Micronutrient deficiencies may be common during human immunodeficiency virus (HIV) infection. Insufficient dietary intake, malabsorption, diarrhoea, and impaired storage and altered metabolism of micronutrients can contribute to the development of micronutrient deficiencies. Low plasma or serum levels of vitamins A, E, B6, B12 and C, carotenoids, Se, and Zn are common in many HIV-infected populations. Micronutrient deficiencies may contribute to the pathogenesis of HIV infection through increased oxidative stress and compromised immunity. Low levels or intakes of micronutrients such as vitamins A, E, B6 and B12, Zn and Se have been associated with adverse clinical outcomes during HIV infection, and new studies are emerging which suggest that micronutrient supplementation may help reduce morbidity and mortality during HIV infection.

Concentrations of pyridoxal phosphate and pyridoxic acid were measured in fasting plasma samples from British men and women aged 65 years and over, participating in a National Diet and Nutrition Survey during 1994–5, selected to be representative of the population of mainland Britain. In this population, the concentration of pyridoxal phosphate declined, whereas pyridoxic acid rose, with increasing age and frailty; however, both status indicators were strongly and directly (with a positive coefficient) correlated with estimates of vitamin B6 intake. This was little affected by the inclusion of food energy and protein intakes in the model. Forty-eight percent of the participants living in the community and 75% of those living in institutions had plasma pyridoxal phosphate concentrations below a range considered normal from other studies. In a univariate regression model, plasma pyridoxal phosphate concentrations were inversely correlated with plasma homocysteine concentrations, consistent with the hypothesis that vitamin B6 status may influence plasma homocysteine levels, and hence vascular disease risk. However, this relationship was partly attenuated in a multiple regression model including age, sex, domicile and biochemical status indices, including those of folate and vitamin B12. There was evidence that plasma pyridoxal phosphate was sensitive to metabolic conditions associated with inflammation and the acute-phase reaction, and that plasma pyridoxic acid was sensitive to renal function. Thus, neither index is an ideal predictor of vitamin B6 status in older people, unless these confounding factors are allowed for. Since poor vitamin B6 status may have health implications, e.g. for immune function, cognition, and for essential intermediary metabolic pathways in older people, it needs to be investigated as a possible public health problem.

Coriandrum sativum (coriander) has been documented as a traditional treatment of diabetes. In the present study, coriander incorporated into the diet (62·5 g/kg) and drinking water (2·5 g/l, prepared by 15 min decoction) reduced hyperglycaemia of streptozotocin-diabetic mice. An aqueous extract of coriander (1 mg/ml) increased 2-deoxyglucose transport (1·6-fold), glucose oxidation (1·4-fold) and incorporation of glucose into glycogen (1·7-fold) of isolated murine abdominal muscle comparable with 10−8 m-insulin. In acute 20 min tests, 0·25–10 mg/ml aqueous extract of coriander evoked a stepwise 1·3–5·7-fold stimulation of insulin secretion from a clonal B-cell line. This effect was abolished by 0·5 mm-diazoxide and prior exposure to extract did not alter subsequent stimulation of insulin secretion by 10 mm-l-alanine, thereby negating an effect due to detrimental cell damage. The effect of extract was potentiated by 16·7 mm-glucose and 10 mm-l-alanine but not by 1 mm-3-isobutyl-1-methylxanthine. Insulin secretion by hyperpolarized B-cells (16·7 mm-glucose, 25 mm-KCl) was further enhanced by the presence of extract. Activity of the extract was found to be heat stable, acetone soluble and unaltered by overnight exposure to acid (0·1 m-HCl) or dialysis to remove components with molecular mass < 2000 Da. Activity was reduced by overnight exposure to alkali (0·1 m-NaOH). Sequential extraction with solvents revealed insulin-releasing activity in hexane and water fractions indicating a possible cumulative effect of more than one extract constituent. These results demonstrate the presence of antihyperglycaemic, insulin-releasing and insulin-like activity in Coriandrum sativum.

The aim of the present study was to evaluate the importance of social status and lifestyle for dietary habits, since these factors may influence life expectancy. We studied the association of four indicators for healthy dietary habits (fruits and vegetables, fibre, fat and Hegsted score) with sex, age, socio-economic status, education, physical leisure exercise, smoking and personal attention paid to keeping a healthy diet. Data were gathered with a self-administered quantitative food-frequency questionnaire distributed to a representative sample of Norwegian men and women aged 16–79 years in a national dietary survey, of whom 3144 subjects (63%) responded. Age and female sex were positively associated with indicators for healthy dietary habits. By separate evaluation length of education, regular physical leisure exercise and degree of attention paid to keeping a healthy diet were positively associated with all four indicators for healthy dietary habits in both sexes. Socio-economic status, location of residence and smoking habits were associated with from one to three indicators for healthy dietary habits. In a multiple regression model, age, education and location of residence together explained from 1 to 9% of the variation (R2) in the four dietary indicators. Length of education was significantly associated with three of four dietary indicators both among men and women. By including the variable ‘attention paid to keeping a healthy diet’ in the model, R2 increased to between 4 and 15% for the four dietary indicators. Length of education remained correlated to three dietary indicators among women, and one indicator among men, after adjusting for attention to healthy diet, age and location of residence. Residence in cities remained correlated to two indicators among men, but none among women, after adjusting for age, education and attention to healthy diet. In conclusion, education was associated with indicators of a healthy diet. Attention to healthy diet showed the strongest and most consistent association with all four indicators for healthy dietary habits in both sexes. This suggests that personal preferences may be just as important for having a healthy diet as social status determinants.

The nutritional quality of milk proteins, evaluated both in terms of digestibility and postprandial oxidation and retention in human subjects, was investigated in this study. Five healthy adult volunteers were given 480 ml 15N-labelled milk (i.e. 190 mmol N). 15N was subsequently determined at the ileal level, using a naso-intestinal intubation technique, as well as at the faecal level. Plasma and urine were sampled for 8 h after meal ingestion. Dietary exogenous N recovered at the terminal ileum after 8 h reached 8·6 (se 0·8) mmol while the amount collected in the faeces was 6·5 (se 0·7) mmol after 5 d. The true ileal and faecal digestibilities were 95·5 (se 0·4)% and 96·6 (se 0·4)% respectively. The appearance of [15N]amino acids in the plasma was rapid and prolonged. The measurement of 15N in the body urea pool and in the N excreted in the urine allowed us to calculate the deamination occurring after [15N]milk protein absorption. The net postprandial protein utilization (i.e. NPPU = (Nabsorbed - Ndeaminated)/Ningested), calculated as an index of protein quality 8 h after milk ingestion, was 81·0 (se 1·9)%. Our data confirm that milk protein has a high oro-ileal digestibility in man and demonstrate that milk protein has a high NPPU, an index corresponding to a period in which the dietary protein retention is maximal.

The aim of this experiment was to determine CH4 production and energy partition for a range of diets fed to Bos indicus cattle. Six Brahman cattle were fed on three different diets in a replicated Latin square experiment over three periods. The diets were (1) long-chopped Angleton grass (Dicanthium aristatum) hay ad libitum (DM digestibility (DMD) 41 (se 2)%; 4 g N/kg), (2) long-chopped Rhodes grass (Chloris gayana) hay ad libitum (DMD 60 (se 1)%; 14 g N/kg) or (3) 2 kg long-chopped lucerne (Medicago sativa) hay/d plus a high-grain diet (ad libitum) (DMD 70 (se 1)%; 31 g N/kg). CH4 production was measured using confinement-type respiration chambers. Metabolizable energy intake (MJ/d) of cattle fed on Angleton grass (18·4 (se 2·0)) was lower (P< 0·01) than that for Rhodes grass (54·9 (se 2·1)), which was lower (P< 0·01) than that for the high-grain diet (76·7 (se 5·8)). CH4 production (g/d) for cattle fed on Rhodes grass (257 (se 14)) was higher (P< 0·01) than that for cattle fed on both the high-grain diet (160 (se 24)) and Angleton grass (113 (se 16)). CH4 conversion rate (MJ CH4 produced per 100 MJ gross energy intake) was not significantly different between cattle fed on Angleton (10·4 (se 1·1)) and Rhodes (11·4 (se 0·3)) grass, but was higher (P< 0·01) than for cattle fed on the high-grain diet (6·7 (se 0·7)). CH4 production (g/kg live-weight gain) was associated (P< 0·001) with both live-weight gain and feed: gain ratio. We conclude that the relationships between CH4 production, energy utilization and live-weight change of cattle fed on tropical forages differ from those of cattle fed on diets based on temperate forages.

The effect of 16 d intake of 300 mg carotenoids/kg diet (β-carotene (βC), bixin (BX), lycopene (LY), lutein (LU), canthaxanthin (CX) or astaxanthin (AX)) on xenobiotic metabolizing enzymes in the liver, lung, kidney and small intestine of male Wistar rats was assessed. A control group received the basal diet (AIN-76) without carotenoids and a positive control group for enzyme induction received 3-methylcholanthrene (3-MC) at 666 mg/kg diet. Cytochrome P450 activity was assessed using the substrates ethoxyresorufin for P450 1A1, methoxyresorufin for P450 1A2, pentoxyresorufin for P450 2B1/2 and benzyloxyresorufin for P450 types 1A1/2, 2B1/2 and 3A. Glutathione-S-transferase (EC 2.5.1.18) and reduced glutathione status were assessed. Carotenoid uptake by the tissues was also determined. 3-MC and the carotenoids BX, CX and AX led to significant increases compared with control in liver, lung and kidney ethoxyresorufin-O-deethylation. Methoxyresorufin-O-demethylation activity was significantly increased in liver and lung by BX, CX and AX but only CX and AX significantly increased activity in kidney. Pentoxyresorufin-O-depentylation and benzyloxyresorufin-O-dearylation increased in liver of 3-MC-, BX-, CX- and AX-treated rats, but to a much lesser degree than for the other two substrates. Benzyloxyresorufin-O-dearylation in lung was significantly decreased by all carotenoids. Activities of any of the measured enzymes in the small intestine were undetectable in all treatment groups except the 3-MC group. Glutathione status was unaffected by any of the treatments. This is the first study identifying the carotenoids BX, CX and AX as inducers of rat lung and kidney xenobiotic metabolizing enzymes.

Maternal protein deficiency causes fetal growth retardation which has been associated with the programming of adult disease. The growth of the rat fetus was examined when the mothers were fed on diets containing 180, 90 and 60 g protein/kg. The numbers of fetuses were similar in animals fed on the 180 and 90 g protein/kg diets but the number was significantly reduced in the animals fed on the 60 g protein/kg diet. The fetuses carried by the mothers fed on the 90 g protein/kg diet were 7·5% heavier than those of mothers fed on 180 g protein/kg diet on day 19 of gestation, but by day 21 the situation was reversed and the fetuses in the protein-deficient mothers were 14% smaller. Analysis of the free amino acids in the maternal serum showed that on day 19 the diets containing 90 and 60 g protein/kg led to threonine concentrations that were reduced to 46 and 20% of those found in animals fed on the control (180 g/kg) diet. The other essential amino acids were unchanged, except for a small decrease in the branched-chain amino acids in animals fed on the 60 g protein/kg diet. Both low-protein diets significantly increased the concentrations of glutamic acid+glutamine and glycine in the maternal serum. On day 21 the maternal serum threonine levels were still reduced by about one third in the group fed on the 90 g protein/kg diet. Dietary protein content had no effect on serum threonine concentrations in non-pregnant animals. Analysis of the total free amino acids in the fetuses on day 19 showed that feeding the mother on a low-protein diet did not change amino acid concentrations apart from a decrease in threonine concentrations to 45 and 26% of the control values at 90 and 60 g protein/kg respectively. The results suggest that threonine is of particular importance to the protein-deficient mother and her fetuses. Possible mechanisms for the decrease in free threonine in both mother and fetuses and the consequences of the change in amino acid metabolism are discussed.

Conjugated linoleic acids (CLA) are positional isomers of linoleic acid which have been suggested by some to possess antiatherosclerotic properties. To test this hypothesis, three groups of twenty C57BL/6 mice were fed on atherogenic diets containing: 5 g CLA/kg, 2·5 g CLA + 2·5 g linoleic acid/kg or 5 g linoleic acid/kg. All diets were fed for 15 weeks and contained (g/kg): triacylglycerol 145, free fatty acids 5, cholesterol 10 and cholic acid 5. At the completion of the experimental period, when data from both groups fed on CLA were combined, dietary CLA did not produce significant differences in body weight, serum total cholesterol concentration or serum HDL-cholesterol concentration. However, mice receiving CLA developed a significantly higher serum HDL-cholesterol: total cholesterol ratio and a significantly lower serum triacylglycerol concentration than controls. Despite causing a serum lipoprotein profile considered to be less atherogenic, the addition of CLA to the atherogenic diet increased the development of aortic fatty streaks. Considering the increased atherogenesis associated with dietary CLA in the present study, and the failure to demonstrate a significant beneficial effect of CLA in other animal studies, there is currently no conclusive evidence to support the hypothesis that CLA protect against atherogenesis.