We thank Dr. Mullie & colleagues for expressing their interest in our study featuring a diet rich in prebiotic fibers and fermented foods, published in Molecular Psychiatry last year [1, 2]. This diet was designed to specifically target the gut microbiome with the intent to positively impact mental health in a healthy population. It is now over a decade since we coined the term psychobiotic [3, 4] and thereafter expanded the term to encompass interventions, including diets, that target the microbiome for mental health benefit [5, 6]. Due to the intended goal, namely conferring mental health benefits by targeting the gut microbiome, as well as the promising results of the study, including a reduction in microbial volatility and improvement in perceived stress, we describe this diet as the psychobiotic diet [5]. Limiting the description of the diet as a pro-and prebiotic rich diet would not reflect the nature of the diet which clearly falls under the umbrella of our expanded definition of a psychobiotic.

Albeit limited in scope due to COVID pandemic-associated recruitment issues, the results were encouraging and fit well in the context of existing literature where nutritional psychiatry approaches are being increasingly studied [7]. We discuss that, albeit promising, our results should be considered preliminary rather than definitive. Thus, much work remains to be done and we gratefully welcome the interest Mullie & colleagues expressed in this topic. Here, we will revisit some of the key findings of the study and discuss some of the questions in the field that remain to be addressed.

我们感谢 Mullie 博士及其同事对我们的研究感兴趣，该研究以富含益生元纤维和发酵食品的饮食为特色，该研究于去年发表在《分子精神病学》上 [1, 2]。这种饮食专门针对肠道微生物群而设计，旨在对健康人群的心理健康产生积极影响。自我们创造“心理生物学”一词以来已有十多年了 [3, 4 ] ，此后将该术语扩展到包括针对微生物组以有益于心理健康的干预措施，包括饮食 [5, 6]。由于预期的目标，即通过针对肠道微生物组来赋予心理健康益处，以及研究的有希望的结果，包括减少微生物波动和改善感知压力，我们将这种饮食称为心理饮食[5] 。将饮食限制为富含益生元和益生元的饮食并不能反映饮食的性质，而饮食的性质显然属于我们对精神生物的扩展定义的范畴。

尽管由于与新冠大流行相关的招募问题而导致范围有限，但结果令人鼓舞，并且非常符合现有文献的背景，其中营养精神病学方法正在得到越来越多的研究[7]。我们讨论的是，尽管我们的结果很有希望，但应该被认为是初步的而不是确定的。因此，仍有许多工作要做，我们非常欢迎 Mullie 及其同事对此主题表达的兴趣。在这里，我们将回顾该研究的一些主要发现，并讨论该领域仍有待解决的一些问题。