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 an inverse relationship between Fe absorption and the amounts excreted (r 0.58, P > 0.05).

7. Isotope exchange between 55Fe(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.

1. Serum levels of retinol-binding protein (RBP), total vitamin A and retinyl ester were measured in twenty-four malnourished children with corneal lesions and nine normal children.

2. Initially, the RBP and vitamin A levels were significantly lower in malnourished children than in normal children.

3. After intramuscular injection of 30000 μg of aqueous vitamin A, serum levels of total vitamin A were increased significantly at 24 h and tended to fall within 5 d of treatment in both groups.

4. Before treatment, retinyl ester accounted for less than 10% of the vitamin in circulation. After vitamin A injection, it increased to 30%, a level much lower than that reported in patients with hypervitaminosis A.

5. There was no significant difference between the two groups of children and none of them showed clinical signs of toxicity. These observations indicate that administration of massive doses of vitamin A over a short period will not produce toxic effects even in malnourished children.

1. The hypocholesterolæmic effect of soya-bean protein compared with that of casein, when fed at 200 g/kg diet for 3 weeks, was studied in rats.

2. Using a cholesterol-free low-fat (10 g maize oil/kg) diet, the hypocholesterolæmic effect was demonstrated not only with soya-bean protein but also with an amino acid mixture simulating this protein. The addition of lysine to these diets did not modify their intrinsic effects on serum cholesterol.

3. By feeding the vegetable protein or its amino acid mixture, both high-density-lipoprotein-and very-low-density-lipoprotein plus low-density-lipoprotein-cholesterol decreased to a similar extent, and the concentration of serum apolipoprotein A-I decreased and that of apolipoprotein B increased.

4. Although rats given soya-bean protein excreted more neutral and acidic steroids, the difference disappeared when the amino acid mixture was fed, indicating that the hypocholesterolæmic effect of the vegetable protein is not ascribed only to the increased elimination of steroids.

5. It is likely that the difference in the amino acid composition between animal and vegetable proteins is in fact responsible for the different response of serum cholesterol.

1. Milk productions and 7d dietary records were determined on twenty-seven mothers who had been breast-feeding for 1, 3, 6, 9, 12 and 15 months.

2. The mean milk productions for each group of mothers was 1.187, 1.238, 1.128, 0.884, 0.880 and 0.951 kg/24 h at 1, 3, 6, 9, 12 or 15 months of lactation respectively. There was no significant difference between two milk determinations 3–7 d apart on each mother or between the mean milk production of each group of mothers.

3. Energy intakes of the infants was found to be higher than the usually-accepted values at 1 and 3 months of age but by 6 months were similar to the accepted normal values.

4. Energy intakes of the mothers although greater than those recommended for similar non-lactating women were not sufficient to take into account the energy content of the milk.

1. Reproductive competence, as measured by weight gain during pregnancy, duration of pregnancy and foetal outcome, was assessed in primiparous rats (4–6 months of age) with various histories of malnutrition.

2. Although weight gain during pregnancy was reduced in rats with intergenerational malnutrition, the duration of pregnancy and number of live births did not differ from well-fed controls, suggesting adaptation of these measures to long-term dietary deprivation.

3. Rats malnourished from birth through pregnancy (one generation of malnutrition) had fewer live births than did rats with chronic, intergenerational malnutrition or well-fed control rats.

4. Gestation was prolonged and weight gain accelerated among female rats with histories of intergenerational malnutrition, who had been provided with an adequate diet from birth through pregnancy.

1. It has been suggested previously that people in developed countries do not expose themselves to cold severe enough to induce a metabolic response. The energy expenditure, as both heat production and total heat loss, of nine women was therefore measured continuously while each lived for 30 h in a whole-body calorimeter on two occasions, one at 28° and the other at 22°. All subjects followed a predetermined pattern of activity and food intake. The environmental conditions were judged by the subjects to be within those encountered in everyday life. In the standard clothing worn, 28° was considered to be comfortably warm but not too hot, while 22° was judged to be cool but not too cold.

2. Heat production for 24 h was significantly greater at the lower temperature, by (mean ± SE) 7.0 ± 1.1%. The range was between 2 and 12%. Total heat loss was also significantly greater, by 6%, and there was a large change in the partition of heat loss. At the lower temperature sensible heat loss increased by 29% while evaporative heat loss decreased by 39%.

3. Resting metabolism measured in the morning 12–13 h after the last meal was significantly greater at 22° than at 28°, whereas there was no difference when the resting measurement was made for 2.5 h following a meal.

4. In conclusion: (a)environmental temperature may play a more important role than was previously recognized in the energy balance of those living in this country, and (b) there is an indication of at least a partial replacement of cold-induced by diet-induced thermogenesis in man.

1. A partial purification of kynureninase (L-kynurenine hydrolase, EC 3.7.1.3) from rat liver and a total resolution of the apoenzyme have been achieved. The hypothesis that conjugates of oestrogenic steroids compete with pyridoxal phosphate for the cofactor binding site of the enzyme, and so disturb tryptophan metabolism, leading to apparent vitamin B6 deficiency, has been tested.

2. Kynureninase from rat liver was partially purified, and the cofactor-free apoenzyme was prepared. Oestrone sulphate inhibited the enzyme uncompetitively with respect to pyridoxal phosphate, and competitively with respect to kynurenine, with a mean (±SE) inhibitor constant (Ki) of 82 ± 6 μM.

3. The addition of a saturating concentration of pyridoxal phosphate to unfractionated liver homogenates led to an approximately fivefold increase in kynureninase activity, indicating the presence of a relatively large amount of apo-kynureninase in the tissue.

4. It is suggested that the abnormal results of tryptophan load tests in women receiving oestrogens are the result of inhibition of kynureninase by oestrogen conjugates, and that there is no evidence for oestrogen-induced vitamin B6 deficiency in such cases.

1. The hypothesis that soya-bean saponins, by binding bile salts in the gastrointestinal lumen, are responsible for some of the plasma-cholesterol-lowering effect of soya-bean preparations, was tested. In a double-blind crossover study 50 g soya-bean flour/d, containing either 22 or 4 g saponins/kg (adjusted by ethanol extraction) was incorporated in biscuits as a substitute for biscuits or bread into the diet of ten outpatient hypercholesterolaemic men over two consecutive 4-week study periods. The diet was monitored to ensure constancy, saponin-rich foods excluded, faeces collected for bile acid and neutral sterol analysis, and blood taken for plasma lipoprotein lipid analysis.

2. Neither diet had any effect on cholesterol in any plasma lipoprotein fraction, on fasting plasma triglyceride, or on faecal bile acids and neutral sterols.

3. These results suggested that soya-bean saponins are not responsible for the hypocholesterolaemic effect of soya-bean products.

1. An experimental model for the determination of dietary fibre according to the definition of Trowell et al. (1976) is described. Food was subjected to in vivo digestion in ileostomy patients, and the ileostomy contents were collected quantitatively, the polysaccharide components of which were analysed by gas–liquid chromatography and the Klason lignin by gravimetric determination. The model was used for the determination of dietary fibre in AACC (American Association of Cereal Chemists), wheat bran and for studies on the extent of hydrolysis of wheat-bran fibre in the stomach and small intestine. The effect of wheat bran on ileostomy losses of nitrogen, starch and electrolytes was also investigated.

2. Nine patients with established ileostomies were studied during two periods while on a constant low-fibre diet. In the second period 16 g AACC wheat bran/d was added to the diet. The ileostomy contents and duplicate portions of the diet were subjected to determinations of wet weight, dry weight, water content, fibre components, starch, N, sodium and potassium.

3. The wet weight of ileostomy contents increased by 94 g/24 h and dry weight by 10 g/24 h after consumption of bran. The dietary fibre of AACC bran, determined as the increase in polysaccharides and lignin of ileostomy contents after consumption of bran, was 280 g/kg fresh weight (310 g/kg dry matter). Direct analysis of polysaccharides and lignin in bran gave a value of 306 g/kg fresh weight. Of the added bran hemicellulose and cellulose 80–100% and 75–100% respectively were recovered in ileostomy contents. There was no significant difference between the two periods in amount of N, starch and K found in the ileostomy contents. The Na excretion increased during the ‘bran’ period and correlated well with the wet weight of ileostomy contents.

4. In conclusion, it seems probable that determination of dietary fibre by in vivo digestion in ileostomy patients comes very close to the theoretical definition of dietary fibre, as the influence of bacteria in the ileum seems small. Bacterial growth should be avoided by using a technique involving the change of ileostomy bags every 2 h and immediate deep-freezing of the ileostomy contents. True dietary fibre can be determined by direct analysis of polysaccharides and lignin in the food, at least in bran. Very little digestion of hemicellulose and cellulose from bran occurs in the stomach and small bowel. The 10–20% loss in some patients may be due to digestion by the gastric juice or to bacterial fermentation in the ileum, or both. The extra amount of faecal N after consumption of bran, reported by others, is probably produced in the large bowel.

1. Two groups of weanling male rats were fed on a powdered proprietary diet for up to 6 weeks. The diet of one group was supplemented with 2 g Cu/kg and the other group received the unsupplemented diet.

2. The livers in the supplemented group accumulated more Cu within the right vascular compartment than the left. This difference was observed in the unsupplemented group after 6 weeks but not at 4 weeks.

3. The distribution of Cu between the different lobes of the livers of the supplemented groups displayed a characteristic pattern, the median lobe containing the most Cu and the omental lobe the least.

4. The distribution of Cu within the liver is thought to reflect the site of its absorption from the gastointestinal tract and a consequence of portal streaming.

1. One hundred and fourteen pigs between 7 and 35 d of age were given diets containing milk or soya-bean proteins in four separate experiments.

2. The substitution of milk protein by soya-bean meal (SBM) to 75% of the total dietary protein reduced the weight gains and food conversion efficiencies of the pigs by 85% between 7 and 14 d of age and 31% between 21 and 28 d of age.

3. The treatment of soya-bean protein with alkali did not improve the performance of the pigs.

4. The substitution of milk protein by two different isolated soya-bean proteins (ISP) resulted in weight gains of 34 and 60% of the gains of pigs given milk protein diets.

5. Supplementation of the soya-bean-protein diets with methionine to 13.7 g/kg (5 g/16 g nitrogen) resulted in reduced food intakes and weight gains of the pigs and a 20-fold increase in the concentration of methionine in the blood plasma.

6. Supplementation of soya-bean-protein diets with lysine to 22 g/kg (8g/16 g N) in addition to methionine doubled the concentration of lysine in the blood plasma.

7. The apparent digestibility (AD) of dry matter (DM) and N of the diets containing soya-bean protein increased with increasing age of the pigs, but the AD of the milk-protein diet was not affected by the age of the pigs. The retention of N as a percentage of the N intake increased from 57–67% for soya-bean protein over the duration of the experiments while the average value for the milk-fed pigs was 85% at all ages.

8. At 35 d of age, the fat content of the carcasses of the pigs given the ISP diet was 249 g/kg DM compared to 164 g/kg DM for the pigs given the milk diets.

1. In two separate experiments, forty-four pigs weaned at 4–5 d of age were given diets containing milk or soya-bean proteins until slaughtered at 14, 28 or 35 d of age.

2. The retention times of digesta in the stomach and the entire gastro-intestinal tract did not differ between pigs given pelleted diets containing milk or soya-bean protein.

3. Digesta retention times in the stomach were shorter (61 v. 146 min) in pigs given a milk-protein diet in a liquid form than in pigs given the same diet in a pelleted form. The retention times in the whole gastro-intestinal tract were 42.8 v. 29.6 h on the respective diets.

4. The total retention time of digesta in the gastro-intestinal tract increased with age of pigs between 14–35 d of age when given pelleted diets but not when given a liquid diet.

5. The daily amount of digesta flowing through the anterior small intestine was unaffected by the source of protein. Greater endogenous secretions into the anterior small intestine were observed when pigs were fed ad lib. than when fed at 2 g nitrogen (45 g dry matter (DM))/kg live weight0.75 per d.

6. The apparent digestion of DM to the ileum of pigs given milk, isolated soya-bean protein (ISP) (Promine D) or soya-bean meal (SBM) protein at 28 d of age was 0.826, 0.825 and 0.644 respectively.

7. The apparent digestion of DM to the ileum of pigs given ISP (Supro 610) significantly increased with age of pigs from 0.851 at 14 d of age to 0.883 at 35 d of age. No increase was observed for pigs given milk protein.

8. Differences in the digestibility of DM between protein sources were greater to the ileum than over the entire gastro-intestinal tract. The greatest increase in DM digestion from the ileum to the faeces occurred in pigs given SBM (0.644–0.874).

9. Neither the protein source nor age of pigs influenced gastric pH values, the mean value being 4.05. pH increased along the small intestine and was not affected by the protein source or age of pig.

1. In two separate experiments, forty-four pigs weaned at 4–5 d of age were fed on diets containing milk or soya-bean protein until slaughtered at 14, 28 or 35 d of age.

2. Daily amounts of nitrogen flowing through the stomach and proximal small intestine of pigs were similar with both sources of protein fed.

3. Endogenous N flows in the duodenum, jejunum and ileum of pigs given an N-free diet were 22.9, 7.4 and 4.6 g N/kg dry matter (DM) intake. Endogenous N in faeces was 0.970 g N/kg DM intake.

4. The apparent and true digestibility of N to the ileum of 28-d-old pigs was 0.86 and 0.92 for the pigs given the milk-protein diets, 0.80 and 0.86 for the pigs given the isolated soya-bean protein (ISP; Promine D) diets and 0.51 and 0.62 for pigs given the soya-bean meal (SBM)-protein diet. These values over the entire gastro-intestinal tract were 0.98 and 1.00 for milk, 0.92 and 0.95 for ISP and 0.82 and 0.85 for SBM.

5. The apparent and true digestibility of N to the ileum of 14-d-old pigs given a liquid milk diet was 0.92 and 0.94, while the values for the pigs given a pelleted milk diet were 0.86 and 0.87. At 35 d of age there were no differences in the apparent digestibility of the N in the liquid and pelleted milk diets.

6. The apparent digestibility of N to the ileum and over the entire gastro-intestinal tract of pigs given ISP (Supro 610) increased with increasing age of pigs from 0.83 at 14 d of age to 0.88 at 35 d of age.

7. Of the N in the stomach 14–32% could not be precipitated by trichloroacetic acid (TCA; 30 g/l).

8. In the jejunal and ileal contents an average of 46 and 24% of the N was precipitated by TCA in pigs given soya-bean proteins and milk proteins respectively.

1. In two experiments, forty-four pigs weaned at 4–5 d of age were given diets containing milk or soya-bean proteins until slaughtered at 14, 28 or 35 d of age.

2. Additions of methionine and methionine plus lysine to the diets did not increase the proportions of these amino acids in ileal digesta.

3. In the pigs given a nitrogen-free diet, ileal digesta contained more threonine, proline and glycine than in pigs given diets containing protein.

4. The apparent and true digestibility of amino acids were greater when milk protein was fed than when soya-bean proteins were fed.

5. The apparent digestion of amino acids to the ileum of pigs given isolated soya-bean protein (ISP; Supro 610) increased with increasing age of pigs from a mean of 0.82 at 14 d of age to 0.87 at 35 d of age.

6. When milk protein was fed apparent digestibilities of methionine and lysine to the ileum were 0.912 and 0.905. The apparent digestibility of threonine to the ileum was 0.800, 0.774 and 0.504 for pigs given the milk-, ISP and soya-bean-meal (SBM)-protein diets respectively.

7. Apparent digestibilities of total essential and non-essential amino acids were 0.79 and 0.69 respectively, and true digestibilities of both were 0.82.

1. In two separate experiments, forty-two pigs weaned at 4–5 d of age were given diets containing milk or soya-bean protein and slaughtered at 7, 28 or 35 d of age.

2. The amino acid composition of the empty body of the pigs did not vary with age or sources of protein fed.

3. The nitrogen and amino acid contents of the empty body gain were calculated between 7 and 28, and 7 and 35 d of age. The retention of absorbed N was greater in pigs given a soya-bean meal (SBM) diet than in pigs given milk or isolated soya-bean protein (ISP) diets.

4. The retention of total absorbed N was greater in pigs given a pelleted milk diet (0.72) than in pigs given a liquid milk diet (0.58).

5. Methionine and threonine appeared to be the first two limiting amino acids, as indicated by their high incorporation into the empty body, for pigs given soya-bean proteins in Expt 3, while methionine and lysine were the first two limiting amino acids for pigs given ISP in Expt 4.

6. The addition of methionine to diets in Expt 3 reduced the retention of absorbed methionine in the empty body by 43–76%. Lysine supplementation did not alter the retention of the absorbed lysine.

7. Retention of arginine, proline and glycine in the body was greater than the apparent absorption of each of these amino acids.

1. Ten castrated young adult sheep were brought indoors and given lucerne chaff (four animals with a phosphorus intake of 2.40 g/d) and fresh Ruanui ryegrass (six animals with a P intake of 3.72 g/d) to determine various kinetic indices of their P metabolism.

2. The results obtained from combined nutritional balance and 32P radioactivity measurements were analysed using the simulation, analysis and modelling computer (SAAM) program. Since the plasma P specific activity curve was described by at least four exponential terms, a four compartmental model (M1, M2, M3 and M4) was used to describe the experimental values.

3. The mean mass of the total exchangeable P pool (MT) for the lucerne chaff-fed and Ruanui ryegrass-fed sheep was 25.5 and 28.8 g respectively, while the total P transport (VT) to the exchangeable pool (MT) was markedly lower for sheep given lucerne chaff compared to those given Ruanui ryegrass (54.1 v. 111.3 mg/kg body-weight per d). Likewise the rate of P absorption (Va), faecal endogenous loss of P (Vf), urinary P excretion (Vu) as well as the movement of P to (Vo+) and from (Vo−) the skeleton and soft tissue was also lower in the lucerne chaff-fed sheep.

4. The availability of P, that is the proportion of ingested P which is absorbed, was 0.56 and 0.62 for the sheep given chaff and fresh herbage respectively.

5. The P metabolism of one sheep (sheep no. 30) differed from the other sheep in that its plasma inorganic P concentration was higher (95 v. 54 mg/l). This was associated with a larger first compartment (M1), a more rapid P transport between M1 and M2, an increase in (Va) and a marked increase in (Vu).

1. Measurements were made of the hepatic concentrations and contents of total and thionein-bound zinc and copper in late foetal and newborn rats and of the distribution of these metals between the particulate and soluble components of the liver.

2. The decrease in the hepatic concentration of thionein-bound Zn, which occurred with age after birth, was proportional to the increase in liver weight until the 16th day post partum; thereafter it was greater.

3. Throughout the period from birth to 25 d of age the Zn concentration remained constant in the cytosolic non-thionein fraction (i.e. total cytoplasmic Zn – thionein-bound Zn). but decreased in other compartments of the liver.

4. The same constant concentration of cytoplasmic non-thionein-bound Zn also was observed in animals with reduced total hepatic Zn contents, but normal body-weights, and in 20-d-old Zn-deficient pups.

5. The concentration of thionein-bound Cu exhibited two maxima, one at 2 d of age and the second at 14 d.

6. The total hepatic content of Cu increased significantly only between the 6th and 14th day post partum. The age-related variations in Cu contents of the particulate components closely paralleled those in the whole liver, whereas the Cu contents of the cytosolic thionein and non-thionein fractions did not increase appreciably until after the 10th day.

7. It is concluded that the cytosolic non-thionein fraction of newborn rat liver may contain particularly important metabolic sites that require Zn and a major function of Zn-thionein is to regulate is to regulate the supply of the metal to these sites. As, from birth to 26 d of age, the sum of the concentrations of thionein-bound Zn and Cu was correlated with whole liver Zn, the accumulation of Cu as a soluble metallothionein seems to be a secondary event, dependent on the hepatic Zn concentration.

1. The concentration of copper in the rat intestine was found to increase rapidly after birth to a maximum greater than 140 μg/g wet weight at 2 d of age and then to decline, at first slowly to 90 μg/g wet weight on day thirteen and then rapidly to 40 μg/g and 3.4 μg/g wet weight on the 15th and 19th day respectively. The intestinal concentration of Zn, which doubled between 1 d prepartum and 2 d post partum, also fell slowly until 10 d of age, but thereafter remained constant.

2. From the 2nd to the 15th day post partum approximately 60% of the total Cu and 50% of the total zinc in the intestine was located in the soluble fraction of the tissue. Most of the Zn in this fraction was bound by proteins of molecular weights greater than 13700 daltons, whereas most of the Cu was present as an extremely polydisperse complex of lower molecular weight. This complex in the intestine of the 5-d-old rat, in contrast with the soluble proteins of higher molecular weight. This complex in the intestine of the 5-d-old rat, in contrast with the soluble proteins of higher molecular weight, did not incorporate either 3H or 35S within 4 h of the administration of L-[4,5-3]leucine and L-[35S]cystine.

3. The loss of Cu from the intestine between the 13th and 15th day of post-natal age occurred mainly from this complex and was accompanied by the transient appearance of Cu in a fraction of low molecular weight.

4. At 21 d of age the soluble fraction of the intestine contained only a small amount of Cu. This was distributed between two protein fractions, one of which contained Zn and appeared to be a metallothionein.

5. The results are discussed in relation to the control of Zn and Cu absorption.

1. The availability of lysine in seven vegetable protein concentrates was determined using the slope-ratio assay with growing pigs and rats and with two chemical techniques.

2. With pigs, estimates of availability were lower using carcass compared to live-weight values, but there was no consistent effect of including food intake in the criterion of response. Availability estimates, using food conversion efficiency on a carcass basis were (proportion of total) linseed meal − 0·23, lupin-seed meal 0.74, rapeseed meal no. 1 0.97, no. 2 0.77, sunflower meal no. 1 0.59, no. 2 0.66, no. 3 0.54.

3. Availability estimates for lysine with rats were also lower using carcass compared to live-weight values. Estimates based on food conversion efficiency were higher than those based on weight gain. Availability estimates in lupin-seed meal and sunflower meals were in general agreement with the pig estimates, whilst that with linseed meal was considerably higher (0·82). Assays were not conducted with rapessed meal due to problems of food rejection with this meal.

4. The differences in available lysine were not detected by the chemical Silcock available-lysine test (Roach et al. 1967) nor by the direct fluoro-dinitrobenzene procedure (Carpenter, 1960).