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TABLE 3. Body Weights (kg) of 12 Adult Thai Village Men Consuming Their Usual Diets for Three Months

a. Average body weight of the last five days of each period

Fat intake was approximately 7 to 8 per cent of the daily energy intake. A five-day menu for one subject (B.B.) is shown in table 2.

Neither vitamins nor mineral supplements were given to the subjects during the study.

Duration

One month prior to the beginning of the study a three-day dietary survey was made and complete medical examinations were performed for selection of healthy subjects in preparation for the study.

The actual study lasted for 90 days, divided into three periods. Each dietary period was again subdivided into six shorter periods lasting five days each, to fit the five-day diet menu.

Measurements Taken

1. Dietary intakes of protein (N), energy (bomb calorimetry), and fat were measured for 10 days of each month from samples of a whole day's diet. In addition, dietary intakes of N. energy, and fat were measured daily.

2. Blood samples were taken in the morning after subjects had fasted from midnight on at the beginning of the study and at the end of each study period for measurements of haemoglobin, haematocrit, aspartate, and alanine amino transferase (AST and ALT), retinol-binding protein, and zinc.

3. Twenty-four-hour urine samples were collected throughout the study for analyses of total N. urea N. and creatinine.

4. Ten-day faecal collections were done at the end of each period for measurements of total N. energy, and fat.

5. Body weight was recorded daily, and other anthropometric measurements were done at the beginning and end of each period.

6. N balance was calculated from urinary N excretion during the last five days of each period, while faecal N was calculated during the last 10 days of each period An allowance of 5 mg N/kg/day for integumentary loss was used in the N-balance calculation.

Physical Activities

The subjects were allowed to continue their usual activities but not allowed to participate in heavy or competitive sports. They were asked to keep a record of their daily physical activities for estimation of energy expenditures.

Main Results

Body Weight

The majority of the subjects maintained their body weights well, despite some subjects (B.B., S.D.) who lost weight, and those (S.B., P.N., P.P. and T.C.) who gained weight. However, the mean body weights of all subjects showed almost no change during the entire study period, as shown in table 3.

Energy Intake, Expenditure, and Absorption

The average energy intakes of the last five days of each period showed a significant steady decrease as compared with the initial data, although the actual energy intakes of these subjects were strikingly high 62.8, 60.4, 51.4 kcal/kg/day during periods 1, II, and 111, respectively. Several subjects had energy intakes even higher than 65 kcal/kg/day (table 4).

TABLE 4. Energy Intakes (kcal/kg/day) of 12 Adult Thai Village Men Consuming Their Usual Diets for Three Months

TABLE 5. Estimated Energy Expenditure (kcal/kg/day) of 12 Adult Thai Village Men Given Their Usual Diets for Three Months

TABLE 6. Energy Absorption of 12 Adult Thai Village Men Given Their Usual Diets for Three Months

a. Faecal collections were obtained during the last 10 days of each period

Table 5 shows the estimated energy expenditure based on the daily record of activities. There were no significant differences in estimated energy expenditure throughout the study periods. These values varied from 45 to 47 kcal/kg/day, which appeared lower than the energy intake.

Energy absorption was quite satisfactory, at about 96 per cent during all periods, as shown in table 6.

N Balance

Table 7 shows true N-balance data calculated with an assumed integumentary N loss of 5 mg/kg/day. When the average protein and energy intakes were 1.31 g/kg/day (or 209.1 mg N/kg/day) and 62.8 kcal/kg/day during period 1, only two subjects (S.B. and P.P.) were in positive N balance. The mean of N balance was -10.6 mg N/kg/day.

During period 11, when the average protein intake was 1.3 g/kg/day (or 209.8 mg N/kg/day), with an energy intake of 60.4 kcal/kg/day, six subjects were in positive balance. The mean N balance for this period was 2.5 mg N/kg/day.

TABLE 7 True N Balance (mg/kp/day) of 12 Adult Thai Village Men Consuming Their Usual Diets for Three Months

TABLE 8 Protein Quality Indices of Habitual Diets Given to 12 Adult Thai Village Men for Three Months

TABLE 9. Urinary Creatinine Excretion (g/d) of 12 Adult Thai Village Men Given Their Usual Diets for Three Months

TABLE 10. Fat Absorption of 12 Adult Thai Village Men Eating Their Usual Diets for Three Months

a. Faecal collections were obtained during the last 10 days of each period b. P < 0.001, compared with period I c. P < 0.02 compared with period I

TABLE 11. Serum Retinol-Binding Protein (ma/l) of 12 Adult Thai Village Men Eating Their Diets for Three Months

a. P < 0.005 compared with initial value

During the last period, the average protein intake was 1.07 g/kg/day (or 171.2 mg N/kg/day), with an energy intake of 51.4 kcal/kg/day. All subjects except one were in negative N balance, with a mean N balance of -11.1 mg N/kg/day.

Table 8 shows protein quality indices. Digestibility values in periods II and III were 81.8 and 84.0, respectively, which were significantly higher than those in period I. The biological values and net protein utilization were rather low. at about 20-30 per cent.

Urinary Creatinine Excretion

The means of daily urinary creatinine excretion of the 12 subjects showed almost no change during all three study periods, as shown in table 9. The levels varied from 1.23 to 1.26 9 creatinine/day.

Fat Absorption

Table 10 shows fat-absorption rates of 89, 94 and 93 per cent, respectively, during periods I, II, and III. There were statistically significant differences between fat absorption during period I and subsequent periods.

TABLE 12. Haemoglobin, Haematocrit and Blood Chemistry of 12 Adult Thai Village Men Consuming Their Usual Diets for Three Months

Other Measurements

Table 11 shows serum levels of retinol-binding protein (RBP) measured initially and at the end of each period. There were no significant changes except when RBP levels decreased significantly during period 11, with a value of 44.8 mg/l compared to an initial value of 53.5 mg/l.

The haemoglobin and haematocrit levels of the subjects were within normal ranges. However, there were significant increases in haemoglobin and haematocrit levels during period I compared to initial values, as indicated in table 12. Serum amino transferase (AST and ALT) levels showed no striking changes during the study periods.

Conclusions and Comments

Table 13 shows the summary of data from a study in 12 adult Thai village men consuming their usual diets for three months.

The majority of the subjects maintained their weights well during the study despite their steady decreases in energy intake. The physical activities of these subjects were not reduced, and estimated energy expenditures also showed no significant changes during the whole study period. However, the method for estimating energy expenditure, based on personal recording of physical activities. may be insensitive in predicting any changes.

A previous study based on the N balance response method with adult Thai male subjects indicated that the requirements for egg protein of these subjects was almost 1 g/kg/day, which was certainly higher than the 1973 FAD/WHO recommendation of 0.57 glkg/day. In this study of male subjects eating their usual diets, the N balance data indicated that levels of protein intake between 1.07 to 1.31 g/kg/day, or 170.8 to 209.1 mg N/kg/day, were marginal even when energy intakes were adequate. Fat and energy absorptions were over 90 and 95 per cent, respectively.

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