250 E. V. McCOLLUM 



They involve specific starvation or partial starvation for specific dietary 

 factors which are essential for the maintenance of normal metabolism, and 

 the type of pathological condition which develops is characteristic for 

 each of the three factors in this class of nutrient principles whose ex- 

 istence has been definitely established. There is no instance known where 

 xerophthalmia has resulted in a breast-fed infant, or in a nursing animal as 

 the result of a lack of the substance, fat-soluble A in the diet of the mother, 

 and consequently in the milk. Miss Simmonds and I have, however, 

 definitely proven that the factor in question is not present in the milk 

 unless it is furnished in the diet of the mother. Diets deficient in fat- 

 soluble A may in certain instances lead to nutritional disturbance in 

 human infants, although this must be very uncommon. There is much 

 reason to believe, on the other hand, that deficiency of this factor to a 

 degree which brings the infant or older child into a state of nutritional 

 instability, and contributes to the severity of the effects of other deficiencies 

 such as lack of calcium, low protein, etc., is by no means uncommon. 



The fact that the "deficiency" syndromes develop so rarely in infants 

 which are nursed should not be interpreted as an assurance that all is well 

 with the nursed infant so far as the composition of the food supply 

 is concerned. For every child which actually develops a condition which 

 is clinically recognizable, there are many which reach the stage of border- 

 line malnutrition of a more or less specific type. As a rule two or more 

 dietary factors are sufficiently below the optimum in quality to cause 

 damage which will in the course of time become recognizable in some 

 manner. 



The prominence which the unidentified dietary factors, popularized 

 under the term "vitamines," have had in discussions of nutrition during 

 recent years has tended to mask the importance of other factors of equal 

 significance to health. Chief among these is calcium. There is' much 

 evidence that the calcium intake of the breast-fed infant is as a rule not 

 far from the minimum on which normal growth can take place. This 

 is made clear by the occurrence of rickets with such frequency as to make 

 the disease a national health problem in the United States and in most 

 of the countries of Europe at the present time. Calcium and phosphorus 

 are two of the factors which play a prominent role in the etiology of rickets. 

 Another factor is an organic substance, whose chemical nature is not 

 known, but which is normally supplied by milk in sufficient amounts to 

 meet the needs of the developing child. There is much reason to suspect 

 that milk, even when of good quality and produced by a lactating female 

 whose diet is satisfactory according to our ordinary standards, does not con- 

 tain enough of the antirachitic factor to give an appreciable margin of 

 safety. When the diet of the mother is not well chosen, this is one of the 

 factors in which its quality is most likely to fall below normal. The anti- 

 scorbutic factor in milk is also not ordinarily sufficiently abundant to much 



