HINT1 and inflammatory bowel disease: At circulating protein level, genetically predicted higher levels of PARK7 (OR 0.36, 95% CI 0.25–0.52) and HINT1 (OR 0.47, 95% CI 0.30–0.74) were inversely associated with IBD risk; genetically predicted higher level of HINT1 was associated with a decreased risk of Crohn's disease (CD) (OR 0.26, 95% CI 0.14–0.49) and a higher level of ACADM (OR 0.67, 95% CI 0.55–0.83), PDK1 (OR 0.63, 95% CI 0.49–0.81), FIS1 (OR 0.63, 95% CI 0.47–0.83) was associated with a decreased risk of UC.