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At least 19 recordsLinked to original sources
PubMed1995

Iron absorption from the whole diet: comparison of the effect of two different distributions of daily calcium intake.

The possibility of reducing calcium inhibition of iron absorption by decreasing calcium intake in lunch and dinner meals, which provided the most dietary iron, was examined in 21 healthy female volunteers. During a 10-d period, nonheme iron in all meals was extrinsically labeled with radioisotopic iron to a uniform specific activity. Iron absorption from two identical 10-d periods was compared when meals were labeled with two different iron radioisotopes and when the same amount of calcium (937 mg) was distributed in two ways, in either mainly breakfast and late evening meals or more evenly in all meals. About 30-50% more iron was absorbed when no milk or cheese was served with lunch or dinner. The difference was statistically significant. Median iron requirements (1.61 mg/d) calculated from body weight and menstrual iron losses agreed with the mean value of median iron absorption in the two 10-d periods (1.54 mg/d), which supports the validity of the present method. A reasonable separation of calcium and iron intakes would improve iron nutrition.

Adult↗
PubMed1986

A study on the mechanism of the postoperative fall in serum iron concentration.

The purpose of this study was to investigate the mechanism of the postoperative fall in serum iron concentration. Simultaneous measurements of iron uptake from, and release to, the plasma were made using two iron radioisotopes. Eight rabbits were submitted to laparotomy and eight were used as controls. Six hours after laparotomy, when the plasma iron concentration was decreasing, the clearance half-time from the plasma was decreased from 82.0 +/- 3.0 min in controls to 25.0 +/- 4.0 min (P less than 0.001) but the amount of iron uptake was increased from 0.289 +/- 0.013 to 0.574 +/- 0.092 mumole/liter blood/day (P less than 0.001). Twenty-four hours after laparotomy, when the plasma iron concentration was increasing, the half-time remained shortened in the operative group but the amount of iron uptake was decreased from 0.39 +/- 0.28 to 0.25 +/- 0.1 mumole/liter blood/day although this difference is not significantly different. At both times studied there was no difference in the amount of iron released to the plasma. These results suggest that the fall in iron concentration after surgery is due to increased uptake from the plasma.

Animals↗
PubMed1996

Improved zinc and iron absorption from breakfast meals containing malted oats with reduced phytate content.

The absorption of Zn or Fe from breakfast meals containing oat porridge prepared from malted and soaked oats and a control porridge made from untreated oats was measured in human subjects. The effect on Zn and Fe absorption of reducing the phytate content of oat-porridge meals was examined in each subject by extrinsic labelling of porridge with 65Zn and of bread rolls with 55Fe and 59Fe, and measuring whole-body retention and the erythrocyte uptake of isotopes. Each experiment comprised nine to ten subjects. The absorption of Zn from malted-oat porridge with a phytate (inositol hexaphosphate) content of 107 mumol was 18.3%, and significantly higher (P < 0.05) than from the control porridge containing 432 mumol phytate (11.8%). Fe absorption from the meal containing malted-oat porridge with 107 mumol phytate (Expt 2) was also significantly improved (P < 0.05) compared with that from the meal containing control porridge with 437 mumol phytate. The average increase in Fe absorption was 47%, or from 4.4 to 6.0%. In the breakfast meal containing malted porridge with 198 mumol phytate (Expt 3) the increase in Fe absorption was not significantly improved. Even though the phytate content was reduced to a greater extent in Expt 3 than Expt 2, the average increase in Fe absorption in Expt 3 was only 25% more than that from the meal containing control porridge (with 599 mumol phytate), depending on the higher absolute amount of phytate. In conclusion, an improvement in Zn and Fe absorption from oat products can be achieved by practising malting and soaking in the processing of oats. This may be of importance in the prevention of mineral deficiency in vulnerable groups.

Adult↗
PubMed2004

Calcium, zinc, and iron bioavailabilities from a commercial human milk fortifier: a comparison study.

Adding human milk fortifiers (HMF) to human milk (HM) is one way of overcoming the nutrient deficits found in the latter. In this study, the bioavailabilities of calcium, zinc, and iron in S-26/SMA HMF added to HM were compared with those in HM fortified with various bovine milk proteins: alpha-lactalbumin, colostrum, caseinate, casein phosphopeptides, and whey protein concentrate. The bioavailability of each mineral was assessed using an in vitro digestion/Caco-2 cell culture model. Calcium and zinc uptake by the cells was traced with radioisotopes; iron uptake was assessed via cell ferritin levels. Samples were prepared on an equal protein content basis and with added calcium, but no zinc or iron was added. Results revealed that calcium uptake from HM + S-26/SMA was not different from any of the HM fortified with the bovine milk proteins, except for unfortified HM and HM + colostrum in which calcium uptake was significantly lower (-89 and -38%, respectively). Uptake of zinc and iron were significantly higher for HM + S-26/SMA than for the other HM + fortifiers.

Animals↗
PubMedDate not supplied

Brain iron uptake in hypotransferrinemic mice: influence of systemic iron status.

The relationship of the heterogeneity of iron concentrations in the brain with the regulation of iron uptake into specific brain regions remains unresolved. We used hypotransferrinemic mice and an iron-deficient or control diet to explore whether plasma transferrin (Tf), transferrin saturation, and plasma iron levels influence the uptake of (59)Fe and whether there was brain region specificity. Weaning wild-type (+/+) and heterozygotic mice (+/hpx), were sorted randomly to either a iron-deficient diet or a control iron diet for 8 weeks, whereas homozygous mice (hpx/hpx) ate the control diet for 8 weeks before (59)Fe uptake studies. Iron-deficient heterozygous and wild-type mice both had significantly greater plasma Tf levels (37.5 and 42.5 microM) than control mice had (heterozygous and wild-type controls were 20 and 32.5 microM) and far more than homozygous mice (<0.2 microM) had, thus providing five distinct levels of plasma Tf concentrations. After intravenous injection of (59)Fe, brains of iron-deficient wild-type mice took up significantly more (59)Fe (0.15% dose) compared to control wild-type mice (0.056%) at 2 hr, a treatment effect that persisted through 24 hr. In contrast, diet had no effect in heterozygous mice. Importantly, homozygous mice had equivalent uptake to other groups (0.089% dose) by 24 hr. Early brain radioactivity varied by regions (hypothalamus and prefrontal cortex approximately 10-18% brain uptake > cerebellum, pons, thalamus, and striatum approximately 7-12% > cortex, hippocampus, and substantia nigra approximately 6-8%). This distribution of radioactivity changed over 24 hr in the hypothalamus of heterozygous mice, homozygous mice, and iron-deficient wild-type mice. Homozygous mice also showed higher uptake (13-15%) in some regions (hypothalamus and cerebellum) than in other regions. In wild-type and heterozygous mice, (59)Fe uptake was inversely related to brain Tf and was independent of regional brain iron concentrations and plasma Tf levels or saturation. These experimental data suggest that brain iron uptake may be constitutive and independent of plasma Tf, transferrin saturation, or regional brain iron concentration. The proteins and mechanisms responsible for additional iron uptake into specific regions, or perhaps the redistribution are unclear though the data are supportive of a non-transferrin-bound iron uptake pathway.

Analysis of Variance↗
PubMed1986

The influence of isotopic and nonisotopic carriers on the biodistribution and biokinetics of M3+-citrate complexes.

The influence of carrier amounts of Fe, Ga, and Tm on the biodistribution of 67Ga-, 59Fe-, and 167Tm-citrate in mice was investigated. Our results suggest that 167Tm, unlike 67Ga and 59Fe, is not transported by transferrin in the blood. Of the three radioisotopes tested, 167Tm had the highest tumor/background ratio (10 h after the injection). The application of Fe carrier led to an enhancement of the elimination of 67Ga from the blood and muscles, resulting in a better tumor/background ratio.

Animals↗
PubMed1982

Haematological studies on 90Sr-90Y-toxicity: II. Femoral CFU-s kinetics and mitogen response of spleen cells.

Ferrokinetic perturbations in peripheral blood of mice treated with 90Sr-90Y were demonstrated previously. This paper deals with the effects of 90Sr-90Y treatment (2.5, 5, and 10 microCi/mouse), on the haemopoietic stem cell compartment and on the immune-status. The frequency and kinetics of haemopoietic stem cells in femoral marrow (determined as colony forming units in spleen, CFU-s) and their haemopoietic efficiency (as gauged by 59Fe- and 125IUdR-uptake) were estimated. The responsiveness of splenic lymphocytes of the same animals to mitogens (Con A, PHA, and LPS) were also measured. In all assays striking dose-dependent changes marked either by depressions or overshoots were observed during the first week post-incorporation. These are correlated with the pattern of deposition (primary and secondary) of the radionuclides 90Sr-90Y. Towards the end of the period of observation and presumably thereafter, the dependence on dose disappeared and the values remained subnormal. An exception to this was the response of splenic lymphocytes to mitogens. Much higher reactivity was recorded up to the end. This higher reactivity is attributed to augmented cellular turnover, the newly recruited lymphocytes (in accord with thier extreme radiosensitivity), being probably more reactive.

Animals↗
PubMed2007

Improved iron bioavailability in an oat-based beverage: the combined effect of citric acid addition, dephytinization and iron supplementation.

BACKGROUND: Iron deficiency in children is a major worldwide nutritional problem. An oat beverage was developed for 1- to 3-year-old children and different treatments were used to improve the iron bioavailability. AIM OF THE STUDY: To investigate the effects of citric acid addition, phytase treatment and supplementation with different iron compounds on non-heme iron absorption in human from a mineral-supplemented oat-based beverage. METHODS: A 240 g portion of a 55Fe-labeled test product (T) or a 59Fe-labeled reference dose (R) was served as breakfast after overnight fasting on four consecutive days in the order of TRRT. On day 18 the retention of 59Fe was measured by a whole-body counter and the erythrocytes uptake of 55Fe and 59Fe by a liquid-scintillation counter. Forty-two healthy subjects (men and women) were randomized into four study groups, members of each being given one of the studied four products (A, B, C, and D) supplemented with Fe (1.3 mg/portion), Zn, Ca, Se and P. Ferric ammonium citrate (FeAC) was added to products A, B, and C and ferric pyrophosphate (FePP) to product D. Citric acid (60 mg/portion) was added to products B, C, and D and phytase treatment applied to products C and D. RESULTS: Citric acid improved iron absorption by 54% from 3.9% in product A to 6.0% in product B (p = 0.051). Phytase treatment increased iron absorption by 78% (from 6.0 to 10.7%, p = 0.003) by reducing the phytate-phosphorus content per portion from 16.3 mg in product B to 2.8 mg in product C. The two compounds gave similar iron absorption rates (p = 0.916). CONCLUSIONS: A combination of citric acid addition, dephytinization and iron supplementation significantly increased the iron absorption in an oat-based beverage. Such a beverage can be useful in the prevention of iron deficiency in 1- to 3-year-old children.

6-Phytase↗
PubMed1986

Double labeling of transferrin: tritium labeling of sialic acid and 125I or 59Fe labeling of the protein moiety.

A method is described in which the glycoprotein transferrin was double labeled. Its sialic acid residues were labeled with 3H through a consecutive oxidation-reduction technique utilizing tritiated NaBH4. Its protein moiety was labeled with either 125I or 59Fe. Incubation of this double-labeled molecule at 4 degrees C with K562 cells gave overlapping curves, indicating identical patterns of binding for all labels. At 37 degrees C, 3H and 125I demonstrated identical patterns while 59Fe was cummulatively retained. This method can be used to follow the fate of other glycoproteins and their possible desialation in vivo.

Biological Transport, Active↗