en Nutrition Nutrition Review Review <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b>Background and Objectives:</b> Anxiety is the feeling of worry or nervousness that may manifest as physical, cognitive and behavioral symptoms. When these symptoms persist and affect performance, anxiety can be regarded as a disorder. Several anxiety disorders have been described, including generalized anxiety disorder (GAD) and panic disorder. Maintaining a healthy diet is critical for physical and mental well-being. Recent studies have shown that the brain can be affected by dietary components and nutrients. Probiotics have become increasingly popular as part of a healthy diet due to their potential to regulate brain health through the microbiota-gut-brain axis. This review was designed to identify effective probiotic <a name="_Hlk180066208">species</a> in decreasing anxiety.<b> </b></span></span></span><br> <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b>Materials and Methods:</b> A systematic search was carried out in Google Scholar, Science Direct, PubMed and Web of Science for studies published until January 2024. The search was carried out with terms of &ldquo;probiotic supplements&rdquo; AND anxiety and &ldquo;probiotic supplements&rdquo; AND &ldquo;anxiety disorders&rdquo;. First, duplicated studies were removed and 2024 studies were screened. Then, 23 studies met the selection criteria. </span></span></span><br> <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b>Results:</b> Based on the results obtained from the 23 selected studies, 16 studies showed that supplementation with probiotics improved anxiety symptoms, although the improvement was small in cases<b>. </b></span></span></span><br> <span style="font-size:10pt"><span style="unicode-bidi:embed"><span new="" roman="" style="font-family:" times=""><b>Conclusions:</b> <a name="_Hlk179894599">Based on the results</a>, probiotics are sometimes effective in decreasing anxiety and can be an adjunctive treatment in persons with psychiatric disorders (e.g. depression and GAD). However, there is a need of further clinical trials with larger sample sizes. Furthermore, <i>Lactobacillus plantarum</i> and <i>Bifidobacterium longum</i> are more effective than other probiotics in decreasing anxiety.</span></span></span> Probiotics, Probiotic supplements, Anxiety, gut-brain axis 7 16 http://nfsr.sbmu.ac.ir/browse.php?a_code=A-10-1145-1&slc_lang=en&sid=1 Seyyed Mohammad jalal Hakimi matinhakimi2000@gmail.com 10031947532846006933 0009-0001-4599-9570 No Department of Nutrition, Science & Research Branch, Islamic Azad University, Tehran, Iran Ariyo Movahedi amm35@mail.aub.edu 10031947532846006934 10031947532846006934 Yes Department of Nutrition, Science & Research Branch, Islamic Azad University, Tehran, Iran