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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Healthy Body Weight Research » Research » Publications at this Location » Publication #101108
Title: IRON SUPPLEMENTATION REDUCES IRON ABSORPTION FROM FOOD, EVEN FOR WOMEN WITHLOW IRON STORES

Author
item Hunt, Janet
item Roughead, Zamzam

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/18/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Human adaptation in iron absorption was evaluated by measuring iron absorption and serum ferritin in healthy volunteers before and after 12 wk of iron supplementation. Men and women (n=57) with normal hemoglobin and serum ferritin values from 10-230 ug/L were randomly assigned to consume capsules daily containing either 50 mg iron (as ferrous sulfate) or a placebo, with their evening meals. Radioisotopic tracers were used to measure heme and nonheme iron absorption from an unsupplemented test meal containing (by analysis) 1.2 mg heme iron and 5.1 mg total iron from a hamburger, French-fries, and a vanilla milkshake. Iron supplementation did not affect the absorption of heme iron, but reduced nonheme iron absorption from 5.0 to 3.2%, p<0.001 (versus 5.2 to 5.0% with placebo). The reduction was at least as substantial for women with serum ferritin <21 ug/L (11.8 to 4.5% with iron, n=5; 16.8 to 12.8% with placebo, n=4), who would be most likely to benefit from high iron absorption. Iron supplementation reduced (p<0.05) the total iron absorbed from the meal by approx 25%. Procedural phlebotomy modified changes in serum ferritin, which were significant after 12 wk supplementation (iron, +5; placebo -9 ug/L, p<0.05) and remained so at 36 wk (iron, +5; placebo, -10 ug/L, p<0.05). In those with serum ferritin <21 ug/L, serum ferritin was greater after 12 wk (iron, +9; placebo, -2 ug/L), but was not different at 24 or 36 wk. Iron supplementation reduced nonheme, but not heme iron absorption from food, even in women with low iron stores, whose increase in serum ferritin was not sustained after discontinuing supplementation.