Selenium intake and a selenium-centered nutrient pattern are inversely associated with remnant cholesterol among older women in rural China: partial mediation by tumor necrosis factor-α

Abstract Backgrounds Micronutrients are crucial for metabolic health. Selenium, a vital micronutrient, exerts cardiovascular protection through its anti-inflammatory properties. Remnant cholesterol (RC) is an emerging cardiovascular risk marker, yet the relationship between selenium, nutrient patterns (NPs), and RC remains underexplored, particularly in older people. This cross-sectional study investigates these associations and evaluates the inflammatory marker TNF-α as a potential mediator. Methods We analyzed 378 older adults (aged 60–84 years; 55.5% women) from rural northern China, using a 24-hour dietary recall and principal component analysis (PCA) to derive NPs. RC was assessed through a computerized method. Multiple linear regression and restricted cubic splines (RCS) were primarily used to examine the associations, and mediation analysis was used to explore mediating effects, with subgroup analyses to assess sex-specific effects. Results Over 80% of participants had inadequate intakes of selenium, vitamin A, vitamins B1/B2/B3, vitamin C, potassium, calcium, and magnesium, with higher prevalence in women. In multiple linear regression, higher selenium intake (quartiles) showed progressively stronger inverse associations with RC and TNF-α (P for trend < 0.001 and = 0.016), with more pronounced effects in women. RCS confirmed a linear association with RC in the overall (P for nonlinear = 0.058), but no significant relation to TNF-α; in women, both associations were linear. Among four PCA-derived NPs, the “high selenium-vitamin A” pattern showed a significant negative association with RC (β [95% CI]: -0.078 [-0.128, -0.029], P = 0.002), particularly in women (β [95% CI]: -0.148 [-0.239, -0.058], P = 0.001). TNF-α partially mediated the relationship between selenium and RC in women (indirect effect: -0.002 [-0.0052, -0.0004]), accounting for 15.38% of the total effect. Conclusions Selenium intake and a selenium-centered nutrient pattern are inversely associated with RC, with stronger associations in older women. In women, TNF-α partially mediated the association between selenium intake and RC, seeming to suggest a potential inflammation-related pathway. These sex-specific, nutrition-linked correlates of RC may inform geriatric lipid management.