232 



VITAMINS 



pensate for these losses white flour and bread are now usually enriched 

 with the three pure vitamins, at least to the levels. 



Table 9-4 



B vitamins in bread and flour 



Whole wheat Enriched white Enriched white 



Vitamin flour* White flour* flour *1i bread *t 



Thiamine 0.55 0.066 0.44 0.33 



Riboflavin 0.12 0.033 0.26 0.26 



Niacin 5.56 0.77 3.52 2.75 



* Milligrams per 100 g. t Minimum standards. 



RIBOFLAVIN 



Physiological function 



The outstanding symptom in young animals or birds fed on a ration 

 low in riboflavin is retarded growth. In poultry, deprivation of this 

 vitamin leads to diminished egg production and especially to a failure 

 of the eggs to hatch. Continued deficiency in the chick causes a condi- 

 tion known as "curled toe paralysis," in which the bird is unable to walk 

 and eventually dies. Examination of such chickens reveals extensive 

 nerve degeneration. 



The necessity of riboflavin has also been demonstrated for rats, dogs, 

 pigs, and man. In a series of outstanding studies Sebrell and his co- 

 workers of the United States Public Health Service have shown that 

 when adult persons subsist for an extended period of time on a diet low 

 in riboflavin, they contract an illness of which characteristic symptoms 

 are soreness and inflammation of the tongue (glossitis), and cracks and 

 sores on the lips and at the corners of the mouth (cheilosis). Further- 

 more, such patients nearly always suffer from various disorders of the 

 eye. These include abnormal sensitivity to light, dimness of vision, and 

 inflammation and development of blood vessels in the cornea. All of 

 these symptoms respond promptly to the daily administration of 5 to 

 10 mg. of pure riboflavin. It is probable that human riboflavin deficiency 

 often accompanies pellagra, although masked somewhat by the more 

 striking symptoms of the latter disease, and that it is rather widespread 

 among the population of America. It has also been reported in India, 

 the West Indies, and many parts of Africa. A children's disease known 

 as "perleche," occasionally" seen in the southern United States, is actually 

 a riboflavin deficiency. 



In living tissues riboflavin is built up into more complex substances, 

 namely, riboflavin phosphate and flavin-adenine-dinucleotide (abbreviated 

 FAD, p. 277), which serve as coenzymes for a series of enzymes involved 

 in metabolism. These enzymes, which are called flavoproteins or "yellow 



