Oxidative balance score and mortality: mediating role of insulin resistance across age strata in the NHANES cohort

TL;DR

Higher oxidative balance scores are linked to lower mortality risk, especially in younger adults, with insulin resistance playing a mediating role.

Contribution

This study innovatively shows that insulin resistance mediates the protective effect of oxidative balance scores on mortality in younger adults.

Findings

Higher oxidative balance scores reduced all-cause and cardiovascular mortality risks.

Insulin resistance indices mediated 17% of the protective effect in adults under 65 years.

No mediation by insulin resistance was observed in adults aged 65 years or older.

Abstract

This study examined the association between oxidative balance score (OBS), a composite measure of oxidative/antioxidative factors, and mortality, while investigating insulin resistance (IR) indices as potential mediators using a nationally representative cohort.

A cohort of 11,849 U. S. adults from NHANES (2007–2018) was analyzed. OBS integrated 16 dietary and 4 lifestyle components. Mortality risks (all-cause, cardiovascular, cancer) were assessed via weighted Cox models. Mediation analysis evaluated the indirect effects of five IR indices (TyG index, TG/HDL-C, HOMA-IR, eGDR, VAI) on OBS-mortality associations, with statistical validation of mediation effects. Analyses were stratified by age (<65 vs. ≥65 years) and adjusted for sociodemographic, behavioral, and clinical covariates.

Higher OBS reduced risks of all-cause (HR = 0.652, 95% CI: 0.525–0.81) and cardiovascular mortality (HR = 0.605, 95% CI: 0.408–0.898), but not cancer mortality. Innovatively, eGDR mediated 17% of OBS’s protective effect on all-cause mortality in adults <65 years, while TyG index and HOMA-IR showed weaker mediation. No IR mediation occurred in older adults (≥65 years).

Higher OBS levels were inversely associated with all-cause and cardiovascular mortality, partially mediated by insulin resistance pathways. These findings highlight OBS as a potential prognostic indicator for mortality risk.

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