A few weeks ago the first video in our monthly series with Dr. Drew Ramsey came out on Medscape Psychiatry, discussing some of the highlights of brain food and the microbiome from research in 2015. Some interest expressed in the comments focused on one of the last studies we mentioned, published late in the year in the journal Nutrition: “Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial.”
There are a number of fascinating things about this paper, which to my knowledge is the first trial of probiotics in people with major depressive disorder specifically looking at biomarkers of inflammation and depressive symptoms. 40 patients total so not huge, but bigger than most pilot trials. They used three strains of probiotics in a capsule (Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum, two billion colony forming units of each), and checked not only records of diet, but also serum glucose and other measures of metabolism along with a lab test that looks at inflammation called C reactive protein.
Probiotics are anti-inflammatory microbes that seem to affect the gut in a positive way, decreasing stress signaling in the body and possibly even increasing the transformation of the amino acid tryptophan to serotonin in the brain. In both their anti-inflammatory capacity and their serotonin capacity, probiotics have *some* overall effects similar to antidepressants such as SSRIs, but so far I’ve seen no literature to suggest that probiotics could cause problems such as serotonin syndrome, anxiety, jitteriness, or an increase in suicidal thoughts, or an uncomfortable discontinuation syndrome that SSRIs can sometimes cause when stopping the medication too suddenly.
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