(introductory text...)

Objective
Experimental details
Summary of the main results
Conclusions and comments

Jin Soon Ju, W.l. Hwang, T.G. Ryu, and S.H. Oh
Department of Nutrition and Biochemistry, Korea University College of Medicine, Seoul, Republic of Korea

Objective

The digestion and absorption of protein and energy may be affected by intestinal parasite infestation. The purpose of this study is to observe the effects of intestinal helminths on the protein absorption of adult men before and after deworming.

Experimental details

1. Subjects
Twenty men were selected after a faecal screening test on 305 farmers from an agricultural village in southwestern South Korea, about 240 km from Seoul. They were 20 to 45 years old, weighed 51.8 to 72.0 kg, and measured 155.8 to 176.6 cm in height. They were healthy and had no abnormalities except for the intestinal parasites, based on medical history, physical examination, and laboratory tests (blood cells, haemoglobin, haematocrit, serum transaminases, alkaline phosphatase, and urinalysis).

2. Study Environment
The study was performed during winter in a metabolic unit. Outdoor temperature:

-2° to-10°C; indoor 18° to 22 C.

3. Physical Activity
Before the study: heavy agricultural work; during the study: light exercise.

4. Duration of the Study
Twenty-eight days divided into three periods:

a. Experimental diet before deworming: 7 days.
b. Deworming and break, free choice of diet at home: 14 days.
c. Experimental diet after deworming: 7 days.

5. Diets
Daily dietary allowances were 50 to 60 kcal/kg and 1.2 to 1.5 9 protein/kg. The subjects were given an adequate level of calories based on individual diet history. Three different daily menus, based on local diets, were offered on alternate days (see table 1). All covered daily dietary requirements. Sometimes additional food intake, mainly rice, was allowed according to individual requests, and all food intake was recorded.

Although the total energy intake varied among the subjects, based on individual dietary history (50 to 60 kcal/kg/day), it was relatively constant for each man throughout the experimental feeding periods.

Mineral and vitamin supplements were given once a day to meet recommended dietary allowances.

Three isoenergetic, isonitrogenous meals were offered at 8.30 a.m., 1.00 p.m., and 5.30 p.m. and eaten under a dietitian's supervision. Table 2 shows the essential amino acid composition of the experimental diet.

6. Anti-holminthic Treatment
Combantrin (10 mg/kg) was used to treat those without hookworms, and Amidantol (Bayer Co.) (6 mg/kg) was given to those who had hookworms with or without ascaris. The drugs were given as a single dose on the first morning of the second experimental period. (See "Duration of the Study," above.)

7. Indicators and Measurements
a. Complete urine and faecal collections were made daily throughout the experimental feeding periods before and after deworming. Faecal samples were pooled the last four days of each experimental feeding period.

b. Total nitrogen (micro-Kjeldahl), urea nitrogen (Folin-Wu), and creatinine (diacetyl monoxime) were determined in urine. Nitrogen was also measured in faeces and food.

c. Fats (Soxhlet) and ash (combustion) in food and faeces were measured. Carbohydrates were calculated by subtracting protein, fat, ash, and moisture from total weight of food and faeces. The energy contents of diets and faeces were calculated using 4, 4, and 9 kcal per gram of carbohydrate, protein, and fat, respectively.

d. True nitrogen balance was calculated assuming integumental and miscellaneous losses of 5 mg N/kg/day. The true digestibility of protein was calculated using 12 mg N/kg/day for obligatory faecal losses.

TABLE 1. Foods Offered Each Day, in Grams

	Diets
Food	A*	B*	C*
Rice, 70% polished	750	750	750
Potato	-	-	50
Vegetables	500	580	520
Soybean curd	30	30	-
Soybean paste	25	40	-
Soy sauce	-	-	30
Fruits	90	90	-
Candy	27	-	27
Crackers	-	30	-
Egg	45	45	45
Beef	20	-	45
Pork	-	20	-
Fish	60	75	40
Vegetable oil	8	3	3
Sodium glutamate	3	3	3
Energy, kcal**	3,150	3,200	3,100
Protein, g, total***	88	93	83
animal	20	22	18
Fat, % of energy	25	25	20

* A: days 1.4,7; 8: days 2,5; C: days 3,6.
** 50 to 60 kcal/kg/day.
*** 1.2 to 1.5 g protein/kg/day.

TABLE 2. Essential Amino Acid Composition of Experimental Diet A (mg/g N)*

Amino Acid	FAD/WHO mg (S)	Diet mg (D)	D/S %
Isoleucine	40	41.2	103.0
Leucine	70	70.9	101.3
Lysine	55	52.1	94.7
Methionine + Cystine	35	31.6	90.3
Phenylalanine + Tyrosine	60	69.0	115.0
Threonine	40	35.3	88.3
Tryptophan	10	10.5	105.0
Valine	50	48.9	97.8
Total	360	359.5

* Total essential amino acid intake was about 18.7 g/day.

e. The apparent biological value (by) of protein was calculated as:

BV = [N intake-(N faecal + N urinary )]/N intake

and net protein utilization (NPU) was calculated as:

NPU = digestibility x biological value

f. Subjects were weighed each morning without clothes after voiding and before breakfast.

g. Venous blood samples were drawn before breakfast on the first and last days of each experimental dietary period. Haemoglobin, haematocrit, urea, creatinine, SOOT, SGPT, thymol turbidity, alkaline phosphatase, total proteins, albumin, and total and differential leukocyte counts were determined.

TABLE 3. Parasitological Observations

Group		Egg count per gram of faeces before treatment*	Worms expelled after treatment
A	Ascaris
	lumbricoides	2,600-12,500	2
	(n = 7)	(6,800)**	(6)
B	Ascaris +	Al: 0-1,800	1-4
	hookworm	(200)	(2)
	(n = 6)	Hw; 300-12,000	1-72
		(3,000)	(28)
C	Hookworm	300-4,400	5-21
	(n = 7)	(1,200)	(11)

* All men in group A, four men in group B, and four men in group C also had Trichuris trichiura (100 to 700 eggs/g faeces) One of the men in group C also had Taenia saginata.
** Mean.

h. Quantitative parasitological stool examinations were performed daily on the first three days of each experimental feeding period. The type and number of parasites expelled in the first three days after vermicidal treatment were recorded.

Summary of the main results

1. Parasitological Observations
Table 3 shows the ova counts before treatment and the number of helminths collected during the three days after treatment. Some men did not have ova in the initial stool examination, but expelled parasites after treatment. Fifteen men also had Trichuris trichiura and one of them had Taenia saginata.

After treatment all analyses were negative for Ascaris lumbricoides and hookworm, but 13 men still had T. trichiura (100 to 300 eggs/g of faeces).

2. Body Weight
Changes before and after deworming were small and inconsistent.

3. Nitrogen Digestibility and Balance
Group results are summarized in table 4. The men in group C (without ascaris) had lower faecal nitrogen and higher apparent nitrogen digestibility after treatment. Although group B showed higher urinary nitrogen excretion after treatment, nitrogen balance, biological value, and NPU did not change in any group.

4. Dietary Energy Absorption
Before treatment, the apparent absorption was (mean ± S.D.) 95.1 ± 2.0, 94.6 ± 2.8, and 94.3 ± 2.8 per cent in groups A, B, and C, respectively. It did not change with treatment.

5. Other Observations
Only one man with hookworm was anaemic, as shown in table 5 (11.5 9 haemoglobin/100 ml). All men with hookworm showed slight increases in haemoglobin after treat ment. All other biochemical indicators remained constant, within normal ranges.

Conclusions and comments

1. The men had light intestinal loads of helminths.
2. Apparent protein digestibility improved after treatment in some but not all men. Energy absorption was not affected by the parasites.
3. Nitrogen balance was not affected by the parasites.
4. Unusually heavy infestations with an intestinal helminth can probably interfere with the intake, absorption, and retention of proteins, but the mere presence of a parasite does not justify an assumption of metabolic or clinical significance. The contribution of these parasites to protein malnutrition is often overemphasized.

TABLE 4. Nitrogen-Balance Data

Nitrogen	Group A Ascaris (n = 7)	Group B Ascaris+ hookworm (n = 6)	Group C Hookworm (n = 7)
Intake (mg N/kg/day)
Before deworming	204.9 ± 11.1	241.1 ± 9.3	2218. ± 11.3
After deworming	209.7 ± 13.8	245.6 ± 8.1	226.9 ± 6.8
Urinary nitrogen output (mg N/kg/day)
Before	135.8 ± 6.3	147.4	123.6 ± 7.6
After	136.3 ± 7.0	163.1 ± 5.9*	142.7± 9.0
Faecal nitrogen output(mg N/kg/day)
Before	44.1 ± 4.3	58.1 ± 3.3	53.1 ± 4.4
After	42.6 ± 4.3	53.6 ± 4.4	43.5 ± 4.1
Nitrogen Balance(mg N/kg/day)
Before	20.0 ± 4.3	30.6 ± 10.0	40.7 ± 6.5
After	25.9 ± 7.4	24.1 ± 9.1	35.6 ± 9.2
True digestibility (%)
Before	84.6 ± 1.0	81.0 ± 0.8	81.7 ± 1.4
After	86.0 ± 1.4	83.2 ± 1.4	86.2 ± 1.7
Biological value (%)
Before	36.3 ± 1.7	34.8 ± 3.2	43.0 ± 3.3
After	38.2 ± 2.5	31.6 ± 3.0	39.5 ± 3.9
NPU (%)
Before	30.7 ± 1.6	28.1 ± 2.1	35.4 ± 3.3
After	32.8 ± 2.3	26.3 ± 2.7	34.1 ± 3.5

Changes with deworming: * p < 0.05; ** p < 0.01.

TABLE 5. Haematological Observations

Group	Parasite	Subject no.	Haemoglobin			Haematocrit
			Initial	Final	Difference	Initial	Final	Difference
A	Ascaris Lumbricoides	4	14.5	15.5	1.0	41	45	4
		6	14.0	15.4	1.4	40	45	5
		8	14.2	14.8	0.6	40	42	2
		10	13.8	13.7	- 0.1	41	41	0
		12	13.7	13.7	0	41	40	- 1
		22	14.5	14.2	- 0 3	45	40	5
		31	14.8	15.0	0.2	43	43	0
B	Ascaris + hookworm	3	13.3	14.9	1.6	37	43	6
		7	14.5	15.7	1.2	41	45	4
		9	14.4	15.4	1.0	46	41	- 5
		21	15.0	15.6	0.6	43	45	3
		28	14.2	14.7	0.5	41	41	0
		30	14.6	15.3	0.7	43	44	1
C	Hookworm	1	16.1	17.1	1.0	48	50	2
		3	11.5	12.0	0.5	33	36	3
		11	14.0	14.6	0.6	41	43	2
		23	14.4	16.2	1.8	43	46	3
		24	13.8	14.0	0.2	40	41	1
		25	13.6	14.4	0.8	39	42	3
		29	14.0	14.6	0.6	41	42	1

 

(introductory text...)

Objectives
Experimental details
Summary of main results
Conclusions

R.E. Schneider, B. Torún, M. Shiffman, C. Anderson, and R. Helms
Institute of Nutrition of Central America and Panama (INCAP), Guatemala City, Guatemala, and Institute of Nutrition, University of North Carolina, Chapel Hill, North Carolina, USA

This brief report summarizes the results of two studies carried out with healthy adult males from the rural Pacific lowlands of Guatemala consuming a diet qualitatively similar to that habitually eaten in that region. Some of these men lived for certain periods of time in environments with improved sanitary conditions, as described below.

Objectives

1. To determine the apparent absorption of total energy, protein, and fat from the customary rural diet in: (a) military conscript males (soldiers) who were born and had lived all their life in rural Guatemala except for the two years before being studied, during which they lived in military installations with better sanitary conditions than those prevailing in their rural homes; and (b) men living in two rural communities.

2. To evaluate the effect of sanitation measures, such as the introduction of an intra-domiciliary water supply system and a sanitary education programme, on the absorptive capacity of men from one of the rural communities studied.

Hypothesis
Environmental sanitary conditions influence the capacity of Guatemalan adults to absorb the major food nutrients present in their habitual diet. if this is true, the soldiers should absorb the nutrients better than men living in their rural homes.

Furthermore, the absorptive capacity of the rural men in the community where sanitary measures were introduced should also improve.

Experimental details

1. Absorption Studies in Soldiers
One hundred soldiers who were born and had always lived in the lowlands of Guatemala and who had been for two years at an army station (MZ) near Guatemala City were interviewed and evaluated clinically. Besides being exposed during this period to improved environmental sanitation, these men had been eating a better diet than the one commonly eaten in rural areas. From this group 13 volunteers, 18 to 22 years old, who fulfilled the following criteria were selected: (a) there was no history of acute or chronic gastrointestinal diseases; (b) the result of the physical check-up was normal; (c) there was normal urinary excretion of d-xylose five hours after an oral dose of 25 9; and (d) two direct examinations of fresh stools for ova and parasites proved negative. Table 1 gives the volunteers' pertinent characteristics.

The soldiers lived for 21 days in a metabolic unit set up at the military post infirmary in Guatemala City (altitude 1,500 metres above sea level; temperature 19 to 22 C; low humidity). The experimental protocol followed was: Days 1 and 2: adaptation to the typical rural diet. Days 3 to 18: five consecutive three-day balance periods (Balances 1 to 5). Days 19 and 20 were used to complete faecal collections. A final physical check-up was done on day 21 before discharging the subjects from the unit.

2. Absorption Studies in Men from Two Rural Communities
In 1973, two villages, Guanagazapa (GU) and Florida Aceituno (FA), located in the lowlands near the Pacific coast of Guatemala, were chosen in order to carry out a study to evaluate the effect of introducing sanitation measures on the absorptive capacity of their inhabitants. The villages were within one hour's drive from Guatemala City, with a distance of 32 km between the two villages. Their altitudes were 200 and 235 m above sea level, with an annual rainfall of 2,000 mm. Temperature was 20° C during the day and cooler at night. Their populations of 973 for GU and 923 for FA were approximately 20 per cent Maya Indian and 80 per cent Ladino (mixed Maya and Caucasian descent). Both communities had water supplies of poor quality consisting of private wells and some communal faucets.

Studies were carried out for four years in both villages, divided into three stages: (a) two years of basal studies were made (1973-1974); (b) sanitary measures were implemented in GU (test village). In December 1974 an intra-domiciliary water supply system became operative, and a sanitary education programme was started in early 1975-neither measure was implemented in FA (control village); (c) two years were spent evaluating the impact of the sanitary interventions (1975-1976).

TABLE 1. General Characteristics of the 13 Soldiers Studied

Age, years	20.7 ± 1.2*
Body weight, kg	60.1 ± 4.5
Height, cm	164.0 ± 4.6
Body surface, m2	1.66 ± 0.39
Weight/height (kg/m)	37.0 ± 0.04
D -xylose, % excreted	28.3 ± 4.6
Plasma proteins, g/dl	8.1 ± 0.8
Haemoglobin, g/dl	16.4 ± 1.5
Haematocrit, %	49.0 ± 2.4
Urine analysis	Normal
Two direct stool examinations	Negative for parasites
Ethnic background	Maya Indian or Ladino (mixed Maya/Caucasian descent)

* Mean ± S.D.

In 1973, 60 male volunteers aged 14 to 45 years were randomly chosen in each community among those men who had lived there at least ten years. By 1974 some had emigrated and were replaced by others of the same ages, also chosen at random, in order to study 120 men each year. The same procedure was followed in 1975 and 1976. Therefore, at the end of the four years there was a "longitudinal" group formed of men who participated one, two, or three times in the study. Table 2 gives the number of subjects in both groups each year. All were healthy at the time of the studies. Table 3 gives their characteristics. All men had mild or moderate infestations with one or more of the following intestinal parasites: Ascaris lumbricoides, Trichuris trichiura, hookworms.

Absorption studies were carried out between May and November in four consecutive years beginning in 1973. The men were housed in groups of 8 to 10 in a rural metabolic unit built adjoining the hospital of a nearby city (Escuintla) with the same climate as that of the study villages.

TABLE 2. Number of Subjects Included in the Statistical Analyses

	Balance I				Balance II
	1973	1974	1975	1976	1974	1975	1976
Guanagazapa
Longitudinal	34	34	34	34	34	34	34
Non-longitudinal	12	13	14	15	13	14	15
Whole sample	46	47	48	49	47	48	49
Florida Aceituno
Longitudinal	28	28	28	27*	28	28	28
Non-longitudinal	18	23	23	26	23	23	26
Whole sample	46	51	51	53*	51	51	54

* One of the longitudinal subjects from FA was excluded from Balance I in 1976 due to diarrhoea.

TABLE 3. General Characteristics of the Men from Florida Aceituno (FA) and Guanagazapa (GU), 1973

	FA	GU
Number of men	46	46
Body weight, kg	50.2 ± 6.8*	57.1 ± 9.5
Height, cm	155.6 ± 6.8	162.5 ± 7.9
Body surface, m²	1.47 ± 0.13	1.62 ± 0.42
Weight/height, kg/m	32.0 ± 3.5	32.2 ± 3.1
D-xylose, % excreted	18.5 ± 6.4	19.9 ± 5.8
Plasma proteins, g/dl	6.8 ± 1.2	6.9 ±1.6
Haematocrit, %	40.6 ± 7.7	44.0 ± 4.9

* Mean ± S.D.

The groups alternated between men of each village and they lived in the metabolic unit for five days in 1973 and for eight days in each of the following years. Metabolic-balance studies began on the day after admission; in 1973 only one three-day metabolic-balance study was performed, and in each of the following years two consecutive three-day balance studies were done (hereafter referred to as Balance I and Balance II). During the last two days, faecal collections were completed and d-xylose absorption tests were carried out.

3. Rural Diet Study
The same diets were used in the absorption studies with soldiers and with men from GU and FA. The diet was prepared with the foods and recipes used by the population from which these men came, except it included certain amounts of commercial canned black beans and more animal protein, since the men did not eat meat every day at home. Table 4 gives the amounts of food offered each day, divided into three meals. These amounts provided 2,800 kcal (28 per cent of animal origin), 95 g protein (34 per cent animal protein), and 35 g fat (22 per cent animal fat). The men were encouraged, but not forced, to eat all the food served in the metabolic unit.

The maximum amount of food offered to each man from GU and FA in 1973, 1975, and 1976 provided 2,800 kcal/day, based on the mean intakes of 75 men from each village surveyed in 1972. In 1974, diets that provided 2,000, 2,400, or 2,800 kcal/day were offered during the first three days (Balance I ) to each man, depending on his personal dietary history; during the following five days (which included Balance II), food amounts equivalent to 2,800 kcal/day were offered to all men. This was done in an effort to assess the effect of the usual dietary intakes preceding admission to the metabolic unit. The proportions of nutrients offered were constant at all levels of energy intake, since the changes were achieved through proportional variations in the amounts of each food served.

4. Measurements
The amounts of each food eaten by each man were weighed at every meal, and the nutrient intake was calculated from the analyses of representative food aliquots. Complete urine and faecal collections were also obtained, using carmine red as the faecal marker. Aliquots of the foods and of the three-day stool collections from each balance period were analysed, and their contents of total energy (bomb calorimetry), nitrogen (macro-Kjeldahl), and fat (Van de Kamer) were used to calculate apparent absorptions. Urinary nitrogen was also determined (macro-Kjeldahl) to calculate apparent nitrogen balance.

Summary of main results

1. Soldiers
Table 5 summarizes the results of the five consecutive three-day balance periods. One man's data were excluded from Balances ill and IV because he had diarrhoea.

TABLE 4. Amount of Food Prepared and Offered Daily in the Metabolic Unit, in Grams

Cooked beans*	307
Fried beans*	40
Corn tortilla	570
Rice	200
Bread	45
Sweet rolls	66
Meat	1 07
Cheese	1 09
Chayote**	100
Squash	68
Carrots	66
Sugar	37

Total energy 2,800 kcal
Total protein 95 9 = 380 kcal (13.6% energy)
Total protein 95 9 = 380 kcal (13.6% energy)
Total fat 35 9 = 315 kcal (11.2 % energy)

* Black beans: Phaseolus vulgaris.
** Chayote: Sechium edule.

1. There was a clear tendency to gain weight through tout the 15 days. This suggests that energy intake was in excess of expenditure.
2. Stool weight was higher in the first balance period. This might be due to faecal residues of the food ingested before coming into the metabolic unit and suggests that two days are not enough for "adaptation" to the new diets.
3. Apparent absorption of nitrogen and of total energy was also lower during the first balance period. This is probably related to the larger faecal excretion in that balance period.
4. Urinary nitrogen excretion was constant throughout the five balance periods.
5. Nitrogen balance was lower in Balance I than in Balances II and IV. It did not differ from the overall mean balance of Balances II to V.

TABLE 5. Guatemalan Soldiers: Results of Metabolic-Balance Studies in Five Consecutive Three-Day Periods (Mean + S.D.)

Measurement	Three-day balance periods					Average of balance periods II-V	Least significant difference**
	I (13)*	II (13)	III (12)	IV (12)	V (13)
Body weight, kga	62.27 ± 3.08	62.77 ± 3.02	63.30 ± 2.91	62.47 ± 2.98	63.21 ± 2.94	62.94 ± 2.89	0.17
Stool weight, g/3 days	789 ± 303c	627 ± 291b	633 ± 255b	660 ± 273b	630 ± 261b	636 ± 261b	60
Nitrogen, mg/kg/day
Intake	289 ± 14	285 ± 14	286 ± 13	286 ± 14	285 ± 13	285 ± 13
Faecal	60 ± 16C	40 ± 20b	43 ± 20b	46 ± 20b	37 ± 14b	41 ± 18b	11
Urinary	200 ± 27	193 ± 21	213 ± 33	194 ± 29	216 ± 23	204 ± 28
Apparent	30 ± 20b	52 ± 22c	30 ± 31b	47 ± 24c	32 ± 25b	40 ± 27	15
Apparent absorption, %	79 ± 5b	86 ± 6c	85 ± 6c	84 ± 6c	88 ± 5c	86 ± 6c	3.8
Energy, kcal/kg/day
Intake	50 ± 3	50 ± 2	49 ± 2	50 ± 2	49 ± 2	49 ± 3
Faecal	6 ± 3c	4 ± 2b	4 ± 2	4 ± 1b	4 ± 2b	4 ± 2b	1.4
Apparent absorption, %	89 ± 5b	93 ± 4c	92 ± 3	92 ± 2c	93 ± 5c	92 ± 4c	3.0
Fat, mg/kg/day
Intake	556 ± 27	583 ± 28	515 ± 23	586 ± 28	547 ± 25	558 ± 38
Faecal	87 ± 32	88 ± 34	80 ± 28	71 ± 27	68 ± 31	70 ± 32
Apparent absorption,%	84 ± 6	85± 3	84 ± 5	88 ± 5	88 ± 6	86 ± 6

* Number of men in parentheses. ** L.S.D. shown only when groups differed by analysis of variance, p < 0.05.
a Linear tendency to gain weight with time. b Lower than values with superscript c, P <0.05..

2. Rural Men

1. There were some differences between Balances I and II but they were not consistent throughout the four years of the investigation. Based on these findings, on the studies in the soldiers, and on the fact that some men were offered less than 2,800 kcal of diet in Balance I of 1974, the data from the second Balance period were used for comparisons.
2. There were no consistent differences between 1974, 1975, and 1976 in FA or between 1974 and 1975 in GU. Absorption of nutrients was higher in GU in 1976 than in other years (see tables 6 and 7).
3. There were no differences between the "longitudinal" and "non-longitudinal" groups.
4. Table 6 summarizes the results of the second Balance periods in 1974 and 1976. Table 7 shows the differences in absorption of nutrients and in nitrogen balance between the two communities and between them and the soldiers.
5. The differences in nitrogen balance seem to be mainly due to the high urinary nitrogen excretion in GU in 1976. f. The men from FA had a tendency for larger stool volumes throughout the four years of the study than those of men from GU and MZ, although the differences were not always statistically significant.
6. The men from FA were thinner and weighed less. Consequently, dietary intakes per unit of body weight tended to be higher in them than in GU and MZ men.
7. The apparent absorption of nutrients was lower in 1974 and 1975 in both villages than in MZ. In 1976, however, the men from GU absorbed as well or better than those from MZ men.
8. All men from GU and FA had between one and seven intestinal parasite species at the metabolicbalance studies (A. lumbricoides, T. trichiura, hookworm, Enterobius vermicularis, Giardia tamblia, Enterococcus coli, Entamoeba histolytica). All were asymptomatic, and ova counts suggested mild-tomoderate infections. There was no correlation between apparent absorption of nitrogen total energy and the number of parasite species in the host's intestine.

TABLE 6. Guatemalan Rural Men: Results of Metabolic-Balance Studies after Three Days in the Metabolic Unit (Balance I I, Longitudinal Group) and Comparison with Soldiers^a

Measurement	FA—1974 n=28b	GU—1974 n=34	FA—1976 n=28	GU—1976 n=34	MZ—11 n=13
Body weight, kg	50.35 ± 5.67c	58.86 ± 10.39	51.02 ± 5.51	60.69 ±10.53	62.77 ± 3.02
Stool weight, g/3 days	1,056 ± 442	776 ± 238	928 ± 442	759 ± 229	627 ± 291
Nitrogen, mg/kg/day
Intake	324 ± 46	300 ± 62	329 ± 42	303 ± 49	285 ± 14
Faecal	83 ± 32	70 ± 29	71 ± 24	44 ± 20	40 ± 20
Urinary	194 ± 40	171 ± 51	220 ± 37	225 ± 46	193 ± 21
Apparent balance	59± 62	79 ± 25	34 ± 39	31 ± 26	52 ± 22
Apparent absorption, %	75 ± 8	77 ± 8	78 ± 9	84 ± 6	86 ± 6
Energy, kcal/kg/day
Intake	57 ± 8	53 ± 10	56 ± 6	49 ± 8	50 ± 2
Faecal	7± 3	5± 2	6± 3	3± 1	4± 2
Apparent absorption, %	88 ± 5	90 ± 3	89 ± 6	95 ± 2	93 ± 4
Fat, mg/kg/day
Intake	702 ± 78	589 ± 106	574 ± 60	573 ± 89	583 ± 28
Faecal	150 ± 51	115 ± 45	96 ± 46	54 ± 26	87 ± 34
Apparent absorption, %	79± 6	81± 6	84± 7	91± 7	85±3

1. Men from villages FA and GU in 1974 and 1976, and soldiers from MZ (Balance 11).
2. Number of men.
3. Means ± S.D. Results of comparisons betueen groups shown in table 7.

TABLE 7. Comparisons between the Second Metabolic-Balance Periods Rural Men (FA and GU,1974 and 1976) and Soldiers (Mz)a

	FA-1974 Compared with				GU-1974 Compared with			GU-1976 Compared with
	GU		FA	GU		GU	FA		FA
	1974	MZ	1976	1976	MZ	1976	1976	MZ	1976
Stool weight, 9/3 days	­ **b	­ **	-	­ **	-	-	-	-	-
Apparent absorption
Nitrogen	-	¯ **	-	¯ **	¯ **	¯ **	-	-	­ **
Total energy	-	¯ **	-	¯ **	¯ **	¯ **	-	-	­ **
Fat	-	¯ **	¯ **	¯ **	¯ **	¯ **	-	­ ***	­ **
Nitrogen balance, mg/kg/day
Intake	-	­ **	-	-	-	-	¯ *	-	¯ *
Faecal	-	­ **	-	­ **	­ **	­ **	-	-	¯ *
Urinary	-	-	¯ **	¯ **	-	¯ **	¯ **	­ *	-
Balance	-	-	-	­ *	­ **	­ **	­ **	¯ *	-

a From data shown in table 6.
b Mean values were higher ( ­ ) or lower ( ¯ ) based on student's grouped ''t" test with p < 0.05 (*) or 0.01 (**).

Conclusions

The results indicate that adult men from rural areas of a developing country who live under conditions of poor sanitation, without appropriate use of potable water, and who eat diets largely based on corn and black beans with some animal protein and low fat (about 11 per cent of total energy intake) have apparent absorptions of the order of 90 per cent of total energy, 75 to 80 per cent of protein, and 75 to 85 per cent of fat. It is also evident that these men's absorptive capacity improves after they have lived for two years in environments with better sanitation and have modified their hygiene habits through education. Their apparent absorptions become about 93 per cent of total energy, 85 per cent of protein, and 90 per cent of fat.

If we assume faecal obligatory losses of 12 to 14 mg N/kg/day, the "true" nitrogen digestibilities would be about 5 per cent higher than apparent digestibilities.

The diets used in this study were typical of the region, although their protein content (P% about 13.6 ) and the contribution made by protein of animal origin (about 34 per cent of total protein) were higher than those in the diets of most men of similar ethnic, cultural, and socioeconomic conditions in other parts of the country. It is conceivable that protein absorption may be somewhat lower in the latter, whose diets have a P% closer to 10 than 13, with animal proteins contributing only 20 to 25 per cent to the total.

The results obtained also indicate that future research studies involving measurements of absorptive capacity in rural subjects should allow about five days of dietary adaptation before starting the metabolic-balance studies.

Acknowledgements

These studies were done as part of a project carried out jointly by the University of North Carolina and INCAP with the economic support of the US Agency for International Development. The United Nations University contributed support for the last stages of data analysis.

(introductory text...)

Objective
Experimental details
Summary of main results

Chen Hsue-cun
Institute of Health, Chinese Academy of Medical Sciences, Beijing, China

Objective

Several studies have been conducted by Chinese nutritionists in the last 30 years to assess energy intake, expenditure, and requirements of Chinese men and women engaged in various working activities. A summary of the main results will be presented.

Experimental details

1. Energy Intakes
Energy intakes were calculated from individual dietary surveys.

2. Energy Costs of Activities
Energy costs of activities were calculated by indirect calorimetry using Douglas bags and analysing the O2 and CO2 contents of exhaled air. Measurements were obtained under basal conditions, at rest and at work.

3. Energy Expenditures
Energy expenditures were calculated using time-motion techniques and the average energy cost of work.

Summary of main results

1. Basal Energy Expenditure of Young Men
The mean value obtained from 19 college students 20 to 30 years old was 0.63 kcal/m2 of body surface/minute.

2. Energy Expenditure of College Students
Table 1 shows the energy cost of different activities of college students. The mean total energy expenditures of 16 men and 6 women were 2,420 and 2,170 kcal/day, respectively.

The make-up of the dietary energy absorbed by 9 men was 12.0 per cent from proteins, 27.9 per cent from fats, and 60.1 per cent from carbohydrates. Based on their non-protein respiratory quotient and urinary nitrogen, the different sources of expended energy were 12.3 per cent from proteins, 28.8 per cent from fats, and 58.9 per cent from carbohydrates.

3. Energy Expenditures of Iron and Steel Workers and of Coal Miners
Tables 2 and 3 give the mean energy expenditure of men engaged in these physically demanding jobs. The figures include the pauses and resting periods during the eight-hour shift. The average cost (kcal/min/m2) of the specific activities performed by the men varied widely. For example, among iron and steel workers, energy costs ranged from 1.67 while putting core into moulds and 1.71 when walking in the furnace area, to 4.93 during heavy hand-rolling. Among coal miners, the energy costs ranged from 1.60 while packing holes with explosives and 1.75 while drilling rocks, to 4.43 when climbing in the wind tunnels, and 5.09 carrying trestles in such tunnels.

4. Dietary Intakes of Workers
Table 4 gives the mean energy and protein intakes of labourers engaged in different jobs in several provinces of China.

5. Energy Expenditures of Peasants
Tables 5 and 6 give the energy costs of work-related activities for male and female peasants. Total energy expenditure varies cyclically, being greater during the summer harvest and spring digging. Table 7 gives time allocations in the various seasons, and table 8 gives some of the corresponding total daily energy expenditures of men and women engaged in different agricultural chores.

TABLE 1. Energy Cost of Different Activities of College Students

Sedentary	Activity	Energy expenditure
		(kcal/m /mm)
	Lying at ease	0.65 (0.58 - 0.74)*
	Sleeping	0.73 (0.69 - 0.82)
	Snooze; resting between classes;
	reading Iying down	0.79 (0.65 - 0.89)
	Sitting (watching movie; watching demonstration;
	writing; reading; studying; attending meeting)	0.82 (0.71 - 1.08)
	Taking examinations	0.92 (0.73 - 1.02)
	Writing on blackboard; standing and listening	0.98 (0.88 - 1.09)
	Working in laboratory	1.00 (0.71 - 1.19)
	Cleaning window	1.98 ( - )
	Dressing or undressing	2.20 (2.06 - 2.23)
	Making bed	2.26 (2.20 - 2.32)
	Washing clothes	2.36 (2.17 - 2.56)
Moderate	Standing and conducting singing	2.64 (2.37 - 2.92)
	Ordinary morning drill	2.65 (2.22 - 3.80)
	Walking	2.70 (2.33 - 3.30)
	Cleaning floor	2.72 (2.62 - 2.81)
	Broadcast drill	2.77 (2.56 - 2.98)
	Scrubbing floor	2.82 ( - )
	Dancing	4.03 (3.31-4.80)
	Playing baseball	4.03 (3.91 - .1 5)
Vigorous	Playing volleyball	4.07 (3.82 - 4.32)
	Running	5.30 (3.85 - 6.75)
	Playing basketball	5.78 (5.00 - 7.92)
	Playing football	5.96 (5.33 - 6.60)

* Mean, with range between parentheses.

TABLE 2. Energy Expenditure of Iron and Steel Workers in an Eight-Hour Shift

Type of work	Working time (%)*	Energy cost of work		Total energy expenditure (kcal/man/8 hrs)
		(kcal/m²/min)	(kcal/min)
Furnaceman	55	1.86	2.92	1402
Ore-carrying worker	72	3.06	5.28	2534
Ore-sieving worker	60	2.71	4.97	2386
Blast furnaceman	72	2.97	4.82	2314
Sintering (non-mechanized)	80	2.69	4.42	2122
Open-hearth furnace	42	1.77	2.84	1363
Electric open-hearth	40	1.78	2.86	1373
Coke-oven man (mechanized)	70	1.95	2.95	1416
Coke-oven man (semi-mechanized)	60	1.60	2.41	1157
Rolling worker	55	1.66	2.71	1301
Rolling worker	46	1.52	2.36	1138
Tube-casting foundry work
Moulder	75	1.60	2.58	1238
Core layer	46	1.40	2.25	1080
Fettling work	59	1.92	2.89	1387
Fettling work	63	1.88	3.21	1541
Chassis-making	74	2.12	3.40	1637
Core removal	82	1.93	3.10	1488

* The remaining time was spent in pauses and rest periods.

TABLE 3. Energy Expenditure during Coal Mining in an Eight-Hour Shift

Type of work	Working time (%)	Energy cost of work		Total energy expenditure (kcal/man/8 furs)
		(kcal/m²/min)	(kcal/min)
Coal miner	56	2.21	3.45	1655
Coal-timbering worker	56	2.28	3.55	1702
Coal-drilling worker	64	1.93	3.01	1444
Blasting worker	82	2.35	3.66	1756
Tunnelling worker	58	1.81	2.92	1403
Rock-transferring worker	48	1.95	3.63	1513
Timbering worker	63	2.09	3.35	1607

* The remaining time was spent in pauses and rests.

TABLE 4. Dietary Energy and Protein Intakes of Workers

Type of work	Location	Energy (kcal)	Protein (g)
Iron and steel work	Wuhan	4028	125
Iron end steer work	Hunan	3368	110
Iron and steel work	Anshan	3921	132
Electric power industry	Chonguing	3112	105
Coal mining	Anhui	3713	96
Iron factory	Hangzhou	3347	80
Machine factory	Guangxi	3168	86
Silk plant	Hangzhou	2885	89
Building worker	Beijing	3614	108
Mining	Guangdong	3950	86

TABLE 5. Energy Cost of Activities Performed by Male Peasants during Work

Activity	kcal/m2 /min
Resting	1.02
Loading corn onto carts	1.30
Pulling radishes by hand	1.54
Winnowing beans	1.54
Picking corn	1.57
Mowing beans	1.82
Binding corn stalks	1.89
Picking potatoes with hoe	1.97
Weeding with hoe	2.03
Walking	2.13 ± 0.39
Transplanting rice seedlings	2.28 ± 0.31
Spreading manure	2.30
Picking corn roots with hoe	2.51
Raking the soil	2.71
Weeding seedling fields	2.72 ± 0.33
Mowing wheat	2.79 ± 0.20
Picking radishes with hoe	2.93
Light ploughing	2.94 ± 0.18
Carrying water in pails	3.19 ± 0.14
Weeding rice fields (shallow)	3 33 ± 0 54
Carrying manure in holder on shoulder	3 50
Shovelling earth	3.51 ± 0.08
Planting fields	3.91 ± 0.35
Weeding rice fields (deep)	4.12 ± 0.42

TABLE 6. Energy Cost of Activities Performed by Female Peasant during Work

Activity	kcal/m2 /min
Resting	0.88 ± 0.28
Spreading fertilizer (standing)	1.62 ± 0.22
Mowing wheat	1.79 ± 0.06
Weeding rice field	1.91 ± 0.16
Walking	2.00 ± 0.29
Spreading manure	2.95 ± 0.14
Spreading fertilizer (stooping)	3.04 ± 0.21
Thinning young shoots	3.16 ± 0.33
Pulling up wheat	3.30 ± 0.21
Shovelling earth	3.44 ± 0.14
Planting fields	3.86 ± 0.63

TABLE 7. Distribution of Daily Time in Hours

	Spring and autumn		Summer		Winter		Summer harvest		Deep digging
Type of work	Part- time labour	Full- time labour	Full- time labour	Part- time labour	Part- time labour	Full- time labour	Part- time labour	Full- time labour	Part- time labour	Full- time labour
Productive labour	7.5	8.25	6.0	7.0	6.0	7.0	9.0	11.5	8.2	10.75
Sleeping	8.5	8.5	9.0	9.0	10.0	10.0	8.5	6.5	9.0	7.5
Taking meal	1.5	1.5	1.5	1.5	1.0	1.0	2.0	2.0	2.0	2.0
Sewing	0.5	0.0	1.0	0.0	1.5	0.0	0.0	0.0	0.0	0.0
Cleaning street	0.25	0.0	0.25	0.25	0.25	0.25	0.25	0.0	0.25	0.0
Rest	1.0	1.0	1.0	1.0	0.5	0.5	1.0	1.0	1.5	1.5
Reading and attending meeting	1.5	1.5	1.0	1.0	2.0	2.0	0.0	0.0	0.0	0.0
Toilet	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
Dressing and undressing	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5	0.5
Chatting	0.5	0.5	1.0	1.5	0.75	1.0	0.25	0.25	0.5	0.0
Washing clothes	0.5	0.0	1.0	0.0	0.25	0.0	0.25	0.0	0.25	0.0
Carrying water	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25	0.25
Walking	1.0	1.5	1.0	1.5	0.5	1.0	1.5	1.5	1.0	1.0

TABLE 8. Average Daily Energy Expenditure (kcal) of Male and Female Peasants in Spring, Fall, and Summer

Type of work	Average daily energy expenditure in spring and fall			Average daily energy expenditure in summer
	Male	Female		Male	Female
	Full-time labour	Full-time labour	Part-time labour	Full-time labour	Full-time labour	Part-time labour
Light ploughing	3,898	-	-	3,691	-	-
Spreading	-	3,408	3,310	-	3,310	3,055
Thinning young shoots	-	3,647	3,445	-	3,365	3,102
Spreading fertilizer (stooping)	-	3,563	3,369	-	3,437	3,163
Planting field	4,681	4,189	3,938	4,356	3,897	3,558
Shovelling earth	4,343	3,886	3,663	4,069	3,640	3,337
Mowing	-	-	-	4,538	3,003	2,740
Pulling up wheat	-	-	-	-	4,568	4,008
Deep digging	4,954	4,435	3,812	-	-	-