Fe deficiency is considered to be the commonest of nutritional deficiencies worldwide. Adverse effects are stated to include lower growth rate and impaired cognitive scores in children and poor pregnancy outcome and lower working capacity in adults. In the present review, Fe intake, stores of the element, the magnitude of deficiencies and the benefits from interventions, as reflected in the results of clinical trials, are discussed. Because of inadequacies of knowledge in numerous respects, more information is needed regarding the extent to which clinical trials relate to public health realities, before introducing regional or national supplementation programmes. While Fe supplements are needed in certain groups, and in particular regions, increased dietary intakes could be supplied by food fortification, as well as by individual improvements in intake.

The present study examined the endogenous urinary excretion of purine derivatives (PD; allantoin, uric acid and xanthine plus hypoxanthine) in fed animals. Four Rasa Aragonesa ewes fitted with simple cannulas in the rumen and proximal duodenum were used. Animals were given a lucerne (Medicago sativa) hay diet, as sole feed (A) or supplemented, respectively, with 220 (B), 400 (C), and 550 (D) g rolled barley grain/d following a 4 × 4 random factorial design. Duodenal flow of purine bases (PB) was determined by the dual-phase marker system. 15N was infused continuously into the rumen to label exogenous or microbial PB. Duodenal PB flow and urinary excretion of PD increased with digestible organic matter intake showing a constant recovery of duodenal PB. The isotope dilution of PD in urine samples confirmed the presence of an endogenous fraction, originating from tissues, that increased from 115.2 (SE 5.84) μmol/kg W0.75 for the basal diet to 304.2 (SE 7.6) μmol/kg W0.75 at the highest level of duodenal PB.

There is indirect evidence from previous studies that the physiological responses to a liquid test meal may differ from those seen after consumption of a solid meal. The aim of the present study was to determine the metabolic and cardiovascular responses to isoenergetic high-carbohydrate mixed nutrient liquid or solid test meals, providing 2.1 MJ (approximately 70% of which was from carbohydrate), in eight healthy men following an overnight fast. Metabolic rate increased significantly after both meals (P < 0.0001, time effect), but the increase was significantly greater after the solid than after the liquid test meal (0.40 (SE 0.14), 0.26 (SE 0.10) kJ/min respectively, P = 0.001). The respiratory exchange ratio increased significantly after both the liquid and solid test meals, with no significant differences between them. Forearm blood flow increased significantly after the liquid test meal (0.70 (SE 0.33) ml/100 ml per min, P < 0.0001), whilst it decreased after the solid meal (−0.28 (SE 0.16)ml/100ml per min, P< 0.0001). Heart rate increased on both occasions, but the response was significantly greater after the solid meal (P=0.02). There were no significant plasma noradrenaline responses, but there were significantly higher increases in serum insulin and blood glucose following the solid meal. Thus, the physical form of a test meal affects the physiological responses to nutrient ingestion.

In pregnancy, the additional demands for Fe are thought to be met principally through increased maternal dietary Fe absorption and by mobilization of maternal Fe stores. In a general population sample of 576 women we examined the maternal and dietary characteristics which influenced Fe stores (assessed by serum ferritin concentration) in early pregnancy. The effects of these characteristics on two measures of functional Fe status (mean cell volume and haemoglobin concentration) were also considered. Serum ferritin concentrations were lower in multiparous women (P < 0.0001) and in those with a lower BMI (P = 0.01), and rose with increasing alcohol intake (P < 0.0001). Ferritin concentrations fell with increasing Ca intake (P < 0.0001); the proportion of women with serum ferritin values ≤ 12 μg/l rose from 14% of the women in the lowest quarter of Ca intake to 29% of the women in the highest quarter. Mean cell volume and haemoglobin concentration were not related to Ca intake in early pregnancy. Although Ca added to test-meals reduces Fe absorption, long-term Ca supplementation has not been shown to lower plasma ferritin concentration, suggesting that high habitual Ca intakes would be unlikely to influence Fe status in non-pregnant individuals. Our findings show that in early pregnancy there is an association between high dietary Ca intake and lower Fe stores. This effect of Ca on one aspect of Fe status may result from its influence on Fe bioavailability.

Pregnant women consuming plant-based diets are at risk of Zn deficiency; Zn requirements for fetal growth and maternal tissue accretion are high. Therefore we have studied, at 24 and 33 weeks gestation, the Zn status of eighty-seven pregnant rural Malawian women (mean age 22·7 years) who consume maize-based diets, using anthropometry, dietary intake data, plasma and hair Zn concentrations, and infection status via serum C-reactive protein, leucocyte count, and malaria blood smear. Of the women, 12% were stunted (height-for-age Z score < -2 SD) and 20% lost weight over the 9-week period; weight gain averaged 0·13 kg/week. Mean plasma Zn concentration declined significantly from 24 to 33 weeks (7·9 (SD 2·2) v. 6·6 (SD 2·0) μmol/l; P < 0·0003). Both plasma and hair Zn values were very low; nearly 50% of the women had both plasma and hair Zn values below acceptable cut-off values. No significant differences in biochemical Zn indices existed between those who tested positive and negative for infection. Cereals (mainly maize) provided more than two-thirds of mean energy intake compared with less than 5% from flesh foods. As a result about 60% of the subjects had dietary phytate: Zn molar ratios greater than 15, and more than 35% had inadequate Zn intakes based on probability estimates and WHO basal requirements. Biochemical evidence of Zn deficiency was attributed in part to low intakes of poorly available Zn. The anthropometric, biochemical, and dietary data together indicate that Zn deficiency may be a factor limiting pregnancy outcome in rural Malawian women.

Wool growth is derived directly from protein synthesis in the skin of sheep, and is affected by the nutritional status of the animals. The present experiment examined both protein synthesis in the skin and muscle and wool growth in Merino lambs differing in live weight, intake and dietary protein source. The experiment was a 23 factorial design: twenty-four 5-month-old lambs initially weighing 33 kg (heavy) or 25 kg (light) were fed on a hay-based diet with either lupin seed or rapeseed meal as the major protein sources to maintain live weight (M) for 56 d, or were fed at 0.6M for 28 d (period 1) followed by 28 d at 1.6M (period 2). Fractional protein synthesis rates (FSR, % per d) in the skin and the m. longissimus dorsi on days 4 and 24 of period 1 and day 4 of period 2 were measured by means of a flooding dose of l-[ring-d5]phenylalanine, and wool growth on a skin patch over period 1 was also measured. The FSR ranged from 13.2 to 20.2% per d in the skin, higher than reported for other breeds, and 1.53–3.07% per d in the muscle. Sheep on the low intake (0.6M) had significant reductions in FSR, protein content (g), protein synthesis (g/d) in the skin, and wool growth (g/d). The heavy lambs had similar FSR to the light lambs, but had a higher skin protein content and total protein synthesis per unit of skin area (100 cm2) and, therefore, grew more wool. The rapeseed-meal diet increased FSR and wool growth only in the light lambs over the short term. The protein deposited in wool over period 1 was 0.185 of the total protein synthesis in the skin, regardless of live weight, intake or diet, a result similar to other breeds. With the changes in dietary intake, protein synthesis in the skin and muscle responded differentially, with nutrient partitioning at sub-maintenance in favour of wool growth but at supra-maintenance, following a nutrient restriction, in favour of weight gain in young growing sheep.

The effect of dietary intake level on in vivo plasma leucine and plasma palmitate flux rates and on the response to a bolus injection of bovine growth hormone (GH) was investigated in six young steers. Animals were fed on a pelleted diet of dried grass–barley (0.7:0.3, w/w) in quantities sufficient to supply 0.8, 1.2, 1.6, 2.0, 2.4 or 2.65 × maintenance energy requirement, offered in hourly portions. Continuous intravenous infusions of [1-13C]leucine or [1-13C]palmi-tate were used to determine the flux of amino acid and fatty acid through the plasma pool before, immediately (1–3 h) after and 22–24 h after a subcutaneous injection of bovine GH (0.55 mg/kg body weight). Hourly blood samples were taken for 27 h to monitor the temporal responses of circulating hormones and metabolites following GH administration. The animal on the lowest plane of nutrition had elevated plasma GH and reduced insulin-like growth factor-1 concentrations compared with those fed on higher intake levels. Plasma leucine flux and leucine concentration increased with intake while palmitate flux and plasma non-esterified fatty acid (NEFA) concentrations were inversely related to intake. Leucine flux rate decreased in the animals fed on the two highest intake levels in response to GH 22–24 h after administration, but plasma leucine concentrations were reduced in all animals at this time. Only the animal fed on the lowest intake level showed an immediate response to GH (within 3 h of administration) with increased palmitate flux and plasma NEFA concentrations but a lipolytic response was apparent in other animals 22–24 h post-administration although the magnitude of the response was markedly reduced at high intakes. We conclude that lipid and protein metabolism are differentially responsive to GH and nutritional status.

Four preruminant calves with implanted electrodes in the duodenum and a catheter in the external jugular vein were used for investigation of plasma gut regulatory peptide profiles during different phases of migrating myoelectric complex (MMC) in the small intestine. The effects of different dietary proteins on the rhythmic activity of gut peptides and gastrointestinal motility were compared. In particular, the effects of skimmed-milk protein (retaining physiological patterns of abomasal clotting, and abomaso-intestinal digesta flow) v. fish protein (devoid of clotting activity and modifying the digesta flow) were studied. In calves fed on the milk diet, plasma concentrations of pancreatic polypeptide, motilin, secretin, cholecystokinin (CCK) and somatostatin, but not vasoactive intestinal polypeptide or gastrin, fluctuated in phase with the duodenal MMC in the preprandial period. Feeding transiently affected the intestinal MMC and abolished the peptide fluctuations in a specimen-specific manner. In contrast, calves fed on the fish-protein diet showed more profound changes in intestinal MMC. In these animals the MMC-related fluctuations were significant only for plasma CCK. In conclusion, the source of dietary protein has an impact on the physiological endocrine function of the small intestine. Observed fluctuations of plasma gut regulatory peptides seem to be secondary to duodenal motility cycles.

This study was carried out to analyse glucocorticoid-induced muscle wasting and subsequent recovery in adult (6-8 months) and old (18-24 months) rats because the increased incidence of various disease states results in hypersecretion of glucocorticoids in ageing. Adult and old rats received dexamethasone in their drinking water for 5 or 6 d and were then allowed to recover for 3 or 7 d. As dexamethasone decreased food intake, all groups were pair-fed to dexamethasonetreated old rats (i.e. the group that had the lowest food intake). At the end of the treatment, adult and old rats showed significant increases in blood glucose and plasma insulin concentrations. This increase disappeared during the recovery period. Protein synthesis of different muscles was assessed in vivo by a flooding dose of [13C]valine injected subcutaneously 50 min before slaughter. Dexamethasone induced a significant decrease in protein synthesis in fast-twitch glycolytic and oxidative glycolytic muscles (gastrocnemius, tibialis anterior, extensor digitorum longus). The treatment affected mostly ribosomal efficiency. Adult dexamethasone-treated rats showed an increase in protein synthesis compared with their pair-fed controls during the recovery period whereas old rats did not. Dexamethasone also significantly decreased protein synthesis in the predominantly oxidative soleus muscle but only in old rats, and increased protein synthesis in the heart of adult but not of old rats. Thus, in skeletal muscle, the catabolic effect of dexamethasone is maintained or amplified during ageing whereas the anabolic effect in heart is depressed. These results are consistent with muscle atrophy occurring with ageing.

Riboflavin deficiency interferes with the growth and multiplication of malaria parasites as well as the host response to malaria. The objective of the present work was to determine the effects of riboflavin deficiency on erythrocyte glutathione peroxidase (EC 1.11.1.9; GPx) and superoxide dismutase (EC 1.15.1.1; SOD) in rats infected with Plasmodium berghei malaria. Riboflavin in its co-enzyme form, FAD, is required by glutathione reductase (EC 1.6.4.1) to regenerate GSH and GSH is an important cellular antioxidant both in its own right and also as a substrate for the enzyme GPx. Weanling rats were deprived of riboflavin for 8 weeks before intraperitoneal injection of 1 × 106P. berghei parasites. Control animals were weight-matched to the respective riboflavin-deficient group. At 10d post-infection, parasite counts were higher in the weight-matched control group than the riboflavin-deficient group (P = 0.004). GPx activity was higher in erythrocytes of rats parasitized with P. berghei than comparable non-infected rats regardless of riboflavin status (P < 0.05). As mature erythrocytes do not synthesize new protein, the higher GPx activities were probably due to the presence of the parasite protein. In erythrocytes from riboflavin-deficient rats, GPx activity tended to be lower than in those rats fed on diets adequate in riboflavin (weight-matched controls) whether parasitized or not, but the difference was not significant. Neither riboflavin deficiency nor malaria had any effect on erythrocyte SOD activity. It was concluded that riboflavin deficiency has no marked effect on erythrocyte GPx or SOD activity in the rat.