Dietary advice and medical treatments are recommended to patients with irritable bowel syndrome (IBS). Studies have not yet compared the efficacy of dietary treatment with pharmacological treatment targeting the predominant IBS symptom. We therefore aimed to compare the effects of two restrictive dietary treatment options versus optimised medical treatment in people with IBS. This single-centre, single-blind, randomised controlled trial was conducted in a specialised outpatient clinic at the Sahlgrenska University Hospital, Gothenburg, Sweden. Participants (aged ≥18 years) with moderate-to-severe IBS (Rome IV; IBS Severity Scoring System [IBS-SSS] ≥175) and no other serious diseases or food allergies were randomly assigned (1:1:1) by web-based randomisation to receive a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) plus traditional IBS dietary advice recommended by the UK National Institute for Health and Care Excellence (hereafter the LFTD diet), a fibre-optimised diet low in total carbohydrates and high in protein and fat (hereafter the low-carbohydrate diet), or optimised medical treatment based on predominant IBS symptom. Participants were masked to the names of the diets, but the pharmacological treatment was open-label. The intervention lasted 4 weeks, after which time participants in the dietary interventions were unmasked to their diets and encouraged to continue during 6 months’ follow-up, participants in the LFTD group were instructed on how to reintroduce FODMAPs, and participants receiving pharmacological treatment were offered diet counselling and to continue with their medication. The primary endpoint was the proportion of participants who responded to the 4-week intervention, defined as a reduction of 50 or more in IBS-SSS relative to baseline, and was analysed per modified intention-to-treat (ie, all participants who started the intervention). Safety was analysed in the modified intention-to-treat population. This trial is registered with , , and is complete. Between Jan 24, 2017, and Sept 2, 2021, 1104 participants were assessed for eligibility and 304 were randomly assigned. Ten participants did not receive their intervention after randomisation and thus 294 participants were included in the modified intention-to-treat population (96 assigned to the LFTD diet, 97 to the low-carbohydrate diet, and 101 to optimised medical treatment). 241 (82%) of 294 participants were women and 53 (18%) were men and the mean age was 38 (SD 13). After 4 weeks, 73 (76%) of 96 participants in the LFTD diet group, 69 (71%) of 97 participants in the low-carbohydrate diet group, and 59 (58%) of 101 participants in the optimised medical treatment group had a reduction of 50 or more in IBS-SSS compared with baseline, with a significant difference between the groups (p=0·023). 91 (95%) of 96 participants completed 4 weeks in the LFTD group, 92 (95%) of 97 completed 4 weeks in the low-carbohydrate group, and 91 (90%) of 101 completed 4 weeks in the optimised medical treatment group. Two individuals in each of the intervention groups stated that adverse events were the reason for discontinuing the 4-week intervention. Five (5%) of 91 participants in the optimised medical treatment group stopped treatment prematurely due to side-effects. No serious adverse events or treatment-related deaths occurred. Two 4-week dietary interventions and optimised medical treatment reduced the severity of IBS symptoms, with a larger effect size in the diet groups. Dietary interventions might be considered as an initial treatment for patients with IBS. Research is needed to enable personalised treatment strategies. The Healthcare Board Region Västra Götaland, the Swedish Research Council, the Swedish Research Council for Health, Working Life and Welfare, AFA Insurance, grants from the Swedish state, the Wilhelm and Martina Lundgren Science Foundation, Skandia, the Dietary Science Foundation, and the Nanna Swartz Foundation.

中文翻译：

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低 FODMAP 饮食加传统饮食建议与低碳水化合物饮食与药物治疗治疗肠易激综合征 (CARIBS)：一项单中心、单盲、随机对照试验

建议肠易激综合征 (IBS) 患者接受饮食建议和药物治疗。研究尚未比较饮食治疗与针对主要 IBS 症状的药物治疗的疗效。因此，我们的目的是比较两种限制性饮食治疗方案与优化药物治疗对 IBS 患者的效果。这项单中心、单盲、随机对照试验在瑞典哥德堡萨尔格伦斯卡大学医院的专门门诊进行。患有中重度 IBS（罗马 IV；IBS 严重程度评分系统 [IBS-SSS] ≥175）且无其他严重疾病或食物过敏的参与者（年龄≥18岁）通过网络随机分配（1:1:1）基于随机化，接受低可发酵寡糖、二糖、单糖和多元醇 (FODMAP) 的饮食，加上英国国家健康与护理卓越研究所推荐的传统 IBS 饮食建议（以下简称 LFTD 饮食），这是一种低纤维优化饮食总碳水化合物含量高、蛋白质和脂肪含量高（以下简称低碳水化合物饮食），或根据主要 IBS 症状进行优化治疗。参与者不知道饮食的名称，但药物治疗是开放标签的。干预持续 4 周，之后饮食干预的参与者被告知他们的饮食，并鼓励他们在 6 个月的随访期间继续进行，LFTD 组的参与者被指导如何重新引入 FODMAP，接受药物治疗的参与者提供饮食咨询并继续用药。主要终点是对 4 周干预做出反应的参与者比例，定义为 IBS-SSS 相对于基线减少 50 或更多，并根据修改后的意向治疗进行分析（即所有开始的干预）。在修改后的意向治疗人群中分析了安全性。该试用已在 、 、 注册，并已完成。 2017年1月24日至2021年9月2日期间，对1104名参与者进行了资格评估，其中304名被随机分配。 10 名参与者在随机分组后没有接受干预，因此 294 名参与者被纳入修改后的意向治疗人群（96 名参与者分配至 LFTD 饮食，97 名参与者分配至低碳水化合物饮食，101 名参与者分配至优化医疗治疗）。 294 名参与者中有 241 名 (82%) 为女性，53 名 (18%) 为男性，平均年龄为 38 岁 (SD 13)。 4周后，LFTD饮食组的96名参与者中有73名（76％），低碳水化合物饮食组的97名参与者中有69名（71％），优化药物治疗组的101名参与者中有59名（58％）有与基线相比，IBS-SSS 减少 50 或更多，各组之间存在显着差异 (p=0·023)。 96 名参与者中的 91 名 (95%) 在 LFTD 组中完成了 4 周，97 名参与者中的 92 名 (95%) 在低碳水化合物组中完成了 4 周，101 名患者中的 91 名（90%）在优化药物治疗组中完成了 4 周。每个干预组中都有两人表示不良事件是停止 4 周干预的原因。优化治疗组的 91 名参与者中有 5 名 (5%) 由于副作用而提前停止治疗。没有发生严重不良事件或与治疗相关的死亡。两次为期 4 周的饮食干预和优化的药物治疗减轻了 IBS 症状的严重程度，并且饮食组的效果更大。饮食干预可被视为 IBS 患者的初始治疗。需要进行研究以实现个性化治疗策略。西约塔兰地区医疗保健委员会、瑞典研究委员会、瑞典健康、工作生活和福利研究委员会、AFA 保险、瑞典政府、Wilhelm 和 Martina Lundgren 科学基金会、Skandia、饮食科学基金会和南娜·斯沃茨基金会。