Poster Topical Area: Vitamins and Minerals
Location: Hall D
Poster Board Number: 481
Objectives: Iron deficiency affects more people worldwide than any other condition. Although most affected individuals reside in developing nations, iron deficiency is one of the few nutritional deficits present at significant levels in developed countries. The setting of accurate Recommended Dietary Allowances (RDAs) for iron is, therefore, important for population health and nutritional well-being. We have recently examined the method used to calculate the RDA for iron and believe the current guidelines may, in fact, encourage iron deficiency.
Methods: The RDA for iron is based on an estimate of the proportion of dietary iron absorbed, which is used to determine the amount required to replace obligatory daily losses. Currently, the amount absorbed is based on that of a person with normal functional iron levels, but only minimal storage iron as indicated by a serum ferritin (SF) of 15μg/L. However, the amount of iron absorbed from the diet is inversely regulated by body iron stores. The average SF for men in developed countries is generally over 100μg/L and, as such, they will absorb far less iron than an individual with a SF of 15μg/L. Therefore, basing the RDA for iron on the absorption rate of a population with a SF of 15μg/L will encourage iron deficiency, as a population with a higher SF will not absorb enough iron to replace obligatory losses when following the current guidelines. Body iron stores would continue to fall until a SF of 15μg/L is reached, at which point iron absorption would balance iron losses.
We have used recently published estimates of iron absorption to re-calculate the RDA for iron using a target SF of 70μg/L in premenopausal women, as this represents the level of storage iron required to avoid iron deficiency during pregnancy.
Results: Using an estimated iron absorption of 10%, the RDA increases from 8mg/day to 15mg/day for adult males, from 18mg/day to 33 mg/day for premenopausal women, and from 8 mg/day to 14 mg/day for postmenopausal women.
Conclusions: These estimates represent a significant increase in the RDA for iron for each population examined. As the average iron intake for premenopausal women is estimated to be lower than both the current and proposed RDA, public health policy should be re-evaluated to reflect the higher iron requirements of this population.
Senior Research Officer
QIMR Berghofer Medical Research Institute
Herston, Queensland, Australia