Studies were carried out in eight normal adults to simplify the continuous infusion-end product method for measuring whole-body protein turnover using 15N-glycine. When a priming dose of label suitable for the urea pool was followed by intermittent oral doses of label, plateau enrichment was maintained in urinary urea and ammonia from 9 to 18 h, giving values for nitrogen flux (18 h) of 0.69 +/- 0.05 g N/kg/d with urea and 0.46 +/- 0.01 g N/kg/d with ammonia. With a priming dose appropriate for the ammonia pool, plateau was reached in urinary ammonia in less than 120 min and maintained for up to 6 h. Nitrogen flux (3 h) with oral 15N-glycine was 0.96 +/- 0.12 g N/kg/d, and with intravenous label was 0.61 +/- 0.13 g N/kg/d. There was a significant linear relationship between flux measured with oral and intravenous isotope. It is suggested that different components of protein turnover are measured with the different approaches, and that the short method in particular measures rapidly turning over proteins associated with the gastrointestinal tract.
The pattern of excretion of taurine was measured in four omnivore and four vegan/vegetarian women during pregnancy and lactation, and was compared with the changes in urinary excretion of other amino acids, including the precursors of endogenous taurine, observed in ten pregnant omnivores. The loss of taurine in breast milk was also determined in fourteen omnivore and fourteen vegan mothers. In contrast to the rise in excretion of all amino acids during pregnancy, including methionine and cysteine, taurine excretion fell dramatically from week 9 of pregnancy in all subjects, and, in the vegan/vegetarian subjects, fell still further during lactation. Although the concentration of taurine in breast milk was lower in vegan subjects, the mean value fell within the range found in omnivore subjects. Our findings indicate that the suppression of urinary taurine excretion, both during pregnancy and lactation, is a physiological response to reproduction that satisfies the needs of the fetus and the suckling infant for this amino acid. The data also suggest that taurine is stored in the maternal tissues in early pregnancy for later transfer to the fetus.
Cooked dried legumes have been shown to stimulate low blood glucose responses, and their consumption by individuals with diabetes has been encouraged. However, canned beans are more convenient to use than dried beans. Since the glycaemic effects of canned beans have not been determined, we fed 50 g carbohydrate portions of five varieties of beans, both cooked dried and canned, to groups of diabetic patients and calculated their glycaemic indices (GI). All canned and dried beans tested had significantly lower GIs than that of white bread, which was ascribed a GI of 100. The mean GI of the five types of canned beans, 71 +/- 4, was less than that of bread, 100 (P less than 0.001), and greater than that of the same five varieties of cooked dried beans, 47 +/- 5 (P less than 0.001). It is concluded that the glycaemic effect of dried legumes is increased by the canning process. Nevertheless, canned beans give lower blood glucose responses than bread and may be of use in low glycaemic index diets.
Nutritional factors associated with intrauterine growth retardation (IUGR) were studied in 118 mothers, from an inner London population, 24-48 h after delivery. Lower socio-economic status, smoking and, in the diet, only a low dietary intake of zinc were significantly associated with IUGR. It is suggested that women at risk of delivering babies small-for-gestational-age might benefit from an increased zinc intake.
The contractile properties of the adductor pollicis and quadriceps muscles have been studied before and 4 and 10 d after major abdominal surgery in 15 patients. Eight patients were considered well nourished and 7 malnourished on the grounds of body mass index, recent weight loss and serum albumin. There were no significant changes in the contractility of the adductor pollicis at 4 and 10 d post-operatively compared to pre-operative values. The only change in the quadriceps was seen in the malnourished patients and was a potentiation of the force:frequency relationship at day 4, affecting force generation at 1 Hz. There was a tendency for the malnourished patients to generate higher forces at low stimulation frequencies and to have slower relaxation rates, but there was no significant difference between the two groups. Pre-operative contractile properties of those patients who developed post-operative complications were not different from those who were free of complications, nor did the post-operative results of the two groups of patients differ. The patients generated higher forces at lower stimulation frequencies than is usually found in young normal subjects. This may be due to age, disease or nutritional factors, but it is not possible to determine the relative contributions of these factors from this study.
Protein turnover was studied in nine non-pregnant (NP) and eight pregnant (P) women. The data from two gestational diabetic (GDM) women are included for comparison. Pregnant women were studied at 30-36 weeks gestation. Whole-body protein turnover, synthesis and catabolism rates were measured using a single dose of 15N-glycine followed by measurement of enrichment of urinary ammonia during the next 10 h. P and NP women had similar rates of protein turnover (4.8 g protein/kg/d) and synthesis (3.8 g protein/kg/d). GDM women appeared to have considerably higher rates for both turnover (5.6 g protein/kg/d) and synthesis (4.7 g protein/kg/d). Normal pregnant women excreted significantly more urinary 3-methylhistidine (3MH) than did non-pregnant women (190 vs 149 mumole/d). Correlation between 3MH excretion and protein catabolism rate approached significance (P = 0.087) in the NP women, but was poorly correlated (P = 0.355) in the P women.
The basal metabolic rate (BMR) and diet-induced thermogenesis (DIT) in 11 Asians (4 men, 7 women) who had lived in Britain for longer than 2 years were compared with a matched group of Europeans. The mean basal oxygen consumption was 226 ml O2/min in the Asians and 218 ml O2/min in the Europeans, values not significantly different. When BMR was expressed in absolute terms, per unit body weight, per unit body surface area or lean body mass, still no significant difference was observed. DIT was measured in the two groups fed a mixed meal containing 2800 kJ. The main increase in the metabolic rate over 20-120 min was 19 per cent in the Asians and 20 per cent in the Europeans. These results indicate that, in contrast to Asians living in the tropics, Asians living in Britain show no difference in BMR or DIT. It is concluded that Asians living in the temperature regions behave metabolically differently from those living in the tropics.
Indirect test weighing (ITW), for estimating night-time breast milk intake, is based on separate weighings of mother and infant before and after night-time sleep. Weight changes due to the exchange of milk overnight are reciprocal, so that if all other sources of weight change (eg, urine loss, supplementary fluid intake) are either controlled or measured, the difference between the mother's overnight weight loss and her infant's overnight weight gain represents their combined net evaporative water loss (EWL). The proportion of the combined EWL due to the infant is partitioned out as a function of the relative metabolic body sizes (kWt0.73) of mother and infant, and added to the infant's net overnight weight gain to provide an estimate of night-time breast milk intake. Validation studies, conducted in Northern Thailand, in which ITW was compared with direct test weighing (DTW) at each night feed, are reported for 13 infants over 3 nights at 5 d of age, and for 19 infants over 2 nights at 6 weeks of age or more. The regression equation for estimated milk intake against measured milk intake across all ages was y = 0.988x + 2.75, r = 0.927, n = 69 with 95 per cent prediction intervals of +/- 36 g for a range of intakes of 0-250 g. Rigorous control of data collection and taking account of the infant's age suggest that the prediction intervals for individual estimates can be improved to +/- 18 g at 5 d, and +/- 27 g at 6 weeks and over. Theoretical aspects of the relationship of EWL to body weight are discussed with a view to optimizing the accuracy of the technique.
Four hundred babies were recruited at birth and visited at intervals of 2 weeks. At each visit weight, length and morbidity were recorded. Growth in weight and length began to fall below the international reference by 5 months. 'Faltering' was defined as a weight gain less than the reference -1 s.d. for two consecutive 2-week periods. Fifty per cent of children had begun to falter by 16 weeks. Initially almost all the children were exclusively breast-fed. The mothers were neither encouraged nor discouraged from introducing supplementary food; 50 per cent had done so by 16 weeks. There were only minor differences in attained weight, length, weight gain and length gain between supplemented and unsupplemented children. The results emphasize the wide variability in this population both in feeding patterns and in growth from period to period. Although the average outcome was satisfactory, this average conceals a minority whose growth was unacceptably low.
Anthropometric data are presented on 412 rural Gambian infants measured longitudinally from birth to 18 months of age. Maternal parity was shown to exert a marked influence on growth. Firstborn babies had significantly depressed birthweights (parity 1: 2.79 +/- 0.06 kg, n = 62; parities 2-9: 3.05 +/- 0.09 kg, n = 309; P less than 0.001) but catch-up growth was complete by 3 months. In contrast, children born to mothers of very high parity (10 and above) had average birthweights (2.90 +/- 0.07 kg, n = 41) but early growth was poor. At 3 months their weights, mid-upper arm circumferences and triceps skinfolds were significantly below those of other infants (eg, weight-for-age (% NCHS): parities 10+: 90.3 +/- 2.3 per cent; parities 2-9: 97.4 +/- 2.7 per cent; P less than 0.01). Supine length and head circumference were not affected. After 3-6 months all children experienced severe growth retardation reflected in poor weight, length and head circumference gains. No catch-up growth occurred in the high parity group. Consequently, anthropometric differentials set up by 3 months were maintained throughout infancy (eg, weight-for-age at 12 months: parities 10+: 76.4 +/- 1.9 per cent; parities 2-9: 81.5 +/- 2.6 per cent; P less than 0.01). The relationship between these infant growth patterns and maternal lactational performance is discussed.
Menstrual cycle and menses lengths were determined in 31 healthy premenopausal women randomized into one of two sets of weight-maintaining diets, those with a ratio of polyunsaturated to saturated fatty acids (P/S ratio) of 1.0 and those with a P/S ratio of 0.3. After a baseline interval of one menstrual cycle, both groups were fed a high fat diet (40 per cent energy from fat) for four menstrual cycles per subject, followed by a similar interval on a low fat diet (20 per cent energy from fat). There was a significant increase of 1.3 d (P = 0.02) in the average menstrual cycle length and 0.5 d (P = 0.01) in menses length on the low fat diet. Although no significant differences were evident between the P/S groups, the effect of low fat on menstrual cycle and menses length was most pronounced in the P/S = 1.0 group.
The resting metabolic rates (RMRs) of 10 adult males of body mass index around 19 were estimated between 6-36 (mean 18.2 +/- 2.3) months of an earlier recording. There were no significant differences in the body weights, RMRs and respiratory quotients (RQ). The coefficients of variation (CV) of intra-individual differences in body weight and RMR were both 2.5 per cent. In those subjects who showed a change in body weight ie, greater than +/- 1 kg over a period of 22.0 +/- 3.0 months, the CV (4.3 per cent) of weight change was greater than the CV (1.9 per cent) of intra-individual differences in RMR.
Forty-three apparently healthy young adult male volunteers underwent an evaluation of their nutritional status, blood chemistry and faecal excretion of enteropathogens, which did not reveal current malnutrition or illnesses. Ten of them were further studied for small intestinal histology, culture of aerobic and anaerobic bacteria in the duodenal juice, disaccharidase activities, glucose absorption and faecal excretion of fat and nitrogen. The study revealed mild morphological changes associated with the appearance of anaerobic bacteria in the upper intestine, decreased glucose transport and increased faecal losses of nitrogen. Although all these changes were rather mild, they may be significant for people whose diet is of borderline nutritional quality.
The concentration of magnesium in muscle was determined and a standardized magnesium load test was performed in 21 patients, who 4 to 10 years previously had undergone intestinal bypass operations for severe obesity. The plasma concentration and 24-h urinary excretion of magnesium were also studied. Basic urinary excretion of magnesium and muscle magnesium were significantly lower in patients compared to healthy controls, while no differences were found in plasma magnesium. A slight negative correlation between muscle magnesium and retained magnesium was demonstrated (r = -0.51, P less than 0.05). Patients with magnesium retention greater than 20 per cent showed a significant decrease of magnesium retention after treatment with magnesium chloride mixture. Four patients with primarily low muscle magnesium all demonstrated an increment in the amount of magnesium in muscle after treatment. The load test described can be applied as a screening test in diagnosing magnesium deficiency.
To study the interaction between diarrhoea and malnutrition, an average of 300 children aged 5-24 months were followed from January 1981 to January 1983 in Teknaf, Bangladesh. Diarrhoea episodes, differentiated according to stool appearance, were recorded weekly while weight and height measurements were taken every 6 months. Results showed no relationship between the nutritional indicators and diarrhoea incidence recorded within 60 d after anthropometric assessment. However, the duration of dysentery was significantly longer in the severely malnourished children who were stunted but not for those wasted. Although many children with watery diarrhoea had episodes of long duration, these were not associated with any nutritional indicator. We conclude that the key factors in this interaction are the invasive type of pathogen and chronic malnutrition.
Anthropometric parameters (height and weight) were used to assess the nutritional status of 1407 black children in a Soweto lower primary school. Cross-sectional profiles were obtained in 1981 and 1983 as well as a longitudinal study of 362 pre-adolescent children who remained in the school over the 2-year period. The major proportion of the distribution of percentage weight-for-age and percentage height-for-age was less than 100 per cent of NCHS reference median. There was a small but significant increase in mean percentage weight-for-height between 1981 and 1983. Children who were stunted and those whose growth rate over a 2-year period was known to be reduced failed more frequently. Apart from these the general range of anthropometric findings did not clearly correlate with classroom achievement as assessed by end-of-year marks. The age ranges of children in the different grades exceeded 5 years. The highest failure rate occurred in the school entry grade (Substandard A). Only in this grade were the older boys found to be less adequately nourished than their age peers in higher standards. Untested adverse social, family and environmental effects may mask the real consequences of suboptimal growth. Without anthropometry the latter would frequently not be apparent because of the generally proportional reductions in weight and height for age.
Rates of oxygen consumption and carbon dioxide production have been measured in healthy adults during 4 h of fasting followed by 4 h of hourly small meals. Both rates rose to new steady values during feeding, and the respiratory quotient (RQ) increased from 0.792 to 0.924. The RQ was consistent in repeat studies on any individual (coefficient of variation: 2.5 per cent), and differences between individuals were significant in the fasted but not the fed state. Simultaneous measurements were made of the rate of protein oxidation by primed constant infusion of (1-13C)leucine for 8 h. Rates were calculated from the enrichment of plasma alpha-ketoisocaproate and the production of 13CO2 in the breath, taking account of the incomplete recovery of 13CO2 and the changes in baseline enrichment resulting from natural 13C in the food. Leucine oxidation increased by 87 per cent during the feeding period. Rates of nutrient utilization were calculated from respiratory gas exchange and rates of protein oxidation. These showed that fat was predominant in the fasted state, contributing 61 per cent of total energy expenditure, compared with 27 per cent for carbohydrate and 11 per cent for protein. On feeding there was a switch to carbohydrate as the main fuel (62 per cent), with smaller contributions from fat (20 per cent) and protein (18 per cent). During feeding total utilization of each nutrient exceeded its intake from the diet, indicating storage in the body. Dietary carbohydrate was stored without conversion to fat. It is concluded that this method is useful for studying the control of nutrient utilization by food intake.
