Iron from supplements and biological aging in US adults
What it found
In 8692 US adults, iron from food was not linked to faster biological aging, but high iron from supplements was.
Eating an anti-inflammatory or antioxidant diet appeared to offset this link.
What they found
Studies in people
Total iron and aging
Total iron intake showed a U-shaped link with biological aging in people. Below 18.441 mg per day, more iron was tied to slower aging. Above that amount, more iron was tied to faster aging.
Food iron versus supplements
Iron coming only from food was not linked to faster aging in people. However, iron from supplements was tied to faster biological aging.
High supplement iron group
Researchers grouped participants by their iron sources. One group got most of their iron from food and stayed below the upper limit of 45 mg per day. Another group exceeded 45 mg per day, with supplements making up 83.44% of their total iron on average, and this group showed faster biological aging.
Diet may offset effects
People in the high-supplement group who also ate diets rich in anti-inflammatory or antioxidant foods did not show the same faster aging. Those eating pro-inflammatory diets in the high-supplement group aged faster than those getting iron mostly from food.
Inflammation as a pathway
Six blood markers related to inflammation explained between 15.53% and 25.63% of the link between heavy supplement use and faster aging in people. Markers of oxidative stress did not show this mediating role.
What the authors conclude
- They suggest that taking too many iron supplements may speed up biological aging through inflammation-related pathways.
- They advise that eating a diet rich in anti-inflammatory or antioxidant foods could help counteract this effect.
- The authors call for caution when using iron supplements to avoid excessive intake.
How it was done
Iron is essential for the body, but too much can build up because the body removes it at a steady rate regardless of how much is stored. The authors wanted to see how total iron, food iron, and supplement iron relate to biological aging and whether inflammation plays a role.
They analyzed survey data from 8692 US adults aged 20 or older collected between 2017 and 2018. Participants reported everything they ate and drank over two separate days, including any supplements taken. The researchers compared these reports against a calculated measure of biological aging based on blood tests.
What it can’t tell you
- Because this study looked at everyone at a single point in time, it cannot prove that iron supplements cause faster aging. It can only show a link. People who take high doses of iron supplements might differ in other ways that affect aging. Future studies following people over time are needed to confirm these findings.
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 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error