ANNUAL REPORT, 1936 67 



DEPARTMENT OF HOME ECONOMICS 

 Helen S. Mitchell in Charge 



Cause and Control of Nutritional Cataract. (H. S. Mitchell and G. 

 M. Cook.) The production of nutritional cataract in rats fed on lactose or 

 galactose rations has been previously demonstrated. Further studies in this 

 field have been reported or are at present in progress. 



1 . Susceptibility of different strains of rats to nutritional cataract. A report of 

 these findings was made at the American Home Economics meeting in Seattle, 

 Washington, July 7, 1936, and was published in the Journal of Nutrition 12: 

 447-453, 1936. Rats from different colonies showed variable susceptibility to 

 cataract. The Battle Creek strain had the highest incidence and the mature 

 cataracts developed in the shortest time of any of the three breeds tested on the 

 70 percent lactose ration. The Massachusetts State College and the Wistar 

 strains showed advanced lens changes but complete opacities developed in 

 only 10 and 9 percent, respectively, of the rats tested. On the 35 percent galac- 

 tose rations the incidence of mature bilateral cataract was 100 percent in the 

 Battle Creek and Massachusetts State College strains and slightly less in Wistar 

 and Johns Hopkins strains. The time for cataract to develop/was shortest in 

 the Battle Creek strain. Severity of intestinal disturbances did not correlate 

 with cataractous changes in the lens. Growth was normal on the galactose but 

 slightly retarded on the lactose ration, probably due to the persistent diarrhea 

 in the young rats. Cataract development was more rapid in young rats than 

 in older ones. The age at which animals are started on experimental rations 

 must be kept constant if results are to be consistent. 



2. The relation of ingested carbohydrate to the type and amount of blood and 

 urine sugar and to the incidence of cataract in rats. The report of this work has 

 been accepted for publication in the Journal of Nutrition early in 1937. Blood 

 and urine sugar studies have been made on rats fed on adequate rations con- 

 taining 62 and 70 percent lactose, 25 and 35 percent galactose, 35 percent fruc- 

 tose, 35 percent xylose, and 70 percent starch. Determinations of total and 

 nonfermentable sugar were made on both blood and urine specimens from the 

 various ration groups. Total blood-sugar values were higher on galactose 

 rations than on lactose but above normal in all animals on cataract-producing 

 rations. The nonfermentable fraction of blood sugar was the variable in the 

 different groups, the fermentable fraction remaining more nearly constant 

 and within the range of normal blood glucose. Average total blood-sugar values 

 of three strains of rats fed on the 35 percent galactose ration were strikingly 

 similar, in contrast to the differences observed in susceptibility to cataract 

 among the same groups. Insulin-protamin (Lilly) failed to lower blood galac- 

 tose or reduce the speed of cataract development on a 25 percent galactose ra- 

 tion. Galactose is chiefly responsible for both the high blood and urine sugars 

 observed in rats fed on lactose and galactose rations and must be the major 

 etiological factor in this type of cataract. 



3. Effect of other dietary variations on susceptibility to cataract. The cataract- 

 producing action of lactose or galactose rations containing variable types and 

 amounts of other ingredients has been investigated. Work is still in progress 

 on the effect of fat content of the diet. So far the carbohydrate type and 

 amount is the crucial factor. 



