212 



VITAMINS 



and this observation, if confirmed, would go a long way toward explaining 

 the action of vitamin D in rickets. 



Prevalence of vitamin D deficiency 



No other deficiency disease has been as noticeable in the United 

 States as that due to lack of vitamin D. Infants from 3 to 24 months of 

 age are most susceptible. Not only is rickets seasonal in appearance, but 

 it is observed more frequently in the North than in the South, where 

 more sunshine is available throughout the year. In fact, it is almost 

 inevitable during the cold Northern winters unless the diets of the young 

 are supplemented with vitamin D. 



Rickets is said to be most prevalent in Great Britain, France, Belgium, 

 Germany, European Russia, Austria, Hungary, and the United States. 

 Sebrell cites reports of the U. S. Census Bureau to the effect that 244 

 deaths resulted from rickets in 1938. Before vitamin D therapy was 

 used (1928) the Ministry of Health reported 87 per cent of London ele- 

 mentary school children as giving evidence of having had some degree 

 of rickets. A survey of children in Sydney, Australia, revealed that 

 about one-half of them either were or had been rachitic. In 1943 Follis 

 and co-workers reported the results of examining 230 consecutive cases 

 of children from 2 to 14 years of age who had died from various causes 

 in Baltimore, Maryland. No less than 46.5 per cent were found on 

 autopsy to have had some degree of rickets. It will be noted that coun- 

 tries of the extreme north are not included in the above list, a fact which 

 is probably due to the important place that fish and glandular organs 

 assume in the diets of these peoples. Young girls of the upper Moham- 

 medan classes in India suffer from rickets as a result of religious tenets, 

 now rapidly disappearing, that require the women to remain in seclusion 

 after becoming 12 years of age. Lower classes fare better, even though 

 their diet is less satisfactory, because they live more in the open air. 



Chemical nature 



Although the existence of as many as ten different antirachitic com- 

 pounds has been rather well established, only two of the D vitamins have 

 been proved to be of any practical importance so far as antirachitic 

 medicines and foods are concerned. These may be produced in the 

 laboratory from ergosterol and from 7-dehydrocholesterol, respectively, 

 by irradiation with ultraviolet light. The principal structural changes 

 associated with acquisition of antirachitic potency are shown by com- 

 parison of the formulas of ergosterol and calciferol. Ring B is opened, 



