Biomedical subjects
R G Whitehead
Publications and source records attributed to R G Whitehead.
Validation of estimates of energy intake by weighed dietary record and diet history in children and adolescents.
Energy intakes assessed by 7-d weighted dietary records (EI-WDRs) and diet histories (EI-DHs) were compared with concurrent estimates of total energy expenditure (TEE) by the doubly labeled water method in 78 subjects aged 3-18 y. EI-WDRs were not obtained from the 3- and 5-y-old subjects. EI-WDRs in the 7- and 9-y-old children were 108 +/- 25% (n = 12) and 97 +/- 15% (n = 12), respectively, of corresponding TEE values showing good agreement. However in the 12-, 15-, and 18-y-old subjects EI-WDR averaged 89 +/- 12% (n = 12), 78 +/- 18% (n = 12), and 73 +/- 25% (n = 10), respectively, of corresponding TEE values. The difference was greater than or equal to 20% in 13 adolescents. Mean EI-DHs were 114 +/- 19% (3 y), 111 +/- 19% (5 y), 111 +/- 23% (7 y), 106 +/- 9% (9 y), 114 +/- 17% (12 y), 101 +/- 21% (15 y), and 98 +/- 21% (18 y) of TEE estimates. Differences were significant in the 3-, 9-, and 12-y-old subjects. Results suggest that 7-d EI-WDRs tend to underestimate food intake of adolescents. Although EI-DHs were biased towards overestimation in most age groups and individual measurements lacked precision, EI-DHs were more representative of habitual intake than were EI-WDRs.
COMA dietary reference values and the elderly.
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Vitamins, minerals, schoolchildren, and IQ.
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Potential contribution of leisure activity to the energy expenditure patterns of sedentary populations.
Total daily energy expenditure (TEE) by the doubly-labelled (2H218O) water method and basal metabolic rate (BMR) by indirect calorimetry were measured in thirty-two healty free-living adults in Northern Ireland. Habitual physical activity patterns in occupational and discretionary activities were assessed by interview questionnaire. Expressed as a multiple of BMR the TEE values for the sixteen males (1.88 (SD 0.28), range 1.44-2.57) and sixteen females (1.77 (SD 0.16), range 1.50-2.06) were compatible with current Department of Health and Social Security (DHSS; 1979) and Food and Agriculture Organization/World Health Organization/United Nations University (FAO/WHO/UNU; 1985) estimates of energy requirements. The results suggest that discretionary physical activity is now emerging as an equally important determinant of energy expenditure in the UK as the occupational classifications currently used as the basis of DHSS (1979) and FAO/WHO/UNU (1985) recommendations for energy requirements. Therefore, realistically achievable inputs of recreational exercise can have a significant impact in counteracting low levels of energy expenditure which are associated with modern lifestyles and are implicated as a risk factor for coronary heart disease and obesity.
Dietary allowances: what to recommend.
Within recent years Recommended Dietary Allowances (RDAs) have come to play a major role in a wide range of governmental, health and industrial affairs. Each of these applications, however, sets different specific requirements. All too frequently the basic RDA values end up by becoming processed in ways which exceed the limits of the science on which the recommendations were formulated. Currently, the same sets of RDAs are being applied to functions as varied as food labelling, public health assessments of populations, agricultural planning, the organisation of diets for institutional feeding and the diagnosis of under-nutrition or malnutrition. In order that these actions can be carried out effectively and meaningfully, a knowledge of how RDAs are derived and expressed is essential.
Free-living energy expenditure measured by two independent techniques in pregnant and nonpregnant Gambian women.
Free-living energy expenditure (EE) was assessed in 37 young pregnant Gambian women at the 12th (n = 11, 53.5 +/- 1.7 kg), 24th (n = 14, 54.7 +/- 2.1 kg), and 36th (n = 12, 65.0 +/- 2.6 kg) wk of pregnancy and was compared with nonpregnant nonlactating (NPNL) control women (n = 12, 50.3 +/- 1.6 kg). The following two methods were used to assess EE: 1) the heart rate (HR) method using individual regression lines (HR vs EE) established at different activity levels in a respiration chamber and 2) the doubly labeled water (2H2(18)O) method in a subgroup of 25 pregnant and 7 control women. With the HR method the EE during the agricultural rainy season was found to be 2,408 +/- 87, 2,293 +/- 122, and 2,782 +/- 130 kcal/day at 12, 24, and 36 wk of gestation and were not significantly different from the control group (2,502 +/- 133 kcal/day). These findings were confirmed by the 2H2(18)O measurements, which failed to show any effect of pregnancy on EE. Expressed per unit body weight, the free-living EE was found to be lower (P less than 0.01 with 2H2(18)O method) at 36 wk of gestation than in the NPNL group. It is concluded that, in these Gambian women, energy-sparing mechanisms that contribute to meet the additional energy stress of gestation are operating during pregnancy (e.g., diminished spontaneous physical activity).
A comparison of physical activity in Gambian and UK children aged 6-18 months.
The activity patterns of 81 Gambian and 53 UK children aged six, 12 or 18 months were compared by means of an activity diary technique. Major differences between communities were observed in the duration of play (2-3 times longer in UK compared to Gambian children) and in the duration of vigorous activities such as crawling, walking and running (2-4 times longer duration in the UK compared to the The Gambia). To investigate whether the lower activity of Gambian children could be explained by differences in nutritional or health status, subgroups of Gambian children were compared. Only small differences in activity pattern were found between Gambian children above and below 80% weight for age and between Gambian children who were or were not diagnosed ill within 10 days of study, suggesting that other factors (e.g. socio-cultural differences or the absence of conventional toys) may explain the lower activity of Gambian compared to UK children.
Accuracy of weighed dietary records in studies of diet and health.
OBJECTIVE: To provide an independent evaluation of seven day weighed dietary records, which are currently accepted as the most accurate technique for assessing habitual dietary intake in studies investigating the links between diet and health. DESIGN: Subjects who had previously participated in the Northern Ireland diet and health study were reselected by stratified random sampling to represent the range of energy intakes in the study as assessed by the seven day weighed dietary record. SETTING: Northern Ireland. SUBJECTS: 31 Free living adults (16 men and 15 women). MAIN OUTCOME MEASURES: Energy intake as measured by the seven day weighed dietary record and total energy expenditure estimated concurrently by the doubly labelled water technique. RESULTS: Average recorded energy intakes were significantly lower than measured expenditure in the group overall (9.66 MJ/day v 12.15 MJ/day, 95% confidence interval 1.45 to 3.53 MJ/day). Among those in the upper third of energy intakes the mean (SE) ratio of intake to expenditure was close to 1.0, indicating accurate records (men 1.01 (0.11), women 0.96 (0.08]. In the middle and lower thirds the ratios for men were only 0.74 (0.05) and 0.70 (0.07) respectively and for women 0.89 (0.07) and 0.61 (0.07). CONCLUSIONS: These results show a serious bias in reporting habitual energy intake. If substantiated they may have wide implications for the interpretation of many nutritional studies.
Michael Parkin--an international paediatrician.
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A whole body transportable indirect calorimeter for human use in the tropics.
A transportable, whole body indirect calorimeter, designed for use in the tropics, is described. The calorimeter was built to study energy expenditure of people having chronically or acutely low levels of food intake, and it will help to determine energy adaptations made by individuals with restricted food intake. The calorimeter comprises two units: a 27 m3 ventilated chamber connected to an office housing control and monitoring equipment. The system also allows the experimenter to assess the rate of energy expenditure by means of a ventilated hood or a baby respiration chamber. The incoming air flow rate is variable and is typically set at approximately 30 l/min. Carbon dioxide production (VCO2) and oxygen consumption (VO2) are continuously monitored by means of differential gas analysers via a computerized data acquisition unit. Gas production/consumption rates are measured with a delay of 80 s, the complete response to step changes in VCO2 or VO2 consumption being calculated over 15 min using the rate of change terms in the gas exchange equations. The total electrical power required for the whole system is 12 kW. The calorimeter has been functioning for nearly 4 years in a rural village of The Gambia during which ambient temperatures have ranged from 16 to 44 degrees C and dewpoints from -8 to 24 degrees C. The performance and accuracy of the calorimeter were tested using 20 per cent CO2 in N2 infusion and butane burning. Agreement between the theoretical and the measured values was found to be 99 per cent for VO2 and 100 per cent for VCO2 with a precision for both gases of +/- 10 ml/min over a 1-h period.
Energy expenditure of Gambian women during peak agricultural activity measured by the doubly-labelled water method.
The doubly-labelled water (2H218O) method was used to measure total energy expenditure (TEE) in ten non-pregnant, non-lactating (NPNL), six pregnant (P) and fourteen lactating (L) women in a rural Gambian community. Measurements were made on free-living subjects at a period of peak energetic stress when high agricultural work loads coincided with a hungary season to induce moderately severe negative energy balance. TEE averaged 10.42 (SD 2.08) MJ/d, equivalent to 1.95 (SD 0.38) times resting metabolic rate (RMR). The energy cost of physical activity plus thermogenesis, derived as TEE-RMR, averaged 4.94 (SD 1.96) MJ/d. Expressed per kg body-weight (103 kJ/kg per d) this component of expenditure was 2.5 times greater than comparative values from inactive, affluent women studied previously (39 kJ/kg per d). Estimated energy intake (EI) in a subset of the women (n 13) was only 4.80 (SD 1.58) MJ/d, yielding an apparent deficit of 6.08 MJ/d between EI and TEE. Weight changes suggested that endogenous fat oxidation accounted for only about 0.85 MJ/d, leaving an unexplained difference of over 5 MJ/d. Critical analysis of possible errors suggests that the new doubly-labelled water method has provided the most reliable estimates and that the estimates of EI were substantially in error. This finding has important consequences for other food intake studies.
Recommended dietary amounts for the United Kingdom.
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Identification of factors affecting infant growth in developing countries.
The anthropometric progress of seven infants was followed throughout their first year of life. Weight, length, mid upper arm circumference, triceps and subscapular skinfold thicknesses were measured on a mean (SD) of 30 (6) occasions with weight alone being measured on a further 6 (2) occasions. The effects of infection and energy intake were identified and illustrated using both standard deviation (SD) score graphs for individual subjects, and more traditionally, regression analysis for the group. Diarrhoea and vomiting, pneumonia, and diarrhoea alone each resulted in significant reductions in growth velocity of 30 g/day. Multimeasurement SD score graphs showed the effects of all illnesses, and permitted simultaneous comparison of anthropometric measurements.
Factors influencing sleeping metabolic rate in infants.
Seven West African infants were studied prospectively from birth to 1 year to investigate factors affecting sleeping metabolic rate (SMR), particularly acute infection. There was no rise in SMR associated with acute infection, after adjustment for the effects of changes in body weight and body temperature. In the case of two illnesses, malaria and 'fever', there were falls in adjusted SMR. It is suggested that these falls can be accounted for by the effects of altered energy intake. Other effects on SMR were in close agreement with previous work.
Are current dietary guidelines for young children a prescription for overfeeding?
New estimates for the energy requirements of young children have been derived by combining the energy deposited during growth with measurements of total energy expenditure obtained by use of the new doubly-labelled water (2H2(18)O) method in 355 healthy infants aged 0-3 years. The resultant values of 110, 95, 85, 83, 83, 84, and 85 kcal/kg/day at 1, 3, 6, 9, 12, 24, and 36 months, respectively, are substantially lower than current Department of Health and Social Security and FAO/WHO/UNU recommended dietary allowances. Evidence from diet surveys suggests that changes in infant feeding practices are largely responsible for the apparent reduction in energy requirements. Dietary guidelines may need to be reappraised, to avoid overfeeding of infants.
Fatness and the energy cost of carrying loads in African women.
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Energy requirements of pregnancy in The Gambia.
At most times of the year adjustments in maternal energy expenditure and energy balance in rural Gambian women can provide sufficient energy to sustain reasonable rates of fetal growth without an increase in food intake, although this study suggests that the overall level of energy intake has been substantially underestimated in the past. At certain times of year, however, pre-harvest food shortages and the energy demands of subsistence farming did substantially reduce maternal fat stores and fetal growth. Dietary supplementation, already known to increase birthweight, also had measurable effects on the mothers' physiology, resulting in increased energy expenditure on basal metabolism and improving maternal fat deposition. These findings suggest that the precise energy cost of pregnancy varies as a function of the additional energy intake consumed at this crucial period.