1. The combined effects of feeding hydrogenated fats and varying the levels of biotin and linoleate (18:2ω6) on polyunsaturated fatty acids were studied in the chicken.

2. Biotin deficiency signs were not exacerbated by feeding hydrogenated fats or by diets low in linoleate for 21 d.

3. Biotin deficiency resulted in proportionately higher levels of 18:2ω6 and γ-linolenate (18:3ω6) in liver triglycerides, and lower levels of dihomo-γ-linolenate (20:3ω6) in liver and heart phospholipids irrespective of the 18:2ω6 level in the diet.

4. Biotin deficiency did not alter arachidonate (20:4ω6) levels in tissue lipids at 21 d.

5. Feeding high levels of trans-18:1 isomers with adequate biotin led to reduced 20:3ω6 and 20:4ω6 levels in liver and heart phospholipids with compensatory increases in ω3 fatty acids.

6. The trans-isomers of 18:1 were incorporated into several tissues of the chick. Incorporation was dependent on the levels fed. Very small amounts were incorporated into brain compared with other tissues when dietary trans-isomer levels were high, but were similar when dietary trans-isomer levels were low. The trans-18:1 isomers appear to be preferentially incorporated into phospholipids as opposed to triglycerides in heart and liver.

1. Mn and Cu intake and retention in twenty full-term infants and six preterm infants were studied on the basis of 72 h balances. The age of the infants was 2–16 weeks and the gestational age of the preterm infants (triplets) 34 and 36 weeks. Three nutrition schemes were pursued: breast-fed, formula-fed with unsupplemented adapted formula and formula-fed with trace element supplementation.

2. The mean Mn concentration of all breast-milk samples (n 2339) was 6·2 μg/1. The two formulas had similar Mn concentrations (77 and 99 μg/1) but had different Fe, Cu (121 and 619 μg/1), Zn and I contents. The mean Cu concentration in mother's milk was 833 μg/1.

3. The following mean daily Mn intakes and retentions (μg/kg) respectively were measured: breast-fed fullterm 1·06 (sd 0·43) and 0·43 (sd 0·65), formula-fed full-term 14·2 (sd 3·1) and 2·8 (sd 4·8), formula-fed preterm 15·0 (sd 2·2) and 0·06 (sd 5·87). The results for Cu were 114·5 (sd 22·3) and 88·0 (sd 46·5) μg/kg in breast-fed, 19–8 (sd 4·2) and 4·6 (-11·5–9·6) in the unsupplemented formula-fed and 106·4 (sd 18·9) and 55·5 (sd 20·3) in the supplemented formula full-term infant group. No significant influence of the trace element contents of the formulas on the relative retention of Mn or Cu was found.

4. Young preterm infants, and to some degree young full-term infants, often had negative Mn balances caused by a high faccal excretion. The formulas with a Mn concentration below 100 μg/l gave a sufficient supply of Mn. Preterm infants fed on the unsupplemented formula had a marginal Cu supply and their first balances were negative (-3·8 (sd 1·8) μg/kg).

5. In accordance with the estimated safe and adequate daily dietary intakes (recommended dietary allowances), formula-fed infants receive much more Mn than breast-fed infants and their absolute retention is higher.

6. Cu from breast-milk had a significantly better biological availability than that from cow's milk formula. If retentions similar to those in breast-fed infants are intended, we conclude, therefore, that cow's milk formula should be fortified with Cu up to a level of at least 600 μg/l.

1. In vivo 59Fe absorption from intrinsically labelled Fe-containing fractions of liver and blood were measured in rats by intragastric dosing. All rats were fed on a low-Fe diet for 3 d before dosing in order to standardize the Fe status of the intestinal mucosal cells.

2. An increase in digestion time from 2 to 12 h increased 59Fe absorption (P < 0.01) from all fractions except ferritin.

3. Fe-deficient rats when compared with essentially Fe-replete rats showed decreased gastric retention for all fractions, but increased 59Fe absorption over 2 h only from ferritin. Ferritin showed several unusual absorption characteristics.

4. Dietary tungsten supplementation of Fe-deficient rats reduced the ferroxidase activity of intestinal mucosal xanthine oxidase. In addition, gastric retention and 59Fe absorption (P < 0.05) from all fractions were increased.

1. Healthy male volunteers consumed at noon, hot test meals with four different carbohydrate: fat ratios varying between 2.64 and 0.50, and composed of fried beefsteak, mashed potatoes, French beans, and a dessert of custard with mashed peaches. The energy content of the meals was 40% of the daily intake of the volunteers, estimated from their individual dietary histories.

2. Before, and at different times after the start of the meal, blood samples were taken and a number of indices of carbohydrate and lipid metabolism were determined in the samples, i.e. glucose, insulin, free fatty acid, free and total glycerol, free and total cholesterol, high-density-lipoprotein (HDL)-cholesterol and low-density-lipoprotein (LDL)-cholesterol.

3. Increasing the carbohydrate: fat ratio resulted in higher postprandial peaks of glucose and insulin. In addition, the peak area under the postprandial glucose curve showed a significant increase. The peak area under the postprandial insulin curve had also increased, indicating that a larger amount of insulin was secreted by the pancreas on increasing the carbohydrate content in the meal. There was no significant correlation between the height of the postprandial peak of blood glucose and the size of the meal.

4. All four meals caused elevated postprandial blood triacylglycerol levels. However, the decline of this elevated level took a much longer time after the meals with the lower carbohydrate: fat ratios, i.e. containing larger amounts of triacylglycerols. There was a significant decreasing linear relation between the carbohydrate content of the meals and the peak area under the postprandial triacylglycerol curve. Free glycerol and free fatty acids showed lower postprandial levels in the blood after the meals with the higher carbohydrate: fat ratios, and the peak areas of the postprandial curves of both variables displayed a significant decrease. Little or no effect of the meal carbohydrate: fat ratio was observed on the postprandial concentrations of total cholesterol, unesterified cholesterol, HDL-cholesterol or LDL-cholesterol.

1. In a 4x4 Latin square design experiment, four cattle were given grass silage in two meals per d to satisfy maintenance energy requirements. In addition, sucrose (170 g/kg silage dry matter (DM)) was infused intraruminally at a constant rate with no nitrogen supplementation; with the infusion intraruminally of either casein (23 g/kg silage DM) or urea (8 g/kg silage DM); or with soya-bean meal (64 g/kg silage DM) fed in two equal portions.

2. Samples of duodenal digesta representative of a 24 h period were obtained using chromium-EDTA and ytterbium acetate for flow estimation and 35S as a marker of microbial N entering the small intestine. Samples of rumen fluid were also taken for estimation of rumen pH and concentrations of ammonia-N and volatile fatty acids. Estimates of apparent organic matter (OM) and N digestibility and of the rates of silage DM and N disappearance from porous synthetic-fibre bags incubated in the rumen were also made.

3. The N supplements had no significant effects on rumen pH, concentrations of volatile fatty acids, their molar proportions or the disappearance of DM or N from porous synthetic-fibre bags. N supplementation increased rumen ammonia-N concentrations (urea, P < 0.05; casein, soya-bean meal, not significant).

4. N supplementation had no significant effects on the digestion of OM, acid-detergent fibre or soluble carbohydrate.

5. Infusion of casein increased the quantities of total non-ammonia-N (not significant) and microbial N (P < 0.05) entering the small intestine daily and the efficiency of rumen microbial N synthesis (not significant). Giving soya-bean meal twice daily resulted in marginal increases in the quantities of non-ammonia-N and microbial N entering the small intestine, while infusing urea intraruminally had no effect.

1. The effects of four diets on water intake, rumen fluid outflow-rate, rumen pH and mineral metabolism were studied in wether sheep. The diets were barley and hay, flaked maize and hay, dried grass and frozen grass.

2. Experimental periods were of 12 d duration, and plasma magnesium concentrations were lower at the end of treatment periods when the grass diets were given and were significantly different (P < 0.05) at 11.00 and 20.45 hours. Also, the concentration was significantly lower with the dried-grass diet than with the frozen-grass diet (P < 0.05).

3. The concentration of Mg in rumen fluid centrifuged at 30000 g (ultracentrifuged) varied with the diet. Maximum concentrations (tmax) were reached 4 h later on the grass diets than on the hay and concentrate diets. In the latter case tmax coincided with that for calcium, potassium, chloride and ammonia. At this time sodium and phosphate were at a minimum. The concentration of Mg in ultracentrifuged rumen fluid was negatively correlated (r −0.89) with pH, which was significantly higher (P < 0.01) at all times on the grass diets. This relation was also reflected in the apparent availability of Mg.

4. Total water intake on the frozen grass was about twice that on the barley and hay diet. The outflow rate of liquid from the rumen was higher on the frozen grass than on the other three diets.

5. The proportion of absorbed Mg excreted in urine was significantly influenced by diet.

1. Three studies were carried out in each of six normal volunteers to investigate how lipid, when given at different stages during the course of a meal, affects gastric emptying and postprandial blood glucose and insulin concentrations.

2. The control meal consisted of 300 ml beef consommé (50 kJ, 12 kcal), followed 20 min later by 300 g mashed potato (908 kJ, 217 kcal). In the two test meals, 60 g margarine were incorporated into either the soup or the mashed potato.

3. The addition of margarine to either component of the meal delayed gastric emptying of the mashed potato (P < 0.05), but the pattern varied according to the component to which the fat was added.

4. Incorporation of fat into the soup increased the lag phase (P < 0.05) but did not influence the slope of emptying of the mashed potato, while incorporation of fat into the mashed potato reduced the slope of emptying of the mashed potato (P < 0.05) but did not influence the lag phase.

5. Addition of fat to either component of the meal reduced postprandial blood glucose (P < 0.05) and insulin responses, but when the fat was incorporated in the soup, peak glucose and insulin responses were delayed as well (P < 0.05).

6. The results show that the effect of fat on gastric emptying and absorption of nutrients depends on when, in relation to the other components of the meal, the fat is consumed.

1. The extent of utilization of α-amylase (EC 3.2.1.1)-resistant retrograded starches in vivo was assessed in male Wistar rats (about 100 g body-weight). All animals were given a fibre-free semi-synthetic basal diet (SS) containing sucrose as the only carbohydrate source, ad lib., for 13 d. On day 14, after an overnight fast, rats were allocated to one of five dietary treatments (n 30):1, fibre-free basal SS diet; 2-5, basal SS diet supplemented with 100 g sucrose, Solka floc (cellulose), resistant maize starch (RCS) or resistant pea (Pisum sativum) starch (RPS)/kg diet. Animals allocated to each dietary treatment were divided into three groups of ten rats which were given the appropriate diet for 8 or 9, 17 or 18 and 29 or 30 d (8/9, 17/18 or 29/30 d groups respectively). Rats were fed on 12 g diet/d (treatment 1) or 13.2 g diet/d (treatments 2-5) for the first 20 d, and 14 or 15.4 g/d respectively until the end of the experiment. Rats fed on the supplemented basal diets were thus given 10% more food to allow for the addition of the test carbohydrate. Faecal carbohydrate excretion was determined at intervals in the 17/18 d groups. At the end of each experimental period animals were killed after consuming their daily food ration and small intestinal length, weight of caecal and ileal contents and tissue, and pH of caecal contents measured. The amount of carbohydrate in the caecal and ileal contents from the 8/9 and 17/18 d groups was determined.

2. Weights of ileal and caecal contents, caecal tissue and faecal output were significantly greater at all time points for rats fed on the resistant starches compared with those fed on basal and sucrose-supplemented diets. Values were higher for RPS-fed rats than for RCS-fed rats.

3. The quantity of carbohydrate recovered from ileal and caecal contents showed that both RCS and RPS were partially digested and absorbed as carbohydrate, but that RPS was digested to a lesser extent.

4. The concentration of carbohydrate decreased between the ileal and caecal sites when RPS and RCS were given but was essentially unchanged when cellulose was given. This is consistent with rapid fermentation of a fraction of these starches.

5. Faecal carbohydrate elimination in the 17/18 d groups fed on RCS and RPS declined with time, which suggested an adaptive response resulting in increased utilization of the starches. This adaptive response was slower in the RPS-fed rats than the RCS-fed rats.

6. The present study indicates that, in the rat, there are significant differences in the utilization of resistant starches from different sources.

1. In the first trial, hourly blood samples were drawn during the light period (06·30–20·30 hours) from thirtyfour dairy heifers in two groups of different ages.

2. Concentrations of serum folates were 8·2 (se 0·1) ng/ml at the age of 18·2 (se 0·6) d and 14·8 (se 0·2) ng/ml at 120·7 (se 2·9) d (P ≤ 0·001).

3. In the second trial, forty heifers were randomly assigned to a factorial experiment where age (2 weeks v. 4 months) and quantity of pteroylmonoglutamic acid injected intramuscularly (2·5, 5·0, 10·0 and 20·0 mg) were the two factors studied. Blood samples were taken immediately before injection and on days 1,2,3,4,7 and 10 after the injection.

4. Serum folates reached a maximum on day 1 after the injection of pteroylmonoglutamic acid. The response to the injection was different for the two age groups (P ≤ 0·0002); concentration of serum folates for 2-week-old heifers markedly increased, while in 4-month-old heifers the effect of a supplement of pteroylmonoglutamic acid was less marked.

5. These results might indicate a need for pteroylmonoglutamic acid in young animals during the development of rumen function.

1. For a period of 32 d young rats were given a diet containing (g/kg) 220 casein, 120 casein +1.93 L-cysteine (Cys), or 120 casein.

2. The formation of 3,5,3'-triiodothyronine (T3)-nuclear protein complexes was reduced in rats fed on the Cys-deficient diet.

3. Scatchard analysis showed that decreased formation of T3 -nuclear protein complexes was due to a decreased affinity of T3 receptors; this decrease was induced, at least in part, by a reduced glutathione content.

4. In rats fed on the Cys-deficient diet there was an expected decrease in growth but an unexpected increase in the activities of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+) (EC 1.1.1.40). It is suggested that this increase is related to an increased oxidized glutathione: reduced glutathione ratio.

1. Studies were carried out on the distribution of ascorbic acid in human fetal tissues with the progress of gestation.

2. Fetuses and stillborn babies varying in gestational age from 12 to 38 weeks were obtained from various Baroda hospitals. Ascorbic acid levels were determined in selected tissues: brain, adrenal, liver, kidney, lung, heart and placenta.

3. Ascorbic acid concentration in the brain was higher than that in the adrenal at all gestational ages, suggesting the importance of this vitamin in brain development. The concentrations of this vitamin in liver, kidney, lung and placenta were comparable, but that in the heart tended to be lower. In all the tissues, there was a fall in ascorbic acid during late gestation. However, the levels in tissues of stillborn babies were higher than those reported for adults.

1. In Expt 1 three male goat kids of the Swedish Landrace breed were bottle-fed on isoenergetic liquid diets composed of goat's milk alone or substituted with 200, 400, 600 and 800 ml of a nitrogen-free liquid diet/1. The goat kids were 3 weeks old at the start of the experiment and weighed on average 5.3 (sd 0.22) kg. The experiment lasted for 45 d divided into nine 5 d periods. The goat kids were kept individually in metabolism cages, and faeces and urine were collected daily.

2. In Expt 1 there was a significant (P < 0.001) relation between N intake and N retention, with an estimated (extrapolation) basal N excretion of 211 mg N/kg metabolic live weight (W0.75). While the creatinine excretion remained fairly constant (19.9 mg/W0.75), there was a tendency for both the allantoin and uric acid excretions to change with N intakes. Hypoxanthine showed no consistent excretion pattern, and xanthine could not be detected.

3. In Expt 2 three male goat kids of the Swedish Landrace breed were used to study the effect of level of intake on N and purine metabolism. The first experimental period (period 1) started at 2 weeks of age (5.5 kg live weight) and the second experimental period (period 2) at 9 weeks of age (9.8 kg live weight). The goat kids were bottle-fed on goat milk at intended intakes of 400, 600, 800 and 1000 kJ gross energy/kg W0.75. Each treatment was given for 7 d with adaptation for 3 d and collections for 4 d.

4. In Expt 2 there were significant (P < 0.001) increases in both live weight and N retention when level of intake was increased. With increasing N intakes both total N and urea-N excretions increased significantly (P < 0.05). The proportions of urea-N and ammonia-N were fairly constant within periods, and were on average respectively 0.81 and 0.059 in period I and 0.84 and 0.068 in period 2. There was no significant effect of treatment on the urinary excretion of allantoin, hypoxanthine, xanthine and creatinine. In period 2 uric acid excretion was significantly (P < 0.01) affected by the treatments.

5. From the presented findings it is concluded that the endogenous urinary excretion of purine derivatives in a young growing ruminant was only marginally affected by large variations in protein supply, and also by the level of intake of milk.

1. Two experiments were conducted to determine whether or not high dietary levels of vitamin E affect the development of atherosclerotic lesions in aortas of cholesterol-fed (5 g/kg diet) rabbits that were mechanically deendothelialized by balloon catheterization.

2. In the first experiment, the aortas of rabbits fed 2000 mg vitamin E/kg diet (i.e. 50-fold their nutritional requirement) for 8 weeks showed no gross morphological differences, either within or outside experimentally damaged areas, from those of rabbits fed the nutritionally adequate control level (40 mg/kg) of the vitamin.

3. In the second experiment, rabbits fed 10000 mg vitamin E/kg diet (i.e. 250-fold requirement) for 14–15 weeks showed significantly greater endothelial loss and plaque formation at aortic sites outside of the mechanically damaged area than did controls. Plasma cholesterol levels were very high (9000–14000 mg/1) and were not affected by dietary vitamin E level until 10–12 weeks when they were reduced moderately (18%).

4. It is concluded that very high levels of vitamin E can potentiate spontaneous atherosclerotic lesions, and it is suggested that this effect may depend on high cholesterol status.

1. In vitro, pyridoxal phosphate extracts steroid-hormone receptors from tight nuclear binding (Cidlowski & Thanassi, 1981); in vitamin B6-deficient rats there is increased and prolonged nuclear accumulation of oestradiol in the uterus and testosterone in the prostate, associated with enhanced biological responsiveness of these target tissues to steroid hormone action (Symes et al. 1984; Bowden et al. 1986).

2. Slices of uterus from vitamin B6-deficient rats accumulated more [3H]oestradiol than did tissue from repleted animals. Acute repletion with vitamin B6 (0.5–1 h before killing) further increased the uptake of the steroid.

3. Isolated hepatocytes from vitamin B6-deficient rats accumulated more [3H]dexamethasone than did cells from repleted animals. Pre-incubation of the hepatocytes with pyridoxal phosphate resulted in a further increase in the uptake of the steroid.

4. The results suggest that in addition to the putative role of pyridoxal phosphate in releasing steroid-hormone-receptor complexes from tight nuclear binding (Cidlowski & Thanassi, 1981), vitamin B6 deficiency may also increase the concentration of steroid-hormone receptors or enzymes and other steroid-binding proteins in target tissues.

1. Nitrite and nitrate levels were measured in samples from ileostomy bags or stomal samples of thirty-one ileostomists (twenty-two ulcerative colitis, nine Crohn's disease), 14-16 h after ingestion of a conventional meal or a meal containing a high content of nitrite and nitrate.

2. Ileostomy samples were decolourized with barium chloride, sodium sulphate and charcoal. Nitrite was determined spectrophotometrically by the Griess reaction and nitrate determined as nitrite after reduction with nitrate reductase (ec 1.7.99.4) in the presence of sodium formate. The mean percentage recovery from twentysix spiked samples was 101.9 (se 3.5)% for nitrite and 82.9 (se 3.3)% for nitrate.

3. Ileostomy bag samples were obtained in twenty-nine cases of which ten had measurable nitrite (median 0, range 0-20.7 nmol/g) on a conventional meal compared with twenty-three cases (median 7.2, range 0-31.1 nmol/g) on the test meal (P < 0.01). Nitrate levels were measurable in sixteen (median 6.7, range 0-48.2 nmol/g) after a conventional meal compared with twenty-one (median 20.5, range 0-53.2 nmol/g) after the test meal (P <0.01).

4. Stomal fresh-catch samples were obtained in twenty-four cases: combined nitrate and nitrite was higher in eighteen, lower in four and unchanged in two subjects after the test meal (P < 0.05).

5. The type of foodstuff ingested can significantly alter measurable levels of nitrite-nitrate in the distal ileum and is one factor determining nitrite-nitrate input into the proximal colon.

1. Feeding rats on a low-tryptophan, niacin-free, high-leucine diet resulted in impaired synthesis from tryptophan of the nicotinamide nucleotide coenzymes, NAD and NADP, and N1-methyl nicotinamide in isolated hepatocytes, compared with cells from animals fed on a low-tryptophan, niacin-free control diet providing an appropriate amount of leucine. This was accompanied by reduced accumulation of the tryptophan metabolites kynurenine, 3-hydroxykynurenine and xanthurenic acid.

2. With hepatocytes from animals fed on the low-tryptophan, niacin-free control diet, the addition of leucine to the incubation medium resulted in reduced synthesis of niacin from tryptophan, and a small increase in the accumulation of 3-hydroxykynurenine.

3. With hepatocytes from animals fed on the low-tryptophan, niacin-free control diet, the addition of 2-oxo-isocaproate to the incubation medium resulted in increased synthesis of NAD(P) and niacin, and increased accumulation of 3-hydroxykynurenine.

4. The results suggest that a dietary excess of leucine alters the activity of the enzymes of tryptophan→niacin metabolism, or the uptake of tryptophan into the liver, in a different manner from the simple inhibition and activation seen in experiments in vitro.

5. Differences between studies in isolated hepatocytes and intact animals suggest that extra-hepatic metabolism of tryptophan, catalysed by indoleamine dioxygenase, is more important than has been believed hitherto.

1. Bioavailability of Fe from beef, spinach (Spinacea oleracea L.) and their mixtures was studied using anaemic and non-anaemic rats by haemoglobin regeneration efficiency (HRE) and apparent Fe absorption in two trials.

2. The initial haemoglobin levels of severely anaemic, mildly anaemic and non-anaemic rats were 63, 88 and 113 g/l, respectively. The Fe level in diets was about 30 mg/kg. All other nutrients equalled or exceeded the requirement of the growing rat.

3. The spinach Fe was well utilized by the rats with average HRE of 0.41, 0.53 and 0.36, and apparent Fe absorptions averaging 0.48, 0.59 and 0.37 for the severely anaemic, mildly anaemic and non-anaemic animals respectively.

4. Beef Fe was efficiently used by rats as reported by others. Average HRE were 0.42, 0.51 and 0.44, and average apparent Fe absorptions were 0.44, 0.47 and 0.46 for the severely anaemic, mildly anaemic and non-anaemic rats respectively.

5. When the percentage of meat Fe was increased from 0 to 25, 50, 75 or 100 of the dietary Fe, HRE and apparent Fe absorption were not increased significantly. A meat enhancement effect on total Fe absorption, reported by others for non-haem-Fe, did not occur in the present experiment.

6. Negative correlation coefficients between initial haemoglobin and HRE (r -0.79), and initial haemoglobin and apparent Fe absorption (r -0.73) were seen with the rats fed on dietary Fe from FeSO47H2O. This was not seen with the rats fed on dietary Fe from beef or spinach.

7. The Fe absorption pattern for the different Fe sources is evidence for a third Fe pool, a pool made up of highly soluble inorganic Fe salt, in addition to haem-Fe and non-haem-Fe complex pools. FeSO4 7H2O is not in the same gastrointestinal pool as non-haem-Fe complex such as spinach Fe. A suggested mechanism of absorption is discussed.

1. Eight women maintained on a constant diet throughout a single menstrual cycle were studied for cyclical changes in body-weight, carbohydrate, fat and protein metabolism.

2. A cyclical variation in weight occurred with two phases corresponding to the time of ovulation and menstruation.

3. Creatinine and nitrogen excretion in the urine also tended to be higher in the luteal phase.

4. Analysis of gas exchange in a respiratory chamber for 24 h periods at intervals during the cycle suggested that carbohydrate utilization tended to be less in the early follicular phase.

5. Feeding with a mixed diet produced marked increases in carbohydrate utilization during the day with little change in fat utilization from the fasting state. Carbohydrate utilization was less when fasting at night and tended to be less when fed during the day in the early follicular phase of the menstrual cycle.

6. Weight changes were not readily ascribed to changes in colonic function, or in glycogen or body protein storage.