What question did this study set out to answer?

This study aims to clarify the relationship between dietary antioxidant potential and the risk of irritable bowel syndrome (IBS).

June 3, 2026BMC Public Health0 citationsOpen Access

Nonlinear association between composite dietary antioxidant index and irritable bowel syndrome: insights from UK Biobank

LLLaifu Li YZYan Zhuang YRYan Ran

Key Points

This study aims to clarify the relationship between dietary antioxidant potential and the risk of irritable bowel syndrome (IBS).
Included 157,900 participants from the UK Biobank without IBS at baseline between 2006-2010.
Dietary intake assessed via online 24-hour dietary recall; IBS identified using ICD-10 code (K58).
Analyzed associations using restricted cubic spline, segmented Cox regression, and inflection points for dietary antioxidants.
During an average follow-up of 13.41 years, 2,007 cases of IBS were identified.
Increased CDAI significantly reduced IBS risk at levels < -0.9 (HR: 0.900, 95% CI: 0.820–0.988, P = 0.027), but increased risk was noted at ≥ -0.9 (HR: 1.030, 95% CI: 1.001–1.060, P = 0.046).
Participants in Quintile 1 of CDAI had a 23% increased risk of IBS compared to Quintile 2 (HR: 1.228, 95% CI: 1.071–1.408, P = 0.003).

Abstract

The relationship between overall dietary antioxidant potential and risk of irritable bowel syndrome (IBS) is unclear and needs further epidemiologic evidence. In this study, we included a total of 157,900 participants from the UK Biobank without irritable bowel syndrome at baseline between 2006 and 2010. Dietary intake was assessed using the online 24-hour dietary recall questionnaire, Oxford WebQ. IBS was identified using the ICD-10 code (K58). The composite dietary antioxidant index (CDAI) was the sum of Z scores for mean intake of individual vitamins A, C, E, manganese, selenium, and zinc from five 24-hour dietary recalls. During a mean follow-up time of 13.41 years, 2,007 incident cases of IBS were identified among the 157,900 participants. Restricted cubic spline (RCS) showed a nonlinear association (p for nonlinear < 0.001) between CDAI and the risk of IBS, and two-piecewise linear regression identified an inflection point at -0.9. Segmented Cox regression demonstrated that increasing CDAI significantly reduced the risk of IBS when CDAI < -0.9 (HR: 0.900, 95% CI: 0.820–0.988, P = 0.027); however, when CDAI ≥ -0.9, there was a 3% increased risk of IBS (HR: 1.030, 95% CI: 1.001–1.060, P = 0.046). Furthermore, compared to participants in Quintile 2 of CDAI, individuals in Quintile 1 had a 23% increased risk of IBS (HR: 1.228, 95% CI: 1.071–1.408, P = 0.003), while no significant differences were observed for participants in the other quintiles. Nonlinear analysis of independent dietary nutrients suggested a significant U-shaped association only between vitamin C and the risk of IBS, with an inflection point at Z score = -0.1. Sensitivity analyses with multiple imputation for missing covariates supported a negative association between antioxidant intake and IBS risk before the inflection point of CDAI. In contrast, after the inflection point, CDAI seemed to be unrelated to IBS risk. Moderate supplementation of antioxidants, particularly vitamin C, is beneficial in reducing the risk of IBS. However, excessive intake of dietary antioxidants tends to have no protective effect on IBS risk.

Demander à l'IA

Bookmark

View Full Paper