SP-368 Biomedical Results of Apollo

 

CHAPTER 6

NUTRITIONAL STUDIES

 

by
Paul C. Rambaut, Sc.D.*
Malcolm C. Smith, Jr., D.V.M.
Harry O. Wheeler, Ph.D.
 
Lyndon B. Johnson Space Center
 

Introduction

 

[277] The importance of nutrition in the adaptation of man to weightlessness was recognized long before the first Apollo flight. Nutrition remained a primary concern despite the fact that early projections of difficulties in swallowing, defecating, and urinating in weightlessness had proved unfounded. By the conclusion of the Gemini Program, space life scientists had noted several subtle changes with possible nutritional etiology.

Changes in musculoskeletal function appeared to be significant among these findings (Rambaut et al., 1973; Vogel et al., 1974). Prior to the first manned space flight, it had been suspected that the musculoskeletal system would be particularly susceptible to prolonged withdrawal of gravitational stress. Astronauts were subjected to a nullified gravitational field while they were confined in a vehicle in which mobility and physical activity were restricted. These conditions singly, or in combination, were expected to cause deterioration of bones and muscles.

The control studies by Deitrick, Whedon, and Shorr (1948) of the immobilization of four young, healthy men for as long as seven weeks clearly demonstrated that immobilization in body casts led to marked increases in urinary calcium. These levels more than doubled in five weeks and were accompanied by negative calcium balances as well as by related changes in nitrogen and phosphorus metabolism. In addition, a decrease in the mass and strength of the muscles of the lower extremities occurred, and deterioration in circulatory reflexes to gravity resulted within one week.

Other studies with immobilized subjects indicated that the clinical disorders most likely to be encountered during prolonged space flight are primarily a consequence of an imbalance between bone formation and resorption. As a result of these conditions, there is a loss of skeletal mass, which could eventually lead to hypercalcemia, hypercalciuria, osteoporosis, and possibly nephrolithiasis (Issekutz et al., 1966).

[278] Since the most meticulous work has disclosed that the greatest loss of calcium during bed rest is a result of increased urinary excretion, studies in which only urine calcium was measured are pertinent. The total evidence indicates that a one to two percent per month loss of body calcium is a reasonable prediction for persons in a weightless environment (Hattner & McMillan, 1968).

With the advent of space flight, additional studies have been performed on the effects of simulated weightlessness on skeletal metabolism. Graybiel and co-workers (1961) found there was no increase in urinary calcium excretion after one week of almost continuous water immersion. Negative balances of small magnitude and changes in bone density of the calcaneus during bed rest are indicated by Vogt and co-workers (1965).

The role of simulated altitude in modifying the metabolic effect of bed rest has been investigated (Lynch et al., 1967). In a study of 22 healthy men, four weeks of bed rest at ground-level atmospheric pressure conditions resulted in expected increases in urinary and fecal calcium and in urinary nitrogen, phosphorus, sodium, and chloride. In similar metabolic studies performed with another 22 subjects at bed rest at simulated altitudes of 3000 and 3700 meters, urinary calcium losses were significantly less as the altitude increased (Lynch et al., 1967). Urinary losses of phosphorus, nitrogen, sodium, and chloride were less at a simulated altitude of 3700 meters than they were during bed rest studies at ground level. Results of these studies indicate that diminished atmospheric pressure, or perhaps a decreased partial pressure of oxygen or a change in pH, may have a preventive effect on mineral loss from the skeleton. Limited data available from inflight studies tend to support the use of immobilization as a terrestrial model to simulate alterations in calcium metabolism during space flight. During the 14-day Gemini 7 flight, loss of calcium occurred in one of the two astronauts, and the changes in phosphorus and nitrogen balance also indicated a loss of muscle mass (Lutwak et al., 1969; Reid et al., 1968).

As evidenced from bed rest studies lasting from 30 to 36 weeks, mineral losses are likely to continue unabated during prolonged space flight. In balance studies (Vogel & Friedman, 1970; Donaldson et al., 1970), calcium losses from the skeleton during bed rest averaged 0.5 percent of the total body calcium per month. In the same subjects, tenfold greater rates of localized loss from the central portion of the calcaneus were detected by gamma-ray-transmission scanning.

lnflight weight losses were experienced throughout Project Mercury, Gemini, and the Apollo missions. Such weight losses were attributed, in part, to losses in body water. Since weight was not regained completely in the 24-hour period immediately postflight, it was probable that tissue had also been lost. What part of these losses was brought about by insufficient caloric intakes was unknown.

Speculation on the theoretical energy requirements of man during space flight began before the United States Project Mercury and the Soviet Vostok flights. At one time, it had seemed logical to assume that activity in a weightless environment would require less energy than at one g because work associated with counteracting the force of gravity would be eliminated However, caloric requirements are affected by numerous variables including age, physical and mental activity, stress, body size and composition, together with relative humidity, radiation, pressure, and environmental temperature. During the [279] Apollo missions, therefore, the question of inflight caloric requirements was explored in much greater depth

Metabolic changes in addition to they associated with an inadequate intake of energy were also elucidated during the Gemini Program. The possibility remained that space flight conditions would exert exaggerated demands on the micronutrients and would thus lead to some marginal deficiency state. It is believed that Soviet nutritionists provided their crewmen with elevated quantities of water-soluble vitamins, and that they had observed increased destruction of the B vitamins under conditions of prolonged low frequency vibration of test subjects. These observations were not confirmed during the Gemini Program. However, because alterations were seen in red cell mass and plasma volume, the vitamin E content of the diet in the presence of the hyperoxic Gemini spacecraft atmosphere was questioned (Fischer et al., 1969).

The development of future space food systems necessitated an accurate knowledge of inflight human nutrition requirements. Food systems having minimum weight and minimum volume are required for space flight (Heidelbaugh et al., 1973). For this reason, the Apollo foods were generally dehydrated and formulated to occupy little volume. The nutritional consequence of these measures was a matter of continuing interest in the Apollo Program.

 

Approach

 

Food Analysis

With very few exceptions, all foods used during the Apollo Program were analyzed for nitrogen, fat, carbohydrate, crude fiber, calcium, phosphorus, iron, sodium, potassium, and magnesium content. Some composite Apollo menus were analyzed for water- and fat-soluble vitamins. It was not always feasible to analyze the same lot of food that was actually used during the mission, and the variation in analytical values from one lot to another and from one item to another must be considered when the intake data are reviewed.

 

Dietetics

The menus used by the Apollo astronauts were formulated from flight qualified Apollo foods in combinations that complied with the personal preferences of the crewmen and that met the Recommended Daily Dietary Allowances (NAS, NRC, 1968). The menus were primarily composed of dehydrated foods that could be reconstituted before eating. The foods were consumed in a prearranged sequence but could be supplemented by a variety of additional items that were packaged in am individually accessible form.

 

Nutrient Intake Measurements

The quantity of individual nutrients consumed during all Apollo missions is presented in table I as a composite estimate derived from numerous measurements. The crewmen were provided with prepackaged meals that were normally consumed in a numbered sequence. Foods omitted or incompletely consumed were logged. During the Apollo 16 [280] and 17 missions only, these deviations from programmed menus were reported to flight controllers in real time. Snack items consumed that were not in the programmed prepackaged menus were also recorded in the flight logs. On all Apollo flights, most food residue and unopened food packages were returned; the residue was weighed only to provide more precise information on inflight food consumption and to verify inflight logging procedures. For the Apollo 16 and 17 missions, nutrient intake information was obtained for 72 hours before flight and for approximately 48 hours after flight.

 


Table 1

Average Nutrient Intake During Apollo Missions

Mission Number

Mission Duration, Days

Nutrient, gm

Protein

Fat

Carbohydrate

Fiber

.

7

10

84

69

269

-

8

6

64

40

229

-

9

10

77

53

257

-

10

8

51

31

211

-

11

10

81

64

279

-

12

10

64

47

264

3.9

13

7

58

49

234

-

14

8

83

75

286

-

15

11

112

99

370

7.8

16

11

73

61

272

4.9

17

12

91

86

285

4.8

.

Average, all Apollo missions

76

61

269

5.4


 

For the Apollo 17 mission, a five day metabolic balance study was performed approximately two months before the mission by using the flight menus and collecting urine and fecal wastes. Low residue diets were generally used commencing three days before each Apollo flight in order to reduce fecal mass and frequency during the first few days of flight.

 

Fecal Measurements

Fecal samples were returned from all Apollo flights and analyzed for a variety of constituents either by nuclear activation analysis or by wet chemistry techniques.

 

Metabolic Balance

Analysis of blood obtained postflight on early Apollo missions, together with certain endocrinological and electrocardiographic changes in Apollo 15, made it desirable to measure urine volume and bring back samples of urine on Apollo 16. During this mission, it was also possible to continue to return fecal samples and to continue to measure nutrient intake. Sufficient data were therefore available to conduct a partial metabolic study.

[281] For a more detailed metabolic balance study in conjunction with Apollo 17, accurate measurements of fluid intake and output were performed approximately two months before the mission. A five-day food compatibility/metabolic study was performed in which the three Apollo 17 prime and backup crewmembers consumed their flight foods, and metabolic collections were performed. The study was designed to obtain baseline data on the excretory levels of electrolytes and nitrogen in response to the Apollo 17 flight menus. The crewmembers consumed the flight menu foods for five complete days. During the last three days of this test, complete urine and fecal collections were made.

Beginning 64 hours before Apollo 17 lift-off and continuing throughout the mission until 44 hours following recovery, all food and fluid intake was measured. For the Lunar Module Pilot, these collections continued until suit donning; for the Commander and the Command Module Pilot, collection continued until approximately 12 hours before lift-off. All urine was collected, measured, sampled, and returned for analysis. Urine was collected before and after flight in 12-hour pools. Complete stool collections were performed.

All deviations from programmed food intake were logged and reported. All foods were consumed according to preset menus arranged in four-day cycles. Every food item used during the flight was derived from a lot of food that had been analyzed for the constituents to be measured. Inflight water consumption was measured by use of the Skylab beverage dispenser. During the preflight and postflight periods, conventional meals were prepared in duplicate for each astronaut. One duplicate of each meal was analyzed in addition to the residue from the other duplicates to measure intake and output.

Apollo 17 inflight urine samples were collected by means of a biomedical urine sampling system (BUSS). Each BUSS consisted of a large pooling bag, which could accommodate as much as four liters of urine collected during a day, and a sampling bag, which could accommodate as much as 120 cc. The BUSS was charged with 30 mg of lithium chloride. The lithium chloride concentration in the sample bag was used as a means of determining total urine volume. Each BUSS also contained boric acid to effect stabilization of certain organic constituents.

The inflight urine collection periods began with suit doffing at approximately 00:07:00 ground elapsed time (GET). The collection periods were the times between scheduled effluent dumps and were approximately 24 hours each. During undocked flight of the Command Module, urine was collected only from the Command Module Pilot. During periods in which the crewmen were suited, urine was collected in the urine collection and transfer assembly and subsequently dumped overboard without sampling. However, urine collected in the Commander and Command Module Pilot assemblies during the Command Module extravehicular activities (255:00:00 to 260:00:00 GET) was also returned. For the Apollo 17 mission, the periods during which urine was not collected are as follows:

 

1. Commander and Command Module Pilot-lift-off to suit doffing (00:00:00 to 00:07:00 GET)

2. Command Module Pilot - Lunar Module activation and lunar descent (108:00:00 to 114:30:00GET)

3. Command Module Pilot-rendezvous (187:00:00 to 195:00:00 GET)

[282] 4. Commander and Lunar Module Pilot-Lunar Module activation, lunar descent, lunar surface operations and rendezvous (107:00:00 to 208:00:00 GET)

 

Urine collected from the Commander and the Command Module Pilot from rendezvous to the beginning of the first collection period after rendezvous (approximately 197:00:00 to 208:00:00 GET) was also dumped directly overboard.

Each BUSS was marked with the name of the crewmember and the ground elapsed time of collection. Following each collection period, the urine pool was thoroughly mixed before a sample was taken. The urine samples represented a 24-hour void and were subsequently analyzed for electrolytes, nitrogen, and creatine.

All fecal samples collected from each crewmember for the following periods were returned: beginning 64 hours before lift-off, during the mission, and for 44 hours after the flight. Inflight fecal samples were chemically preserved for storage in the spacecraft.

 

Body Volume Measurements

For the Apollo 16 crewmembers, a measurement of body volume was made by stereophotogrammetry, using a special computer program, three times before the flight and three times after the flight (Peterson & Herron, 1971). Body density was calculated from body volume and weight. Density was used to calculate the percentage of fat by means of the following formula.

 

(495/ body density) - 450 = percent fat

 

Changes in calculated lean body mass and total body fat were converted into caloric equivalents by means of standard values of 37.6 kJ/gm** for fat and 16.7 kJ/gm for protein.

Total body water was measured by means of potassium-42 dilution (Johnson et al, 1974) Lean body mass was calculated as follows

 

 

LBM = (total body water)/73

 

body weight - LBM = total body fat

 

Findings

 

The nutritional composition of the typical Apollo inflight diet is given in table 2 This diet, which is characteristically high in protein and carbohydrate and low in residue and fat, was not necessarily consumed by all astronauts in its entirety.

 


[283] Table 2

Nutritional Composition of Typical Apollo Diet

Nutrient

Percent of Dry Weight

.

Protein

18

Fat

17

Total carbohydrate

61

Fiber

1.0

Minerals

3.0


 

A typical Apollo diet was analyzed for vitamins, and results were compared with Recommended Daily Dietary Allowances (NAS, NRC, 1968). The data indicate the Apollo diet provided an excess of some vitamins (A, E, C, B12, B6, and riboflavin) and marginal amounts of others (nicotinate, pantothenate, thiamine, and folic acid).

The average intake of protein, fat, and carbohydrate for the Apollo 7 through 17 crewmen is given in table 3. Fiber intake measurements are given for the Apollo 12, 15, 16, and 17 missions.

The quantity of energy supplied by dehydrated food for the Apollo 15 to 17 missions is given in table 4. The average energy intake of each Apollo crewmember is given in table 5. These energy values were calculated from the composition of the food consumed. Average energy intakes expressed on the basis of body weight are given in table 6. For comparison, the average energy intake of selected Apollo crewmembers during a mission and on the ground is given in table 7.

The average intakes of calcium, phosphorus, sodium, and potassium for each Apollo crewman are given in table 8. Diets for the Apollo 16 and 17 missions were fortified with potassium gluconate. The contribution of supplementary potassium gluconate to the total intake for the Apollo 15, 16, and 17 crewmen is given in table 9.

Inflight fecal samples were analyzed for inorganic constituents using nuclear activation analyses and wet chemistry techniques. The findings were summarized by Brodzinsky and co-workers (1971). Inflight fecal samples were also analyzed for total fat, fatty acids, and conjugated and unconjugated bile acids (tables 10 and 11). Data on fat absorption in flight (Apollo 16 and 17) are given in table 12.

 

Apollo 16 Metabolic Study

The input and output of various elements, particularly potassium, were carefully examined in the Apollo 16 balance study and a detailed assessment of energy metabolism was made (Johnson et al., 1974). The average daily inflight potassium intake for the Commander was 113.6 milliequivalents. During the mission, potassium was lost by the fecal route at a rate of approximately 6.4 mEq/day, whereas approximately 18.8 mEq/day were lost before the flight and 20.5 mEq/day after the flight. During the mission, absorbed potassium levels were 107.2 mEq, whereas preflight and postflight levels were 94.8 and 77.6 mEq, respectively. During the extravehicular and lunar surface periods, the Commander consumed a maximum of 152.4 mEq daily.

 


[284] Table 3

Nutrient Intake During Apollo Missions

Mission Number

Mission Duration, Days

Crewman

Nutrient, gm

Protein

Fat

Carbohydrate

Fiber

.

7

10

CDR

81

72

259

-

CMP

96

78

280

-

LMP

74

56

268

-

8

6

CDR

59

39

231

-

CMP

80

49

240

-

LMP

52

33

217

-

9

10

CDR

86

60

280

-

CMP

78

53

240

-

LMP

66

47

252

-

10

8

CDR

58

34

213

-

CMP

46

30

213

-

LMP

49

30

208

-

11

10

CDR

79

65

290

-

CMP

71

54

224

-

LMP

94

73

322

-

12

10

CDR

70

50

263

4.6

CMP

65

49

249

3.9

LMP

57

42

280

3.3

13

7

CDR

59

50

239

-

CMP

57

47

235

-

LMP

57

49

228

-

14

8

CDR

90

76

309

-

CMP

79

61

230

-

LMP

81

89

319

-

15

11

CDR

126

115

356

8.2

CMP

109

94

334

7.9

LMP

100

89

421

2.2

16

11

CDR

88

73

319

6.2

CMP

79

60

295

5.3

LMP

52

50

203

3.1

17

12

CDR

88

68

248

3.9

CMP

87

87

293

5.3

LMP

98

104

314

5.3


[285] Table 4

Energy Supplied by Dehydrated Food

(Values in percent of total Joules consumed)

 

Apollo Mission Number

Crewman

CDR

CMP

LMP

.

15

57.7

57.3

63.9

16

57.7

62.4

59.4

17

43.0

44.2

46.9


Table 5

Average Energy Intake During Apollo Missions

[Values in kJ/day (kcal/day)]

 

Apollo Mission Number

Crewman

CDR

CMP

LMP

.

7

8235 (1970)

8945 (2140)

7524 (1800)

8

6186 (1480)

7064 (1690)

5601 (1340)

9

8028 (1920)

7190 (1720)

6855 (1640)

10

5643 (1350)

5267 (1260)

5225 (1250)

11

8527 (2040)

6855 (1640)

9530 (2280)

12

7315 (1750)

8981 (1670)

7064 (1690)

13

6604 (1580)

6437 (1540)

6354 (1520)

14

9656 (2310)

7190 (1720)

9739 (2330)

15

12 134 (2903)

10456 (2492)

10 751 (2572)

16

10 044 {2403)

6542 (1565)

9890 (2366)

17

7545 (1805)

9547 (2284)

8389 (2007)


 

The average daily inflight potassium intake for the Lunar Module Pilot was 114.7 mEq, compared with an average daily preflight intake of 110.5 mEq and an average daily postflight intake of 97.5 mEq. During the preflight, inflight, and postflight phases, the average daily fecal losses were 33.5, 11.1, and 31.0 mEq, respectively. The absorbed daily potassium levels for preflight, inflight, and postflight phases were 77.0,103.6, and 66.5 mEq, respectively. Although these levels were less than the recommended levels of 150 mEq per day, they were adequate for ground-based requirements. A peak level of 148 mEq per day was consumed by the Lunar Module Pilot during lunar surface activities.

 


[286] Table 6

Apollo Inflight Energy Intake Based on Body Weight

[Values in kJ/kg day (kcal/kg day)]

Apollo Mission Number

Crewman

CDR

CMP

LMP

.

7

93.7 (22.4)

128.8 (30.8)

106.7 (25.5)

8

80.8 (19.3)

92.0 (22.0)

84.5 (20.2)

9

109.9 (26.3)

97.0 (23.2)

92.5 (22.1)

10

71.1 (17.0)

68.7 (16.4)

66.1 (15.8)

11

108.7 (26.0)

90.8 (21.7)

122.2 (29.2)

12

109.9 (26.3)

99.1 (23.7)

101.1 (24.2)

13

84.1 (20.1)

71.9 (17.2)

89.8 (21.5)

14

123.4 (29.5)

95.8 (22.9)

117.2 (28.0)

15

149.7 (35.8)

141.8 (33.9)

145.2 (34.7)

16

125.5 (30.0)

104.6 (25.0)

135.4 (32.4)

17

93.7 (22.4)

123.8 (29.6)

110.5 (26.4)


 

Table 7

Comparison of Apollo Inflight and Ground-Based Average Energy Intake

[Values in kJ/kg (kcal/kg)]

 

Mission Number

Crewman

Ground-Based Intake*

Inflight Intake**

.

9

LMP

151.4 (36.2)

92.5 (22.1)

12

CDR

157.3 (37.6)

109.9 (26.3)

LMP

147.3 (35.2)

101.3 (24.2)

16

CDR

184.1 (44.0)

125.4 (30.0)

CMP

150.9 (36.1)

104.5 (25.0)

LMP

176.8 (42.3)

135.6 (32.4)

17

CDR

129.6 (31.0)

93.7 (22.4)

CMP

163.9 (39.2)

123.8 (29.6)

LMP

130.8 (31.3)

110.5 (26.4)

* Mean value is 154.7 ± 18.4 kJ/kg (37.0 ± 4.4 kcal/kg)
**Mean value is 110.8 ± 13.8 kJ/kg (26.5 ± 3.3 kcal/kg)


 

For the Command Module Pilot, average daily preflight, inflight, and postflight dietary potassium intakes were 94.3, 79.9, and 82.4 mEq, respectively. Fecal samples for the same periods indicated that potassium levels were 27.6, 6.3, and 26.2 mEq, respectively. Available daily preflight, inflight, and postflight potassium level- were, therefore, 66.7, 73.6, and 56.2 mEq, respectively.

 


[287] Table 8

Inflight Intake of Caleium, Phosphorus, Sodium, and Potassium

(Values in milligrams)

 

Apollo Mission Number

Crewman

Commander

Command Module Pilot

Lunar Module Pilot

Calcium

Phosphorus

Sodium

Potassium

Calcium

Phosphorus

Sodium

Potassium

Calcium

Phosphorus

Sodium

Potassium

.

7

644

1060

3810

1879

938

1125

4000

1958

925

841

3480

1336

8

427

847

3170

1229

478

983

3980

1571

366

760

2730

988

9

562

1146

4000

1677

489

1073

3770

1708

484

892

3410

1386

10

836

814

2970

1463

808

746

2290

1376

854

701

2670

1182

11

1036

1050

2770

1751

851

901

3060

1441

1114

1225

3220

2061

12

1095

1090

3580

1835

1022

1028

3240

1685

1291

865

3290

1484

13

870

780

3630

2036

871

720

3480

1942

786

716

3350

1954

14

802

1308

4870

2485

809

1109

3780

2147

843

1304

4750

2576

15

810

1914

6529

3554

748

1624

5274

2720

790

1636

5131

2923

16

811

1696

3860

4432

470

1074

2743

3345

683

1500

3547

4208

17

655

1376

3657

2847

692

1563

4324

3627

659

1447

3611

3237


 

[288] Table 9

Potassium intake

(Values in milliequivalents)

Apollo Mission Number

Crewman

Total Potassium Intake

Supplementary Potassium as K-gluconate

.

15

CDR

91.1

0

CMP

69.7

0

LMP

74.9

0

16

CDR

114.2

23

CMP

81.8

26

LMP

106.9

26

17

CDR

77.2

10

CMP

88.5

18

LMP

98.1

19


 

Input and output data on sodium, chloride, and calcium levels for the Apollo 16 crewmembers are summarized in table 13.

In the analysis of the balance study performed for the Apollo 17 mission, inflight metabolic data were compared with those obtained during the five-day control study conducted approximately two months prior to flight. Rigorous intake and output measurements were accomplished immediately before the flight and after the flight to detect gross changes; however, the duration of these periods was not sufficient to establish reliable metabolic baselines.

For the Apollo 17 Command Module Pilot, water consumption from all sources was considerably lower during the flight than during the control balance study (table 14). Inflight urine outputs were also proportionately lower for all three crewmembers than those established during the control study. When the conditions of temperature and humidity that prevailed during the flight are considered, it is estimated that in insensible water loss of 900 to 1200 cc/day occurred. This loss was equivalent to the preflight loss. Total body water measurements also did not support the tendency toward negative water balance (see Section III, Chapter 2, Clinical Biochemistry).

Based on numbers adjusted for equilibrium during the control phase and insensible losses, all three crewmembers were in negative calcium balance during the inflight period (table 14). The negative balance was particularly pronounced for the Command Module Pilot. For two of the crewmembers, the negative calcium balance persisted after the flight. All crewmembers had exhibited a pronounced positive balance during the five-day control period study possibly because the flight diets contained a higher calcium level than did the customary daily intake of these crewmembers (table 14). As can be expected from the negative calcium balance, phosphorus balance was generally negative during the flight.

All three crewmembers demonstrated a sustained negative nitrogen balance during the flight (table 14). Occasional negative nitrogen balances of small magnitude were also detected before the flight. Diminished nitrogen retention is supportive evidence for the....

 


[289] Table 10

Analysis of Fecal Samples Based on Dry Weight

(Values are averages ± standard deviation)

Test

Apollo Mission Number

7

8

9

11

12

13

14

15

.

Moisture,

6.78

5.99

6.31

7.72

6.67

7.53

9.56

4.94

percent

± 1.11

± 1.53

± 0.794

± 5.42

± 0.778

± 1.32

± 0.933

± 1.73

Nitrogen,

4.05

5.87

5.70

5.76

4.94

5.34

4.45

5.50

percent

± 0.44

± 0.394

± 0.85

± 1.42

± 0.570

± 0.778

±0.423

± 0.14

Protein,

25.3

38.46

35.61

36.70

30.90

33.39

27.79

34.38

percent

± 2.71

± 3.13

± 5.30

± 9.92

± 3.56

± 4.86

±2.66

± 0.87

Total lipids,

12.9

11.74

12.64

15.14

17.75

15.26

23.76

12.9

percent

± 5.40

±4.46

± 4.25

± 0.509

± 4.54

± 3.92

± 5.91

±3.25

Crude fiber,

7.57

5.22

21.81

7.06

13.20

14.05

14.44

5.97

percent

± 2.47

± 1.42

±4.46

± 1.79

± 7.46

± 5.42

± 6.08

± 0.75

Energy value,

533.68

530.8

523.58

519.15

501.33

547.17

521.8

573.40

*kcal/100 gm

± 27.46

±42.7

± 38.03

± 20.55

+ 33.9

± 55.43

± 42.3

± 20.78

Potassium,

1435.57

1571.6

1724.1

1318.35

1377.5

1967.8

1524.5

1884.7

mg/100 gm

± 357.07

± 239.1

± 516.0

± 503.17

± 352.05

± 284.8

± 448.5

±557.6

Nickel,

4.21

2.70

18.27

3.37

10.58

4.60

-

9.70

mg/100 gm

± 2.08

± 1.48

± 10.10

± 0.948

± O

±2.88

-

± 6.84

*1 kcal = 4.184 kJ

 


[290] Table 11

Fatty Acid Analysis of Fecal Samples Based on Total Fat

(Values are percentage of total fat ± standard deviation)

.

C12

C14

C16

C18

C18:1

C18:2

C18:3

C2X

.

Apollo 7

0.60 ± 0.18

0.88 ± 0.51

24.84 ± 7.28

32.63 ± 11.84

30.8 ± 10.07

5.01 ± 3.79

-

14.22 ± 11.34

Apollo 8

1.00 ± .52

1.70 ± .99

24.34 ± 8.11

22.85 ± 6.30

32.72 ± 3.80

7.95 ± 5.35

-

12.20 ± 3.26

Apollo 9

1.50 ± 1.22

2.76 ± 1.14

31.07 ± 7.70

38.02 ± 4.67

22.10 ± 6.41

2.88 ± 2.66

-

5.01

Apollo 11

1.10 ± .18

2.24 ± .30

21.44 ± 1.56

24.72 ± 13.04

16.10 ± 1.27

2.55 ± 1.27

-

16.81 ± 5.52

Apollo 12

1.70 ± 1.19

4.44 ± 1.99

30.36 ± 7.25

33.99 ± 8.68

17.06 ± 6.31

2.05 ± 1.96

0.58

-

Apollo 13

1.38 ± 1.58

1.48 ± .72

19.8 ± 5.63

37.92 ± 11.66

32.84 ± 12.65

4.94 ± 3.10

0.858 ± 0.316

-

Apollo 14

1.34 ± .81

1.78 ± 1.41

17.06 ± 5.96

30.44 ± 17.81

25.00 ± 9.75

5.85 ± 9.34

.82 ± .01

5.70 ± 4.74

Apollo 15

1.44 ± .78

16.28 ± 1.94

20.81 ± 6.00

49.32 ± 2.28

10.56 ± 8.80

2.11

1.05

-


 

[291] ....general musculoskeletal deterioration noted on previous flights and during ground-based hypokinetic simulations of flight-type conditions.

 

 


Table 12

Analysis of Fat Absorbed

Measurement

Sample Number

1

2

3

4

5

6

.

Apollo 16 mission

.

Food, gm/day

135

73

100

50

98

60

Feces, gm/day

10.28

2.33

7.84

4.99

7.61

1.21

Fat absorbed, percent

92

97

92

90

92

98

.

Apollo 17 mission

.

Food, gm/day

114

68

87

104

73

87

Feces, gm/day

6.03

.86

1.63

2.10

1.87

1.83

Fat absorbed, percent

98

99

98

98

97

98


 

Sodium intakes during the flight were all less than 250 mEq/day. Intake and output measurements for sodium indicated positive balances for this element during the flight for all three crewmembers (table 14). However, sodium output in sweat was not measured and this route of excretion could have accounted for all the apparent "positive balance" and even have resulted in a slight negative balance for sodium. Sodium balance was positive during the flight for all three crewmembers (table 15) if insensible losses are neglected.

In compliance with previous recommendations based on observed inflight potassium deficits, inflight potassium intakes were maintained above normal ground-based intakes (73 to 97 mEq/day) (table 15). Potassium retention during the flight was significantly less than that established during the control study. A summary of overall metabolic balance for Apollo 17 crewmembers with all numbers adjusted to reflect equilibrium during the control period is presented in table 15.

 

Anthropometric Measurements

A summary of body weight changes based on the mean of the weights on 30,15, and 5 days before lift-off compared to those obtained immediately after recovery is presented in table 16. The weight changes during the 24-hour period immediately following recovery are also given.

Body volume was measured before and after the Apollo 16 mission by stereophotogrammetry. An analysis of densitometric data is presented in table 17.

 


[292] Table 13

Intake and Absorption Data - Apollo 16

Commander

Day

Item

Water (gm)

kcal

Protein (gm)

Fat (gm)

CHO (gm)

Crude Fiber (gm)

Ash (gm)

Ca (mg)

P (mg)

Na (mEq)

K (mEq)

Mg (mg)

Cl (mEq)

.

F-3

Total intake

3645

3989

147.7

200.8

366.1

0

22.88

1033

2270

222.3

128.0

473

130.1

.

Feces

54

108

6.7

1.7

7.3

.86

2.10

269

298

4.4

8.7

127

.3

F-2

Total intake

3442

3217

134.6

126.8

391.5

0

21.95

1130

1924

183.9

126.2

424

123.5

.

Feces

123

351

15.8

12.5

224.4

3.25

5.40

919

851

3.6

25.3

364

1.3

F-1

Total intake

2631

2402

103.5

92.9

265.7

0

14.24

580

1677

121.5

86.4

226

60.1

.

Feces

76

276

16.8

9.3

12.5

2.17

5.39

945

803

20.9

22.5

342

.6

F+0

Total intake

1229

2047

79.9

115.3

166.0

1.69

11.74

561

1285

158.7

73.7

184

106.5

.

Feces

36

78

5.2

2.4

4.1

.44

1.70

340

249

.7

7.4

120

.009

F+1

Total intake

2448

2421

81.8

84.2

412.4

8.98

19.3

882

1622

183.5

129.9

262

187.3

.

Feces

82

321

16.1

11.3

15.9

3.00

8.4

1095

945

35.1

27.4

401

3.3

F+2

Total intake

1750

1627

74.8

55.6

221.8

2.70

16.1

564

1106

184.7

77.5

140

148.5

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+3

Total intake

1629

2586

105.6

73.3

412.5

7.18

19.1

791

2002

207.9

129.4

242

168.9

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+4

Total intake

1846

2059

61.5

61.0

338.5

6.06

19.0

938

1144

175.2

152.4

192

121.1

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+5

Total intake

2029

2007

91.5

48.1

322.9

5.86

19.9

990

1624

123.0

81.9

252

103.7

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+6

Total intake

1869

2425

92.4

59.4

400.9

5.84

20.8

962

1481

219.9

147.0

276

186.3

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+7

Total intake

1907

2302

69.3

62.4

414.8

4.07

16.3

1037

1513

141.1

124.0

216

80.5

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+8

Total intake

1437

2405

96.9

103.3

269.8

6.00

19.9

1055

1683

253.5

133.1

272

169.5

.

Feces

10

*

1.18

1.9

1.5

.22

1.3

97

66

16.6

1.8

21

*

F+9

Total intake

216

1432

71.4

36.5

240.6

6.99

14.7

516

1072

130.0

101.1

197

167.2

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

* Insufficient sample.

 

 

[293] Table 13 (Continued)

Intake and Absorption Data - Apollo 16

Commander (continued)

Day

Item

Water (gm)

kcal

Protein (gm)

Fat (gm)

CHO (gm)

Crude Fiber (gm)

Ash (gm)

Ca (mg)

P (mg)

Na (mEq)

K (mEq)

Mg (mg)

Cl (mEq)

.

F+10

Total intake

2301

2363

121.8

105.4

268.0

5.54

25.8

563

1472

253.3

100.0

209

200.5

.

Feces

88

268

17.7

6.8

16.2

2.35

8.5

1927

1193

18.2

29.6

333

2.3

R+0

Total intake

2432

1816

71.5

76.6

200.3

0

12.19

728

1268

97.6

93.0

242

54.2

.

Feces

59

145

8.9

4.4

9.1

1.42

3.36

654

456

1.3

15.7

167

.4

R+1

Total intake

2895

2744

97.9

92.3

388.2

0

13.80

755

1293

120.1

117.6

214

83.6

.

Feces

156

329

22.4

4.9

22.5

5.85

7.95

1221

1039

5.5

45.9

374

1.1

R+2

Total intake

1655

1101

48.1

58.8

95.4

0

8.93

314

881

91.7

83.4

143

61.0

.

Feces

*

*

*

*

*

.54

*

*

*

*

*

*

*

.

Lunar Module Pilot

.

F-3

Total intake

4050

3369

120.7

114.0

352.5

0

18.20

811

1872

179.6

119.6

391

132.1

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F-2

Total intake

4285

3375

128.7

93.1

396.2

0

16.66

734

1743

147.2

113.3

362

117.3

.

Feces

59

179

11.3

4.2

9.6

1.18

4.80

653

747

11.3

20.2

369

.7

F-1

Total intake

3348

2929

118.5

76.5

305.7

0

14.74

515

1914

130.2

98.5

353

83.2

.

Feces

162

435

31.9

14.1

29.0

3.25

16.10

2121

1896

5.1

54.7

1008

3.4

F+0

Total intake

1808

2233

69.7

111.4

252.2

.67

11.32

669

1300

125.6

91.5

176

82.1

.

Feces

71

*

10.8

5.3

9.2

1.54

4.07

653

601

1.8

19.0

320

.8

F+1

Total intake

2365

1980

64.4

56.6

328.9

4.29

16.7

596

1136

169.5

110.2

197

210.2

.

Feces

87

306

17.2

10.2

14.5

1.92

6.5

931

80

4.4

29.9

443

1.8

F+2

Total intake

1794

1588

59.4

51.1

244.0

2.92

13.4

507

938

140.7

83.7

136

167.3

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+3

Total intake

1484

1904

112.0

55.2

274.0

6.04

18.9

513

1627

209.3

129.5

227

190.7

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+4

Total intake

2059

1986

49.0

44.4

406.5

5.67

17.0

862

923

161.9

145.8

172

138.0

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

* Insufficient sample.

 

[294] Table 13 (Continued)

Intake and Absorption Data - Apollo 16

.Lunar Module Pilot (continued)

Day

Item

Water (gm)

kcal

Protein (gm)

Fat (gm)

CHO (gm)

Crude Fiber (gm)

Ash (gm)

Ca (mg)

P (mg)

Na (mEq)

K (mEq)

Mg (mg)

Cl (mEq)

.

F+5

Total intake

1968

1615

89.6

40.0

250.2

5.19

17.86

885

1354

102.3

76.9

232

96.0

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+6

Total intake

1995

2369

16.4

63.9

383.7

7.35

19.96

876

1607

192.1

148.6

283

150.4

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+7

Total intake

1756

2034

64.0

51.1

332.5

3.32

13.20

989

1329

133.4

114.2

175

81.2

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+8

Total intake

1783

2133

93.0

75.2

295.6

5.10

18.03

932

1582

187.5

126.4

268

180.0

.

Feces

177

390

29.4

8.9

16.3

3.88

16.71

2191

1607

6.0

45.9

367

2.5

F+9

Total intake

1126

1388

704

36.1

232.6

7.22

14.0

532

1027

127.6

142.3

177.3

168.1

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+10

Total intake

1645

1679

70.4

71.7

213.7

2.73

17.93

389

1114

153.5

93.3

177

178.0

.

Feces

54

319

15.9

13.6

14.0

1.97

6.55

681

495

51.3

27.5

187

5.9

R+0

Total intake

2298

2585

74.1

97.7

347.4

0

11.30

568

1147

129.3

87.8

165

85.2

.

Feces

394

913

49.9

33.1

57.1

13.26

19.70

2636

2953

79.4

93.0

684

6.6

R+1

Total intake

3175

3373

125.1

108.2

482.5

0

16.67

851

1705

166.0

120.1

264

100.8

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

R+2

Total intake

2246

2436

71.9

111.3

292.3

0

13.01

487

1245

142.7

84.7

185

98.3

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

.

Command Module Pilot

.

F-3

Total intake

2141

2202

76.0

113.3

202.9

0

13.63

566

1141

130.1

98.0

305

101.5

.

Feces

130

293

19.2

9.4

21.2

3.90

6.46

925

866

8.9

29.6

414

1.0

F-2

Total intake

2610

1855

77.6

93.5

136.2

0

11.55

410

1004

100.3

94.3

322

90.1

.

Feces

29

(a)

7.8

4.2

10.0

.75

3.30

514

(a)

1.6

14.2

219

.6

*Insufficient sample.

 

 

[295] Table 13 (Continued)

Intake and Absorption Data-Apollo 16

 

Lunar Module Pilot (continued)

Day

Item

Water (gm)

kcal

Protein (gm)

Fat (gm)

CHO (gm)

Crude Fiber (gm)

Ash (gm)

Ca (mg)

P (mg)

Na (mEq)

K (mEq)

Mg (mg)

Cl (mEq)

.

F-1

Total intake

2356

2338

78.2

82.2

303.9

0

12.10

434

1208

127.4

90.6

224

94.5

.

Feces

99

329

22.3

9.3

12.6

1.89

7.00

1185

977

2.0

34.1

471

1.0

F+0

Total intake

1753

2057

48.2

105.8

221.4

1.30

11.92

630

1046

167.7

91.1

175

109.1

.

Feces*

-

-

-

-

-

-

-

-

-

-

-

-

-

F+1

Total intake

1292

1394

30.0

58.0

201.3

3.38

11.7

382

681

136.7

79.1

110

194.0

.

Feces

37

115

4.8

3.4

7.3

1.26

2.3

345

*

5.7

10.9

131

.7

F+2

Total intake

1227

1052

48.0

31.5

147.8

1.54

10.71

306

658

130.7

53.5

90

107.2

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+3

Total intake

1432

1706

83.2

46.3

267.5

4.41

12.5

614

1389

123.9

95.0

159

100.8

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+4

Total intake

1086

1115

25.1

24.5

200.9

1.68

5.70

400

495

55.2

45.4

97

41.0

.

Feces

32

110

4.9

2.3

7.6

1.52

2.21

382

309

2.0

11.3

126

.4

F+5

Total intake

1476

1348

82.2

44.4

175.5

2.61

13.3

425

1216

124.2

82.6

165

85.7

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+6

Total intake

1089

1165

24.0

57.3

151.0

2.16

11.3

228

546

68.5

75.9

128

38.5

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+7

Total intake

1475

1437

48.6

24.7

233.8

2.29

10.0

856

995

99.4

91.7

118

52.5

.

Feces

144

343

21.9

7.5

20.8

2.52

10.0

1612

1352

28.3

47.2

416

2.6

F+8

Total intake

1186

1263

31.2

55.1

177.3

4.22

11.0

340

613

88.9

81.1

142

75.5

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+9

Total intake

1048

919

41.7

20.1

156.6

3.12

9.9

251

640

85.1

73.3

139

105.0

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

F+10

Total intake

1526

2037

103.2

90.7

224.7

2.94

17.7

714

1551

215.6

110.4

219

136.3

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

 

[296] Table 13 (Continued)

Intake and Absorption Data-Apollo 16

 

Lunar Module Pilot (continued)

Day

Item

Water (gm)

kcal

Protein (gm)

Fat (gm)

CHO (gm)

Crude Fiber (gm)

Ash (gm)

Ca (mg)

P (mg)

Na (mEq)

K (mEq)

Mg (mg)

Cl (mEq)

.

R+0

Total intake

2387

2084

58.3

94.8

250.1

0

10.75

474

1016

108.3

73.1

194

73.8

.

Feces

-

-

-

-

-

-

-

-

-

-

-

-

-

R+1

Total intake

2712

2474

83.8

112.6

289.0

0

13.76

670

1173

121.2

87.0

271

93.3

.

Feces

190

428

26.2

7.6

26.8

3.32

9.87

1678

1365

8.3

53.5

477

2.1

R+2

Total intake

1927

2022

64.1

101.0

216.2

0

11.93

488

1012

126.2

87.0

215

92.5

.

Feces

62

214

13.4

3.7

13.0

1.36

4.67

791

655

1.8

25.2

234

.8

 


[297] Table 14

Balance of Water, Calcium, Phosphorus, Nitrogen, and Sodium During the Apollo 17 Mission

 

Parameter

Control Measurement

Inflight Measurement

CDR

CMP

LMP

CDR

CMP

LMP

.

Water

.

Intake, ml

2666

3734

2268

2143

2705

2270

Urine, ml

1750

2516

1279

1120

1518

992

Feces, ml

63

146

73

68

142

116

Water absorbed, ml

853

1072

916

955

1045

1162

Water absorbed, cc/kg body weight

10.6

13.9

12.1

11.8

13.5

15.3

.

Calcium

.

Intake,mg

673

811

622

675

704

643

Urine,mg

98

204

118

117

182

89

Feces, mg

257

247

269

540

721

591

Calcium absorbed, mg

318

i 360

235

18

-199

- 37

.

Phosphorus

.

Intake, mg

1603

1883

1544

1430

1646

1438

Urine, mg

1139

1056

1087

1267

1561

1253

Feces, mg

239

227

281

280

592

510

Phosphorus, absorbed, mg

225

600

176

-117

-507

-325

.

Nitrogen

.

Intake,N/day/gm

17.6

179

15.9

13.2

16.5

13.7

Urine, N/day/gm

14.0

13.3

16.7

15.7

16.4

15.0

Feces, N/day/gm

2.1

2.2

1.5

1.4

1.9

2.1

Nitrogen absorbed, N/day/gm

1.1

2.4

- 2.3

- 3.9

- 1.8

-3.4

.

Sodium

.

Intake, mEq

216

209

185

168

205

163

Urine, mEq

149

139

192

143

164

135

Feces, mEq

2

5

3

17

26

7

Sodium absorbed. mEq

65

65

-10

8

15

21

.

Potassium

.

Intake, mEq

99

117

95

73

81

97

Urine, mEq

75

81

82

76

75

89

Feces, mEq

4

7

5

12

13

16

Potassium absorbed, mEq

20

29

8

-15

-7

-8


[298] Table 15

Twelve-Day Totals for Apollo 17 Metabolic Balance

 

Parameter

Crewman

CDR

CMP

LMP

.

Water, ml

1224

- 324

2952

Sodium, mEq

- 684

- 600

+ 372

Potassium, mEq

- 420

- 444

- 180

Calcium, mg

-3600

- 11 028

-3264

Phosphorus, mg

- 4104

- 13 284

6012

Nitrogen, gm

- 60

- 101

- 13

Protein (N x 6.25), gm

- 375

- 631

- 75

Mass, kg*

- 4.56

- 2.68

- 3.06

Mass, kg**

.25

- 1.50

- 2.50

* Measurement made on day of recovery.
** Measurement made 24 hours after recovery.

 


 

Discussion

 

Most of the Apollo crewmembers did not eat all the food available. Among the reasons for reduced appetite were decreased hunger, a feeling of fullness in the abdomen, nausea (Berry & Homick, 1973), and preoccupation with the critical mission tasks. Dislike of the food and inadequate rest during the mission were minor problems (Berry, 1970). The evidence suggests that either weightlessness or some other aspect of the mission environment caused the crewmen to restrict their food intake below quantities available and below quantities necessary to maintain body weight.

A reasonable estimate of the energy requirement during a flight can be obtained by correlating careful measurements of food intake with losses or gains in body tissue. The data reveal a mean energy intake of 7384 ± 1735 kJ/day for astronauts during the Apollo missions. If this intake is compared to the NAS, NRC Recommended Daily Dietary Allowance of about 12 000 kJ/day, it is apparent that an average energy deficit was incurred by each Apollo astronaut.

To quantitate the metabolic energy demands throughout the mission and to help define body composition changes, efforts were made during the Apollo 16 mission to control nutrient intake at a constant level throughout the preflight, inflight, and postflight periods. It was believed that stabilizing dietary intake would afford maximum opportunity for detecting body composition changes caused by adaptation to weightlessness.

The mean loss in body weight between the day of the preflight total body water determination and the day of recovery was 3.9 kg. Measurements of total body water loss by tritiated water dilution indicated a mean decrease of 1.77 liters.

 


[299] Table 16

Total Weight Changes During and Following the Apollo Missions

(Values in kilograms)

Mission Number

Crewman

Commander

Command Module Pilot

Lunar Module Pilot

.

Weight losses during mission

.

7

-2.29

- 2.86

- 2.86

8

-3.77

- 2.41

-3.77

9

-3.41

- 3.77

-4.90

10

-3.04

- 4.45

-5.49

11

-4.09

- 3.50

-2.86

12

-.82

- 3.54

- 6.36

13

-4.54

- 5.04

-3.04

14

-1.73

- 5.90

- 3.00

15

-2.18

- 1.54

-3.59

16

-4.81

- 4.04

- 2.63

17

-4.56

- 2.68

- 3.06

.

Weight gains during first 24 hours following each mission

.

7

.75

3.50

4.00

8

2.75

.75

.50

9

2.75

8.50

4.25

10

2.75

1.75

1.50

11

6.00

-

4.00

12

2.00

4.00

3.00

13

-

-

-

14

1.00

7.00

1.00

15

-

-

-

16

2.50

3.00

2.50

17

.25

-1.50

-2.50


Table 17

Apollo 16

Densitometric Data Uncorrected for Lung Volume

.

CDR

CMP

LMP

.

Preflight Weight (kg)

78.822

62.514

72.430

Volume (l)

75.499

62.136

73.199

Density (kg/l)

1.044

1.006

.990

Postflight Weight (kg)

75.425

59.343

70.442

Volume (l)

74.859

57.854

71.399

Density

1.003

1.026

.987


 

[300] When body water loss was converted into lean body mass lost, it was determined that the three crewmembers lost fat in addition to lean body mass because the lean body mass loss does not equal the recorded weight loss. The daily caloric expenditure of the Apollo 16 crewmen can be calculated from the known caloric value of metabolized fat (37.6 kJ/gm and of lean body mass (16.7 kJ/gm). For the three crewmembers, the mean daily caloric expenditure was 17 347 kJ.

Changes in total body potassium measured both by radioactive (potassium 42) dilution and by balance techniques did not reveal a significant loss of lean body mass, an indication that a fat and fluid loss occurred rather than a lean body mass loss. If only body fat were lost, the energy requirement for the three Apollo 16 crewmen would be 21 556, 12 043, and 14 291 kJ/day, with a mean of 15 963 kJ (Johnson et al., 1970).

In an alternate method of summarizing the data, each crewman's body mass loss was calculated from the differences between his mean body weight obtained 30, 15, and 5 days before flight and his weight immediately after flight.

Total body water lost was defined as the mass regained by each astronaut during the 24-hour period following recovery. In this instance, it was assumed that the mean weight loss that was not due to either water or protein loss was due to loss of fat. By this method, a larger loss in body fat was calculated to have occurred in all crewmembers.

Because of difficulties in controlling the respiratory cycle during body volume measurement (Peterson & Herron, 1971), the calculated changes in body composition included the effect of respiration as a random variable; thus, the data have too large a variance for calculation of individual changes in body fat.

During the Apollo 17 mission, a complete collection of urine and feces samples was added to a record of dietary intake so that metabolic balance measurements could be made. By using the results of this study, the energy balance of each crewmember during the Apollo 17 mission was estimated. Each crewmember decreased his intramission energy intake. During the mission, this intake decreased from a mean of 141.3 kJ/kg body weight to 109.1 kJ/kg and represented a 23 percent decrease in the caloric intake of the crewmen. This decrease would result in a net mean deficit in caloric intake of 30 129 kJ throughout the mission (Johnson et al., 1974).

The mean weight loss of the Apollo 17 crewmen was 3.3 kg. Nitrogen balance data reveal a loss of approximately I kg of protein, and the remaining loss can be attributed to fat. A mean caloric deficit of approximately 104 500 kJ is, therefore, assumed to have occurred (Johnson et al., 1974; Leach et al., 1974).

Body tissue losses were first calculated for each astronaut by averaging successive body weights obtained before the mission and subtracting the body weights measured 24 hours after recovery (Rambaut et al., 1973). It had been assumed that any decrease in body mass between the preflight weight and the weight recorded 24 hours after recovery represented water lost. An average of 1.5 kg weight was not regained during this 24-hour period. If this loss was composed entirely of fat, it would represent an additional inflight expenditure of approximately 5643 kJ/day. Commencing with Apollo 16, food and fluid intake, urinary and fecal output, and total body water were measured for each crewman before, during, and after the flight. From these measurements were derived estimates of protein loss, lean body mass, and total body fat. Body volume was estimated by [301] stereophotogrammetry, and body density was calculated. From all these data, it became apparent that crewmembers had lost fat in addition to losing lean body mass.

Losses of musculoskeletal constituents (Rambaut et al., 1973; Vogel et al., 1974) and a variety of fluid and electrolyte anomalies have been detected by biochemical investigations associated with the Gemini, Apollo, Voskhod, and Soyuz flights. The electrolyte anomalies were particularly pronounced during the Apollo 15 mission and may have been associated with inflight cardiac arrhythmias and postflight changes in exercise performance and cardiovascular responses.

Certain therapeutic measures including the elevation of dietary potassium intake were partly responsible for the lack of significant metabolic disturbances following the Apollo 16 mission. Similar elevations in dietary potassium were effected for the Apollo 17 crewmembers

The negative nitrogen and potassium balances that were observed during the Apollo 17 mission are indicative of a loss in the body mass.

 

Summary

 

Apollo nutrient intakes have been characteristically hypocaloric. Estimates of body composition changes from metabolic balance data, from preflight and postflight weights and volumes, and from total body water and potassium provide no evidence for diminished caloric requirements during a flight.

As observed during the Gemini Program and during periods of bed rest, measurements of bone density and metabolic balance confirm a tendency toward loss of skeletal tissue in weightlessness.

No evidence exists that any inflight metabolic anomaly, including hypokalemia, was induced by marginal or deficient nutrient intakes. In general, the Apollo crewmen were well nourished and exhibited normal gastroenterological functions, although appetite was somewhat diminished and the organoleptic response to food was somewhat modified during flight.

 

References

 

 


* Now with Bureau of Food, Food and Drug Administration.

** 1 Joule = .239 calorie.


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