400 V. BLOOD LIPIDS 



However, several workers have maintained that blood cholesterol in- 

 creases with advancing years. Keys 262 reported that the average serum 

 cholesterol of healthy men increased from 173 milligram per cent at nine- 

 teen years to 252 milligram per cent at fifty-two years. For the age range 

 from seventeen to seventy-eight years, Keys et a/. 263 reported a pronounced 

 curvilinear relationship between age and serum cholesterol in men, a maxi- 

 mum concentration being obtained during the sixth decade. During the 

 period of increase, the average rise in serum cholesterol was found to be 

 2.2 mg. of total cholesterol/ 100 ml. serum/year. On the other hand, 

 Sperry and Webb 264 concluded as a result of studies of blood cholesterol on 

 the same fourteen men and eight women over a period of thirteen to fifteen 

 years, that the serum cholesterol concentration may increase with age in 

 some persons, but that the increase is not an obligatory concomitant of 

 aging. 



(e) Chylomicrons and Lipemia. According to Becker, Meyer, and 

 Necheles, 265 there is a definite delay in the rate of absorption of fat, and an 

 increase in the total absorption of corpuscular fat in the aged. These work- 

 ers base their conclusions upon chylomicron curves, which are believed to 

 serve as an index of postabsorptive lipemia. It was found that the oral 

 administration of Tween 80 or of lipase with the fat meal reduced the hy- 

 perchylomicronemia in the aged, but that it was without effect on the chylo- 

 micron curves of young persons after a fat meal. The delayed absorption 

 in older persons may also be reflected in the decreased levels of pancreatic 

 lipase as compared with those of young subjects. 266 Becker et al. 26b sug- 

 gest that the mechanism of fat digestion and/or that of fat absorption may 

 change with aging. 



b. The Effect of Sex. No definite variations in concentrations or in the 

 partition of blood lipids are ascribable to sex. 210 - 213 ' 247 - 267 Gildea and co- 

 workers 268 did report that cholesterol and total fatty acids tended to be high 

 in pyknic (stocky) men, while in leptosomes (slender individuals) the 

 corresponding values were low. On the other hand, no correlation with 

 body build could be demonstrated in females. Moreover, Sperry 257 was 



262 A. Keys, Federation Proc, 8, 523-529 (1949). 



263 A. Keys, O. Mickelsen, E. O. Miller, E. R. Hayes, and R. L. Todd, J. Clin. Invest, 

 29, 1347-1353(1950). 



264 W. M. Sperry and M. Webb, J. Biol. Chem., 187, 107-110 (1950). 



265 G. H. Becker, J. Meyer, and H. Necheles, Science, 110, 529-530 (1949). 



266 H. Necheles, F. Plotke, and J. Meyer, Am. J. Digestive Diseases, 9, 157-159 (1942). 



267 J. A. Gardner and H. Gainsborough, Biochem. J., 21, 130-140, 141-147 (1927). 

 *» E. F. Gildea, E. Kahn, and E. B. Man, Am. J. Psychiat., 92, 1247-1260 (1936). 



