Dietary Fat and Human Health; a Report (1966) / Chapter Skim
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FAT METABOLISM
FAT METABOLISM
Pages 11-20
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From page 11... ...
In addition, the entry of bile into the duodenum contributes important amounts of bile salts and lecithin, the latter quickly undergoing hydrolysis to lysolecithin. Both of these classes of compounds are essential to solubilization of the lipids in the intestinal contents, which form a twophase system -- an oil phase containing almost all the tri- and diglycerides, and a water-clear micellar solution of monoglycerides, bile salts, lysolecithin, and soaps.
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From page 12... ...
Cholesterol is largely re-esterified in the mucosal cell and is incorporated into the chylomicron along with the triglycerides. By contrast, bile acids and fatty acids of chain length shorter than 12 carbon atoms pass into the portal circulation rather than the intestinal lymphatics; they are transported directly to the liver, probably bound to albumin and to the nonparticulate lipoproteins.
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From page 13... ...
Approximately 45 percent of the fasting plasma fatty acid content is in phospholipids, 35 percent in glycerides, 15 percent, relatively more unsaturated, in cholesterol esters, and 5 percent as free fatty acids. a-Lipoproteins In the postabsorptive state, roughly one fourth of the plasma cholesterol by weight and one half of the phospholipids are combined with a specific globulin designated A or a-apolipoprotein.
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From page 14... ...
From patients with Tangier disease (61) it is known that severe deficiency of the A apoprotein is associated with marked tissue storage of cholesterol esters, and this protein may have some special function in transporting cholesterol.
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From page 15... ...
The physiological particle is the chylomicron formed during fat absorption. This package of glyceride is carried up the thoracic duct into the blood stream and is rapidly removed by many tissues, including muscle and adipose tissue.
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From page 16... ...
The biosynthesis of fatty acids from carbohydrate and amino acids and their oxidation are accomplished through reversible reactions involving acetate and coenzyme A Fatty acids may also be interconverted in the body through stepwise alteration of the chain length by addition or removal of two-carbon fragments and by introduction or removal of double bonds.
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From page 17... ...
Thus, fat derived largely by synthesis from carbohydrate is more saturated and more firm than that derived from dietary fat, due to the low rate of conversion of the newly formed monoenoic acids to more unsaturated acids. Arachidonic acid is the principal polyunsaturated fatty acid that the animal synthesizes from linoleic acid.
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From page 18... ...
This caloric reserve is maintained mainly in adipose tissue cells and may derive directly from the fatty acids in food or it may arise from the conversion of glucose or certain amino acids into fatty acids. Adipose tissue is capable of removing fatty acids from circulation for triglyceride synthesis, and can also manufacture fat from blood glucose.
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From page 19... ...
The quantity excreted daily approximates the amount of bile acids produced from cholesterol in the liver (17)
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From page 20... ...
In the kidney, also, abnormal accumulation of lipid induces cellular destruction. Here, however, the sequence of events leads to interference with blood supply of the fatty swollen tubules and culminates in the hemorrhagic renal syndrome of choline deficiency.
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