Too much iron could increase cancer risk

New U.S. research suggests that eating a lot of iron-rich foods may increase the risk of cancer. The research raises questions about fortifying foods with the mineral.

Researchers at the Medical University of South Carolina analysed population-based data from the US National Health and Nutrition Examination Surveys and found that people with elevated levels of serum transferrin saturation - an indicator of iron overload - who consume high levels of dietary iron had an increased risk of cancer and cancer mortality.

Transferrin saturation of more than 60 per cent had already been identified as a cancer risk factor but the researchers wanted to assess whether dietary iron intake increases the risk of cancer among individuals with transferrin saturation of less than 60 per cent.

Their research found that people with transferrin saturation of more than 45 per cent who ingest more than 18 mg of iron per day have a 2.24 times greater relative risk of cancer than those who have normal transferrin saturation levels and report low dietary iron intake.

Approximately 7 per cent of adults in the United States has transferrin saturation levels greater than 41 per cent placing them at more risk of cancers.

Having high transferrin saturation with a normal diet does not carry increased risk and intake of dietary iron was essentially uncorrelated with transferrin saturation.

The researchers say, simple dietary restrictions may help to reduce the cancer risk associated with high transferrin saturation, adding that their findings call into question the strategy of the addition of iron to food by manufacturers.

The research is reported in the current issue of the Annals of Family Medicine.