Association of Copper and Zinc Intake with Inflammatory Bowel Disease and Fecal Incontinence Symptoms: Evidence from the National Health and Nutrition Examination Survey

The associations between copper and zinc intake with the risk of inflammatory bowel disease (IBD) and fecal incontinence symptoms in the general population are not well understood. This study aims to evaluate the associations of zinc and copper intake with the risk of IBD and fecal incontinence symptoms in adults aged >= 20 years using data from the 2009-2010 National Health and Nutritional Examination Surveys (NHANES) (N= 5593). The presence of IBD was analyzed from the NHANES data, directly querying the presence or absence of ulcerative colitis (UC) and Crohn's disease (CD). Fecal incontinence symptoms including accidental bowel leakage of gas, mucus, liquid, or solid stool were determined by using the bowel health questionnaire. Multivariable logistic regressions models were performed controlling for confounding factors (dietary, lifestyle, psychological, and health conditions). No associations between either zinc or copper intake with IBD were found. However, zinc intake was independently associated with increased risk of bowel leakage of gas or liquid. Compared with quartile 1, the multivariate-adjusted ORs (95%CI) of bowel leakage of gas across quartiles 2-4 of zinc intake were 1.41 (1.15-1.71), 1.30 (1.00-1.68), and 1.61 (1.16-2.23). Likewise, there was a trend for higher odds of bowel leakage of liquid among participants in the higher zinc intake. Compared with quartile 1, the multivariate-adjusted ORs (95%CI) of bowel leakage of liquid across quartiles 2-4 of zinc intake were 3.55 (0.94-13.41), 3.65 (1.27-10.47), and 5.06 (1.25-20.50). Future prospective studies are warranted to confirm these findings.