Iron intake, supplements and biological aging in US adults
What it found
In 8,692 US adults, iron from supplements was linked to faster biological aging, while iron from food alone was not.
Anti-inflammatory or antioxidant diets appeared to offset the link.
What they found
Studies in people
U-shaped link
Total iron intake showed a U-shaped link with faster biological aging, with a turning point at 18.441 mg per day. Below that, each extra 1 mg was linked to 0.126 years less aging acceleration; above it, each extra 1 mg was linked to 0.021 years more.
Food iron only
Iron from food alone was not linked to any harmful effect on aging. Below 13.164 mg per day, each extra 1 mg was linked to 0.233 years less aging acceleration.
Supplement iron
Supplemental iron was linked to faster biological aging, with a rise of 0.017 years per extra 1 mg per day. The authors say this points to possible risks from taking too many supplements.
Supplement-driven overload
A cluster of people with supplement-driven iron overload all went over the 45 mg per day upper limit, with supplements making up 83.44% of their iron on average. They showed faster biological aging than the food-iron reference group.
Diet may offset
People who ate anti-inflammatory or antioxidant diets did not show the same aging acceleration from supplement-driven iron overload. Those eating pro-inflammatory, pro-oxidative diets showed a marked worsening.
Inflammation link
Six inflammation-related blood markers partly explained the link between supplement-driven iron overload and faster aging, accounting for 15.53% to 25.63% of the effect. Oxidative stress markers did not show a significant mediating role.
What the authors conclude
“This study suggests that excessive use of supplements, resulting in iron overload, may accelerate individual aging through inflammation-related pathways.”
Also in their conclusions
- They conclude that iron overload caused by supplements may speed up phenotypic aging through inflammatory factors.
- They say diets rich in anti-inflammatory or antioxidant components can efficiently ease this process.
- They advise caution when using supplements to avoid excessive iron intake.
How it was done
The authors say the link between iron intake and biological aging is not well known, and that understanding it matters for aging-related health outcomes.
They looked at NHANES data from 2017-2018 for 8,692 adults aged 20 or older. Iron intake was estimated from two 24-hour diet recalls, and biological age was measured with PhenoAge.
What it can’t tell you
- This was a cross-sectional study, so it can show links but not cause and effect.
- The authors note that other unmeasured factors could still affect the results.
- The findings need checking in long-term studies and animal experiments.
Who paid
- Conflicts
- Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
- Authors work at
- The Second Affiliated Hospital of Harbin Medical University, PR China; Harbin Medical University, PR China
The paper
- Title
- Supplement-driven iron overload accelerates phenotypic aging via inflammatory biomarkers: Potential counteraction through anti-inflammatory or antioxidant diets
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Li B, Ming Z, Wang Y, et al (2025). Supplement-driven iron overload accelerates phenotypic aging via inflammatory biomarkers: Potential counteraction through anti-inflammatory or antioxidant diets. Redox biology. doi:10.1016/j.redox.2025.103733Free full textPubMed 40570516DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error