Estrogenic Effect of Probiotics on Anxiety and Depression: A Narrative Review

Anxiety and depression are mental disorders with significant global impact, and are especially prominent in women during times of hormonal fluctuations. The microbiota-gut-brain axis (MGB axis) has emerged as a crucial pathway in the pathogenesis of these disorders, as it directly influences the production of neurotransmitters such as serotonin (5-HT), gamma-aminobutyric acid (GABA) and dopamine (DA). In addition, they have shown estrogenic effects through enzymes such as β-glucuronidase, which modulate hormone metabolism and consequently mood. A comprehensive search of recent preclinical studies has found that probiotic intake in female rats led to significant improvements in anxiety- and depression-related behaviors. Similarly, clinical trials in certain populations, particularly women with hormonal imbalances during menopause or premenstrual syndrome, have shown promising results. However, there are still significant problems, such as the individual variability of responses and the need for controlled long-term studies. The development of specific probiotics for hormonal modulation and the implementation of personalized approaches integrating omics and neuroimaging technologies to optimize therapeutic interventions in the field of mental health are promising. Accordingly, a comprehensive search was conducted in scientific databases such as PubMed, ScienceDirect, Scopus and Web of Science. Preclinical studies investigating the estrogenic effects of different probiotic strains in animal models and in controlled clinical trials during chronic treatment were selected, excluding those studies that did not provide access to full text.