The effects of fruit juices and fruits on the absorption of iron from a rice meal.

The effects of the chemical composition of fruit juices and fruit on the absorption of iron from a rice (Oryza sativa) meal were measured in 234 parous Indian women, using the erythrocyte utilization of radioactive Fe method. The corrected geometric mean Fe absorptions with different juices varied between 0.040 and 0.129, with the variation correlating closely with the ascorbic acid contents of the juices (rs 0.838, P less than 0.01). Ascorbic acid was not the only organic acid responsible for the promoting effects of citrus fruit juices on Fe absorption. Fe absorption from laboratory 'orange juice' (100 ml water, 33 mg ascorbic acid and 750 mg citric acid) was significantly better than that from 100 ml water and 33 mg ascorbic acid alone (0.097 and 0.059 respectively), while Fe absorption from 100 ml orange juice (28 mg ascorbic acid) was better than that from 100 ml water containing the same amount of ascorbic acid (0.139 and 0.098 respectively). Finally, Fe absorption from laboratory 'lemon juice' (100 ml orange juice and 4 g citric acid) was significantly better than that from 100 ml orange juice (0.226 and 0.166 respectively). The corrected geometric mean Fe absorption from the rice meal was 0.025. Several fruits had little or no effect on Fe absorption from the meal (0.013-0.024). These included grape (Vitis vinifera), peach (Prunus persica), apple (Malus sylvestris) and avocado pear (Persea americana). Fruit with a mild to moderate enhancing effect on Fe absorption (0.031-0.088) included strawberry (Fragaria sp.) (uncorrected values), plum (Prunus domestica), rhubarb (Rheum rhaponticum), banana (Musa cavendishii), mango (Mangifera indica), pear (Pyrus communis), cantaloup (Cucumis melo) and pineapple (Ananas comosus) (uncorrected values). Guava (Psidium guajava) and pawpaw (Carica papaya) markedly increased Fe absorption (0.126-0.293). There was a close correlation between Fe absorption and the ascorbic acid content of the fruits tested (rs 0.738, P less than 0.0001). There was also a weaker but significant correlation with the citric acid content (rs 0.55, P less than 0.03). Although this may have reflected a direct effect of citric acid on Fe absorption, it should be noted that fruits containing citric acid also contained ascorbic acid (rs 0.70, P less than 0.002).(ABSTRACT TRUNCATED AT 400 WORDS)

Failure of transferrin to enhance iron absorption in achlorhydric human subjects.

There is evidence in experimental animals that transferrin, produced either by gastrointestinal cells or derived from bile, mediates the luminal absorption of iron. The applicability of these findings to human subjects was tested by administering diferric transferrin labelled with 3 mg 59Fe to seven patients with pernicious anaemia. Achlorhydric subjects were chosen to ensure that the iron transferrin complex did not dissociate in the stomach. The geometric mean absorption of 1.4% was similar to that of 3 mg iron given as ferric chloride (1.9%) and much less than that of ferrous ascorbate (18.9%). These findings suggest that transferrin does not play a physiological role in the absorption of iron in human subjects.

Does plasma transferrin regulate iron absorption?

It has been suggested that transferrin that has recently donated its iron to receptor sites is 'activated' to take up iron more avidly from donor tissues. The hypothesis was tested in vitro in a system in which use was made of the different electrophoretic mobilities of normal and desialated transferrin. Recently desaturated transferrin and native apotransferrin were added in equal amounts to a solution of radioactive ferric citrate to produce various end saturations. The resultant mixture was electrophoresed on 5.4% polyacrilamide gel, which was then sliced and counted for 59Fe counts. The size of the 2 radioactive peaks was then compared and expressed as a ratio. Using this in vitro system no supporting evidence could be found for the hypothesis that diferric transferrin which has just donated its iron is able to bind available iron more avidly than native apotransferrin.

Erythrocyte pyrimidine-5'-nucleotidase activity as a sensitive indicator of lead exposure.

Since the red cell enzyme pyrimidine-5'-nucleotidase (PN) is inhibited by lead, we examined the feasibility of using the activity of this enzyme as a measure of lead exposure. Erythrocyte PN activity was measured in 110 blood samples obtained from subjects working in industries which utilize lead and 40 control subjects. The measurements were then compared with a number of traditional indices of lead poisoning. These included blood and urine lead concentrations and free erythrocyte protoporphyrin, erythrocyte zinc protoporphyrin, urinary coproporphyrin and urinary delta-aminolaevulinic acid levels. There was a highly significant negative correlation between erythrocyte PN activity and blood lead concentration (-0,83; P less than 0,0001), which was greater than that for any of the other measurements. It was therefore concluded that erythrocyte PN activity is an excellent indicator of lead exposure.

Erythrocyte zinc protoporphyrin determination for screening for lead exposure.

Free erythrocyte protoporphyrin (FEP), erythrocyte zinc protoporphyrin (EZP) and blood lead concentrations were measured in 150 male subjects, 110 of whom were employed in industries where lead exposure was possible. Eighty-seven per cent of these 110 workers had blood lead levels above the maximum safe level of 40 micrograms/dl, which suggests that the factory control of lead toxicity is inadequate. The AVIV dedicated front-face fluorometer (AVIV instruments, New Jersey, USA), which measures EZP, was evaluated as a simple, rapid method of screening for lead accumulation. EZP concentrations agreed well with conventional estimations of FEP (r = 0,987, P less than 0,0001), and both correlated well with the blood lead concentration (r = 0,558, P less than 0,0001 for EZP; r = 0,633, P less than 0,0001 for FEP). The specificity of the EZP level as a screening test was found to be high (98%) and the sensitivity moderately good (83%). In view of the ease and speed of operation of this portable fluorometer, it should prove useful as an aid to the detection of early lead intoxication.

Iron absorption from red and white wines.

Iron (3 mg) was added as ferrous sulphate to 2 dl red wine, white wine and 7% alcohol and its absorption was then measured in 38 fasting male subjects. (The original concentrations of iron in the two wines were low, being 1.01-1.08 mg/l (red wine) and 0.13-0.20 (white wine]. The geometric mean absorption from red wine was only 20% of that from the alcohol solution whilst more than 4 times as much was absorbed from white wine as from the alcohol. Direct comparison showed greater absorption from white wine (10.4%) than from red wine (4.4%). Removal of about 80% of the polyphenols in red wine increased the geometric mean iron absorption from 1.9% to 3.6%. In vitro experiments indicated that iron was less soluble and less dialysable in red wines than in white wines. This was possibly due to the binding of iron to polyphenols in red wines. Electrophoretic studies suggested that the iron in white wines was complexed to hydroxycarboxylic acids.

Isolation of ferritin from human hepatocellular carcinoma.

Ferritin was extracted from human hepatocellular carcinoma tissue and purified using column chromatography, gradient gel electrophoresis and cadmium sulphate crystallization. DEAE cellulose chromatography showed a difference between hepatoma and normal liver ferritin, indicative of a more acidic isoferritin profile in the tumour. Column-purified and crystalline ferritin and that remaining in the mother-liquor after crystallization was subjected to isoelectric focusing. Hepatoma ferritin showed higher concentrations of acidic isoferritins than liver ferritin. This was most obvious with mother-liquor ferritin, as crystallization tended to select out more basic isoferritins. Subunit analysis of hepatoma and liver ferritin showed a higher proportion of heavy subunits in the tumour ferritin, in keeping with the presence of acidic isoferritins. An antibody against hepatoma mother-liquor ferritin was raised in rabbits. However, hepatoma ferritin proved to be antigenically identical with normal liver ferritin, and we were thus unable to develop a specific radioimmunoassay for hepatoma ferritin.

The relative effect of ascorbic acid on iron absorption from soy-based and milk-based infant formulas.

The effect of varying concentrations of ascorbic acid on the absorption of iron from a soy-based infant milk formula containing 6 mg iron/100 g was examined in 64 adult Indian females using the extrinsic radioactive tag method. The corrected geometric mean absorption from the basic soy formula was only 1.8%. Addition of ascorbic acid in a concentration of 40 mg/100 g, did not significantly increase absorption (3.3%; t = 1.8, p greater than 0.07) but raising the concentration to 80 mg/100 g did so (6.9%; t = 2.4, p less than 0.02). No further significant increase was noted when the concentration of ascorbic acid was increased to 160 mg/100 g (7.7%; t = 0.4, p greater than 0.7). The inhibitory effect of soy on iron absorption was further demonstrated by a direct comparison between the soy-based formula and a similar product based on cows' milk. The comparison was made at two concentrations of ascorbic acid. At 40 mg/100 g the geometric mean iron absorption from the soy formula was 2.4% compared with 5.3% from the milk formula (t = 2.8, p less than 0.02), while the corresponding values at 80 mg ascorbic acid/100 g were 7.2 and 19.5%, respectively (t = 3.4, p less than 0.02). The present results confirm the marked inhibitory effect of soy protein on iron absorption and calculations from the absorption figures suggest that such formulas should contain at least 12 mg/100 g iron together with ascorbic acid in a molar ratio of approximately 4:1 if they are to be adequate in terms of iron nutrition.

Factors affecting the absorption of iron from cereals.

Non-haem-iron absorption from a variety of cereal and fibre meals was measured in parous Indian women, using the erythrocyte utilization of radioactive Fe method. The present study was undertaken to establish whether alteration of the phytate and polyphenol contents of sorghum (Sorghum vulgare) affected Fe absorption from sorghum meals, and to assess the influence of fibre on Fe absorption. Removing the outer layers of sorghum grain by pearling reduced the polyphenol and phytate contents by 96 and 92% respectively. This treatment significantly increased the geometric mean Fe absorption from 0.017 to 0.035 (t 3.9, P less than 0.005). The geometric mean Fe absorption from a sorghum cultivar that lacked polyphenols (albino sorghum) was 0.043, which was significantly greater than the 0.019 absorbed from bird-proof sorghum, a cultivar with a high polyphenol content (t 2.83, P less than 0.05). Fe was less well absorbed from the phytate-rich pearlings of the albino sorghum than from the pearled albino sorghum (0.015 v. 0.035 (t 8.4, P less than 0.0005]. Addition of sodium phytate to a highly Fe-bioavailable broccoli (Brassica oleracea) meal reduced Fe absorption from 0.185 to 0.037. The geometric mean Fe absorption from malted sorghum porridge was 0.024 when 9.5 mg ascorbic acid were added and 0.094 when the ascorbic acid was increased to 50 mg (t 3.33, P less than 0.005). This enhancing effect of 50 mg ascorbic acid was significantly depressed to 0.04 by tea (t 38.1, P less than 0.0005).(ABSTRACT TRUNCATED AT 250 WORDS)

The relative dietary importance of haem and non-haem iron.

A study was undertaken to find out the relative amounts of haem and non-haem iron absorbed from meals in which varying amounts of these substances were present. Four meals, each containing 6 mg of iron but with varying ratios of haem and non-haem iron, were fed to two groups of subjects, each group receiving two meals. The geometric mean percentage absorption of non-haem iron decreased from 18.0% (SD range 14.6-22.3%) to 6.4% (SD range 3.4-11.8%) as the non-haem iron content of the meal increased from 1.52 mg to 5.72 mg--there was therefore little variation in the actual amounts of non-haem iron absorbed from the different meals. In contrast, the geometric mean absorption of haem iron was approximately 20% from all four meals, although the haem iron content varied between 0.28 mg and 4.48 mg. The amount of haem iron absorbed was thus a linear function of the amount of haem iron in the meal. Two points emerged from the study. Firstly, the relative importance of haem iron in overall iron nutrition was confirmed. Secondly, the fact that the pattern of absorption in relation to dosage was so different for haem iron and non-haem iron suggested that a controlling mechanism for non-haem iron absorption may be located at the mucosal surface. This conclusion is based on the fact that haem iron, the percentage absorption of which was found to be independent of the size of the dose, is absorbed into the mucosal cell when still contained within the porphyrin ring and the iron thus bypasses some controlling mechanism at the mucosal border.

Iron absorption from ferritin and ferric hydroxide.

Ferritin and ferric hydroxide represent two forms of iron which are less available for absorption than that present in the 'common pool' of non-haem dietary iron. In the present study the absorption of iron from these two compounds was compared in 35 multiparous women when fed in water, in maize porridge and in maize porridge containing 100 mg ascorbic acid. The geometric mean absorption for 3 mg ferritin iron was 0.7% and for ferric hydroxide, 2.4%. Comparable figures when fed with maize porridge were 0.4% and 0.4% respectively. When 100 mg ascorbic acid was present in the porridge, absorption was enhanced from both sources, being 12.1% for ferritin and 10.5% for ferric hydroxide. These results indicate that the fraction of iron in ferritin and ferric hydroxide that enters the 'common pool' of non-haem dietary iron is profoundly influenced by the nature of the diet. The greater the concentration of enhancing ligands, the closer does the absorption of iron from these compounds approximate that of the non-haem dietary iron pool.

A preliminary study of the treatment of trochanteric fractures of the femur with the Kenwright nail.

We present a preliminary study of the results of treatment of 106 fractures of the trochanteric region of the femur, using a new expanding compression nail, the Kenwright nail. The device obtains a secure hold in the femoral head and compresses the fracture line, to give very firm fixation, enabling patients to bear weight immediately with much more confidence than with conventional methods of fixation. Earlier discharge from hospital has been possible, with the release of valuable beds. In no case has the nail cut out. A similar study of its use in intracapsular fractures will be reported.

Mobilisation of iron from peritoneal rat macrophages by desferrioxamine.

The amount of radioiron released from rat peritoneal macrophages after phagocytosis of 59Fe labelled erythrocytes can be enhanced by addition of desferrioxamine. The effect is dose dependent and the iron chelated by desferrioxamine appears to be at the expense of ferritin. However, desferrioxamine does not appear to chelate iron already incorporated into ferritin. It seems likely that the iron comes from a labile chelatable pool through which the iron from haemoglobin catabolism passes before being incorporated into ferritin. The desferrioxamine appears to enter the macrophage and chelate iron to form ferrioxamine which subsequently leaves the macrophage. In vivo it was not possible to show substantial iron chelaton by desferrioxamine in rats when 59Fe labelled non-viable red cells were injected intravenously. This suggests that in vivo mobilization of reticuloendothelial iron by desferrioxamine may be of limited significance.

Iron nutrition in Indian women at different ages.

The iron status of 320 Indian women living in Chatsworth, Durban, who had volunteered for iron absorption studies, was assessed using a number of measurements. These included: radio-iron absorption, the transferrin saturation, the serum ferritin concentration and the haemoglobin concentration. In the sample as a whole, the prevalence of iron deficiency anaemia (haemoglobin concentration less than 12 g/dl, with two or more abnormal measurements of iron status) was 14,4%. A further 26% had depleted iron stores (serum ferritin less than 12 micrograms/l) and 8,4% also had evidence of iron-deficient erythropoiesis (serum ferritin less than 12 micrograms/l and transferrin saturation below 16%). A profile of iron status based on the cumulative frequency distribution of iron stores showed that the sample, with calculated median iron stores of 150 mg and lower and upper 10 percentiles of -355 mg and 655 mg respectively, was significantly more iron deficient than a sample of women studied in Washington State, USA. Of interest was the observation that all measurements of iron status were better in the older age groups, presumably as a result of the cessation of menstruation. In addition, there was evidence that the duration of menstruation, as volunteered in a brief history, had a significant effect on several measurements of iron status. This was particularly true of the serum ferritin concentration and radio-iron absorption, both of which reflect the size of the iron stores.

Factors affecting the absorption of iron from Fe(III)EDTA.

1. The modification of iron absorption from Fe(III)EDTA by agents known to promote or inhibit absorption was examined in 101 volunteer multiparous Indian women. Fe absorption from Fe(III)EDTA was compared with absorption of intrinsic food Fe in a further twenty-eight subjects. Finally the urinary excretion of radio-Fe after oral administration of 59Fe(III)EDTA was studied in twenty-four subjects and evidence of intraluminal exchange of Fe was examined. 2. Fe absorption from maize porridge fortified with Fe(III)EDTA was more than twice that from porridge fortified with FeSO4 . 7H2O. 3. Although bran decreased Fe absorption from FeSO4 . 7H2O approximately 11-fold, it had no significant effect on Fe absorption from Fe(III)EDTA. Nevertheless tea, which is a more potent inhibitor of Fe absorption, decreased absorption from Fe(III)EDTA 7-fold. 4. Fe absorption from Fe(III)EDTA given in water was only increased 40% by addition of 3 mol ascorbic acid/mol Fe but by 7-fold when the relative proportions were increased to 6:1. This enhancing effect was blunted when the Fe(III)EDTA was given with maize porridge. In these circumstances, an ascorbate:iron value of 3:1 (which doubles absorption from FeSO4 . 7H2O) produced no significant increase in Fe absorption, while a value of 6:1 produced only a 2 . 5-fold increase. 5. Fe absorption from Fe(III)EDTA was not altered by addition of maize porridge unless ascorbic acid was present. 6. Less than 1% of 59Fe administered as 59Fe(III)EDTA was excreted in the urine and there was no inverse relationship between Fe absorption and the amounts excreted (r 0 . 58, P less than 0 . 05). 7. Isotope exchange between 59Fe(III)EDTA and 59FeSO4 . 7H2O was demonstrated by finding a similar relative value for the two isotopes in urine and erythrocytes when the two labelled compounds were given together orally. This finding was confirmed by in vitro studies, which showed enhanced 59Fe solubilization from 59FeSO4 . 7H2O in maize porridge when unlabelled Fe(III)EDTA was added. 8. Although Fe absorption from Fe(III)EDTA was marginally higher it appeared to form a common pool with intrinsic food iron in most studies. It is postulated that the mechanism whereby Fe(III)EDTA forms a common pool with intrinsic food Fe differs from that occurring with simple Fe salts. When Fe is present in the chelated form it remains in solution and is relatively well absorbed because it is protected from inhibitory ligands. Simple Fe salts, however, are not similarly protected and are absorbed as poorly as the intrinsic food Fe. 9. It is concluded that Fe(III)EDTA may be a useful compound for food fortification of cereals because the Fe is well absorbed and utilized for haemoglobin synthesis. The substances in cereals which inhibit absorption of simple Fe salts do not appear to inhibit absorption of Fe from Fe(III)EDTA.

Effect of diet on the rate of iron accumulation in idiopathic haemochromatosis.

There is still controversy concerning the effects of increasing the dietary intake of iron on iron nutrition. This debate has not only centered on the question of efficacy but also on that of safety. At particular potential risk are those individuals with disorders such as idiopathic haemochromatosis, who absorb iron excessively from the diet. Data obtained in the present study and in several other investigations suggest that subjects homozygous for the mutant gene responsible for the disorder would develop clinical features of the disease at a younger age were the dietary iron intake to be increased. Iron stores in affected heterozygotes would increase but the size of the stores would probably equilibrate long before they had reached massive proportions. While these conclusions are drawn from a number of studies, there are enough unanswered questions to make it mandatory for any future fortification programmes, whether they be directed at the entire population or only at certain segments of it, to be carefully monitored. This can currently be achieved with serial plasma ferritin measurements, since the concentrations mirror the size of iron stores in the body.

Some properties of human erythrocyte pyrimidine 5'-nucleotidase.

In haemolysates human erythrocyte pyrimidine 5'-nucleotidase had a single optimum at pH 7.2 with CMP and 6.75 with UMP as substrate. The purified enzyme showed two pH optima at pH 6.25 and 7.2 with UMP as substrate. The enzyme was inhibited by both its products - inorganic phosphate and pyrimidine nucleoside. The inhibition by inorganic phosphate appeared to be non-competitive with Ki = 1.5 mM. Contrary to previous reports adenosine and inosine did not inhibit the enzyme.

Iron absorption in patients on regular dialysis therapy.

Various haematological, ferrokinetic and iron absorption measurements were carried out on 15 patients with chronic renal failure who were undergoing regular haemodialysis. There was no evidence that the rate of iron absorption was impaired significantly by the depressed erythropoietic activity present in these patients. In contrast, there was a significant inverse correlation between the rate of iron absorption and the serum ferritin concentration, which has been shown to be an index of the size of the iron stores. This relationship, which was shown with both small (3 mg) and large (50 mg) doses of ferrous iron, was no different from that previously noted in subjects with normal renal function. These results suggest that iron deficiency in patients with chronic renal failure undergoing regular haemodialysis can be adequately prevented or treated with oral iron therapy, since the absorptive mechanism for iron appears to be normal.