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 (**).