Han Ke, Wang Xiangyao, Chen Shimin, Niu Xiaotong, Wang Yan, Xiang Jingyuan, Ru Nan, Liu Miao, Chai Ningli, Linghu Enqiang
Department of Endoscopy, General Hospital of Northern Theater Command, Shenyang, China.
Department of Gastroenterology and Hepatology, First Medical Center of Chinese PLA General Hospital, Beijing, China.
J Neurogastroenterol Motil. 2025 Apr 30;31(2):267-275. doi: 10.5056/jnm23178.
BACKGROUND/AIMS: Obesity is associated with several gastrointestinal (GI) disorders and has been identified as a potential risk factor for various GI symptoms. Bowel frequency is an important indicator of bowel function. However, the causal link between obesity and gastrointestinal motility remains uncertain. This study aims to determine the causal effect of overall and central obesity on stool frequency.
Four obesity-related anthropometric indicators-body mass index, body fat percentage, waist circumference (WC), and waist-to-hip ratio (WHR)-were investigated. Individual-level baseline information from the UK Biobank was used to explore observational associations between obesity and stool frequency. Additionally, summary-level data from published genome-wide association studies were subjected to two-sample Mendelian randomization (MR) analyses to examine causal associations.
For all 4 indicators of obesity, higher levels of obesity were associated with more frequent bowel movements after adjusting for demographic characteristics, lifestyle, and dietary factors. After rigorous screening, 482 body mass index single nucleotide polymorphisms (SNPs), 7 body fat percentage SNPs, 48 WC SNPs, and 287 WHR SNPs were identified as instrument variables for MR analysis. The MR results were generally consistent with observational findings, proving that the associations observed in the overall obesity indicators were causal. For central obesity, the association between WHR and stool frequency remained consistent in both analysis phases, whereas WC showed a multidirectional association.
Obesity-related anthropometric indicators were causally associated with increased stool frequency in the overall and central obesity groups. Weight loss could be a potential approach to improve gastrointestinal regularity in individuals with obesity.
背景/目的：肥胖与多种胃肠道（GI）疾病相关，已被确定为各种GI症状的潜在危险因素。排便频率是肠道功能的重要指标。然而，肥胖与胃肠动力之间的因果关系仍不确定。本研究旨在确定总体肥胖和中心性肥胖对排便频率的因果影响。
研究了四个与肥胖相关的人体测量指标——体重指数、体脂百分比、腰围（WC）和腰臀比（WHR）。利用英国生物银行的个体水平基线信息来探索肥胖与排便频率之间的观察性关联。此外，对已发表的全基因组关联研究的汇总水平数据进行两样本孟德尔随机化（MR）分析，以检验因果关联。
对于所有4个肥胖指标，在调整人口统计学特征、生活方式和饮食因素后，较高的肥胖水平与更频繁的排便相关。经过严格筛选，482个体重指数单核苷酸多态性（SNP）、7个体脂百分比SNP、48个WC SNP和287个WHR SNP被确定为MR分析的工具变量。MR结果总体上与观察结果一致，证明在总体肥胖指标中观察到的关联是因果关系。对于中心性肥胖，在两个分析阶段，WHR与排便频率之间的关联均保持一致，而WC则显示出多向关联。
在总体肥胖和中心性肥胖组中，与肥胖相关的人体测量指标与排便频率增加存在因果关联。减肥可能是改善肥胖个体胃肠道规律性的一种潜在方法。
