IX. OCCURRENCE 543 



U. S. Department of Agriculture.^ The nicotinic acid content of various 

 animal tissues has been determined and compiled by several groups. ^'^^ 

 Cereal products have been analyzed and the results compiled. '^"^^ The 

 nicotinic acid content of many fresh fruits and vegetables is listed by 

 Russell et al}^ Rich sources of nicotinic acid are yeasts and meats, especially 

 organ meats such as liver, pancreas, heart, and kidneys. Wheat, barley, 

 and rye are better sources than corn, oats, or rice. Peanuts are a much 

 richer source than soy and other varieties of beans. Milk and related dairy 

 products are low in nicotinic acid. Wheat germ and brewer's yeast are 

 excellent sources. 



B. FORMS OF OCCURRENCE 



In living animal tissues almost all the nicotinic acid is found as the amide 

 bound into nucleotides (DPN and TPN).-" Meats as purchased for human 

 consumption undoubtedly contain a considerable amount of free nicotina- 

 mide, since the pyridine nucleotides are rapidly inactivated and broken 

 down after cellular death, particularly if the cells are disrupted (p. 507). 

 Krehl and associates'^ studied the relative distribution of nicotinic acid 

 and nicotinamide in a variety of cereals, vegetables, and other natural 

 products. From 7 (yellow corn) to 70% (white potatoes) of the total ac- 

 tivity was found as nicotinamide, the remainder as nicotinic acid or as 

 substances which yielded nicotinic acid on hydrolysis. Skim milk powder 

 and rat tissues, on the other hand, contained 91 to 99% in the amide 

 form.21-22 



8 B. K. Watt, A. L. Merrill, M. L. Orr, W. Wu, and R. K. Pecot, U. S. Dept. Agr., 

 Agr. Handbook 8, (1950). 



9 E. Bandier, Biochem. J. 33, 1130 (1939). 



'" H. A. Waisman and C. A. Elvehjem, The Vitamin Content of Meat. Burgess Pub- 

 lishing Co., Minneapolis. 



" Studies on the Vitamin Content of Tissues, Vols. I and II, Univ. Texas Pubis. 

 4137 (1941); 4237 (1942). 



12 W. J. Dann and P. Handler, J. Nutrition 24, 153 (1942). 



" J. M. Mclntire, H. A. Waisman, L. M. Henderson, and C. A. Elvehjem, J. Nutri- 

 tion 22, 535 (1941). 



1'' B. de M. Braganca, Ann. Biochem. and Exptl. Med. (India) 4, 41 (1944). 



15 L. J. Teply, F. M. Strong, and C. A. Elvehjem, /. Nutrition 23, 417 (1942); 24, 167 

 (1942). 



16 R. McVicar and G. H. Berryman, /. Nutrition 24, 235 (1942). 

 1' E. I. Frazier, /. Am. Dietet. Assoc. 26, 264 (1950). 



18 E. B. Brown, J. M. Thomas, and F. F. Bina, J. Biol. Chem. 162, 221 (1946). 



19 W. C. Russell, M. W. Taylor, and J. F. Beuk, /. Nutrition 25, 275 (1943). 



20 J. Robinson, N. Levitas, F. Rosen, and W. A. Perlzweig, J. Biol. Chem. 170, 653 

 (1947). 



21 W. A. Krehl, J. de la Huerga, C. A. Elvehjem, and E. B. Hart, J. Biol. Chem. 166, 

 53 (1946). 



" P. K. Chaudhuri and E. Kodicek, Biochem. J. 44, 343 (1949). 



