The method of Zinn & Owens (1986; Canadian Journal of Animal Science66, 157–166), based on release of purine bases by HClO4 followed by their precipitation with AgNO3, was used to study recovery of purines from lyophilized rumen microbial or Escherichia coli preparations added to matrices such as cellulose, starch and neutral-detergent fibre. The recovery of purines was poor (approximately 50 %). Under the hydrolysis conditions (12 M-HClO4, 90–95° for 1 h) used in the method of Zinn & Owens (1986), the recovery of purines from the rumen microbial preparations added to matrices measured using an HPLC method was 95–102 %, suggesting that the lower recovery of purines in the method of Zinn & Owens (1986) was not due to incomplete hydrolysis of nucleic acids. Using the HPLC method, adenine and allopurinol (an internal standard) were found to be heat-labile as substantial destruction was observed on heating at 121°. On the other hand, another commonly used internal standard, caffeine, was stable at 121°. A complete hydrolysis of nucleic acids from the rumen microbial preparation was observed with 2·5 ml 0·6 M-HClO4 in a total volume of 3 ml (0·5 M-HClO4 during hydrolysis) at 90–95° for 1 h, and under these conditions adenine, guanine, allopurinol and caffeine were stable. Moreover, under these milder hydrolysis conditions, the recovery of purine bases from the rumen microbial or E. coli preparations added to matrices ranged from 92 to 108 % using the method of Zinn & Owens (1986). Based on the results, changes in hydrolysis conditions have been proposed for accurate determination of purine bases using spectrophotometric or HPLC methods.

The aim of the present study was to determine the reproducibility of measurement of resting metabolic rate (RMR) using a ventilated-hood indirect calorimeter in children using a short protocol suitable for the outpatient setting or home visit. The protocol consisted of an overnight (10–12 h) fast, 5–10 min supine rest, 5–10 min ‘settling in’ under the ventilated hood, and 12–16 min of measurement. Three measurements of RMR were made in eighteen healthy children (nine boys, nine girls, aged 6–11 years) on alternate days. Reproducibility of RMR was assessed using a reproducibility index and by calculating the CV for intra-individual measurements. The mean CV was 2·6 (sd 1·7)% and the reproducibility index was 95·0 %, indicating excellent reliability. The short protocol had higher reproducibility than more stringent protocols described in the literature. The new protocol has a number of practical advantages and should be adequate for most clinical or research purposes.

Homo sapiens has developed during the course of over two million years. The social and physical conditions of life, the availability of milk and infant foods as well as the presence of diseases have all undergone radical transformations from the Stone Age, at first without and then with fire, to the hunter–gatherer, farmer–herder, agricultural and, now, developed societies. These changes in the human environment may have induced modifications in the length of pregnancy, the development of the neonate at birth, the duration of lactation, the composition of breast milk and use of weaning foods and milk substitutes. Darwinian selection for the nutrient, anti-infective and other components of breast milk may have been determined by the effects of nutrition, through genetic variations in milk composition, on the survival of infants and perhaps also on fecundity and disease resistance in later adult life. Today Darwinian selection may no longer be effective in maintaining or modifying human mammary function, because modern hygienic environments, together with the availability of nutritionally adequate breast-milk substitutes, permit infant survival even under conditions of total lactational failure. National and international promulgations strictly control the composition of infant formulas offered as breast-milk substitutes or as weaning foods. These recommendations are modified as beliefs suggest, and research indicates, the effects of nutrients and other factors on the health and well-being of the child. Preliminary observations on child health have often proved valuable in furthering research. Unquestioning acceptance of apparently desirable, but untested, epidemiological associations have led to unexpected but dangerous iatrogenic problems. Recommendations for change cannot safely be made without proper comparisons with present products and procedures under practical conditions. Such tests are time consuming and require protocols of appropriate statistical design and power while still meeting the required sociological and ethical constraints, but are essential to identify possible harmful effects of any proposed change. It is suggested that no novel ingredients should be added, or major changes permitted in any component, until appropriate trials have established the value and safety of the proposed modifications. Breast-feeding is vital to maximize infant survival in developing countries. There are major difficulties in assessing any differences in morbidity and mortality of breast-fed v. artificially reared infants in the developed world. Carefully controlled studies with comparisons of health and well-being, not only in infancy but throughout life, are desirable if the effects of infant nutrition on adult well-being, suggested by epidemiological studies, are to be validated and ultimately applied. There are considerable variations in the composition of breast milk. This variance suggests that it may ultimately be possible to design formulas better able to meet the needs of individual infants than the milk available from the mother's breast.

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.

The aim of the present study was to analyse the different food and nutrition profiles of the section of the Spanish population having either a low or a high intake of energy, fat, saturated fatty acids (SFA) and fibre in order to analyse the compliance with dietary guidelines. Analyses were made from the Catalan Nutrition Survey, comprising a random sample of 1600 people aged 18 to 60. Dietary information was obtained by means of two 24 h recall, and food and energy intake was categorized according to the quartiles of fat, SFA and fibre intake. The results show the food consumption patterns that distinguish low versus high fat, SFA and fibre eaters in the Spanish population, and facilitate the establishment of food-based dietary guidelines in Spain and other Mediterranean countries.

Centrally administered glucagon-like peptide-1 (GLP-1) inhibits feeding in fasted rats, but its role in human satiety has been largely unexplored. The present study investigated the effect of peripheral GLP-1 infusion on gastric emptying and satiety in man. Ten non-obese male subjects were infused in a randomized single-blind within-subject crossover study using saline infusion as control. They received either a GLP-1 infusion (1·2 pmol/kg per min) or a saline infusion for 1 h, at 18.00 hours. At 20 min after starting the infusion the gastric emptying of a 400 ml water load was measured. Subjects completed behavioural self-rating scales to assess hunger and satiety. After 40 min subjects were given a buffet meal ad libitum and their food intake was recorded. GLP-1 infusion raised circulating GLP-1 concentrations to approximately twice those seen following a meal. It did not affect circulating insulin levels but caused a small fall in glucose levels. Gastric emptying of the water load was significantly delayed by the GLP-1 infusion. Energy intake from the buffet was unaffected by GLP-1 infusion. Self-assessment of hunger and satiety was similarly unaffected by the infusion before the buffet meal, although subjects tended to be less hungry after the buffet meal following GLP-1 infusion (P < 0·09). GLP-1 infusion delayed gastric emptying but had a minimal effect on food intake and satiety. This study casts doubts on whether GLP-1 is a major satiety factor in man, although a raised circulating plasma glucose level, as would normally occur postprandially, might be necessary for GLP-1 to increase satiety.

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.

In two separate studies, the cholesterol-lowering efficacy of a diet high in monounsaturated fatty acids (MUFA) was evaluated by means of a randomized crossover trial. In both studies subjects were randomized to receive either a high-MUFA diet or the control diet first, which they followed for a period of 8 weeks; following a washout period of 4–6 weeks they were transferred onto the opposing diet for a further period of 8 weeks. In one study subjects were healthy middle-aged men (n 30), and in the other they were young men (n 23) with a family history of CHD recruited from two centres (Guildford and Dublin). The two studies were conducted over the same time period using identical foods and study designs. Subjects consumed 38 % energy as fat, with 18 % energy as MUFA and 10 % as saturated fatty acids (MUFA diet), or 13 % energy as MUFA and 16 % as saturated fatty acids (control diet). The polyunsaturated fatty acid content of each diet was 7 %. The diets were achieved by providing subjects with manufactured foods such as spreads, ‘ready meals’, biscuits, puddings and breads, which, apart from their fatty acid compositions, were identical for both diets. Subjects were blind to which of the diets they were following on both arms of the study. Weight changes on the diets were less than 1 kg. In the groups combined (n 53) mean total and LDL-cholesterol levels were significantly lower at the end of the MUFA diet than the control diet by 0·29 (sd 0·61) mmol/l (P < 0·001) and 0·38 (sd 0·64) mmol/l (P < 0·0001) respectively. In middle-aged men these differences were due to a mean reduction in LDL-cholesterol of – 11 (sd 12) % on the MUFA diet with no change on the control diet (−1·1 (sd 10) %). In young men the differences were due to an increase in LDL-cholesterol concentration on the control diet of +6·2 (sd 13) % and a decrease on the MUFA diet of −7·8 (sd 20) %. Differences in the responses of middle-aged and young men to the two diets did not appear to be due to differences in their habitual baseline diets which were generally similar, but appeared to reflect the lower baseline cholesterol concentrations in the younger men. There was a moderately strong and statistically significant inverse correlation between the change in LDL-cholesterol concentration on each diet and the baseline fasting LDL-cholesterol concentration (r – 0·49; P < 0·0005). In conclusion, diets in which saturated fat is partially replaced by MUFA can achieve significant reductions in total and LDL-cholesterol concentrations, even when total fat and energy intakes are maintained. The dietary approach used to alter fatty acid intakes would be appropriate for achieving reductions in saturated fat intakes in whole populations.

Six healthy lean male adults, given a mixed meal containing 3190 kJ (16% from protein, 44% from carbohydrate and 40% from fat) were studied for the next 370 min using arteriovenous cannulation techniques across superficial and deep forearm tissues. The meal produced no significant change in forearm blood flow or skin temperature. The major differences between superficial and deep forearm tissues were (a) creatinine release by deep tissues but not superficial tissues; (b) the release of non-esterified fatty acids (NEFA) by superficial tissues and uptake by deep tissues; and (c) the more prolonged large positive arteriovenous concentration difference for glucose across deep than superficial tissues. The similarities were (a) general pattern of individual amino acid exchanges and transient positive amino acid N balance after meal ingestion; (b) consistent uptake of glutamate and release of glutamine (the main carrier of N out of superficial and deep forearm tissues); (c) the magnitude of the arteriovenous concentration differences for glucose, NEFA and total amino acids were related to the changes in their circulating concentrations and to the oxidation of carbohydrate, fat, and protein in the whole body; and (d) increases in the arterio–deep venous and arterio–superficial venous differences for glucose did not result in increased release of lactate, alanine or pyruvate, implying no increase in the activity of glucose–lactate and glucose–alanine cycles between forearm tissues and the liver. This study suggests that in a number of ways superficial and deep tissues can be regarded, at least qualitatively, as behaving as a ‘single metabolic unit’.

Vitamin B6 is a water-soluble vitamin, and is readily metabolized and excreted, so it has generally been assumed to have negligible toxicity, although at very high levels of intake it can cause peripheral nerve damage. Nutritional deficiency disease is extremely rare, although a significant proportion of the population shows biochemical evidence of inadequate status, despite apparently adequate levels of intake. The vitamin has been used to treat a wide variety of conditions, which may or may not be related to inadequate intake. In some conditions use of vitamin B6 supplements has been purely empirical; in other conditions there is a reasonable physiological or metabolic mechanism to explain why supplements of the vitamin many times greater than average requirements may have therapeutic uses. However, even in such conditions there is little evidence of efficacy from properly conducted controlled trials.

Seven men and seven women participated in a randomized crossover trial to study the effect of intake of parsley (Petroselinum crispum), containing high levels of the flavone apigenin, on the urinary excretion of flavones and on biomarkers for oxidative stress. The subjects received a strictly controlled diet low in flavones and other naturally occurring antioxidants during the 2 weeks of intervention. This basic diet was supplemented with parsley providing 3·73–4·49 mg apigenin/MJ in one of the intervention weeks. Urinary excretion of apigenin was 1·59–409·09 μg/MJ per 24 h during intervention with parsley and 0–112·27 μg/MJ per 24 h on the basic diet (P < 0·05). The fraction of apigenin intake excreted in the urine was 0·58 (se 0·16) % during parsley intervention. Erythrocyte glutathione reductase (EC 1.6.4.1; GR) and superoxide dismutase (EC 1.15.1.1; SOD) activities increased during intervention with parsley (P < 0·005) as compared with the levels on the basic diet, whereas erythrocyte catalase (EC 1.11.1.6) and glutathione peroxidase (EC 1.11.1.9) activities did not change. No significant changes were observed in plasma protein 2-adipic semialdehyde residues, a biomarker of plasma protein oxidation. In this short-term investigation, an overall decreasing trend in the activity of antioxidant enzymes was observed during the 2-week study. The decreased activity of SOD was strongly correlated at the individual level with an increased oxidative damage to plasma proteins. However, the intervention with parsley seemed, partly, to overcome this decrease and resulted in increased levels of GR and SOD.

Lime-treated maize husks (LTCH), a by-product of tortilla manufacturing in Mexico, have been shown to decrease plasma LDL-cholesterol levels in guinea-pigs by specific alterations in hepatic cholesterol metabolism. To determine whether LTCH would also lower plasma cholesterol levels in normal and hyperlipidaemic individuals, the fibre content of a typical diet was increased by supplementing free-living subjects in North-West Mexico with cookies containing 450 g LTCH/kg. Normal subjects (n 11) with plasma cholesterol levels of less than 5·7 mmol/l and hypercholesterolaemic subjects (n 12) with plasma cholesterol levels higher than 5·7 mmol/l participated in the study. Plasma glucose, cholesterol, triacylglycerol, LDL-cholesterol and HDL-cholesterol concentrations, LDL: HDL values and blood pressure were determined at baseline and after 6 weeks of supplementation with LTCH. LTCH supplementation significantly lowered the plasma total cholesterol level by 11–15 % and LDL-cholesterol by 25 %, and improved the LDL: HDL value by 29–33 % (P < 0·01) in both normal and hypercholesterolaemic subjects. HDL-cholesterol, triacylglycerol and glucose concentrations did not change. Both groups consumed equal amounts of LTCH per week; individuals showed excellent compliance and good acceptance of the product. Neither group changed their dietary habits during the time of the experiment as determined by 3 d dietary records at baseline and at week 6. We conclude that LTCH supplements are suitable to increase fibre intake and reduce plasma LDL-cholesterol levels in healthy and hypercholesterolaemic subjects in this population.

The effect of previous malnutrition on the metabolic response to surgical hysterectomy was investigated in adult female rats. Malnutrition was achieved by feeding a 20 g protein/kg diet and restricting food intake to 50 % of normal. This dietary regimen was maintained for 3 weeks before surgery and for 4 d after surgery. Unoperated control rats were pair-fed with the hysterectomized rats after surgery. Energy balance was measured by the comparative carcass technique and, in a second experiment, urinary N excretion was measured. Surgery caused energy expenditure to increase by 37 % in ad libitum-fed rats but in malnourished rats it increased by only 22 %. Urinary N excretion rose immediately after surgery. In the ad libitum-fed rats it was on average 85 % greater in hysterectomized rats than controls for the first 3 d after surgery, whereas in the restricted rats it was 74 % greater on the first day and not significantly elevated thereafter. Thus, malnutrition attenuated the metabolic response to surgery but did not abolish it completely.

Based on the premise that elevated blood pressure and low bone mass have both been associated with poor Ca nutriture and disturbances in Ca metabolism, a cross-sectional study was employed to determine if blood pressure and dietary Ca intake were significantly related to bone mass. Forty-seven men between 24–77 years of age with blood pressure values ranging from normal to mildly elevated comprised the study group. Blood pressure was measured with a random-zero sphygmomanometer. Bone mineral content (BMC) and density (BMD) of the hip, spine and total body were measured with dual-photon absorptiometry. Dietary intake and physical activity were also assessed. Multiple linear regression analysis was used for statistical analysis. After adjusting for known confounding variables (age, BMI, Ca intake, and others) diastolic blood pressure was negatively related to BMC (P ≤ 0·05) and BMD (P ≤ 0·01) of the total body, trochanteric region (P < 0·01) and Ward's triangle (P < 0·05), and to BMC of the femoral neck (P < 0·05) and lumbar spine, although the latter was just shy of statistical significance (P = 0·058). Systolic blood pressure was negatively related to trochanteric BMD (P = 0·04) and BMC (P = 0·06). Ca intake was positively related to total body BMD (P = 0·005), and BMC of the lumbar spine (P = 0·05). In this population of men, Ca intake was a positive predictor, and blood pressure was a negative predictor of regional measures of bone mass. These findings support the concept that independent of age, BMI and Ca intake, elevated blood pressure varies indirectly with bone mass and density, known predictors of osteoporotic fractures. Future studies are needed to determine whether elevated blood pressure is causally related to the development of low bone mass, and what role dietary Ca plays in that pathway.

Presently, no national dietary guidelines — neither food- nor nutrient-based — exist for Austria. Usually, the recommendations of the German Society of Nutrition are used instead. The determination of national characteristics of nutritional behaviour and food consumption can reveal starting-points for the improvement of nutritional status in Austria. Seven-day weighed records (children and adolescents, n = 2.173) and 24-h-recalls (adults, n = 2.488) were used for the evaluation of nutrient intake and food consumption. For a sub-sample of children and adolescents, results from laboratory assessment of biomarkers were also available (n = 1.400). Based on fat intake, the age groups were divided into low fat intake (less than 25th percentile = 28–34 % fat energy) and high-fat eaters (greater than 75th percentile = 38–45 % fat energy). Approximately 75 % of the Austrian population have fat intakes above 30 % of energy intake, older age groups having a higher prevalence of high fat intakes. Intakes of saturated fatty acids reach 40–46 % of total fat. The usual intake of dietary fibre in the Austrian population is between 17–21 g/d; some individuals are able to achieve the recommended intakes for dietary fibre, but do not represent a significant majority of the population. The mean intakes of fruits are clearly higher in children and adolescents (10 % of total food intake) than in adults (2–6 %). Differences in the intake of selected nutrients in foods between low and high fat consumers, unexpectedly, did not result in different plasma concentrations of cholesterol, nor did it result in differences in fat soluble vitamins. Therefore, one of the primary dietary guidelines for Austria should be the reduction of fat consumption, which is also associated with increasing intakes of fruits and vegetables, increasing intakes of dietary fibre and decreasing intakes of cholesterol.