Circulating non–transferrin-bound iron after oral administration of supplemental and fortification doses of iron to healthy women: a randomized study,,,

doi:10.3945/ajcn.113.081505

The American Journal of Clinical Nutrition

Volume 100, Issue 3, September 2014, Pages 813-820

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ABSTRACT

Background:

After the oral administration of iron, the production of circulating non–transferrin-bound iron may contribute to an increased risk of illness in malaria-endemic areas that lack effective medical services.

Objective:

In healthy women with a range of body iron stores, we aimed to determine effects on the production of circulating non–transferrin-bound iron resulting from the oral administration of 1) a supplemental dose of iron (60 mg) with water, 2) a supplemental dose of iron (60 mg) with a standard test meal, and 3) a fortification dose of iron (6 mg) with a standard test meal.

Design:

With the use of serum ferritin as the indicator, healthy women with replete iron stores (ferritin concentration >25 μg/L; n = 16) and reduced iron stores (ferritin concentration ≤25 μg/L; n = 16) were enrolled in a prospective, randomized, crossover study. After the oral administration of aqueous solutions of ferrous sulfate isotopically labeled with ⁵⁴Fe, ⁵⁷Fe, or ⁵⁸Fe, blood samples were collected for 8 h, and iron absorption was estimated by erythrocyte incorporation at 14 d.

Results:

At 4 h, serum non–transferrin-bound iron reached peaks with geometric mean (95% CI) concentrations of 0.81 μmol/L (0.56, 1.1 μmol/L) for 60 mg Fe with water and 0.26 μmol/L (0.15, 0.38 μmol/L) for 60 mg Fe with food but was at assay limits of detection (0.1 μmol Fe/L) for 6 mg Fe with food. For the 60 mg Fe without food, the area under the curve over 8 h for serum non–transferrin-bound iron was positively correlated with the amount of iron absorbed (R = 0.49, P < 0.01) and negatively correlated with serum ferritin (R = −0.39, P < 0.05).

Conclusions:

In healthy women, the production of circulating non–transferrin-bound iron is determined by the rate and amount of iron absorbed. The highest concentrations of non–transferrin-bound iron resulted from the administration of supplemental doses of iron without food. Little or no circulating non–transferrin-bound iron resulted from the consumption of a meal with a fortification dose of iron. This trial was registered at clinicaltrials.gov as NCT01404533.

Cited by (0)

^¹: From the Human Nutrition Laboratory, Institute of Food, Nutrition and Health, ETH Zürich, Zürich, Switzerland (IE, JTF, CZ, MA, and RFH); the Intrinsic LifeSciences LLC, La Jolla, CA (MEW); and the Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, NY (GMB).

^²: Supported by the Medicor Foundation, Vaduz, Liechtenstein; ETH Zürich (Eidgenössische Technische Hochschule Zürich), Zürich, Switzerland; the US NIH (grant 5 U01 HD061233); the Eunice Kennedy Shriver National Institute of Child Health and Human Development; and the Office of Dietary Supplements.

^³!: Current address of IE: Swiss Federal Institute of Technology Board, Zürich, Switzerland. Current address of JTF: Fresenius Kabi Deutschland GmbH, Bad Homburg, Germany.

^⁴: Address correspondence to GM Brittenham, Columbia University, Children’s Hospital of New York, Room CHN 10-08, 3959 Broadway, New York, NY 10032. E-mail: [email protected].