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DIET 



amount should be provided. Even though 

 the submariner may spend a considerable 

 fraction of the year away from the natural 

 source of ultra violet rays, it is doubtful 

 if any disturbances could result therefrom. 

 The adult requirement for this vitamin has 

 not been adequately estabhshed and most 

 of the evidence indicates that normal young 

 men can be adequately maintained on the 

 small amounts that occur in the ordinary 

 mixed diets (55). 



How about the other vitamins? A num- 

 ber of the vitamins in the B-complex group, 

 together with vitamin C, are easily de- 

 stroyed both in storage and during the 

 preparation of foods. Even when such a 

 relatively staple food as flour is stored at tem- 

 peratures approaching 100° F., considerable 

 amounts of the thiamine added for fortifica- 

 tion are destroyed. In the preparation of 

 foods, important losses of the vitamins may 

 occur if the food is kept hot for a matter of 

 hours. In both of these cases, proper atten- 

 tion to relatively minor details will go far 

 in reducing the nutritive loss. Of as great 

 significance as the loss of vitamins is the 

 change in the taste of such foods. Although 

 very little work has been done in this field, 

 a statement by Dr. Faith Fenton is sugges- 

 tive of the possible imphcations. In one of 

 her Office of Scientific Research and De- 

 velopment reports, she wrote that the de- 

 hydrated cabbage with the highest vitamin 

 C content on reconstitution rated highest 

 on the taste tests. 



Both clinical reports (2, 25, 38, 61) and 

 experimental studies (6, 32, 54, 60) indi- 

 cate that prolonged or very drastic reduction 

 in the intake of the vitamins of the B-com- 

 plex results in profound alterations in body 

 chemistry, work capacity, and personal ad- 

 justment. However, unless the submariner 

 selects a very peculiar diet, and it should be 

 noted that one has to go to great lengths to 

 provide a diet severely deficient in the B 

 vitamins (1), there is httle danger of de- 

 veloping a B-complex deficiency. 



It was originally thought that a modera- 



tely low intake of the vitamin B complex 

 for a period as short as two weeks was likely 

 to produce marked deficiency symptoms (3, 

 29). More recent work under well- 

 controlled laboratory conditions has shown 

 that normal young men can maintain a high 

 level of physical activity for more than two 

 weeks with small amounts of thiamine, ribo- 

 flavin, niacin, and vitamin C in the diet 

 (13, 31). Should unforeseen circumstances 

 reduce the crew of a submarine to a very 

 restricted but calorically adequate diet, no 

 physiological disturbances are likely to re- 

 sult during the first two weeks. The psy- 

 chological repercussions resulting from a mo- 

 notonous diet are likely to be of far more 

 importance than any physiological effects. 



A deficiency of vitamin C eventually pro- 

 duces scurvy, the plague of the saihng- vessel 

 era. The submariner need have no worry 

 on this point. Even if the diet were low in 

 this vitamin during the entire cruise, it is 

 very doubtful whether any deficiency symp- 

 toms directly attributable to this vitamin 

 would appear. This has been brought out 

 by the experiment made on a young surgeon 

 who voluntarily lived on a diet devoid of 

 any vitamin C for six months. The subject 

 maintained his full schedule of activities, 

 and only toward the end of the experiment 

 did he show any signs suggestive of a vi- 

 tamin C deficiency (14). 



Although night vision may be extremely 

 important to the look-out on a submarine, 

 most of the crew must give constant atten- 

 tion to various lighted instruments and 

 gauges. It is doubtful whether a decreased 

 ability to see at night could result, in the sub- 

 marine crew, from a deficiency of dietary 

 vitamin A. It might be noted that the 

 question of time needed for the development 

 of deficiency symptoms is at present in a 

 confused state, but there is increasing evi- 

 dence that normal young men can subsist on 

 a diet very low in this substance for a long 

 time before showing any abnormalities (41, 

 67). Impairment of dark adaptation has 

 been associated with a low intake of vita- 



