PURE AND IMPURE FOODS 



Edited by C. F. Langworthy, Ph.D. 



Author of "Qn Citraconic, Itaconic and Mesaconic Acids," "Fish as Food," etc. 



"What a Man Eats He Is." 



DIGESTIBILITY OF VEGETABLES. 



The object of a numoer of experiments 

 recently reported by A. P. Bryant and R. 

 D. Milner was to study the digestibility of 

 some important classes" of vegetables, but 

 the results also throw light on the effect 

 of the different vegetables on the digesti- 

 bility of other materials in the diet of 

 which they form a part. The potato was 

 taken as representative of the most im- 

 portant class of vegetables in a large sec- 

 tion of the country ; the cabbage was se- 

 lected as typical of succulent vegetables ; 

 and the beet as a type of roots. Apple 

 sauce was also studied, because it is not 

 infrequently used as a substitute for some 

 vegetable, and because apples are one of 

 the cheaper and common fruits ; and one 

 experiment was made with green corn, to 

 learn whether it is as indigestible as com- 

 monly supposed. 



The subjects in these experiments were 

 3 young, healthy men, with good appetites 

 and normal digestive functions. Each of 

 the articles enumerated above was eaten 

 with a simple basal ration and the digesti- 

 bility of the foods under consideration was 

 calculated from the digestibility of the ra- 

 tion as a whole. 



Of the vegetables studied the results 

 with cabbage were the lowest. According 

 to the estimates for vegetables alone, the 

 digestibility of protein, 47.0 per cent., was 

 particularly low. Considering that cabbage 

 contains so little protein, and that at least 

 half of it is nonproteid, the results for 

 protein in cabbage are of little importance. 

 The other extract of cabbage, designated 

 fat, probably consists of chlorophyll and 

 other matters soluble in ether with little 

 or no food value. On the average for the 

 3 subjects, 82 per cent, of the carbohy- 

 drates was digested and utilized by the 

 body. Of the total energy of the cabbage 

 only 60 per cent, was contained in the 

 digested material, and when allowance is 

 made for the energy of the incompletely 

 oxidized portion excreted in the urine, not 

 much over 57 per cent, of the energy of the 

 cabbage was actually available to the body. 



Considering the average of the 3 experi- 

 ments with potatoes, about 73 per cent, of 

 the protein and 99 per cent, of the carbo- 

 hydrates appeared to be digested, while the 

 energy of the digested material was 94 per 

 cent, of the total quality in the potatoes 

 consumed. 



Although the beets were not particularly 

 relished, their digestibility was high in the 

 experiments with all 3, the average being: 

 for protein, 72 per cent., and for carbohy- 

 drates, 97 per cent. ; while 90 per cent, of 

 the total energy of the beets was contained 

 in the digested material. 



The factors of the digestibility of pro- 

 tein in the apple sauce were low ; but the 

 quantity of protein present was too small 

 to be considered. Some fat, however, was 

 present, as the sauce was made of baked 

 apples to which butter had been added, 

 and the digestibility of the fat, as estimated 

 for the apple sauce alone, averaged 98 per 

 cent, for the 2 experiments. 



On the whole, the results for the digesti- 

 bility for crude fiber were higher than 

 might have been expected, though the ma- 

 terials were all eaten before they had fully 

 ripened, consequently the cellulose may 

 have been in a more tender condition and 

 more readily acted on by the digestive 

 juices. The highest factor was that for 

 apple sauce, 95 per cent., and the lowest 

 that for green corn, 60 per cent. 



The conclusions which were drawn from 

 the investigation follow : As far as .sources 

 of protein or fat are concerned, the vege- 

 tables included in these studies may be 

 considered of little value. They do, how- 

 ever, contain carbohydrates, which the re- 

 sults of these and other experiments indi- 

 cate to be quite well digested and absorbed ; 

 and they may, therefore, be considered as 

 of value as sources of energy, a large pro- 

 portion of which appears to be available 

 to the body. The chief value of many 

 vegetables, however, is perhaps aside from 

 the nutrients or energy they furnish ; they 

 add a pleasing variety and palatability to 

 the diet, supply organic acids and mineral 

 salts, and give the food a bulkiness that 

 seems to be of importance in its mechani- 

 cal action in maintaining a healthy activity 

 of the alimentary tract. Possibly the re- 

 sult of these conditions is a favorable in- 

 fluence on the digestion of other food 

 eaten with the vegetable ; at least such an 

 effect was suggested by the results of some 

 of these experiments. For instance, in the 

 studies with potatoes and with apple sauce 

 added to the basal ration, the digestibility 

 of the total ration, including such material, 

 was noticeably higher than that of the 

 basal ration alone. 



195 



