The use of probiotics, prebiotics, synbiotics or fermented foods can modulate the gut-brain axis and constitute a potentially therapeutic intervention in psychiatric disorders. This systematic review aims to identify current evidence regarding these interventions in the treatment of patients with DSM/ICD psychiatric diagnoses. Forty-seven articles from 42 studies met the inclusion criteria. Risk of bias was assessed in all included studies. Major depression was the most studied disorder (n = 19 studies). Studies frequently focused on schizophrenia (n = 11) and bipolar disorder (n = 5) and there were limited studies in anorexia nervosa (n = 4), ADHD (n = 3), Tourette (n = 1), insomnia (n = 1), PTSD (n = 1) and generalized anxiety disorder (n = 1). Except in MDD, current evidence does not clarify the role of probiotics and prebiotics in the treatment of mental illness. Several studies point to an improvement in the immune and inflammatory profile (e.g. CRP, IL6), which may be a relevant mechanism of action of the therapeutic response identified in these studies. Future research should consider lifestyle and dietary habits of patients as possible confounders that may influence inter-individual treatment response.

使用益生菌、益生元、合生元或发酵食品可以调节肠脑轴，并构成精神疾病的潜在治疗干预措施。本系统综述旨在确定有关这些干预措施治疗 DSM/ICD 精神科诊断患者的当前证据。 42 项研究的 47 篇文章符合纳入标准。所有纳入的研究均评估了偏倚风险。重度抑郁症是研究最多的疾病（n = 19 项研究）。研究经常集中在精神分裂症 (n = 11) 和躁郁症 (n = 5) 上，而关于神经性厌食症 (n = 4)、ADHD (n = 3)、抽动秽语症 (n = 1)、失眠症 (n = 1) 的研究有限1)、创伤后应激障碍 (n = 1) 和广泛性焦虑症 (n = 1)。除MDD外，目前的证据并未阐明益生菌和益生元在精神疾病治疗中的作用。一些研究指出免疫和炎症谱（例如CRP、IL6）的改善，这可能是这些研究中确定的治疗反应的相关作用机制。未来的研究应将患者的生活方式和饮食习惯视为可能影响个体间治疗反应的混杂因素。