Dietary Habits and Related Factors in Fbm Crew Members

A dietary study was conducted on board the USS CASIMIR PULASKI (SSBN 633) (Blue) during patrol. Sixteen crew member volunteers provided data concerning daily food intake, daily meal and snack distributions, weekly appetite changes, weekly food preferences, pure taste thresholds and body weight values. The eating patterns tended to change to a reduction in the number of regular meals and an increase in the number and amount of between meal snacks. Thelate evening"soup down" accoiInfecT for the major part of the between meal eating. Food preferences showed little change as the patrol progressed and certainly did not reflect the predilection of submariners for sweets alluded to in some previous diary type reports. Appetite ähd~welght gam showed a positive relationship and both tended to decrease as the patrol progressed. Taste thresholds to citric acid were increased and thresholds to sucrose were unchanged as the patrol progressed. It is concluded that the dietary patterns of submariners are not remarkably changed on patrol. The changes that do occur are difficult to relate to any one aspect of the environment; but in any event, are of a nature not considered alarming. DIETARY HABITS AND RELATED FACTORS IN FBM CREW MEMBERS INTRODUCTION The nutritional status of submariners on patrol, and the associated area of weight control, has been of interest for many years; however, little objective information has been gathered to date. Martin (1) reported the prominence of between meal snacks in the "submarine routine during World war II, but he included no data in his report to substantiate this impression. In 1950, Schute (2) published a dietary study conducted aboard a submarine deployed to the Arctic. He made no attempt to record food selection habits but did report a protein-carbohydratefat ratio (1:4:1 by weight) which deviated somewhat from the 1:3.6:1.5 ratio of the master menu of the U. S. Army (3). These studies indicate a change in dietary pattern and, while they are products of the "conventional boat" era, it can be assumed that a similar change occurs on nuclear submarines. Of course, the reasons may be different and, in either case, may be difficult to define. Taste discrimination plays some part in food selection (4) and it has been postulated that elevated concentrations of carbon dioxide might alter this function. Indeed, a crude determination of the taste thresholds of two individuals in a pressure chamber breathing three percent carbon dioxide (5) and a study in FBM crew members (6) showed some changes in sour (citric acid) taste discrimination. Other atmospheric contaminants, even strong odors, might also have a significant effect. Another important aspect of diet is related to weight control, a problem that is receiving more and more attention in both military and civilian circles. It is recognized that obesity, of all the health defects in the United States, is the most common reason for the refusal of standard risk life insurance (7). Based on statistical studies (8), it can reasonably be stated that even minor degrees of corpulence (10 to 15 percent above optimum weight) are accompanied by lower productivity, higher incidence of illness, and higher mortality rates. It is hoped that this paper will offer insight into these questions and contribute some knowledge to our understanding of weight control, diet adequacy, etc. MATERIALS AND METHODS Twenty members of the Blue Crew of the USS CASIMIR PULASKI (SSBN 633) were selected at random for this study. Although, as stated, no special criteria was established for participation, personnel on voluntary diet restriction for weight control at any time during the patrol were excluded. This reduced the final number of participants to sixteen. In general, data were collected four times during the prepatrol-patrol period. A. Taste Thresholds. Taste threshold determinations for sucrose and citric acid were performed during the prepatrol period (to establish a control value) and then repeated during the second, fifth, and seventh weeks of patrol. A refined technique modified after Henkin (9, 10) was used for measuring the taste threshold and is described as follows: First, each individual's approximate taste threshold was determined using an array of solution concentrations covering the complete spectrum of normal threshold ranges reported in literature. The definitive taste threshold was then established employing four groups of medicine cups, each group consisting of three cups. One of these groups was employed as a placebo or control group in which all three cups contained distilled water. Each of the other three groups contained one taste sample and two distilled water samples to eliminate guessing by the subject. The three taste sample concentrations used were as follows: One in the concentration of the previously determined approximate threshold; one each .00025M above and below this value for citric acid; and one each .005M above and below for sucrose. B. Dietary Questionnaire. 1. Detailed daily dietary questionnaires (Appendix I) were administered during the seven day period immediately prior to the patrol and then were repeated during the second, fifth, and seventh weeks of patrol. The data were recorded and organized, for the purposes of this paper, into the following groups: a. Meal distribution: A list of the major meals eaten during the specified periods was compiled. This included the normally recognized breafast, lunch, and dinner plus "soup down" at 2300. It was noted that "soup down" does, in fact, take on the prominence of a major meal in the shipboard routine. b. Between meal eating: List of the number of between meal snacks eaten during the specified periods, including a semi-quantitative estimate of the amount ingested with each snack. From this information the number of between meal snacks per day per man and the number of "helpings" per snack were calculated. c. Food selection: A list of the "best liked" and "least liked" dishes served at lunch and dinner was compiled. This section of the questionnaire was to be left blank if there was no definite preference or dislike. Relative frequencies of selection were then determined by comparisons with the number of times each item appeared on the menu. Breakfast and "soup down" were excluded from this part because of the narrow and unvaried selection routinely available. d. Between meal food selection: This consisted of a list, by name, of the foods eaten between meals. The frequency each item was mentioned is also tabulated. 2. Once during each of the specified periods, each man was asked to express a subjective evaluation of his appetite using his predeployment appetite as a comparison reference. C. Weight. Each man's weight was recorded once during each of the specified intervals. Age and height are included for comparison purposes. RESULTS Taste thresholds. The citric acid threshold data are tabulated in Table I. The reported normal threshold for citric acid is 0.00043-0.00190M. All subjects except one (case #16) were within this range during the control (prepatrol testing). Case #16 was also noted to be the only man to demonstrate progressive deterioration of taste sensitivity through the entire patrol. The data of Table I were analyzed employing the paired t test. Only the mean differences between the first patrol samples were significantly different from the prepatrol values. Comparison on an individual basis revealed two men recording one test value for the entire series, six men recording two test values, and two men recording all three test values higher than their control values. Ten men (63%) showed some degree of deterioration in citric acid taste sensitivity during the patrol. In contrast, only one man recorded lower values, i.e., increased taste sensitivity, and five men (31%) showed no change when compared to the corresponding control values. Table I. — Taste Thresholds for Citric Acid Pre-patrol Case # (Control) 2nd Week 5th Week 7th Week 1. .00075M .00075M .0Ü075M .00075M 2. .00075M .00075M .00075M .00075M 3. .00075M .00125M .00075M .00100M 4. .00100M ■00100M .00125M .00100M 5. .00150M .00100M .00100M .00100M 6. .00150M .00150M .00150M .00150M 7. .00150M .00200M .00250M .00200M 8. .00075M .00100M .00100M .0007BM 9. .00075M .00150M .00075M .00100M 10. .00100M .00125M .00125M .00100M 11. .00100M .00100M .00100M .00100M 12. .00125M .00150M .00125M .00125M 13. .00150M .00150M .00250M .00200M 14. .00150M .00150M .00150M .00150M 15. .00125M .00200M .00125M .00150M 16. .00200M .00250M .00300M .0030+ M Mean .00118 .00138 .00138 .00131 Mean differences from prepatrol + .00020* + .00020 + .00013 Standard deviation of the difference ±.000281 ±.000387 ±.000292 * Significantly different from prepatrol values p<.05. Note: Cases 1-7 are nonsmokers and cases 8-16 are smokers. There were some differences in citric acid taste between smokers and non-smokers. The smokers accounted for approximately 75% of the increased threshold (decreased sensitivity) values; however, mean differences between smokers and non-smokers were not statistically significant for any test period (Table II). Table IV. Sucrose Taste Thresholds (Smokers versus Non-Smokers) N Prepatrol (Control) 2nd v ;eek 5th week 7th week