ACTIVITY A N D ENERGY INTAKE IN UGANDAN CHILDREN

A comparison of energy intake and expenditure in a group of Ugandan children aged between one-and-one-half and three years showed that normal growth was maintained

despite a low energy intake. A reduction in physical activity appeared to be the 'adaptive mechanism" whereby energy requirements were reduced.

K e y Words: Uganda, children, energy, calories, growth, activity.

Several groups of workers studying, in the main, populations in the developing coun- tries have reported energy intakes that were considerably below the normal accepted international standards for energy require- ments. In some cases both physical and nutritional status have appeared to be normal, and this has raised the questions whether these populations have developed some adaptive mechanism to compensate for their apparent energy deficit and, i f so, what is the nature of this mechanism. Measurement of energy intake and expendi- ture within these populations usually poses technical difficulties and there is always a question of doubt with regard to the possibility that experimental error is the root cause of these discrepancies.

I . H. E. Rutishauser and R. G. White- head' have estimated the energy intake and energy expenditure of Ugandan children who were growing a t a normal rate, as well as a control group of European children living under the same climatic conditions.

The children studied, aged between 18 months and three years, were part of a group of healthy Ugandan children living in an environment where kwashiorkor i s prev- alent. The paper reports the measurements made on 20 children, three of whom were between 18 months of age and two years, and four between two and two-and-one- half years. The control group of Europeans was made up of the children of expatriate staff, the children having spent a t least six months in a tropical environment.

Standard anth ropo logica I measurements of length and weight were made a t regular intervals and these showed that over the six months of the study the rate of gain in length was similar to that found with

English children.2 The rate of gain in weight was also similar except for the youngest children, whose weight gain was a l i t t le lower.

Energy intake was estimated by two different techniques. The first was by a modified 24-hour dietary recall, where the mother was asked to give details of the child's previous day's intake when she visited the clinic. Typical Ugandan foods and household measures were available a t the clinic during the interview. The second technique involved collection of replicates of the food eaten over a seven-day period. The energy value of the diet was estimated by bomb calorimetry3 and from food tables?

The mean daily energy intakes obtained by these two procedures gave similar results with intakes ranging between 41 and 96 kcal. per kilogram body weight per day. All of the intakes about 80 kcal. per day were, however, for children having a milk supple- ment and the values for most children fell within 50 and 70 kcal. per day.

Statistical comparison of the results obtained with the two techniques showed that the mean energy intake was a little higher, 70 kcal. per kilogram per day, as estimated by the recall technique, com- pared with 65 from the analyses of replicate diets. The differences were not statistically significant and the results ob- tained by the two techniques were com- bined to give a mean intake of 67 ranging between 44 to 95 kcal. per kilogram per day.

Corresponding measurements could only be made with two of the five expatriate children constituting the control group. These gave values of over 100 kcal. per kilogram per day.

The energy expenditure of the children was measured by a simplified activity diary

84 NUTRITION REVIEWSIVOL 31. No. JIMARCH 1973

meth~d;~ the recording was done over ten-minute intervals with a mark made every time an activity occurred during the time. The same technique was used for both African and European children, but with the latter, timing the activities on a minute-by-minute basis was also employed.

To avoid disturbing the households un- necessarily, African observers made the observations on the Ugandan children and Europeans on the European children. The two groups of observers also kept records of the European children in order to obtain some estimate of observer variation. These showed no statistically significant differ- ences between observers. Statistical com- parison of the records obtained with the simplified activity diary and the conven- tional minute-by-minute activity diary showed a few differences which were statistically significant. The simplified pro- cedure tended to overestimate the time spent walking and running and to under- estimate the time spent sitting. For the purposes of the paper it was assumed that the errors in the use of the simplified method would be of the same order for both the African and European children and the results presented in the paper are based on the simplified method.

There was a distinct difference in the patterns of time spent in the various activities by the African and European children. The African children spent more of their time sitting and standing but less in being carried, walking, or running. There were no significant differences between the times spent lying down, although this was the activity that showed the greatest individual variation. The mean energy ex- penditure of the African children calcu- lated from these records was 78 kcal. per kilogram per day, compared with 98 for the European children.

The authors, in their discussion of the results, make the important point that the typical Ugandan diet, which provides 85 percent of i t s energy from carbohydrate, is much more bulky than the European diet, so that in order to obtain the same amount of energy the Ugandan child would have to eat twice the weight of food.

Children with kwashiorkor have been shown to have a lower resting metabolic rate,6 but the children in this study were not ill, and furthermore the resting meta- bolic rate rises rapidly on recovery.

The authors thus come to the conclusion that the only possible explanation of the lower energy requirement is the reduced energy expenditure associated with reduced activity .

Rutishauser and Whitehead then consider the possible implications of their observa- tions. The first concerns whether the lower level of activity of the Ugandan children plays any part in delaying development of the motor skills and mental ability associ- ated with play, a topic which they feel should be explored in greater detail.

The second concerns a more theoretical aspect, in the sense that the observed energy intake of Ugandan children is very close to the theoretical limit7 when energy requirements are met preferentially to protein requirements. They feel that this may account for the relative rapidity with which a minor infection and an associated reduction in food intake can precipitate these children into a state of protein deficiency.

The authors of this paper have attempted to measure energy intake and expenditure under technically and socially difficult conditions. They have, moreover, shown that, provided care is taken to test both the observers and the methodology, it is possi- ble to obtain results that are sufficiently reliable to make reasonably confident de- ductions.

The authors consider this work only a preliminary study, and it is possible to take exception to the choice of the children in the European group used for comparison. The differences in patterns of activity, for example, could be influenced by a number of factors, including socioeconomic and cultural ones.

Selecting and obtaining a satisfactory control group in a developing country is a matter of extreme difficulty in whatever field one is working. Doubts as to the suitability of the group used in the present study do not invalidate the, confirmation, by actual measurement, of a reduced level

NUTRITION REVIEWSIVOL. 31. No. 3fMARCH 1973 85

of physical activity and the accompanying reduced energy expenditure which in turn corresponded to the reduced energy intake. The findings indicate why the growth of these children may be normal by Western standards even though caloric intakes are low, and also make it very clear that it is difficult to evaluate the adequacy of an observed calorie intake.

1. I. H . E. Rutishauser and R. G. Whitehead, Brit. J. Nutrition 28: 145, 1972

2. J. M. Tanner, R. H. Whitehouse, and M. Takaishi, Arch. Dis. Child. 41 : 613, 1966

3. D. S. Miller and P. R. Payne, Brit. J. Nutrition 13: 501,1959

4. B. S . Platt, S;oecial Report Series Medical Research Council, No. 302. HMSO, 1962

5. R. C. Garry, R. Passmore, G. M. Warnock, and J. V. G. A. Durnin, Special Report Series Medical Research Council, No. 289. HMSO, 1955 J. G. Ablett and R. A. McCance, Lancet 2: 517,1971 D. S. Miller and P. R. Payne, J. Nutrition 75: 225,1961

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PARATHORMONE, CYCLIC AMP AND NEONATAL KIDNEYS Phosphate and cyclic AMP excretion increase from the first to the third day of life. Parathormone infusion stimulates renal cyclic AMP excretion on the third day but

not the first day, suggesting that a maturation of renal response to the hormone occurs following birth.

Key Words: parathormone, cyclic AMP, kidney, neonates, phosphate, hypocalcemia

The pediatrician‘s understanding of cal- cium metabolism in the neonatal period has long been hampered by an inability to measure essential components of the story. The recent development of sensitive assay techniques for parathormone, calcitonin, and cholecalciferol and i ts metabolites will enable the physiology of the hormonal control of calcium balance in the newborn to be described in the near future. Another important factor is the kidney. An inability to excrete the high dietary load of phos- phate in bottle-fed infants is part of the traditional explanation for the hypocal- cemic fits these babies may suffer a t about the age of one week. The phosphaturic effect of parathormone is believed to be a direct consequence of activation of adenyl cyclase in the proximal renal tubule.’ Increased urinary excretion of adenosine 3’,5’monophosphate (cyclic AMP) occurs when the kidneys are stimulated by para- thormone,’ and in the adult approximately one-third of the urinary cyclic AMP is thought to originate in the kidneys under normal conditions.

Using this information L. G. Linarelli, J. Bobik, and C. Bobik3 have studied the functional maturity of the neonatal kidney

86 NUTRITION REVIEWSIVOL. 31. NO. JIMARCH 1973

by measuring urinary cyclic AMP excretion in the newborn under normal conditions and in response to parathormone. Ten bottle-fed full-term male infants were studied on the first and third days of life. The first feeding, of glucose and water, was given at the age of 12 hours and thereafter the infants were given a formula every four hours. After the first urine had been voided al l urine was collected for 24 hours and the procedure was repeated starting between the ages of 48 and 72 hours. At the mid-point of each 24-hour urine collection blood was collected by heel stab for serum calcium, phosphate, and creatinine deter- minations. Urine specimens were pooled and then analyzed for phosphate, creati- nine, and cyclic AMP. Seven breast-fed infants were studied similarly.

The mean urine volume bS.E.1 of the bottle-fed babies was 53 ? 12 ml. on the first day, rising to 172 rf. 18 ml. on the third day. There was a large rise in phosphate excretion in the same time, from 0.31 f 0.10 mg. per kilogram per 24 hours to 15.56 rf. 2.98 mg. per kilogram per 24 hours. There was a tendency for serum calcium levels to fall and serum phosphate levels to rise on the third day, but the changes were not statistically significant. In nine of the ten infants there was an