The study, published in Nutrition, Metabolism & Cardiovascular Diseases, found markers of iron storage in blood plasma are not associated with the risk of mortality, among a large sample of US adults, not taking iron supplements without a baseline history of cardiovascular disease or cancer.
“In this large, population-based prospective study, higher levels of ferritin and transferrin saturation were not associated with an increased risk of mortality,” said the authors,” led by Dr. Andrew Menke from Johns Hopkins University, USA.
Commenting independently on the research, Duffy MacKay, ND, vice president, scientific & regulatory affairs, for the dietary supplements trade association, the Council for Responsible Nutrition (CRN), told NutraIngredients that there are “no real surprises with the data” from the study.
“The study shows that – in a healthy population – there is no association with the biomarkers for iron storage and mortality … meaning that the upper limits of iron storage are no associated with an increased risk of death,” said McKay.
He added that as such, the results of the study were consistent with previous research that has found similar with regards to iron storage biomarkers.
Iron risk
The authors said that iron has a catalytic role in the generation of highly reactive oxygen species, such as hydroxyl radical.
“As a result, elevated iron levels, below the levels found in genetic hemochromatosis, may have a role in a variety of disease processes,” they explained.
Previous studies have found that elevated makers of iron storage, such as ferritin levels are associated with diabetes, metabolic syndrome, hypertension, dyslipidemia, elevated fasting insulin and glucose.
However Dr. Menke and colleagues noted that the association of ferritin and other biomarkers of iron metabolism with mortality incidence remain controversial.
“Few studies are available investigating the association between iron biomarkers and mortality,” said the authors.
The new study evaluated the association between the iron storage biomarkers ferritin and transferrin levels with all-cause, cardiovascular, and cancer mortality.
The authors explained that the study discounted data from people with the genetic iron storage disease hemochromatosis, as previously research has shown that this population are at risk.
They explained that it is important to assess any potential risks of high iron levels in people with normal iron metabolism.
Study details
The Johns Hopkins scientists analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III) Mortality Study – a cohort of 12,258 people based on a nationally representative sample of US adults
The researchers reported no significant differences in hazard ratios for mortality at all levels of iron storage.
Whilst the study found no association between high levels of iron storage biomarkers and mortality, the authors did report that postmenopausal women with low iron status were at higher risk from mortality.
Menke and co-workers said that this may be a chance finding from sub-group analysis, but offered a possible explanation for the link between low iron statuses as undiagnosed anemia, which is known to be a predictor of mortality.
Speaking on behalf of CRN, McKay said that it was good news “that the prevailing thinking is being re-enforced,” by a larger scale study.
“It’s always good to have a big study, back up and solidify the evidence from smaller studies,” he explained.
McKay added that in for the vast majority of the population, iron supplementation was not needed, though he warned that it is still important for certain groups, who are at risk from iron deficiency, to monitor their iron status, and if needed use a supplement.
Source: Nutrition, Metabolism & Cardiovascular Diseases
Published online ahead of print, doi: 10.1016/j.numecd.2010.11.011
“The association of biomarkers of iron status with mortality in US adults”
Authors: A. Menke, P. Muntner, J.M. Fernandez-Real, E. Guallar