Dr Arch G. Mainous III of the Medical University of South Carolina and colleagues point out that iron and lipids combine to create oxidative stress.
As oxidative stress is thought to play a role in the development of cancer, they decided to assess whether people with high iron status had increased risk of cancer.
Writing in the 15 June issue of the American Journal of Epidemiology (vol 161, issue 12, pp1115-22), the team reports that raised iron increased the likelihood of developing cancer by 66 per cent, and high VLDL cholesterol increased the risk by 54 per cent.
But combining elevated iron with elevated VLDL increased the risk of cancer by 168 per cent, they said.
Their results were derived from 3278 subjects in the Framingham Offspring Study who had elevated iron and lipid levels. All participants were at least 30 years old when they enrolled in the study. They were followed up for development of cancer at least 14 years later.
"These findings support the hypothesis that iron-mediated oxidation of cholesterol increases oxidative stress, which can lead to cancer formation," Mainous and colleagues conclude.
High iron plus low HDL or 'good' cholesterol also increased the risk of cancer to a similar degree.
If the finding is confirmed, it could suggest that consumers need to consider their cholesterol levels before taking iron supplements.
Earlier this year, the same team showed that people with elevated levels of serum transferrin saturation - an indicator of iron overload - who also consume high levels of dietary iron had an increased risk of cancer and cancer mortality.
The researchers have called into question the strategy of the addition of iron to food by manufacturers.