She has authored, coauthored, and ghostwritten more than 40 books, contributes regularly to several websites, and shares information on physical, emotional, and spiritual health on her blog, deborahmitchellbooks.com.
Cepeda MS et al. Microbiome-gut- brain axis: probiotics and their association with depression. Journal of Neuropsychiatry and Clinical Neuroscience 2017 Winter; 29(1): 39-44. Retrieved Feb. 22, 2017.
Huang R et al. Effect of probiotics on depression: a systematic review and meta-analysis of randomized controlled trials. Nutrients 2016 Aug 6; 8(8): pii. Retrieved Feb. 22, 2017.
McKean J et al. Probiotics and subclinical psychological symptoms in healthy participants: a systematic review and meta-analysis. Journal of Alternative and Complementary Medicine 2016 Nov 14. Retrieved Feb. 21, 2017.
Public Health Agency of Canada. What is depression? Retrieved Feb. 22, 2017.
Romijn AR et al. A double-blind, randomized, placebo-controlled trial of Lactobacillus helveticus and Bifidobacterium longum for the symptoms of depression. Australian and New Zealand Journal of Psychiatry 2017 Jan 1: 4867416686694. Retrieved Feb. 22, 2017.
University Health Daily. The best probiotics for mood. Retrieved Feb. 22, 2017.