VITAMINS 



239 



been recommended as a more suitable name for nicotinic acid in com- 

 mercial products. 



Good food sources of this vitamin are liver, lean meat, and yeast. Fair 

 sources are certain whole cereals, legumes, and wheat germ. Milled 

 cereals, fats, and molasses are low in nicotinic acid. Several procedures 

 have been suggested for assaying foodstuffs for their nicotinic acid content. 

 Of these the most widely used are the dog assay based on the cure of 

 black-tongue, a chemical method based on the development of a yellow 

 color when an extract of the sample is treated with cyanogen bromide 

 and aniline, and a bacterial method similar to the procedure described 

 for riboflavin. 



Requirements 



Estimates of the amount of nicotinic acid (or its equivalent in the 

 form of nicotinamide, or other related substances such as DPN and 

 TPN) needed daily by various persons are summarized in Table 9-3. 

 Notice how much larger amounts are required than in the case of other 

 B vitamins. Quantities of representative foods which will probably 

 supply 10 to 20 mg. of nicotinic acid are: 1 oz. dried yeast, 3 oz. pork 

 liver, 1/2 lb. lean beef or pork, 4I/2 lb. spinach, or S^^ lb. tomatoes. 



PANTOTHENIC ACID 



Physiological function 



The existence of pantothenic acid was first suggested by Williams and 

 associates in 1933, as a result of their work on the stimulation of yeast 

 growth by extracts of various biological materials. The active substance 

 present has been found to be identical with the dietary factor that pre- 

 vents chick dermatitis, a disease that was for a time thought to be 

 analogous to pellagra in man. 



When young chicks are placed on a ration deficient in this vitamin, 

 crusty scabs form at the corners of the mouth and gradually enlarge 

 until the skin around the nostrils and underneath the lower mandible 

 is affected. Growth ceases and feathering is retarded. Death may result 

 within two or three weeks after these symptoms become apparent. Ad- 

 ministration of pure calcium pantothenate causes resumption of growth 

 and disappearance of the dermatitis. 



Rats, dogs, and swine have also been found to require this vitamin. 

 The black portions of the fur of rats and foxes kept on diets low in 

 pantothenic acid have been observed to turn gray. They have been found 

 to regain their normal color when the vitamin was administered (Fig. 

 9-15. p. 255). Pantothenic acid has also been shown to be essential 

 in the nutrition of a number of lower organisms, especially yeasts and 

 lactic acid bacteria. There is fairly definite evidence also that panto- 



