Experimental details

1. Subjects
Thirteen adult male Thai students and laboratory assistants participated in the study. Table 1 shows their characteristics. They were healthy and well-nourished, based on medical history, physical examination, urinalysis, stool examination, chest x-ray, and a routine complete blood count.

2. Study Environment
The entire study was conducted at the clinical research ward (a metabolic unit) in Ramathibodi Hospital. Temperature and humidity were those typical of tropical countries.

3. Physical Activity
The subjects were allowed to continue their usual activities but not to participate in competitive, heavy sports.

TABLE 1. Initial Characteristics of 13 Adult Thai Male Subjects

* Also participated in study on obligatory nitrogen losses.

4. Duration of the Study
Five men were studied for 55 days with protein intakes of 0.20, 0.35, 0.50, and 0.65 g/kg/day. Eight men were studied for 41 days with protein intakes of 0.55, 0.70, and 0.85 g/kg/day, during three experimental periods, respectively.

Each experimental period was of 10 days, duration, preceded by 1 day on a protein free diet and followed by 3 days on a free-choice diet between experimental periods. The sequence of protein administration was assigned randomly.

TABLE 2. Multivitamin and Mineral Supplements (Tablets)*

* Panvitan-M, manufactured by Takeda (Thailand, Ltd., Bangkok.

5. Diets
Hen's egg was the protein source, fed scrambled and mixed with mung bean noodles at lunch and supper. The daily energy intake was kept constant at about 45 kcal/kg/day. Fat provided approximately 30 per cent of the daily energy intake. Vitamin and mineral tables (see table 2) were given twice each day. Water intake was provided ad libitum, but the volume was recorded daily.

6. Indicators and Measurements
a. The total nitrogen in diet, urine, and faeces was measured by a calorimetric semi-automated procedure (Munro and Fleck, Mammalian Protein Metabolism, vol. 3,1969). True nitrogen balance was calculated for urinary nitrogen during the last five days and for faecal nitrogen during the last eight days of each period. Fat in food and faecal samples was measured by Van de Kamer's method. Food and faecal energy were measured by bomb calorimetry (Parr Adiabatic Calorimeter). b. Basal metabolic rate (BMR) was measured daily and at the end of each dietary period with a respirometer (closed circuit). c. Body weight was recorded daily. d. Analyses of serum: Total proteins and albumin; urea nitrogen; and aspartate and alanine aminotransferases (AST and ALT) were determined at the beginning and at the end of each dietary period.