502 V. BLOOD LIPIDS 



man. When this regulatory mechanism is not functioning, clinical dis- 

 orders such as hepatic disease, fever, and cutaneous diseases occur. The 

 regulatory mechanism functions abnormally in pregnancy. 895 



(c) The Effect of Massive Doses of Carotene on Plasma Carotene and Vita- 

 min A Levels. When excessive quantities of carotene are ingested by in- 

 dividuals who have severe hepatic disease, diabetes mellitus, or myxedema 

 which prevents a normal utilization of carotene, or even by completely 

 healthy individuals, excessively high values of blood carotene obtain, as 

 indicated by the name of this abnormal condition, carotenemia. It is also 

 sometimes referred to as "carotinosis." 



Carotenemia should be distinguished from hypervitaminosis A, since 

 the causative agent in one case is carotene and in the other instance, vita- 

 min A. Whereas carotenemia is a harmless metabolic condition, hyper- 

 vitaminosis A may result fatally. Both abnormalities can be cleared up by 

 reduction of the intake of the offending substance to a normal level. The 

 amount of carotene is increased not only in the serum, but likewise in the 

 tissues, giving the individual the yellow appearance also characteristic of 

 icterus or jaundice. Normal individuals, especially children, have been 

 known to develop this coloration after an excessive intake of carrots, 896 

 Hubbard squash (Cucurbita maxima), "mikan," or Japanese orange (Citrus 

 nobilis, Lour., var. microcarpa) , 897 or other food sources rich in carotene. 898 



(d) The Effect of Massive Doses of Vitamin A on Plasma Carotene and 

 Vitamin A Levels. When massive doses of vitamin A were given to cows 

 (70,000 to 1,690,000 ^g. per day), a marked suppression of the carotene 

 content of butter fat occurred. 899 ' 900 Coincident with the marked reduc- 

 tion in milk carotene which occurred after the cows had received the high 

 vitamin A supplements for four to six weeks, there was a decrease in blood 

 carotene. This feached as low a level as 30 microgram per cent after 

 eleven weeks of feeding with massive doses of vitamin A. Since a propor- 

 tionality was shown to exist between the vitamin A content of plasma and of 

 milk, 900 the low levels of the latter in many butter samples would indicate 

 that the blood carotenes are concomitantly low. Fountaine and Bolin 901 

 and Jensen et a/. 902 confirmed the depressing action of massive doses of 

 vitamin A on the milk carotene in cows. 



896 A. F. Hess and V. C. Myers, J. Am. Med. Assoc, 73, 1743-1745 (1919). 



897 H. Hashimoto, J. Am. Med. Assoc, 78, 1111-1112 (1922). 



898 H. Koch, Biochem. J., 37, 430-433 (1943). 



899 H. J. Deuel, Jr., N. HaUiday, L. Hallman, C. Johnston, and A. J. Miller, J. 

 Nutrition, 22, 303-313 (1941). 



900 H. J. Deuel, Jr., L. F. Hallman, C. Johnston, and F. Mattson, J. Nutrition, 23, 

 567-579 (1942). 



901 F. C. Fountaine and D. W. Bolin, J. Dairy Sci., 27, 155-158 (1944). 



