418 V. BLOOD LIPIDS 



c. The Effect of the Ingestion of Cholesterol on the Level of Blood 

 Lipids, (a) Hypercholesterolemia in Man. There are conflicting reports 

 as to the effect of ingested cholesterol on the level of blood cholesterol in 

 man. A number of workers have been unable to demonstrate any direct 

 relationship between these two values. Thus, Gardner and Gains- 

 borough 342 reported that no hypercholesterolemia occurred after chole- 

 sterol was fed. Likewise, Turner and Steiner 282 could detect no increase in 

 serum cholesterol after the administration of daily doses as high as 20 g. 

 Moreover, Keys 371 reported that single doses of cholesterol, even when 

 large, produced only trivial and transient changes of serum cholesterol in 

 man. It was also stated that the serum cholesterol levels in the blood of 

 "normal" men was not significantly related to differences in the habitual 

 cholesterol intake over a range of 250 to 800 mg. daily. On the other hand, 

 Keys 371 did note that the ingestion of a fat-free, cholesterol-free, calorically 

 deficient diet produced a marked decline in the serum of hypertensive men. 

 The critical level below which a decrease in serum cholesterol occurs is 

 probably between and 200 mg./day. It is suggested that this critical 

 level may vary from individual to individual. It should be recalled here 

 that although the plasma level of normal rats fed a fat-free diet may be 

 lowered, there is a concomitant increase in the cholesterol deposited in the 

 liver and adrenal glands. Whether a similar situation obtains in man has 

 not been ascertained. 



Okey and Stewart 372 are among the investigators who proved that a 

 noticeable increase in the serum cholesterol obtained in young women when 

 cholesterol was fed in the form of egg yolk ; this result was confirmed by 

 Steiner and Domanski 373 ; however, they attributed the cholesterolemia 

 to the lecithin in the egg yolk, inasmuch as comparable results were not 

 obtained by feeding diets rich in fat and cholesterol, even when the daily 

 amount of dietary cholesterol was increased. Apparently cholesterol is 

 effectively absorbed only when adequate amounts of lecithin are present. 

 Egg yolk affords one of the best sources of this phospholipid. It should be 

 noted, however, that earlier workers failed to obtain hypercholesterolemia 

 when eggs were fed. 374 - 375 Friedman et al., m working with rats, reported 

 that, when normal rabbit serum was substituted for their own plasma, 



371 A. Keys, Science, 112, 79-81 (1950). 



372 R. Okey and D. Stewart, /. Biol. Chem., 99, 717-727 (1933). 



373 A. Steiner and B. Domanski, Am. J. Med. Sci., 201, 820-824 (1941). 



374 A. L. Mjassnikow, Z. klin Med., 103, 767-778 (1926). 



376 H. M. Hunt, New England J. Med., 201, 659-667 (1929). 



376 M. Friedman, R. H. Rosenman. and S. O. Byers, Proc. Soc. Exptl. Biol. Med., 81, 

 393-395(1952). 



