Physical activity modified the association of blood cadmium and lead with Helicobacter pylori infection: A cross-sectional analysis with NHANES data

Cadmium (Cd) and lead (Pb) exposure have been identified as risk factors for Helicobacter pylori seropositivity, possibly due to the immune suppression by Cd and Pb. Physical activity (PA) can induce an immune response. However, whether PA can reduce the effect of Cd and Pb on H pylori infection remains elusive. This study aims to investigate the association of blood Cd and Pb levels with H pylori infection and explore the intermediary effects of PA. This cross-sectional survey was conducted using the National Health and Nutrition Examination Survey (NHANES) of the 1999 to 2000 cycle (n = 9965). Participants without clear serological testing data, or absent in PA, blood Cd, and Pb information were excluded. Collinearity analysis was performed to remove the variables with high collinearity. Restricted cubic spline curve analysis was adopted to assess the nonlinear association of Cd and Pb with H pylori infection. The logistic regression analysis, generalized linear models, sensitivity analysis, and P for trend test were used to further analyze their relationship. Then, we analyzed the association of Cd and Pb with H pylori infection in 2 PA groups. Totally 3638 participants were divided into H pylori-negative (n = 2545) and H pylori-positive group (n = 1093). Pb exhibited a linear relationship but Cd had a nonlinear relationship with H pylori infection. Besides, the elevation of Cd and Pb both independently predicted H pylori infection after adjusting various variables (P < .05). The robust relationship was confirmed by the P for trend test (P for trend < .05). Under Cd exposure, the risk of H pylori infection was lower in the active PA group than in the inactive group (P < .05). A reverse result was found under the Pb exposure (P < .05). Exposure to Cd and Pb are positively linked to H pylori infection. PA may alleviate the effect of Cd on H pylori infection but may enhance H pylori infection under Pb exposure. Therefore, PA should be recommended in the appropriate season or region.