So they looked at relevant studies published in English between 2003 and 2019, which looked at the potential therapeutic contribution of pre-and probiotics in adults with depression and/or anxiety disorders. Out of an initial haul of 71 studies, just seven met all the criteria for inclusion. All seven investigated at least one probiotic strain while four looked at the effect of combinations of multiple strains. In all, 12 probiotic strains featured in the selected studies, primarily Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidium. One study looked at combined pre-probiotic treatment, while one looked at prebiotic therapy by itself. The studies varied considerably in their design but all used standard methods, questionnaires with scoring, to see if depression and anxiety improved.

All of them concluded that probiotic supplements either alone or especially in combination with prebiotics was linked to measurable reductions in depression. Every study showed a significant improvement in depression and anxiety. The theory is that probiotics may help reduce the production of inflammatory chemicals, such as cytokines, as is the case in inflammatory bowel disease, that may influence other chemicals such as of tryptophan, a chemical thought to be important in the gut-brain axis in psychiatric disorders.

Natural prebiotics include – onions, garlic, bananas, leeks, chicory root, popular for its coffee-like flavor, and dandelion greens. Just Google it and you’ll find more of them.