B VITAMIN DEFICIENCY STATES 399 



increased resistance to some infectious agents in deficiency states. 22-24 

 Of even greater interest, however, is a consideration of the increased 

 muscular activity which results in some cases of nutritional deprivation. 

 It has been shown repeatedly in rats deprived of thiamine or riboflavin 

 (but not carotenol or mineral salts) that in the period before the usual 

 signs of deficiency occur, the running activity of these animals is mark- 

 edly increased. Wald and Jackson 25 have pointed out that in a free en- 

 vironment this activity would increase the probability of the animal 

 encountering what it lacks. "In effect it represents a gamble in which 

 the animals' metabolic reserves are staked against the chance of finding 

 its necessities. The possibility of a successful outcome for the individual, 

 however, is not the only point of the reaction. It probably represents also 

 the behavioral basis of mammalian emigration." These authors feel that 

 emigration serves more to relieve nutritional pressures on the home 

 population than to rescue the individual emigre from starvation. 



Thiamine Deficiency. There are three known major causes of thiamine 

 deficiency in the higher animals. Of primary importance, the lack of an 

 adequate nutritional source of thiamine results in a number of conditions 

 typified in man by beriberi. Vying with this for importance, the second 

 cause is an increased or inherently high requirement for thiamine in spe- 

 cific individuals, due (1) to physiological conditions previously men- 

 tioned in the discussion of vitamin metabolism, (2) to the action of toxic 

 agents or pathological conditions, or (3) to circumstances involving an 

 abnormal dietary. Finally, mention has previously been made of the 

 production of deficiencies of thiamine in nature by the action of thia- 

 minases and other anti-thiamine compounds. Since the last two etiological 

 factors have already been discussed in some detail, and their result is 

 much the same as in the case of primary nutritional deficiency, the dis- 

 cussion will be principally concerned with this latter situation. 



Beriberi is endemic in regions where polished rice is a major item in 

 the nutrition, polished rice containing about 6 per cent (0.02 mg. per 

 cent) of the thiamine of brown rice (0.3-0.4 mg. per cent) . White wheat 

 flour and other high carbohydrates staples in the diet have also been 

 responsible for beriberi from time to time. 27, 28 Certain other factors, 

 essentially those which increase the thiamine requirement, 29 tend to pre- 

 dispose toward the condition. The incidence is higher in warm months 

 and under condition of high humidity, much commoner in men than 

 women, most frequent between the ages of 15 and 30 years, and greater 

 in individuals having other forms of disease. 



Infant beriberi is also common in many children breast-fed by mothers 

 with beriberi, and is most common in the second month of life. A recently 

 reported acute case in the United States was found in an infant at birth 



