1. Non-haem iron absorption from a variety of vegetable meals was studied in parous Indian Women, using the erythrocyte utilization of radioactive Fe method.2. The studies were undertaken to establish whether Fe absorption could be correlated with the chemical composition of the foodstuff.3. Addition of the following organic acids commonly found in vegetables, improved the geometric mean Fe absorption from a basic rice meal as follows: from 0.028 to 0.085 with 1 g citric acid, from 0.031 to 0.081 with 15 mg ascorbic acid, from 0,048 to 0.095 with 1 g L-malic acid, from 0.041 to 0.096 with 1 g tartaric acid. The only exception was oxalic acid; the addition of I g calcium oxalate to cabbage (Brassica oleraceae) was associated with some depression in Fe absorption from 0.320 to 0.195.4. There was a marked inhibition of the geometric mean absorption when 500 mg tannic acid was added to a broccoli (Brassica oleraceae) meal ( 6. All the vegetables associated with moderate or good Fe bioavailability contained appreciable amounts of one or more of the organic acids, malic, citric and ascorbic acids.7. Poor Fe bioavailability was noted in vegetables with high phytate contents (e.g. wheat germ 0.007, butter beans 0.012, brown lentils 0.024 and green lentils 0.032).8. The fact that a number of vegetables associated with low Fe-absorption turned bluish-black when Fe was added to them, suggested that the total polyphenol content in them was high. The vegetables included aubergine, spinach, brown lentils, green lentils and beetroot greens. When the total polyphenol content in all the vegetables tested was formally measured, there was a significant inverse correlation (r 0,859, P < 0401) between it and Fe absorption. The inverse correlation between the non-hydrolysable polyphenol content and Fe absorption was r 9. The major relevance of these findings is the fact that the total absorption of non-haem-Fe from a mixed diet may be profoundly influenced by the presence of single vegetables with either marked enhancing or inhibiting effects on Fe bioavailability. 0.901 (P < 0.001).

1. 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.2. 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 < 0.01).3. 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).4. 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 (Prunuspersica), apple (Malus sylvestris) and avocado pear (Persea americana). Fruit with a mild to moderate enhancing effect on Fe absorption (0.03 1–0.088) included strawberry (Fragaria sp.) (uncorrected values), plum (Prunus domestica), rhubarb (Rheum rhaponticum), banana (Musa cavendishii), mango (Mangifera indica), pear (Pyrus cornmunis), cantaloup (Cucumis melo) and pineapple (Ananas comosus) (uncorrected values). Guava (Psidium guajava) and pawpaw (Carica papaya) markedly increased Fe absorption (0.126–0.293).5. There was a close correlation between Fe absorption and the ascorbic acid content of the fruits tested (rs 0.738, P < 0.0001). There was also a weaker but significant correlation with the citric acid content (rs 0.55, P < 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 < 0.002). Similarly, the negative correlation (rs –0.62, P < 0,008) between Fe absorption and the malic acid content of fruits may have been due to the fact that fruits with a high malic acid content tended to have low levels of ascorbic acid (rs–0.45, P < 0.06).6. These various results suggested that most fruits have only a limited effect on overall Fe nutrition. However, the presence of citrus fruit, guava or pawpaw would be expected to increase Fe absorption markedly from diets of low Fe availability.

1. 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.2. 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.3. 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 < 0405). 4.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 < 0.05). 5.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 < 0.0005)). Addition of sodium phytate to a highly Fe-bioavailable broccoli (Brassica oleracea) meal reduced Fe absorption from 0.185 to 0.037. 6. 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 < 0405). This enhancing effect of 50 mg ascorbic acid was significantly depressed to 0.04 by tea (t 38.1, P < 0.0005). 7. Wheat bran significantly decreased the geometric mean Fe absorption from white flour from 0.1 16 to 0.043 8. Some of the constituents of the dietary fibre complex, such as apple pectin, guar gum, gum tragacanth ana microcrystalline cellulose did not inhibit Fe absorption. On the other hand, hemicellulose and lignin decreased absorption. The geometric mean absorption of Fe given with hemicellulose was 0.079 v. 0.269 with microcrystalline cellulose (t 2.95, P < 0.05). Addition of cocoa, which contains approximately 280 g lignin/kg, reduced the geometric mean Fe absorption from milk from 0.075 to 0.035 (t 2.7, P < 0.05).(t 7.2, P < 0.0005).

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 of59Fe(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% of59Fe administered as59Fe(III)EDTA was excreted in the urine and there was an inverse relationship between Fe absorption and the amounts excreted (r0.58,P> 0.05).7. Isotope exchange between55Fe(III)EDTA and59FeSO4. 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 enhanced59Fe solubilization from59FeSO4. 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.

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.