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TABLE 2. Laboratory Evaluation of the Nutritional Status of "Boias-frias"

Subject

TIBC (yg/dl)

Albumin(g/dl)

Creatinine (mg/24 h) Height (cm)

Lymphocyte Count (mm3)

Haemoglobin (g/dl)

A.A.C. 407.4 4.4 9.45 - 14.8
J.P.M. 351.6 4.2 7.42 2,200 13.3
P.R.S. 340.0 4.3 7.30 3,040 12.7
A.D.B. 260.6 4.2 8.28 1,155 11.0
J.F. 246.4 4.3 6.78 1,224 10.0
L.C.S. 247.7 4.6 7.08 3,510 13.8
R.P. 311.9 4.4 6.04 2,068 14.0
E.M.S. 266.4 4.0 5.82 3,060 13.2
J.A.G. 321.1 4.5 7.88 1,600 14.9
Mean ± SD 306.0 ± 55.2 4.3 ± 0.18 7.34 ±1.12 2,232 ± 892 13.1 ± 1.6

TABLE 3. Creatinine Excretion of the "Boias-frias" (g/day)


Subject

Diet (g prot/kg/bwt/day)

0.4

0.6

0.8

A.A.C. 1.680 + 0.16 1.575 ± 0.060 1.621 ± 0.096
J.P.M. 1.169 ± 0.14 1.182 ± 0.220 1.368 ± 0.140
P.R.S. 1.269 ± 0.22 1.110 ± 0.240 1.368 ± 0.180
A.D.B. 1.279 ± 0.08 1.327 ± 0.300 1.295 ± 0.260
J.F. 1.179 ± 0.07 1.217 ± 0.390 1.123 ± 0.030
L.C.S. 1.232 ± 0.06 1.147 ± 0.130 1.064 ± 0.090
R.P. 0.956 ± 0.27 0.874 ± 0.187 0.907 ± 0.163
E.M.S. 0.986 ± 0.19 0.822 ± 0.250 1.151 ± 0.260
J.A.C. 1.456 ± 0.59 1.272 ± 0.350 -
Mean ± SDa 1.245 ± 0.222 1.169 ± 0.227 1.237 ± 0.220

TABLE 4. Intake of Rice and Bean Diet, Amount per Day (g/kg)

Food Diet (9 pros/kg bwt/day)
  0.4 0.6 0.8
Rice 213 426 582
Beans 128 201 307
Bread 51 52 85
Coffee 570 387 290
Tomatoes 195 207 221
Squash 253 274 297
Soy oil 73 83 83
Apple 251 319 324
Sugar 169 162 86

Metabolic balances, digestibility, biological value, and NPU were calculated from dietary intake and urinary and faecal excretion over the five-day periods. Integumental nitrogen losses were estimated to be 5 mg/kg (1), and the metabolic urinary and faecal nitrogen to be 2.58 and 0.60 mg N/kg, respectively (2). Mean protein requirement and protein allowance were estimated by the individual regression line method described by Rand et al. (3).

TABLE 5. Relationship Between Protein and Calories from Rice and Beans in the Three Diets (Mean ± SD)

 

Diet (g prot/kg bwt/day)

0.4

0.6

0.8

Total protein (g/kg bwt/day) 0.40 ± 0.06 0 59 + 0.01 0.76 ± 0 04
Calories from rice and beans (kcal/day) 389 + 79 701 ± 142 948 ± 129
Calories from other sources (kcal/day) 2,328 + 21 1 2 141 ± 152 1.846 + 122
Protein from rice and beans (g/day) 12.00 ± 2.89 21 .00 ± 4 1 5 28.40 ± 4 02
Proteins from other sources (g/day) 1 1.33 ± 2.10 14.28 ± 1.81 16.39 ± 2 65
Energy density(kcal/g) 1.26±0.10 1.27+0.26 1.31 +0.16
Rice and beans protein ratio 0.98 + 0 38 1.11 ± 0.21 1. 1 3 ± 0. 1 4
Calories/protein (kcal/g) 117.40± 11.90 81.00 + 5.10 62.50 ± 1.20

TABLE 6. Energy Intake (Kcal/kg bwliday) from Rice and Bean Diet for Rural Migrant Workers.

Subject Diet (9 pros/kg bwt/day)
  0.4 0.6 0.8
A.A.C. 44.9 45.8 44.6
J.P.M. 45.3 44.1 44.0
P.R.S. 42.6 46.4 44.4
A.D.B. 46.4 47.9 50.7
J.F. 52.1 49.4 49.7
L.C.S. 46.7 51.3 49.4
R.P. 48.3 51.2 49.4
E.M.S. 44.5 49.5 47.1
J.A.G. 43.0 41.6 -
Mean ± SD 46.0 ± 2.9 47.5 ± 3.3 47.2 ± 2.6

A medical check-up was given to each patient before admission. Blood was always taken for biochemical profile analysis. and stools and urine were collected for routine laboratory examination.

Results

The average intake of each of the ingredients offered to the subjects at each protein level of the diets is shown in table 4. Rice and beans were always the main source of protein, as shown in table 5. The mean caloric density of diets was similar at all three levels of intake. Average daily intakes of energy were 2,750 ± 230 kcal daily during the study (table 5), or 46.9 ± 2.9 kcal/kg (table 6).

Results of the crude nitrogen balance, digestibility, NPU, and biological value of the rice and bean diet are shown in table 7.

The estimation of the mean protein requirement is 107.1 mg N/kg bwt/day, and the protein allowance is 137.6 mg N/kg bwt/day, as shown in table 8.

TABLE 7. True Nitrogen Balance. True Digestibility, NPU and Biologic Value in the Three Diets of Rice and Beans (Averages of Five Days)

Subject

Nitrogen Intake (mg/kg/bwt/day)

Faecal Nitrogen (mg/kg/day)

Urinary Nitrogen (mg/kg/day)

True Nitrogen Balance (mg/kg/day)

True Digestibility (%)

NPU (%)

Biologic Value(%)

Diet of 0.4 g prot kg bwt/day
A.A.C. 55.4 305 61 1 - 413 71.9 21.8 35.60
J P.M 58.6 48.1 54 0 - 48 4 43 4 7.3 2211
PRS 51.6 36.1 537 -432 591 252 5160
A D B 66.6 20.9 65.1 - 24.4 91 2 62 7 72.80
J.F 841 33 7 53.3 - 8 0 77.7 70.6 95.60
L C S 64 7 301 671 - 374 76.7 87.6 53.60
RP 594 469 455 -381 46.2 493 120.80
E M 5 63.8 36.0 39.6 -16.8 671 63.2 10710
J.A.G 66.2 22.2 461 - 71 831 619 78.60
Mean±SD 634±93 338±94 53.9±9.3 -294±157 692±170 499±263 70.9±331
Diet of 0.6 9 prot kg bwt/day
A.A.C. 94 4 43.2 59.4 -1 3.2 70 1 42.2 66 2
J.PM 927 403 59.5 -12.1 72.7 42.8 64.8
PR.S 953 32.7 44.0 + 13.6 81.4 72.3 956
A D.B. 92.2 33.7 72.8 -19 3 79.7 50.8 86.9
J F. 91.5 39.2 58.7 - 11.4 735 611 87.3
L.C.S 97 7 38.1 56 6 - 2.0 77 4 61.2 85.0
R P 94 2 42.7 54.1 - 7 6 70.6 63.5 94 5
E.M.S 93.3 43.0 45.2 -101 69.9 61.3 95.2
J.A.G 919 29.5 63.4 - 61 84.2 45 4 59.3
Mean±SD 93.7±1.9 3804±5.0 571 ±88 -76±9.3 755±5.3 556± 106 79.4±14.9
Diet of 0.8 9 pros/kg bwt/day
A.A.C. 113.9 53.0 71.4 -15.5 66.6 32.9 53.5
JPM. 113.0 41.1 61.3 +5.5 76.9 49.3 69.4
P.R.S. 114.1 43.0 56.4 + 9 7 75 5 56 7 80.3
ADB 129.8 44.8 66.2 - 13.9 771 61.6 82.8
J F. 127.0 40.3 49.4 + 32.3 80.1 78.4 100.9
L.CS. 124.8 634 59.0 -24 61.2 47.5 82.1
R.P. 121.1 38.8 613 + 160 80.3 68.8 886
E.M.S. 123.8 38.0 54.5 + 26.4 81.4 67.4 87.3
Mean ± SD 120.9 ± 65 45.3 ± 8.7 59.9 ± 68 73 ± 17.5 749 ± 72 57.8 ± 14.4 80.6 ± 14.1

TABLE 8. Linear Regression of N Balance Response (mgN/kg/day), of Brazilian Rural Workers with a Rice and Bean Diet (Individual Data)

Subject Regression Equation Intercept y = 0 r
A.A.C. y = - 66.366 + 0.487 x 136.13 0.915
J.P.M. y = - 102.035 + 0.961 x 106.17 0.998
P.R.S. y = - 87.410 + 0.928 x 94.18 0.936
A.D.B. y = - 71.127 + 0.634 x 112.20 0.956
J.F. y = - 102.607 + 1.060 x 96.74 0.977
L.C.S. y = - 70.652 + 0.594 x 118.92 0.890
R.P. y = - 89.429 + 0.867 x 103.15 0.999
E.M.S. y = - 64.991 + 0.730 x 88.91 0.994
Mean   107.05 0.958
SD   15.26 0.041
CV   14.26  

y = N balance (mg/kg/day)
x = N intake (mg/kg/day)
Intercept (y = 0) = N intake for the maintenance of N equilibrium (mg/kg/day)

Discussion

The average daily faecal and urinary nitrogen excretion increased with higher protein intake (table 7).

The true digestibility increased when the intake went from 0.4 to 0.6 g/kg bwt, but stayed at about the same level when the intake increased to 0.8 g/kg bwt (table 7).

The data on biological value and NPU showed a pattern similar to that of true digestibility: an increase when the protein intake went from 0.4 to 0 6, but practically no change at levels from 0.6 to 0.8 9 of protein per kg of body weight (table 7).

Here again, faecal excretion of nitrogen appears to be the most important factor, since values were higher during the 0.6 and 0.8 g/kg levels of intake. Nitrogen retention increased with the higher protein intake, but the increase was less when the 0.6 level is compared with the 0.8. The caloric intake was kept at about the same level throughout the study and did not influence the results.

Using individual response lines, the estimated mean requirement is 66.9 9 protein with a standard deviation of 9.5 (table 8). These results are lower than the ones found by Calloway and Kretsch in their study of adults fed a diet based on beans, corn, and rice (4). They confirm our previous results in children and adults fed rice and bean diets (5, 6), showing the possibility of reaching nitrogen equilibrium at a lower nitrogen intake.

References

1. D.H. Calloway, A.C.F. Odell, and S. Margen, "Sweat and Miscellaneous Nitrogen Losses in Human Balance Studies," J. Nutr., 101: 775 (19711.

2. V.R. Young, Y.S.M. Taylor, W.M. Rand, and N.S. Scrimshaw, "Protein Requirements of Man: Efficiency of Egg Protein Utilization at Maintenance and Submaintenance Levels in Young Men," J. Nutr., 103: 1164 (1974).

3. W.M. Rand, N.S. Scrimshaw, and V.R. Young, "Determination of Protein Allowances in Human Adults from Nitrogen Balance Data," Am. J. Chin. Nutr., 30: 1129 (1977).

4. D.H. Calloway and M.J. Kretsch, "Protein and Energy Utilization in Men Given a Rural Guatemalan Diet and Egg Formulas with and without Added Oat and Bran," Am. J. Clin. Nutr., 31: 1118 (1978).

5. H. Vannucchi, R.M.F. Duarte, and J.E. Dutra de Oliveira, "Nutritive Value of a Rice and Beans-Based Diet for Agricultural Migrant Workers in Southern Brazil," Nutr. Rep. Internat., 24: 129 (1981).

6. J. E. Santos, J.M. Howe, F.A.M . Duarte, and J.E. Dutra de Oliveira, " Relationships between the Nutritional Efficacy of a Rice and Bean Diet and Energy Intake in Preschool Children," Am. J. Clin. Nutr.. 32: 1541 (1979).


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