Association between iron deficiency anemia and accelerated biological aging: evidence from U.S. and Chinese cohorts

Background Iron deficiency anemia (IDA) is the most common nutritional anemia worldwide, yet its role in biological aging remains unclear. Methods We analyzed nationally representative cohorts from U.S. (NHANES; n = 3360) and China (CHARLS; n = 9273) to examine whether IDA was associated with accelerated biological aging, measured using PhenoAge (NHANES) and a PCA-based aging score (CHARLS). IDA was defined according to cohort-specific criteria based on hemoglobin (Hb) and iron indices, consistent with international standards. To reduce bias from hematologic markers, mean corpuscular volume (MCV) and red cell distribution width (RDW) were excluded from the aging algorithms in the sensitivity analysis. Multivariate linear regression and inverse probability of treatment weighting (IPTW) models were employed for balancing demographic and health-related covariates. Results In NHANES, after adjustment for age, sex, race/ethnicity, and poverty-income ratio (PIR), IDA was associated with an average 9.11-year higher PhenoAge residual (95% CI: 7.42 - 10.8 years, P < 0.001), indicating markedly accelerated aging. In CHARLS, IDA corresponded to a 0.70 standard deviation (SD) higher PCA-based aging score (95% CI: 0.55 - 0.84, P < 0.001), after adjustment for age, sex, self-rated health, and chronic conditions. Associations persisted across sexes and remained significant in multiple sensitivity tests. Conclusions These findings demonstrated a convergent, cross-national link between IDA and accelerated aging. Addressing IDA may offer benefits beyond hematologic recovery, potentially informing strategies for healthy aging. Integrating routine IDA screening into geriatric and primary care may be a practical and cost-effective approach to promote healthy aging.