202 VITAMINS 



of one vitamin were often in reality due to a lack of several. To illus- 

 trate, the original vitamin B has been found to consist of some ten or 

 more factors. This accounts, in part, for the lack of a systematic nomen- 

 clature, which is so apparent in the list just given. Now that each of 

 the above vitamins is well known as a distinct chemical substance, much 

 confusion can be avoided if they are designated by their scientific names 

 rather than by mere letters. All of the vitamins listed have been isolated 

 in pure form, and the chemical structures have been worked out, except 

 for vitamin B12. In addition, all the vitamins are produced commercially, 

 mainly by synthetic processes, and hence are available in practically 

 unlimited amounts at much lower prices than formerly. 



Since chemical processes in widely differing organisms are frequently 

 closely related, one might be led to assume that in all higher animals 

 the vitamin requirements would be practically the same. That such an 

 assumption is without foundation, however, is evidenced by the fact 

 that the rat synthesizes its own supply of ascorbic acid. So far as this 

 animal is concerned, therefore, this compound is not a vitamin. Skin 

 disorders resembling those of pellagra in man can be produced in the 

 rat and chick, but they do not respond to treatment with nicotinic acid, 

 as in the case of man, and neither is pellagra in man relieved by the 

 vitamins that effect cures in the above-named species. Other ex- 

 amples of such differences in dietary requirements may be noted in dis- 

 cussions of the various vitamins. 



The relative prevalence of vitamin and other dietary deficiencies in 

 the United States is difficult to estimate closely, but is probably much 

 greater than has been supposed. Sebrell has commented on the situation 

 as follows: 



. . . Today it is recognized that all of the known nutritional diseases probably exist 

 to some extent in the United States. Those that appear to be of most importance 

 are anemia, due to iron or cobalt deficiency; nutritional edema, due to protein 

 deficiency ; hyperkerataosis ^ and night blindness, due to vitamin A deficiency ; beriberi 

 and peripheral neuritis," due to thiamine (vitamin Bi) deficiency, frequently secondaiy 

 to such conditions as alcoholism, pregnancy and diabetes; lip lesions, seborrhea" and 

 keratitis,^ due to riboflavin deficiency; pellagra or encephalopathy,^ due to nicotinic 

 acid deficiency; swollen bleeding gums, skin and subperiosteal hemorrhages,'' due to 

 ascorbic acid deficiency; rickets and osteomalacia,'^ due to vitamin D deficiency; 

 hemorrhagic disease of the newborn, due to vitamin K (phthiocol) deficiency; tetany, 

 due to hypocalcemia,* and probably many other at present less well identified condi- 

 tions with a nutritional background. . . . 



^ JJxcessive growth of the cornea. 



^ Inflammation of the nerve endings. 



^ A chronic disease of the sebaceous, or oil-secreting glands of the skin. 



* Inflammation of the cornea. 

 ^Any disease of the brain. 



* Bleeding under the periosteum, the fibrous membrane covering bones. 

 '' Softening of the bones. 



* Abnormally small amounts of calcium in the blood. 



