Human nutrition. Clinical nutrition最新文献

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.

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.

Feeding histories were collected on 772 randomly selected infants visiting Maternal and Child Health Clinics in Basrah city between October 1983 and May 1984. Weight-for-age data on 557 of these infants (72 per cent) were also obtained. Over 90 per cent of infants were breast-fed initially, and prevalence rates of breast-feeding during infancy were higher among infants of low socioeconomic status (LSES) than those of high socioeconomic status (HSES). Exclusive breast-feeding declined sharply during the first 6 months of life. Supplementation of breast-feeding with bottle-feeding was common, especially among HSES infants. Methods of cleaning infant feeding bottles were more hygienic among HSES than LSES families. Comparison of the weight-for-age of infants on different feeding modes in the 2-7 months age group showed that exclusively breast-fed infants were slightly, but significantly, heavier than partially breast-fed or non-breast-fed infants. Mild faltering of weight-for-age with age was observed, relative to the NCHS median reference weight.

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.

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.

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.

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.

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.

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.