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Iron supplementation does not affect copper and zinc absorption in breastfed infants.
Domellöf, M, Hernell, O, Abrams, SA, Chen, Z, Lönnerdal, B
The American journal of clinical nutrition. 2009;(1):185-90
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Abstract
BACKGROUND Iron supplements are commonly recommended for infants but were suggested to inhibit zinc and copper absorption. OBJECTIVE The objective of this study was to investigate potential effects of iron supplementation, infant age, and mineral status on zinc and copper absorption in infants at 6 and 9 mo of age. DESIGN Twenty-five healthy breastfed term infants were recruited from a larger randomized iron supplementation trial. Six of these infants received iron supplements (1 mg . kg(-1) . d(-1)) from 4 to 9 mo, 8 were supplemented from 6 to 9 mo, and 11 received placebo only. Zinc and copper absorption was measured at 6 and 9 mo of age, using orally administered (70)Zn and (65)Cu and fecal monitoring of recovered stable isotopes. RESULTS Mean (+/-SD) zinc absorption was 51.9 +/- 17.9%, and mean copper absorption was 79.0 +/- 13.5%. No significant difference was observed in zinc or copper absorption between 6 and 9 mo of age. When combining all measurements, no significant effect of prior iron supplementation was observed on zinc or copper absorption. No significant correlation was observed between plasma zinc and zinc absorption or between plasma copper and copper absorption. No significant correlation was observed between erythrocyte copper-zinc-dependent superoxide dismutase activity and copper absorption. CONCLUSIONS The study does not support the contention that iron supplements inhibit the absorption of zinc or copper in healthy breastfed infants at 6-9 mo of age. In addition, we did not find any age-related changes in zinc or copper absorption between 6 and 9 mo of age.
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An inulin-type fructan enhances calcium absorption primarily via an effect on colonic absorption in humans.
Abrams, SA, Hawthorne, KM, Aliu, O, Hicks, PD, Chen, Z, Griffin, IJ
The Journal of nutrition. 2007;(10):2208-12
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Abstract
Calcium absorption efficiency and bone mineral mass are increased in adolescents who regularly consume inulin-type fructans (ITF). The mechanism of action in increasing absorption is unknown but may be related to increased colonic calcium absorption. We conducted a study in young adults designed to evaluate these mechanisms with a kinetic technique using (42)Ca orally and (46)Ca dosed i.v. Those who responded to 8 wk of supplementation with 8 g of a mixed short and long degree of polymerization ITF by increasing their calcium absorption had kinetic measurements analyzed to evaluate the time course of absorption. The area under the curve of the oral tracer in the blood during the 26 h after dosing was calculated and the time dependence of increased absorption determined. Eight young adults (of 13 studied), with mean calcium intake approximately 900 mg/d, responded to the ITF with an increased calcium absorption of at least 3%. In responders, absorption increased from 22.7 +/- 11.3% to 31.0 +/- 15.3%. Colonic absorption, defined as absorption that occurred >7 h after oral dosing, represented 69.6 +/- 18.6% of the increase, or 49 +/- 28 mg/d. These findings suggest that, in those who respond to ITF, its effects on calcium absorption occur principally in the colon. This benefit to ITF may be especially important when absorption in the small intestine is impaired for anatomic or physiological reasons.