LIPIDES (fats and RELATED SUBSTANCES) 95 



surprisingly high value of 17 per cent of the dry weight. Cholesterol 

 is also the chief component of human gallstones, deriving its name from 

 this circumstance (Greek: chole, bile + stereos, solid). It has the 

 formula: 



CH3 CH, 



CH(CH,)3-CH-CH, 



H2 CH3 I 

 C I C 



H2 CH3 I 

 ^C I ^C. H /C CH, 



H, H 



Cholesterol 



The general distribution of cholesterol in the body indicates that it 

 must perform some important function there. It has been found that 

 cholesterol protects the blood corpuscles from the dissolving action of 

 certain poisons (saponins) . It also checks the tendency of the bile salts 

 to dissolve the blood corpuscles and inhibits the action of the fat-splitting 

 enzymes (lipases). A closely related compound, 7-dehydrocholesterol, 

 is the precursor of one of the important D vitamins. 



In some types of heart disease (atherosclerosis) so much cholesterol 

 and other lipides are deposited on the inner walls of the heart arteries 

 that the blood supply to the heart muscle is seriously impaired. Since 

 this condition is associated with a high level of cholesterol in the blood, 

 it has been suggested that diets rich in cholesterol should be avoided. 

 Unfortunately this would eliminate the use of eggs, milk, butter, pork, 

 liver, and other highly nutritious foods. Furthermore, even if no cho- 

 lesterol is ingested, large amounts are synthesized in the body from other 

 substances. It has been shown that the blood cholesterol level is more 

 definitely associated with other factors such as age and obesity than 

 it is wath dietary intake. 



Sitosterol 



Vegetable oils such as corn, wheat, cottonseed, and linseed oils contain 

 sitosterol and other sterols. Sitosterol is found in the nonsaponifiable 

 fraction of the oil. Some investigators have maintained that the plant 

 sterols are converted into cholesterol and other zoosterols in the animal 

 body. There is abundant evidence, however, that cholesterol is syn- 



