Micronutrient intake and risk of ulcerative colitis: A meta-analysis of observational studies

Abstract

Background & aims: Ulcerative colitis (UC) poses a challenge to patients' health status and lifestyle. Micronutrient intake has been associated with the risk of UC, but the association has been inconsistent. Therefore, we performed a meta-analysis to clarify the overall association between micronutrient intake, as potentially modifiable risk factors, and the risk of UC.

Methods: Based on the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) protocols, systematic searches were conducted in PubMed, Scopus, and Web of Science up to September 2021. Studies were considered eligible for inclusion if they met the following criteria: (1) observational studies that compared dietary intake of zinc, calcium, or magnesium between the UC group and the control group and (2) had means and standard deviations or medians and interquartile ranges of outcome variables.

Results: A total of 7 studies with 1197 participants were included in the meta-analysis. The random-effects meta-analysis showed that there was no significant association between the intake of calcium (WMD: -66.25 mg/day, 95% CI: -276.7 to 144.21, P = 0.54), magnesium (WMD: -21.47 mg/day, 95% CI: -95.54 to 52.6, P = 0.57), and zinc (WMD: 0.3 mg/day, 95% CI: -1.5 to 2, P = 0.74) and the risk of UC. However, there was high significant heterogeneity between studies in dietary intake of calcium (I² = 95.1%, P < 0.001), magnesium (I² = 96%, P < 0.001), and zinc (I² = 95.8%, P = <0.001). In a location-based subgroup analysis, calcium intake in non-Asian countries was significantly lower in patients with UC compared to healthy controls. In addition, magnesium intake was negatively associated with the risk of UC in studies with a sample size of less than 190 subjects. However, for the association between zinc intake and UC risk, subgroup analysis failed to find a source of heterogeneity.

Conclusion: No significant association was found between dietary calcium, magnesium, and zinc intake and risk of UC.

Keywords: Diet; Inflammatory bowel disease; Micronutrients; Nutrition; Ulcerative colitis.