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close this bookProtein-Energy Requirements of Developing Countries: Evaluation of New Data (UNU, 1981, 268 p.)
close this folderNitrogen absorption-adults
close this folderProtein absorption of adult men with intestinal helminthic parasites
View the document(introduction...)
View the documentObjective
View the documentExperimental details
View the documentSummary of the main results
View the documentConclusions and comments

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-10C; 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



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)
mg (D)
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.