This letter comments on the conclusion drawn by Shirotsuki et al. (2017) in their article entitled "The effect for Japanese workers of a self-help computerized cognitive behaviour therapy program with a supplement soft drink", recently published in BioPsychoSocial Medicine. The authors concluded that their drink, containing L-carnosine, enhances the effects of a computerized cognitive-behavioural therapy (CCBT) on the psychological well-being of healthy Japanese workers. Yet, we argue that their conclusion is unfounded given their results and the methodological shortcomings of their study. Briefly, while the authors reported improvement on the tension-anxiety subscale of the Profile of Mood States (POMS) in the CCBT only group, they also observed a lack of improvement on this subscale in the CCBT+L-carnosine group suggesting that the drink washes out this beneficial effect of CCBT. Methodological issues include the uncontrolled levels of L-carnosine metabolized by participants jeopardize the study's internal validity. Also, the clinical meaningfulness of the findings seems dubious as post-treatment scores remained within the range of the general Japanese population. Consequently, we argue that Shirotsuki et al.'s study should be re-conducted before drawing any valid conclusion.

中文翻译：

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左旋肌肽可增强日本工人的计算机认知行为疗法，这是不合理的说法。

这封信评论了Shirotsuki等人得出的结论。（2017）在最近发表在《 BioPsychoSocial Medicine》上的题为“带有补充性软饮料的自助式计算机化认知行为治疗计划对日本工人的影响”的文章中。作者得出的结论是，他们的饮料中含有L-肌肽，可以增强计算机认知行为疗法（CCBT）对健康的日本工人心理健康的影响。然而，我们认为，鉴于他们的研究结果和研究方法的缺陷，他们的结论是没有根据的。简而言之，虽然作者报告了仅CCBT组的情绪状态简介（POMS）的紧张焦虑量表有所改善，他们还观察到CCBT + L-肌肽组在该子量表上的改善不足，这表明该饮料可消除CCBT的这种有益作用。方法学上的问题包括参与者无法控制的左旋肌肽水平，从而损害了研究的内部有效性。而且，由于治疗后评分仍在日本普通人群的范围内，因此该发现的临床意义似乎令人怀疑。因此，我们认为Shirotsuki等人的研究应该在得出任何有效结论之前重新进行。研究结果的临床意义似乎令人怀疑，因为治疗后评分仍在日本普通人群的范围内。因此，我们认为Shirotsuki等人的研究应该在得出任何有效结论之前重新进行。研究结果的临床意义似乎令人怀疑，因为治疗后评分仍在日本普通人群的范围内。因此，我们认为Shirotsuki等人的研究应该在得出任何有效结论之前重新进行。