IX. OCCURRENCE 547 



tic for each hybrid. Carroll and Lee Peng^^ analyzed two varieties of corn, 

 four of wheat, two of oats, and two of soybeans all grown under the same 

 environmental conditions and found the nicotinic acid content to be more 

 characteristic of the species than the soil. Futhermore, Leng ei al." grew 

 corn which was a cross between a high nicotinic acid sugar line (48.3 7 per 

 gram) and a low nicotinic acid waxy line (18.0 7 per gram). From each ear 

 of the resultant corn they could pick kernels which were sugary in type 

 (33.8 7 of nicotinic acid per gram), waxy (26.0 7 per gram), and dent (21.4 

 7 per gram). This certainly demonstrates the predominance of heredity 

 over environment in this regard. 



Different strains of corn are known to vary greatly in their nicotinic acid 

 content (Table XV). Sugary corns are generally higher than starchy strains. 



TABLE XV 



Nicotinic Acid in Various Strains of Corn (from Burkholder et al. ^^) 



(7/g. air-dried mature grain) 



Type of corn Number of strains Average nicotinic acid Range 



Yellow field 

 White field 

 Sweet 

 Popcorn 



F. NICOTINIC ACID IN U. S. DIETS 



Studies made by the U. S. Department of Agriculture indicate that our 

 food in 1951 supplied 24% more nicotinic acid than in the 1935-1939 

 period. ^^ Much of this increase can be accounted for by the widespread 

 enrichment of white flour, the Federal Standard for which provides a mini- 

 mum of 10 mg. and a maximum of 15.0 mg. of nicotinic acid per pound. ^^ 

 Booher and Behan^° have analyzed composite food samples representative 

 of the national dietary for nicotinic acid, as well as other nutrients. Ac- 

 cording to their results a 3050-calorie diet provides 20.2 mg. of nicotinic 

 acid, considerably in excess of the recommended allowances of the National 

 Research Council (15 mg.).^^ Earlier studies making direct analyses on foods 

 representative of the national dietary in 1940 and 1941 indicated that the 



" J. C. Carroll and C. A. Lee Peng, Science 113, 211 (1951). 

 " E. R. Leng, J. J. Curtis, and M. C. Shekleton, Science 111, 665 (1950). 

 " C. M. Coons, Chicago Med. Soc. Bull. 53, 1015 (1951). 

 69 Federal Register, Aug. 3, 1943. 



60 L. E. Booher and I. T. Behan, /. Nutrition 39, 495 (1949). 



" Recommended Dietary Allowances, Bull. Natl. Research Council, Reprint and 

 Circ. Ser. 129, (1948). 



