Serum Iron Curves Can Be Used to Estimate Dietary Iron Bioavailability in Humans

• Published in: The Journal of nutrition Vol. 136; no. 7; pp. 1910 - 1914
• Main Authors: Conway, Rana E, Geissler, Catherine A, Hider, Robert C, Thompson, Richard P.H, Powell, Jonathan J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Nutrition 01.07.2006; American Society for Nutritional Sciences
• Subjects: Adult; bioavailability; Biological and medical sciences; Biological Availability; blood sampling; dietary minerals; erythrocytes; estimation; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; human nutrition; Humans; Intestinal Absorption; iron; iron absorption; iron deficiency anemia; Iron, Dietary - administration & dosage; Iron, Dietary - blood; Iron, Dietary - pharmacokinetics; Middle Aged; test meals; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Micronutrient; Human; serum iron; Absorption; Nutrition; Serum; Iron; 58Fe; Bioavailability; iron bioavailability; nonheme iron absorption
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/136.7.1910

Erythrocyte incorporation of isotopic iron (Fe) is the standard method for assessing iron bioavailability, but the process is expensive, technically difficult, and gives no information on the kinetics of absorption. The main objective of this study was to validate serum Fe curves as measures of dietary iron absorption because previous work demonstrated that serum iron curves can be generated with iron doses as low as 5-20 mg and that up to 20 mg iron can be added to meals without affecting relative absorption. In 3 studies, groups (n = 10, 10, 21) of Fe-deficient, mildly anemic women consumed meals of varying calculated Fe bioavailability, with and without added ferric chloride (10 mg Fe). Blood samples were collected at baseline and every 30 min for 4 h after the meal. Serum Fe concentrations were measured. Areas under the serum Fe curves and peak concentrations were used in different models to estimate Fe absorption and uptake. In 21 subjects, ⁵⁸Fe-enriched ferric chloride was added to the meals, and blood was taken 2 wk later to calculate red cell isotope incorporation. The addition of 10 mg Fe to test meals produced measurable serum iron curves even when the meal Fe bioavailability was low. Serum Fe curves were highly reproducible and were affected as expected by food composition. Even the single measurement at the estimated time of peak iron concentration was correlated significantly with erythrocyte incorporation of ⁵⁸Fe (r = 0.72, P < 0.0001). Hence the extent and rate of absorption of nonheme iron from meals, rather than in individuals, can be investigated with such subjects without the need for isotopes.