EDTA and the absorption of iron from food.

Iron EDTA is an effective fortificant in meals of low iron bioavailability. Na2EDTA, added to food to prevent oxidation, enhances iron bioavailability by chelating added iron. This study examines the optimal ratio of EDTA to iron causing enhanced iron absorption. Iron absorption from a rice-based meal of low iron bioavailability containing increasing molar ratios of EDTA to iron, was compared in 127 women volunteers by using standard double isotope techniques. Iron deficiency was present in 38% of the women. Mean standardized absorptions, at EDTA-iron ratios of 0.25, 0.5, and 1, were 11.3%, 13.5%, and 8.8%, respectively, compared with 3.8% when no Na2EDTA was present. In meals of high iron bioavailability, Na2EDTA (EDTA:Fe, 1.0) produced little enhancement (potato-based meal) nor inhibited iron absorption (apple-based meal). Na2EDTA added to meals with molar ratios of EDTA to iron between 1.0 and 0.25 significantly increases iron absorption provided the meal is of low iron bioavailability.

Ascorbic acid prevents the dose-dependent inhibitory effects of polyphenols and phytates on nonheme-iron absorption.

The effects of maize-bran phytate and of a polyphenol (tannic acid) on iron absorption from a white-bread meal were tested in 199 subjects. The phytate content was varied by adding different concentrations of phytate-free and ordinary maize bran. Iron absorption decreased progressively when maize bran containing increasing amounts of phytate phosphorous (phytate P) (from 10 to 58 mg) was given. The inhibitory effect was overcome by 30 mg ascorbic acid. The inhibitory effects of tannic acid (from 12 to 55 mg) were also dose dependent. Studies suggested that greater than or equal to 50 mg ascorbic acid would be required to overcome the inhibitory effects on iron absorption of any meal containing greater than 100 mg tannic acid. Our findings indicate that it may be possible to predict the bioavailability of iron in a diet if due account is taken of the relative content in the diet of the major promoters and inhibitors of iron absorption.

Maternal and fetal iron measurements in a hemochromatotic pregnancy.

The findings in the cord blood sample of an infant from a treated hemochromatotic mother of a raised transferrin saturation (88%) and a raised ferritin concentration (250.2 micrograms/L) together with elevated maternal values (66% and 91.6 micrograms/L, respectively) yet a normal total placental iron content (26.9 mg) suggested that in common with gastrointestinal mucosal cells and reticuloendothelial cells in hemochromatosis, the placental cell may exhibit an abnormality of iron storage and transport.

Effects of alpha-interferon on iron-related measurements in human subjects.

Subcutaneous administration of alpha-interferon to normal volunteers caused hypoferraemia and hyperferritinaemia. There was, however, no concomitant rise in other components of the acute-phase response, including the serum C-reactive protein value, the granulocyte count and the plasma lactoferrin concentration. In fact, the latter two dropped significantly. The hypoferraemic response could be prolonged when a second dose was given 48 hours after the initial one. This hypoferraemic response may play a role similar to that induced by interleukin-1, which limits the proliferation of invading micro-organisms or neoplastic cells. The present findings may therefore have relevance to the clinical mechanism of action of the interferons.

Dietary iron overload in southern African rural blacks.

A survey conducted in rural southern African black subjects indicated that dietary iron overload remains a major health problem. A full blood count, erythrocyte sedimentation rate, serum concentrations of iron, total iron-binding capacity, ferritin, C-reactive protein (CRP), gamma-glutamyltransferase (GGT) and serological screening for hepatitis B and human immunodeficiency virus (HIV) infections were carried out in 370 subjects (214 inpatients and 156 ambulatory Mozambican refugees). The fact that the geometric mean (SD range) serum ferritin concentration was much higher in the male hospital patients than in subjects living in the community [1,581 micrograms/l (421-5,944 micrograms/l) and 448 micrograms/l (103-1,945 micrograms/l) respectively] suggested that dietary iron overload was not the only factor raising the serum ferritin concentration. The major additional factor appeared to be inflammation, since the geometric mean (SD range) serum CRP was significantly higher in male hospital patients [21 mg/l (8-53 mg/l)] than in subjects in the community [3 mg/l (1-5 mg)]. Alcohol ingestion, as judged by history and by serum GGT concentrations, was also associated with significantly raised serum ferritin concentrations. This finding was ascribed to the fact that traditional brews are not only associated with alcohol-induced hepatic damage but are also a very rich source of highly bio-available iron. The role of iron overload in the genesis of the raised serum ferritin concentrations are confirmed in the diagnostic liver biopsy study. The majority of biopsies showed heavy siderosis, with varying degrees of hepatic damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Triiodothyronine treatment for Raynaud's phenomenon: a controlled trial.

The effects of 80 micrograms triiodothyronine (T3) daily were compared with placebo in a double blind controlled crossover trial in 18 patients with Raynaud's phenomenon. Reductions in the frequency, duration and severity of attacks while taking T3 were gradual but highly significant. Four of 6 subjects had skin ulcer healing. Skin temperatures in the hands increased significantly. The skin temperature recovery times after cold exposure were significantly shorter during T3 therapy compared with placebo. Although large dosages of T3 were well tolerated, 6 patients experienced episodic palpitations, and slight but significant increases in heart rate and pulse pressure were observed. Evaluation of the use of physiological doses of T3 (60 micrograms daily or less) in the treatment of Raynaud's phenomenon is suggested.

The promotive effect of soy sauce on iron absorption in human subjects.

The effects on iron absorption of a traditionally fermented Japanese soy sauce added to soy and rice meals were assessed. The addition of soy sauce to a soy flour meal could not overcome the strong inhibition of iron absorption (geometric mean absorption 7.2 per cent with soy sauce vs. 8.7 per cent without, P = 0.5). However, soy sauce added to a rice meal instead of soy flour significantly improved the geometric mean iron absorption (13.9 per cent with soy sauce vs. 5.2 per cent with soy flour, P = 0.002) and had a promotory effect on absorption from a rice meal alone (11.4 per cent with soy sauce vs. 3.5 per cent without, P = 0.0002). Although soy sauce contains appreciable amounts of organic acids, the addition of 340 mg lactic acid to rice did not enhance iron absorption (3.1 per cent with lactic acid vs. 2.2 per cent without, P = 0.11). The promotory effect of soy sauce on iron absorption appears to be due not only to its lack of soy protein content but may also be due to the presence of fermentation products other than organic acids.

Factors involved in the regulation of iron transport through reticuloendothelial cells.

The effects of various maneuvers on the handling of 59Fe-labeled heat-damaged red cells (59Fe HDRC) by the reticuloendothelial system were studied in rats. Raising the saturation of transferrin with oral carbonyl iron had little effect on splenic release of 59Fe but markedly inhibited hepatic release. Splenic 59Fe release was, however, inhibited by the prior administration of unlabeled HDRC or by the combination of carbonyl iron and unlabeled HDRC. When carbonyl iron was administered with unlabeled free hemoglobin, the pattern of 59Fe distribution was the same as that observed when carbonyl iron was given alone. 59Fe ferritin was identified in the serum after the administration of 59Fe HDRC but the size of the fraction was not affected by raising the saturation of transferrin. Sizing column analyses of tissue extracts from the spleen at various times after the administration of 59Fe HDRC revealed a progressive shift from hemoglobin to ferritin, with only small amounts present in a small molecular weight fraction. The small molecular weight fraction was greater in hepatic extracts, with the difference being marked in animals that had received prior carbonyl iron. The increased hepatic retention of 59Fe associated with a raised saturation of transferrin was reduced by a hydrophobic ferrous chelator (2,2'-bipyridine), a hydrophilic ferric chelator (desferrioxamine), and an extracellular hydrophilic ferric chelator (diethylene-triaminepentacetic acid). Transmembrane iron transport did not seem to be a rate-limiting factor in iron release, since no differences in 59Fe membrane fractions were noted in the different experimental settings. These findings are consistent with a model in which RE cells release iron from catabolized red cells at a relatively constant rate. When the saturation of transferrin is raised, a significant proportion of the iron is transported from the spleen to the liver either in small molecular weight complexes or in ferritin. Although a saturated transferrin had no effect on the release of iron from reticuloendothelial cells, prior loading with HDRC conditions them to release less iron.

Severe immune thrombocytopenia and the development of skin infarctions in a patient with an overlap syndrome.

A 49-year-old woman with clinical features of systemic lupus erythematosus, systemic sclerosis, Sjögren's and the antiphospholipid syndromes developed severe immune thrombocytopenia and skin infarctions. Both complications responded to immunosuppressive agents.

Plasma lactoferrin content in pregnancy.

Plasma lactoferrin concentration, leucocyte count, serum prolactin concentration and storage iron status were studied in 313 women at various stages of pregnancy. The mean serum iron value, percentage saturation of transferrin and geometric mean serum ferritin concentrations decreased as pregnancy progressed. In contrast, the total iron-binding capacity showed a highly significant increase with advancing gestation. Plasma lactoferrin concentration showed a mild progressive increase during pregnancy (peaking 29-32 weeks). The increase in lactoferrin concentration was, however, disproportionately small when compared with the concomitant pregnancy-related elevation in leucocyte count. The ratio of plasma lactoferrin concentration to leucocyte count therefore appeared to be abnormally low during pregnancy suggesting an acquired defect of lactoferrin release by leucocytes of pregnant women. It is unlikely that prolactin was the factor responsible for the reduced leucocyte release of lactoferrin. The lactoferrin:leucocyte ratio was already significantly reduced early in pregnancy at a time when prolactin concentration was relatively low. Furthermore, the correlation between prolactin concentration and both lactoferrin concentration and lactoferrin:leucocyte ratio was positive. Pregnancy appears to be associated with an acquired abnormality of leucocyte degranulation, the cause of which is not clear at present.

Iron metabolism in normal and hemochromatotic macrophages.

Certain metabolic pathways of iron were studied in macrophages (cultured human monocytes) obtained from normal and hemochromatotic subjects. The relative abilities of the hydrophobic ferrous chelator 2,2' bipyridine and the hydrophilic ferric chelators desferrioxamine (DFO) and diethylenetriaminepenta-acetic acid (DTPA) to release iron from normal and hemochromatotic macrophages which had previously been loaded with diferric transferrin were tested but there were no differences between the two groups. The relative affinity of the macrophages for diferric transferrin was next studied. Although the hemochromatic macrophages had a somewhat lower affinity for diferric transferrin iron than normal macrophages (Kd 4.7 x 10(-8) M vs. 3.0 x 10(-8)M) the difference did not reach statistical significance (t = 2.01013; P less than 0.07). In a further experiment there was no evidence that apotransferrin was directly involved in the release of iron from hemochromatotic macrophages. A clue to the nature of postendocytotic trans-membrane transport of iron was provided by the finding that it was inhibited by the hydrophobic ferrous chelator 2,2' bipyridine. However, the degree of inhibition was similar in both normal and hemochromatotic macrophages. In summary, none of the metabolic processes examined in the present study was abnormal in cultured human blood monocytes from hemochromatotic subjects.

The fate of intravenously injected tissue ferritin in pregnant guinea-pigs.

The organ distribution of intravenously injected hepatic ferritin either labelled with 59Fe or with 59Fe and 125I, was studied in pregnant guinea-pigs. At 5 h 71.2% of injected 59Fe was present in the placenta and fetus. Transfer of 59Fe to the fetus was slow, with 11.2% present at 5 h and 38.6% at 21 h. Analysis of a placental cellular lysate for 59Fe and 125I revealed that the injected iron was present as intact ferritin at 2 h but by 21 h the ferritin had been catabolized, the 125I excreted and the 59Fe incorporated into endogenous ferritin. Most of the fetal 59Fe counts were detected in the liver, with 35.3% of the transferred 59Fe in ferritin, 30.4% in haemoglobin and 10.6% in a low molecular weight pool. The uptake of labelled ferritin by the placenta was inhibited by a 300-fold molar excess of unlabelled ferritin but not by albumin, asialofetuin or by the injection of carbon particles. A nonsignificant reduction in uptake was noted after injection of mannosylated bovine serum albumin. The mannosidase inhibitor swainsonine had no effect. Iron transfer to the fetus was not affected by various microtubular inhibitors. Presaturation of endogenous transferrin with oral carbonyl iron prevented iron release from the feto-placental unit back into the maternal circulation. In consequence, marrow 59Fe uptake by the maternal marrow was reduced. The ferrous chelator 2,2'-bipyridine significantly reduced 59Fe transfer to the fetus and this occurred irrespective of whether the chelator was given prior to or after 59Fe ferritin administration. The ferric chelator desferrioxamine had no such effect. Electron microscopy of placental tissues revealed endocytosis of ferritin molecules. These results indicate that the guinea-pig placenta takes up homologous tissue ferritin and transfers the iron slowly to the fetus after reductive mobilization. The process is compatible with a receptor-mediated pathway.

Effect of ferrous and ferric chelators on transferrin-iron-macrophage interactions.

A study was done to evaluate the effect of ferrous and ferric chelators on the interaction between transferrin-iron and cultured human blood monocytes. This interaction has been previously shown to involve a specific receptor and vesicle protonation. Transferrin-iron uptake was significantly inhibited by the hydrophobic ferrous chelator 2,2' bipyridine, and the inhibition was shown not to be a consequence of the mobilisation of intracellular iron by the chelator. Chase experiments and prolonged incubation studies suggested that the chelator prevented the iron released from transferrin from negotiating the unit membrane. The iron and transferrin then appeared to be returned independently to the incubation medium. In contrast, a hydrophilic ferrin chelator, desferrioxamine, had only a very modest effect on the interaction. These findings are compatible with the hypothesis that transferrin-iron is reduced to the ferrous state during its uptake by the culture human blood monocyte.

Anaemia in pregnant Indian women in Johannesburg.

A study was performed in 100 subjects to determine the prevalence and cause of anaemia in pregnant Indian women in the Johannesburg area. The geometric mean serum ferritin concentration in all three trimesters of pregnancy was below 12 micrograms/l, with 43.3% of women in the first, 48.6% in the second and 80.0% in the third trimester having concentrations below this value. Estimation of body iron stores revealed a mean deficit of 265 mg iron in subjects in the third trimester, 20% of whom had iron deficiency anaemia. No difference in iron status was demonstrable in subjects from different religious backgrounds. Folate and vitamin B12 nutrition was adequate. Three subjects were diagnosed as being beta-thalassaemia heterozygotes. The findings underline the need for routine iron supplementation of pregnant Indian women in the Johannesburg area.

Nutritional anaemia in pregnant coloured women in Johannesburg.

A nutritional anaemia survey was carried out in 224 pregnant coloured first-time attenders at Coronation Hospital antenatal clinic in Johannesburg during the second quarter of 1986. None had received any form of nutritional supplementation during pregnancy. Haemoglobin concentrations less than 11 g/dl were present in 18.9% of women in the third trimester of pregnancy, while 64% had a saturation of transferrin value of less than 16% and 68% a serum ferritin level less than 12 micrograms/l. Calculations suggested that mean iron stores in the first trimester were 228 mg, with 37.5% of women having absent stores. Comparable figures in the second and third trimesters were 74 mg and -92 mg respectively. The fact that many were iron deficient in the first trimester indicates a high frequency of iron deficiency in non-pregnant women in this population group. Although 20.8% of the women had red cell folate values below the normal range for non-pregnant subjects, folate deficiency did not appear to be a significant problem. Vitamin B12 deficiency was very uncommon.

Nutritional anaemia in 11-year-old schoolchildren in the western Cape.

A nutritional anaemia survey was carried out on 610 11-year-old coloured, black and white schoolchildren in urban and rural communities in the western Cape. The mean (+/- 1 SD) haemoglobin concentration was 13.0 +/- 1.2 g/dl. The coloured and black subgroups considered together had a significantly lower mean haemoglobin concentration than the white subgroup (12.8 +/- 1.2 g/dl v. 13.4 +/- 1.0 g/dl) (F = 37.47; P less than 0.0001). The urban population as a whole had a significantly lower geometric mean (1 SD range) serum ferritin concentration than the rural population (25.6 (13.5-48.6) micrograms/l v. 34.1 (21.3-54.6) micrograms/l) (F = 42.94; P less than 0.0001). The lowest geometric mean serum ferritin values were found in the urban coloured (23.1 (11.5-46.4) micrograms/l) and urban black schoolchildren (23.7 (13.2-42.6) micrograms/l), with figures of less than 12 micrograms/l in 11.7% and 12.5% respectively. Although 28% of the children had red cell folate values below the recommended lower limit of normal (175 ng/ml), probability plot analysis of the data suggested that folate deficiency was not a major problem in the study population. The calculated daily iron and folate intakes were below the age-related recommended dietary allowance (RDA) in all the subgroups, yet anaemia was relatively uncommon. These findings suggest that the RDA values are too high. Overall the prevalence of nutritional anaemia was low and only the urban coloured subgroup showed significant second populations with low haemoglobin and serum ferritin measurements.

Inhibitory effect of nuts on iron absorption.

The effects on iron absorption of nuts, an important source of dietary protein in many developing countries, were measured in 137 Indian women. When the absorption from bread and nut meals (walnuts, almonds, peanuts, and hazelnuts) was compared with that from bread meals, the overall geometric mean absorption from the nut meals (1.8%) was significantly less than from the bread meals alone (6.6%, t = 9.8, p less than 0.0005). In contrast, coconut did not reduce absorption significantly. All the nuts tested contained significant amounts of two known inhibitors of Fe absorption (phytates and polyphenols) but the amounts in coconut were significantly less than in the other nuts. Fifty milligrams ascorbic acid overcame the inhibitory effects of two nuts that were tested (Brazil nuts and peanuts). This is different from that found previously for soy protein, another potent inhibitor of Fe absorption.

Platelet parameters. Part I. Platelet counts and mean platelet volume in normal and pregnant subjects.

Platelet counts and mean platelet volume (MPV) were studied in 564 normal subjects and 297 pregnant women using a Coulter Model S-Plus electronic counter. The reproducibility of these measurements both intra- and inter-sample was documented. The mean platelet count in the normal group was 283 x 10(9)/l while the mean MPV was 9.32 fl. An inverse correlation between platelet volume and platelet number was documented (r = -0.38; P less than 0.0001). By interval analysis, this inverse relationship was shown to be non-linear. In the pregnant subjects there appeared to be a progressive decrease in platelet count with advancing gestation; this reached a significant level when the first and third trimesters were compared with each other (P less than 0.05). The MPV was unchanged. The fact that the platelet count decreased in proportion to the red cell count suggested that a common factor, such as haemodilution, was in part responsible. There was again an inverse relationship between MPV and platelet number (r = -0.39; P less than 0.0001) shown to be non-linear by interval analysis.

Platelet parameters. Part II. Platelet volume-number relationships in various normal and disease states.

The relationship between mean platelet volume (MPV) and platelet count was evaluated in 259 patients with rheumatoid arthritis and 311 patients with various haematological disorders. Platelet volume-number relationships determined in a previous study on normal subjects were used as a reference range. There was a significant inverse relationship between MPV and platelet count in patients with rheumatoid arthritis (r = -0.49; P less than 0.0001), which by interval analysis was shown to be non-linear. In the patients with haematological disorders, the platelets were found to be disproportionately small for number in patients with aplastic anaemia, chemotherapy-induced marrow suppression and some cases of acute idiopathic thrombocytopenic purpura (ITP). In subjects with chronic ITP followed longitudinally, the inverse platelet volume-number relationship was retained. MPV was appropriate for platelet number in myelodysplastic syndromes, variable in iron deficiency anaemia and disproportionately large in myeloproliferative syndromes, most notably in agnogenic myeloid metaplasia. The observation that the MPV was disproportionately large in comparison with the platelet count was used in establishing the diagnosis of an hereditary giant platelet syndrome in a family of British origin.

Curry powder as a vehicle for iron fortification: effects on iron absorption.

Curry powder was investigated as a vehicle for targeted iron (Fe) fortification, and especially for NaFeEDTA, by assessing its acceptability to consumers and its effects on Fe absorption. A random survey in an Indian community in the Republic of South Africa, indicated that fortified premixed curry powder was acceptable in terms of color, palatability, and stability. The effect of curry powder on Fe absorption from a potato meal was assessed in 64 Indian housewives. Curry powder caused a significant though modest rise in Fe absorption in two of the studies (t = 2.716, p less than 0.05 and t = 3.126, p less than 0.025) but, in the third, the effect was noted only in the more Fe-depleted subjects. There was no enhancement of Fe absorption from a dhal soup of low-Fe bioavailability (t = 0.224, p greater than 0.1). The results of both the human and animal studies suggested that curry powder's overall mild enhancing effect on Fe absorption was due to its capacity to stimulate gastric acid secretion.