Dietary iron links to slower biological aging while high supplement doses accelerate it
An analysis of NHANES data identifies source-dependent effects and an optimal serum iron window between 15.2 and 18.8 micromoles per liter.
Asia Pacific journal of clinical nutrition · Cao Q et al. · Paper published 1 Oct 2026
In a study of 13,284 U.S. adults from NHANES, researchers evaluated how different iron sources relate to biological aging. The team assessed total, dietary, and supplemental iron intake alongside serum iron levels against three biological age metrics derived from clinical biomarkers. Dietary iron intake correlated with younger biological age, showing an optimal intake at or above 13.6 milligrams per day. In contrast, iron supplements exceeding 18 milligrams per day were linked to accelerated biological aging. Serum iron showed the strongest protective association, displaying a U- or J-shaped optimal window between 15.2 and 18.8 micromoles per liter. Optimal total iron intake ranged from 15.7 to 37.3 milligrams per day. Subgroup analyses revealed that optimal serum iron ranges widened in postmenopausal women and people with chronic diseases.
Why it matters
Iron is biologically essential yet potentially toxic at excessive levels. These findings demonstrate that biological age relates differently to dietary versus supplemental iron and highlight specific target ranges for serum iron.
Caveats
The study used a cross-sectional observational design, so it cannot prove that iron levels directly cause changes in biological aging. The findings are also limited to adult participants evaluated within the U.S. NHANES cohorts.
Written from the paper’s abstract, and every claim checked against it before publishing. Read the paper for the full methods and data.
The paper
Iron status from diet and serum in relation to biological aging acceleration: A NHANES cross-sectional study
Cao Q, Feng-Gao Y, Chen Y et al.
Asia Pacific journal of clinical nutrition · 1 Oct 2026 · Peer-reviewed
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