Triglycerides intestinal absorption

A supplementation of procyanidins from cocoa significantly decreased plasma or liver cholesterol and triglycerides in rats fed a high cholesterol diet. The capacity of procyanidins to inhibit intestinal absorption of cholesterol appeared to be one of the mechanisms (Osakabe and Yamagishi, 2009). Cocoa procyanidins had sustained benefits to reverse vascular dysfunction in diabetic patients (Balzer et ah, 2008). Such benefits had been attributed to (—)-epicatechin, which is the constituent unit of cocoa procyanidins (Schroeter et ah, 2006). Procyanidins from cacao were found to inhibit growth of human breast cancer and colonic cancer cells (Camesecchi et ah, 2002 Ramljak et ah, 2005). 

Constantinides, P.P. Scalart, J. Lancaster, C. Marcello, J. Marks, G. Ellens, H. Smith, P.L. Formulation and intestinal absorption enhancement evaluation of water-in-oil microemulsions incorporating medium chain triglycerides. Pharm. Res. 1994, 11 (10), 1385-1390. 

In oral formulations, medium-chain triglycerides are used as the base for the preparation of oral emulsions, microemulsions, self-emulsifying systems, solutions, or suspensions of drugs that are unstable or insoluble in aqueous media, e.g. calciferol. Medium-chain triglycerides have also been investigated as intestinal-absorption enhancers and have additionally been... 

Thus, in summary, it may be concluded that much of the cholesterol synthesized in the intestine is apparently used for local purposes. Under circumstances where there is no triglyceride absorption taking place essentially no newly synthesized sterol of intestinal origin can be detected in the lymphatic outflow from the gut. During active triglyceride absorption, however, the rate of sterol synthesis increases markedly in the intestinal absorptive cells, and a portion of this newly synthesized cholesterol is incorporated into chylomicrons and other intestinal lipoproteins and delivered into the lymph. Thus, both the rate of sterol synthesis by the intestine and the rate of entry of this sterol into the body pools is partially dictated by the rate of triglyceride absorption. 

Recent data indicate that ezetimibe inhibits a specific transport process in jejunal enterocytes, which take up cholesterol from the lumen. The putative transport protein is Niemann-Pick Cl-hke 1 protein (NPCILI). In wild-type mice, ezetimibe inhibits cholesterol absorption by about 70% in NPCILI knockout mice, cholesterol absorption is 86% lower than in wild-type mice, and ezetimibe has no effect on cholesterol absorption. Ezetimibe does not affect intestinal triglyceride absorption. In human subjects, ezetimibe reduced cholesterol absorption by 54%, precipitating a compensatory increase in cholesterol synthesis, which can be inhibited with a cholesterol synthesis inhibitor such as a statin. There is also a substantial reduction of plasma levels of plant sterols (campesterol and sitosterol concentrations are reduced by 48 and 41%, respectively), indicating that ezetimibe also inhibits intestinal absorption of plant sterols. 

The mechanism of intestinal absorption of compounds with vitamin K activity varies with their solubility. In the presence of bile salts, phylloquinone and the menaquinones are adequately absorbed from the intestine, almost entirely by way of the lymph. Phylloquinone is absorbed by an energy-dependent, saturable process in proximal portions of the small intestine menaquinones are absorbed by diffusion in the distal portions of the small intestine and in the colon. Following absorption, phylloquinone is incorporated into chylomicrons in close association with triglycerides and lipoproteins. The extremely low phylloquinone levels in newborns may be partly related to very low plasma lipoprotein concentrations at birth and may lead to an underestimation of vitamin K tissue stores. Absorbed phylloquinone and menaquinones are concentrated in the liver, but the concentration of phylloquinone declines rapidly. Menaquinones, produced in the lower bowel, are less biologically active than phylloquinone due to their long side chain. Very little vitamin K accumulates in other tissues. 

This fundamental role of bile salts in the intestinal absorption of sterols is a reflection of the potential requirements for this cholesterol metabolites in various steps of intraluminal and epithelial cell mechanisms of cholesterol absorption (Figure 1), These include solubilization of cholesterol in the intestinal lumen by mixed micelles, containing biliary bile salts and phospholipids, and the products of triglyceride digestion modification of the intestinal surface barriers to cholesterol transfer, including the un-stirred water layer" and the mucin "coat" and the cellular esterification of cholesterol prior to incorporation of the resulting esters into the lipoprotein core lipids. 

Bauch, A.C., Ingenbleek, Y, and Frey, A. The usefulness of dietary medium-chain triglycerides in body weight control fact or fancy J. Lipid Res. 37, 708-725, 1996. earlier, H. and Bezard, J. Electron microscope auto radiographic study of intestinal absorption of decanoic and octanoic acids in the rat. J. Cell Biol. 65, 383-397, 1975. Bloom, B., Chaikoff, I.L., and Reinhardt, WO. Intestinal lymph as pathway for transport of absorbed fatty acids of different chain lengths. Am. J. Physiol. 166, 451 55, 1951. 

Bloch, R. (1974). Intestinal absorption of medimn-chain fatty acids. J. Nutr. Sci.,13,42-49. Bonanome, A., Bennet, M. Grundy, S. M. (1992). Metabolic effects of dietary stearic acid in mice changes in the fatty aeid composition of triglycerides and phospholipids in various tissues. Atherosclerosis., 94, 119-127. 

Jensen, M. M., Christensen, M. S. Hoy, C. E. (1994). Intestinal absorption of octadecanoic, decanoic and linoleic acid effect of triglyceride structure. Ann. Nutr. Metab., 38, 104-16. 

Intestinal absorption of vitamin E is dependent upon normal processes of fat absorption. Specifically, both biliary and pancreatic secretions are necessary for solubilization of vitamin E in mixed micelles containing bile acids, fatty acids, and monoglycerides (Figure 3). a-Tocopheryl acetates (or other esters) from vitamin E supplements are hydrolyzed by pancreatic esterases to a-tocopherol prior to absorption. Following micellar uptake by entero-cytes, vitamin E is incorporated into chylomicrons and secreted into the lymph. Once in the circulation, chylomicron triglycerides are hydrolyzed by lipoprotein lipase. During chylomicron catabolism in the... 

Figure 7. Apical cytoplasm of an intestinal absorptive cell 30 min after administration of a corn oil meal. This micrograph illustrates the sequence of events in the reesterification of triglycerides and the formation of SER lipid-containing vesicles. Free fatty acids and monoglycerides passively diffuse across the microvillus border (MV) and enter the SER of the apical cytoplasm. The latter frequently is in continuity with the RER (arrow 1). As the free fatty acids and monoglycerides are converted into triglycerides, the SER dilates and lipid droplets are formed within the SER cistemae (arrow 2). Eventually the SER loses its continuity with the RER (arrow 3), and discrete, lip id-containing vesicles (L) bud off from the SER to lie free in the cytoplasm. Mitochondria (M). x 26,060. Reduced 12% for reproduction.

VAN VLIET T, SCHREURS w H and VAN DEN BERG H (1995) Intestinal beta-carotene absorption and cleavage in men response to beta-carotene and retinyl esters in the triglyceride-rich lipoprotein fi action after a single oral dose of beta-carotene. Am J Clin Nutr 62(1) 110-16. 

In the studies discussed, wheat bran, cellulose, and psyllium fiber feeding resulted in increased fecal fat losses and in lowered blood serum cholesterol and triglyceride levels (14,15,32,41) as well as increased fecal losses of calcium. Possible involvement of dietary fat with high or low dietary fiber intake has not been extensively investigated. However, that calcium is involved in intestinal fat absorption is generally accepted (42-45). 

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