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Biomedical subjects

R G Whitehead

Publications and source records attributed to R G Whitehead.

At least 55 records · Page 3Linked to original sources
PubMed1987

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.

Activities of Daily Living↗
PubMed1987

Fat gain during pregnancy in rural African women: the effect of season and dietary status.

Body-fat gain during pregnancy (weight--total body water/0.73) was measured in 50 rural Gambian women exposed to seasonal energy demands of subsistence farming and to annual preharvest food shortages. Twenty-eight women received dietary supplements in amounts previously shown to increase birth weight. In unsupplemented women, fat gain was profoundly affected by the seasons through which the pregnancy progressed, ranging from an estimated loss of 4.7 kg to a net gain of 3 kg at various times of the year. Adjustment for season revealed, however, that pregnancy per se was without effect on body fat content. Supplementation increased fat gain during pregnancy by approximately 2 kg (p less than 0.05) and gave protection against the worst effects of season on energy balance. These findings contribute to our understanding of the consequences of low food intake during pregnancy and the effects of dietary supplementation on birth weight.

Adipose Tissue↗
PubMed1987

Increased birthweight after prenatal dietary supplementation of rural African women.

Birthweight data from 197 rural Gambian women who received an energy-dense prenatal dietary supplement over a 4-y period (net intake = 430 kcal/d) was compared with data from 182 women from 4 baseline years. Preintervention birthweights averaged 2944 +/- 43 (SEM) g when women were in positive energy balance during the dry harvest season (pregnancy weight gain greater than 1200 g/mo). Birthweights decreased to 2808 +/- 41 g (p less than 0.01) in the wet season when food shortages and agricultural work caused negative energy balance (weight gain less than 500 g/mo). There were no detectable secular trends in the baseline data. Supplementation was ineffective during the dry season but highly effective during the wet season: +225 +/- 56 g, p less than 0.001 (unadjusted) or +200 +/- 53 g, p less than 0.001 (adjusted for sex, season, and parity) by between-child multiple regression analysis; +231 +/- 65 g, p less than 0.001 by within-mother analysis. The proportion of low-birthweight babies (less than 2501 g) decreased from 23.7-7.5%, p less than 0.002. The observed threshold effect emphasizes the importance of selective targeting of interventions to truly at-risk groups.

Anthropometry↗
PubMed1987

The nutritional role of breast-milk IgA and lactoferrin.

The nutritional enigma concerning the extent to which breast-milk immune proteins are digested has been investigated by measuring the intakes and faecal outputs of IgA and lactoferrin over 7 days in 10 exclusively breast-fed (BF) and 9 formula-fed (FF) fullterm infants at 6 and 12 weeks post-partum. BF outputs (mg/day) greatly exceeded FF values (p less than 0.001): at 6 weeks secretory-IgA BF = 160 +/- 28, FF = 14 +/- 2, lactoferrin BF = 14 +/- 2, FF = 0.9 +/- 0.1; at 12 weeks secretory-IgA BF = 94 +/- 17, FF = 25 +/- 5, lactoferrin BF = 7 +/- 1, FF = 1 +/- 0.3. Secretory-IgA represented 42% and 27% of BF faecal protein at 6 and 12 weeks compared with 6% for FF infants at both ages. BF secretory-IgA outputs were highly correlated with intakes (r = 0.83, p less than 0.001). IgA and lactoferrin outputs and the presence of faecal secretory-IgA fragments in BF and FF infants were influenced by defaecation rate, suggesting that partial degradation occurred in the large intestine. By 6 weeks post-partum only 1% lactoferrin and 17% secretory-IgA intakes appeared in the faeces and 95% breast-milk protein could be regarded as nutritionally available. The elevated BF outputs of IgA and lactoferrin relative to endogenous excretion suggest, however, that breast-milk may still make a considerable contribution to intestinal defence mechanisms after the neonatal period despite the small proportion of daily intake which escapes digestion. The protective action of IgA and lactoferrin may also depend on their site of degradation and the nature of fragments.

Feces↗
PubMed1987

Impaired growth in infants born to mothers of very high parity.

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.

Anthropometry↗
PubMed1986

High levels of energy expenditure in obese women.

Total free living energy expenditure was compared in lean and obese women by the new doubly labelled water method and partitioned into basal metabolism and thermogenesis plus activity by whole body calorimetry. Average energy expenditure was significantly higher in the obese group (10.22 versus 7.99 MJ/day (2445 versus 1911 kcal/day); p less than 0.001) resulting from an increase in the energy cost of both basal metabolism and physical activity. Self recorded energy intakes were accurate in the lean subjects but underestimated expenditure by 3.5 MJ/day (837 kcal/day) in the obese group. Basal metabolic rate and energy expenditure on thermogenesis plus activity were identical in the two groups when corrected for differences in fat free mass and total body mass. In the obese women in this series there was no evidence that their obesity was caused by a metabolic or behavioural defect resulting in reduced energy expenditure.

Activities of Daily Living↗
PubMed1986

Weaning practices in the United Kingdom and variations in anthropometric development.

The influence of different weaning practices on the dietary energy intake and growth of Cambridge infants has been investigated. Bottle fed children were in general given solid foods sooner, 10.6 weeks for boys and 13.9 weeks with girls: among breast-fed babies the average age was 14.9 weeks in the case of boys and 17.4 weeks for girls. All four groups of children exhibited different growth patterns from those of the NCHS and Tanner reference curves. Over the first three months both boys and girls exhibited a faster velocity of growth in weight, length and weight-for-length. After this time, however, growth velocity was slower than that of the reference children particularly among breast-fed boys who were not given solids until after 16 weeks. For most of infancy triceps and subscapular skinfold thicknesses remained around the 10th centile of the corresponding Tanner reference children, although again the babies weaned later had the lower values. Bottle-fed infants had growth patterns similar to those of the earlier weaned breast-fed babies for all parameters. It is concluded that babies grow differently now that infant feeding patterns have changed.

Breast Feeding↗
PubMed1986

Maternal nutrition and breast feeding.

In this short review we will first summarize current theories relating to maternal nutritional needs during human lactation, then deal with dietary situations where theory and experimental findings differ. In fact such a divergence occurs most of the time, both in affluent countries and especially in the Third World. We will then consider the various hypotheses which are currently being tested in an attempt to rationalize this complex but crucially important enigma. These hypotheses suggest that the mother can 'adapt' both physiologically and behaviourally in order to protect the adequate nutrition of her baby. Finally we will discuss the health significance of what happens when the mother's ability to accommodate the nutritional stresses of pregnancy and lactation fails. Although we have been asked to deal just with lactation, from time to time it will also become necessary to consider events occurring during pregnancy in order to place the nutritional stresses of lactation within a rational biological perspective. Whilst in the medical world, parturition tends to be a watershed event which divides one clinical specialty from another, in nutritional terms its main significance is merely that the mother switches feeding her baby from one part of her anatomy to another. In so far as her nutritional requirements are concerned pregnancy and lactation are part of the same continuum.

Adaptation, Physiological↗
PubMed1985

Unexpectedly low levels of energy expenditure in healthy women.

A new method for measuring total energy expenditure (TEE) with stable isotopically labelled water (2H218O) was used to measure average daily energy expenditure over 14-21 day periods in 12 healthy women following their normal activity patterns. TEE expressed as a multiple of basal metabolic rate (TEE/BMR) averaged only 1 X 38 +/- 0 X 04. This result is at variance with the widely held assumption that minimum maintenance requirements are 1 X 5 times BMR.

Adult↗
PubMed1985

The energy cost of common daily activities in African women: increased expenditure in pregnancy?

We have performed, by open-circuit indirect calorimetry, a total of 1546 measurements of energy expenditure on 142 nonpregnant, pregnant, or lactating Gambian village women. Of the 47 common daily activities measured, only 7 would be classified as moderate according to internationally accepted standards, the remainder being light (ie requiring less than 3.5 kcal/min). This was unexpected since many of the tasks, judged subjectively, appeared quite demanding. Furthermore there was no increase towards the end of pregnancy in the energy cost of a range of activities requiring 1-5 kcal/min and involving a variety of body movements, despite the substantial weight gains observed. Only for walking was there the expected increase in energy expenditure. Although in the past it has been assumed that the heavier pregnant women would require additional energy for activity, no special allowance for this is included in current dietary recommendations. The present results indicate that, for women from the developing world, no allowance is necessary. The finding that most activities were light is also of relevance to total energy requirements in this community.

Adolescent↗
PubMed1985

The human weaning process.

The weaning process in relation to the nutritional adequacy of human lactation is reviewed. Current trends in breast-feeding, both in industrialized countries and the developing world, are considered, as well as associated changes in weaning practices. Consideration is also given to infant growth patterns in the Western world and how these are being influenced by current dietary practices. The nutritional requirements of babies during the first year of life are discussed, and recent concepts indicating that current estimates might be in excess of physiologic needs are introduced. These theories are of fundamental practical importance in terms of defining the length of time that exclusive breast-feeding remains adequate and determining when the introduction of complementary foods becomes necessary on nutritional grounds. It is emphasized that the weaning process is naturally a lengthy one, lasting many months rather than a few weeks, and that the provision of additional foods need not inhibit a mother's capacity for lactation as long as these feeds are administered in the correct fashion.

Breast Feeding↗
PubMed1984

Changes in maternal and child mortality rates in three isolated Gambian villages over ten years.

As an adjunct to the general nutrition research programme, the MRC Dunn Nutrition Unit has provided for the past 10 years a continuous medical service to three adjacent rural Gambian villages. There have been substantial reductions in annual childhood mortality rates. Perinatal mortality fell from 109.6 to 45.5 per 1000 births, infant mortality from 148.5 to 24.5 per 1000 live births, and mortality in children aged 1-4 years from 109.1 to 13.3 per 1000. There have been no pregnancy-related maternal deaths in the community for 8 years; 16 could have been expected given current estimates of maternal mortality elsewhere in rural Gambia. Of all the health and nutritional interventions introduced the single most important factor has apparently been the on-the-spot, 24 h availability of a physician or qualified midwife.

Child, Preschool↗