Intestinal absorption of fat

B14. Blomstrand, R., A study on the intestinal absorption of fat in normal adults and in non-tropieal sprue with carbon-labelled oleic acid and palmitic acid. Acta Med. Scand. 152, 129-138 (1955). 

II. Nutritargeting as a Way of Bypassing Absorption Barriers A. Digestion and intestinal absorption of fat-soluble 202... 

They facilitate the intestinal absorption of fat-solnble vitamins (vitamin A, retinol vitamin D, cholecalciferol vitamin E, tocopherol and vitamin K). 

All chemicals absorbed in the gastrointestinal tract first reach the liver, where they normally undergo biotransformation to new, more water-soluble molecules (metabolites). Some of these will eventually be excreted in the bile. Thus, in addition to playing an important role in the digestion and intestinal absorption of fats, bile is also involved in the elimination of chemicals from the body. 

Bile salts Cholesterol derivatives with detergent-like properties used to solubilize cholesterol, assist in intestinal absorption of fat-soluble vitamins, and emulsify dietary lipids passing through the intestine to enable fat digestion and absorption by exposing fats to pancreatic lipases. 

A fused multiple-ring system is the structural framework for steroids. Cholesterol is the nonpolar, nonsaponifiable progenitor of the metabolic and gonadal hormones such as cortisol, testosterone and estrogen as well as the bile acids used for the intestinal absorption of fats and oils. Many toxins fit into this lipid subclass. 

It is well known that dietary fat is not absorbed from the intestine unless it has been subjected to the action of pancreatic lipase [1], Previously, we found that basic proteins such as protamines, histones and purothionine inhibited the hydrolysis of triolein emulsified with phosphatidylcholine [2], The inhibition of hydrolysis of dietary fat may cause a decrease or delay in the intestinal absorption of fat and reduce blood chylomicron levels, an excess of which is known to induce obesity [3], Therefore, there was a possibility that inhibitory substances toward pancreatic lipase activity may prevent the onset of obesity induced by feeding a high fat diet to mice. Recently, we found that natural products such as tea saponin, platycodi radix saponin, chitin-chitosan and chondroitin sulfate inhibited the pancreatic lipase activity. In the following section, the anti-obesity effects of these natural products will be described in detail. 

Vitamin K is poorly absorbed in the absence of bile. Thus, hypoprothrombinemia may be associated with either intrahepatic or extrahepatic biliary obstruction or a severe defect in the intestinal absorption of fat from other causes. 

Osteomalacia, adult rickets, is a meta-boKe bone disorder eharaeterized by inadequate or delayed mineralization of bone. The major risk faetors are a diet low in vitamin D, deereased endoge-nons prodnetion of vitamin D beeause of inadeqnate snn exposnre, impaired intestinal absorption of fats (vitamin D is fat solnble), and disorders that interfere with the metaboKsm of vitamin D to its aetive form. 

BILE ACIDS AND THE INTESTINAL ABSORPTION OF FAT AND ELECTROLYTES IN HEALTH AND DISEASE ... 

Publication of a book devoted entirely to the chemistry, physiology, and metabolism of bile acids indicates a renascence in interest in these poly-functional detergents. Here we will summarize present views on the physical and physiological properties of bile acids in relation to their chemical structure which bear on their participation in the intestinal absorption of fat, their enterohepatic circulation, and their influence on electrolyte and water absorption by the colon. Several of these topics are considered in detail elsewhere in this book, as well as in recent reviews (1-4). This chapter will focus on our own studies but will also emphasize areas in which information is needed. 

Bile Acids and Intestinal Absorption of Fats and Electrolytes... 

Bile acids have two major functions in man (a) they form a catabolic pathway of cholesterol metabolism, and (b) they play an essential role in intestinal absorption of fat, cholesterol, and fat-soluble vitamins. These functions may be so vital that a genetic mutant with absence of bile acids, if at all developed, is obviously incapable of life, and therefore this type of inborn error of metabolism is not yet known clinically. A slightly decreased bile acid production, i.e., reduced cholesterol catabolism, as a primary phenomenon can lead to hypercholesterolemia without fat malabsorption, as has been suggested to be the case in familial hypercholesterolemia. A relative defect in bile salt production may lead to gallstone formation. A more severe defect in bile acid synthesis and biliary excretion found secondarily in liver disease causes fat malabsorption. This may be associated with hypercholesterolemia according to whether the bile salt deficiency is due to decreased function of parenchymal cells, as in liver cirrhosis, or whether the biliary excretory function is predominantly disturbed, as in biliary cirrhosis or extrahepatic biliary occlusion. Finally, an augmented cholesterol production in obesity is partially balanced by increased cholesterol catabolism via bile acids, while interruption of the enterohepatic circulation by ileal dysfunction or cholestyramine leads to intestinal bile salt deficiency despite an up to twentyfold increase in bile salt synthesis, to fat malabsorption, and to a fall in serum cholesterol. 

Bergstom, G., and B. Borgstr5m Intestinal absorption of fats. Progr. in the Chemistry of Fats and other Lipids. 3, 352 (1955). 

Lipstatin is a pancreatic lipase inhibitor produced by Streptomyces toxytricini that interferes with intestinal absorption of fats. A semisynthetic derivative, tetrahydrolipstatin, has been introduced into the market as an antiobesity agent. It appears to be also useful in managing the effects of diabetes (Weibel et al. 1987). 

C24 Cholic acid C24H40O5 Gall bladder and intestines absorption of fats... 

---