Digestion Of Dietary Fat Research Articles

Altered Lipid Response in Hamsters Fed cis‐9,trans‐11+trans‐8,cis‐10 Conjugated Linoleic Acid Mixture

The objective of the present study was to compare the effects of cis-9,trans-11 + trans-8,cis-10 conjugated linoleic acid (CLA) mixture to those of cis-9,trans-11 + trans-10,cis-12 CLA mixture and linoleic acid (LA) on lipoprotein profile, hepatic lipids, body composition and digestibility of dietary fat in hamsters (n = 17) fed diets containing 2% of experimental fat (w/w) for 28 days. The cis-9,trans-11 + trans-10,cis-12 CLA mixture showed higher LDL cholesterol concentrations than LA and the cis-9,trans-11 + trans-8,cis-10 CLA mixture. The cis-9,trans-11 + trans-8,cis-10 CLA mixture induced similar plasma LDL cholesterol and hepatic lipid concentrations, and coefficient of digestibility as LA, indicating no effect of the trans-8,cis-10 CLA isomer on these lipid parameters. On the other hand, the cis-9,trans-11 + trans-8,cis-10 CLA mixture induced higher plasma VLDL cholesterol and triglycerides than LA and the cis-9,trans-11 + trans-10,cis-12 CLA mixture. The cis-9,trans-11 + trans-8,cis-10 CLA mixture also induced the highest plasma glucose concentrations compared with the two other groups, indicating an impairment of glycemic control. No differences in body composition were noted between the three groups. The present results thus show that the cis-9,trans-11 + trans-8,cis-10 CLA mixture can deteriorate plasma VLDL cholesterol and triglycerides in hamsters, possibly due to an increased flux of glucose.

Bile Salt–Stimulated Lipase and Pancreatic Lipase-Related Protein 2 Are the Dominating Lipases in Neonatal Fat Digestion in Mice and Rats

During infancy, the basic conditions for digestion of dietary fat differ from later in life. The bile salt-stimulated lipase (BSSL) is an enzyme expressed in the exocrine pancreas and in some species (including human) also in the lactating mammary gland and secreted with the milk. The aim of this study was to compare the ontogeny of four pancreatic lipases [BSSL, pancreatic triglyceride lipase (PL), pancreatic lipase-related protein 2 (PLRP2), and phospholipase A2 (PLA2)] in one species that supplies BSSL with milk (the mouse) and one that does not (the rat). We followed expression of the four pancreatic lipases from postnatal d 1 until after weaning in both species. We found that BSSL and PLRP2, two lipases with broad substrate specificity, dominated. It was not until weaning that significant expression of PL and PLA2 were induced. Thus, BSSL and PLRP2 seem to be responsible for fat digestion as long as milk is the main food. Moreover, the early temporal pattern of BSSL expression differed between species. We speculate that the milk-borne BSSL is able to compensate for a slower ontogeny of pancreatic BSSL expression in the mouse.

Alternate expression of BSSL and other pancreatic lipases during infancy

Background Bile salt-stimulated lipase (BSSL), pancreatic triglyceride lipase (PTL), pancreatic lipase-related protein 2 (PLRP-2), phospholipase A2 and colipase are all expressed in the exocrine pancreas and involved in digestion of dietary fat in the small intestine. BSSL is also expressed in the mammary gland during lactation and is a constituent of the milk in some species, including human. The contribution of BSSL with the milk compensates the low intraluminal levels of PTL and bile salts in infants that otherwise may lead to fat malabsorption. In fact, such fat malabsorption is almost exclusively seen in formula-fed, but not in breast-fed infants. Aim To compare the ontogeny of the four pancreatic lipases and colipase in one species that secretes BSSL in milk (mouse) and one that does not (rat). Methods Quantitative real-time PCR and Western blots were performed to follow lipase expression in pancreas from birth until adulthood in both species. Results BSSL was expressed already at day 1 post-partum. In mice, the level of BSSL mRNA increased gradually from day 1 to reach a peak value around day 7, where after it declined. In contrast, the rat pancreatic BSSL appeared to be constitutively expressed already from day 1 until adulthood. Previous studies showing that PTL and PLA-2 expression is low until the suckling/weanling transition, whereas PLRP-2 and colipase is expressed from day 1 were confirmed in both species. Conclusion BSSL together with PLRP-2 are the dominating lipases involved in fat digestion as long as pups are suckled. Further, in mice lower expression of BSSL the first days seems to be compensated for by BSSL in milk.

Effects of Tea Polyphenols on Emulsification of Olive Oil in a Small Intestine Model System

Tea catechins have been shown to reduce plasma cholesterol and suppress hypertriacylglycerolemia by reducing triglyceride absorption. However, the mechanism is not yet clear. One of the possible mechanisms is that tea polyphenols may modify dietary fat emulsification in the gastrointestinal tract. The digestive enzyme (lipase) acts on specific emulsion interface properties (droplet size and surface area). Therefore, changes in these properties may modify emulsification and lead to changes in dietary fat digestion and absorption. In this study, the effect of both green and black tea on the changes of emulsification was examined by measuring the droplet size and the surface area. A model emulsion system containing olive oil, phosphatidylcholine (PC), and bile salt was developed to simulate small intestinal conditions. Initial changes in droplet size (from 1.4 to 52.8 microm and from 1.4 to 25.9 microm) of the emulsion were observed in the presence of 1.04 mg/mL and 0.10 mg/mL of total catechins prepared from green and black tea, respectively. Both teas caused similar changes on the emulsion properties; however, black tea was more effective than green tea. The underlying mechanisms of actions of tea polyphenols are discussed.

Absorption and lipoprotein transport of sphingomyelin

Dietary sphingomyelin (SM) is hydrolyzed by intestinal alkaline sphingomyelinase and neutral ceramidase to sphingosine, which is absorbed and converted to palmitic acid and acylated into chylomicron triglycerides (TGs). SM digestion is slow and is affected by luminal factors such as bile salt, cholesterol, and other lipids. In the gut, SM and its metabolites may influence TG hydrolysis, cholesterol absorption, lipoprotein formation, and mucosal growth. SM accounts for approximately 20% of the phospholipids in human plasma lipoproteins, of which two-thirds are in LDL and VLDL. It is secreted in chylomicrons and VLDL and transferred into HDL via the ABCA1 transporter. Plasma SM increases after periods of large lipid loads, during suckling, and in type II hypercholesterolemia, cholesterol-fed animals, and apolipoprotein E-deficient mice. SM is thus an important amphiphilic component when plasma lipoprotein pools expand in response to large lipid loads or metabolic abnormalities. It inhibits lipoprotein lipase and LCAT as well as the interaction of lipoproteins with receptors and counteracts LDL oxidation. The turnover of plasma SM is greater than can be accounted for by the turnover of LDL and HDL particles. Some SM must be degraded via receptor-mediated catabolism of chylomicron and VLDL remnants and by scavenger receptor class B type I receptor-mediated transfer into cells.

Fat absorption in cystic fibrosis mice is impeded by defective lipolysis and post-lipolytic events

Cystic fibrosis (CF) is frequently associated with progressive loss of exocrine pancreas function, leading to incomplete digestion and absorption of dietary fat. Supplementing patients with pancreatic lipase reduces fat excretion, but it does not completely correct fat malabsorption, indicating that additional pathological processes affect lipolysis and/or uptake of lipolytic products. To delineate the role of such (post) lipolytic processes in CF-related fat malabsorption, we assessed fat absorption, lipolysis, and fatty acid uptake in two murine CF models by measuring fecal fat excretion and uptake of oleate- and triolein-derived lipid. Pancreatic and biliary function was investigated by determining lipase secretion and biliary bile salt (BS) secretion, respectively. A marked increase in fecal fat excretion was observed in cftr null mice but not in homozygous DeltaF508 mice. Fecal BS loss was enhanced in both CF models, but biliary BS secretion rates were similar. Uptake of free fatty acid was delayed in both CF models, but only in null mice was a specific reduction in lipolytic activity apparent, characterized by strongly reduced triglyceride absorption. Impaired lipolysis was not due to reduced pancreatic lipase secretion. Suppression of gastric acid secretion partially restored lipolytic activity and lipid uptake, indicating that incomplete neutralization of gastric acid impedes fat absorption. We conclude that fat malabsorption in cftr null mice is caused by impairment of lipolysis, which may result from aberrant duodenal pH regulation.

Use of wood ash extract and germination to improve the feeding value of Ugandan Sekedo sorghum ( Sorghum bicolor) for broiler chicks

Three experiments were conducted to investigate the effect of treating Sekedo sorghum (SK) with wood ash extract on its feeding value for broiler chicks. Sekedo was either soaked in water and germinated for 26 h (WG), soaked in wood extract (AS), germinated after soaking in ash extract (AG) or left untreated (UT). The first experiment was a 1-week-long metabolism trial with SK constituting 980 g/kg diet. In the subsequent 4-week feeding trials (Experiments 2 and 3), the grain constituted 500 g/kg of the experimental diets, to make practical rations. Tannin content of SK was 44.9 ± 2.5 g catechin equivalents (CE)/kg on dry matter basis. Treatment of SK with wood ash extract reduced its tannin content and greatly improved its apparent metabolizable energy (ME n) value. In Experiment 2, there was a significant improvement ( P < 0.05) in growth rate and feed efficiency of chicks fed the AG diet. Ileal digestibility of dietary protein and fat were significantly ( P < 0.05) higher for the AS and AG diets than for the WG and UT diets. In Experiment 3, coefficient of ileal digestibility of dry matter for the UT diet was inferior ( P < 0.05) to that of the AS and AG diets although feed intake and body weight gain were not significantly different.

Effects of supplementing with calcium salts of palm oil fatty acids or hydrogenated tallow on ewe milk production and twin lamb growth.

Two experiments were conducted with Polypay ewes nursing twin lambs to evaluate the effects of supplementing fat (calcium salts of palm oil fatty acids or hydrogenated tallow) on ewe lactation. In Exp. 1, ewes were fed a 52% concentrate:48% hay-based diet (as-fed basis) consisting of alfalfa hay (n = 4), endophyte-free fescue hay (n = 4), or fescue hay with 3.7% fatty acids (n = 4) from d 4 to 56 of lactation. In Exp. 2, ewes were fed similar diets that had endophyte-free fescue hay (n = 6), fescue hay with 3.7% fatty acids (n = 5), or fescue hay with 3.1% tallow (n = 6) from d 14 before lambing until d 57 of lactation. Diet formulations with supplemental fat were more nutrient dense, and treatments were fed to meet ewe nutrient requirements; this caused diets with added fat to be offered at 10 and 17% lower rates than unsupplemented diets in Exp. 1 and 2, respectively. Lambs were maintained to consume only ewe milk. Ewe milk production and composition were determined using a portable milking machine following a 3-h separation from lambs. In Exp. 1, milk fat content was increased (P < 0.01) when ewes consumed fescue hay with fatty acids vs. the fescue hay diet (11.4 vs. 8.3%). Ewes fed fescue hay with fatty acids lost the most (P < 0.05) weight over lactation (-8.6 kg) compared with ewes fed the alfalfa hay (-2.4 kg) and fescue hay (-3.8 kg) diets. Other milk measures, lamb gain, and production efficiencies were not changed. In Exp. 2, ewes supplemented with fatty acids produced more (P < 0.05) milk fat than those fed tallow (290 vs. 210 g/d). The proportion of synthesized milk fat 14:0 was decreased (P < 0.01), but the percentage of incorporated 16:0 increased (P < 0.05) when fatty acids were fed. Dietary fat digestibility by ewes was increased (P < 0.01) by fatty acid supplementation but decreased (P < 0.01) when tallow was added. Although ewe weight measures were not changed in Exp. 2, twin lamb gain per ewe organic matter intake was most efficient (P < 0.05) when ewes were supplemented with fatty acids. Results suggest that feeding hydrogenated tallow decreased nutrient availability for ewe milk fat production. A complete diet based on endophyte-free fescue hay can replace a traditional alfalfa hay diet, whereas supplementing with the calcium salts of palm oil fatty acids may be more feasible when energy is limiting during ewe lactation.

P0057 PP A POLYMORPHISM WITHIN THE GENE ENCODING HUMAN BILE SALT-STIMULATED LIPASE RELATES TO SERUM CHOLESTEROL

Introduction: The bile salt-stimulated lipase (BSSL) is an enzyme originally recognized to facilitate digestion and absorption of dietary fat in the small intestine. BSSL is also present in human serum and it has been suggested that it influences the level of serum cholesterol. We recently characterized a polymorphism consisting of deletions or insertions in the BSSL gene. In the present study we investigated a possible association between serum lipid levels on the one hand and BSSL serum concentration or polymorphisms on the other. Methods: Blood samples were collected from two groups of healthy volunteers, the “Blood donors” (n=295, 19–65 years of age) and the “Youth study group” (n=266, 24–26 years of age). The concentrations of total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol and BSSL in serum were analyzed. Moreover, DNA was isolated from all individuals and the BSSL genotype, i.e. deletions and/or insertions within the gene, was determined by PCR and Southern blots. Results: We found no association between BSSL protein concentration and serum lipid levels, but a significant association between a certain BSSL genotype (deletions in both alleles) and increased TC levels (5.6 mmol/l vs 5.1 mmol/l for all other genotypes combined; p<0.05), as well as increased levels of HDL-C (1.4 mmol/l vs 1.3 mmol/l; p<0.05). The impact of the BSSL genotype increased with increasing age and thus with increasing cholesterol levels, indicating that there is a threshold effect, i.e. the effect is not seen at low cholesterol levels. Conclusion: We have shown that polymorphisms located within exon 11 of the BSSL gene affects serum cholesterol levels. Whether the mechanism is due to functional differences of the different variants in serum or, alternatively, in the uptake of dietary cholesterol in the small intestine remains to be elucidated.

Dietary fatty acids and chylomicron synthesis and secretion.

There is currently considerable interest in potential atherogenic and thrombogenic consequences of elevated concentrations of triacylglycerols, especially in the post-prandial state. Despite this, there is limited information on the effects of dietary fatty acids on the synthesis, secretion and metabolism of chylomicrons, the large triacylglycerol-rich lipoproteins synthesized in the enterocyte following the digestion and absorption of dietary fat. This brief review considers current approaches to the investigation of chylomicron synthesis and summarizes some of the human, cell and animal studies that have investigated effects of different fatty acids on these pathways. Potential sites for modulatory effects of dietary fatty acids on the molecular events of chylomicron synthesis are proposed in the light of the recent model that has been developed from cell and animal studies and observations based on abnormalities in chylomicron formation in human inherited autosomal recessive diseases.

Is the ileal bile acid-binding protein (I-BABP) gene involved in cholesterol homeostasis?

In the body, cholesterol balance results from an equilibrium between supplies (diet and cellular de novo synthesis), and losses (cellular use and elimination in feces, essentially as bile acids). Bile acids are synthesized from cholesterol in the liver. After conjugation to glycine or taurine, bile acids are secreted with bile in the intestinal lumen where they actively participate to the digestion and absorption of dietary fat and lipid-soluble vitamins. In healthy subjects, more than 95% of bile acids are reabsorbed throughout the small intestine and returned by the portal vein to the liver, where they are secreted again into bile. This enterohepatic circulation is essential for maintenance of bile acids balance, and hence, for cholesterol homeostasis. Indeed, the bile acids not reclaimed by intestinal absorption constitute the main physiological way to eliminate a cholesterol excess. Little is known about the molecular mechanisms controlling bile acids reabsorption by the small intestine. The intestinal bile acids uptake mainly takes place through an active transport located in the distal part of the small intestine. To date, four unrelated proteins exhibiting a high affinity for bile acids have been identified in the ileum, and only one, the ileal bile acid-binding protein (I-BABP) is a soluble protein. Therefore, it is thought to be essential for efficient bile acids desorption from the apical plasma membrane, as well as for bile acids intracellular trafficking and targeting towards the basolateral membrane. If this assumption is correct, the I-BABP expression level might be rate limiting for the enterohepatic bile acids circulation, and hence, for cholesterol homeostasis. It was found that both bile acids and cholesterol, probably via oxysterols, are able to up-regulate the transcription rate of I-BABP gene. The fact that intracellular sterol sensors (FXR, LXR, and SREBP1c) are involved in the control of the I-BABP gene expression strongly suggests that I-BABP exerts an important role in maintenance of cholesterol balance.

Time-resolved fluorescence allows selective monitoring of Trp30 environmental changes in the seven-Trp-containing human pancreatic lipase.

Human pancreatic lipase (HPL, triacylglycerol acylhydrolase, EC 3.1.1.3) is a carboxyl esterase which hydrolyzes insoluble emulsified triglycerides and is essential for the efficient digestion of dietary fats. Though the three-dimensional structure of this enzyme has been determined, monitoring the conformational changes that may accompany the binding of various substrates and inhibitors is still of interest. Because of its sensitivity and ease of use, fluorescence spectroscopy of the intrinsic Trp residues is ideally suited for this purpose. However, the presence of seven Trp residues spread all over the HPL structure renders the interpretation of the fluorescence changes difficult with respect to the identification and location of the conformational or environmental changes taking place at the various Trp residues. In this context, the aim of this work was to investigate the contribution of the individual Trp residues to the fluorescence properties of HPL. To this end, we analyzed the steady-state and time-resolved fluorescence parameters of five single-point mutants in which one Trp residue was substituted with a weakly fluorescent Phe residue. In addition to the Trp residues at positions 30, 86, and 252, strategically located with respect to the active site, we also mutated Trp residues at positions 17 and 402, as representative residues of the HPL N- and C-terminal domains, respectively. Taken together, our data suggested that the solvent-exposed Trp30 residue contributed to at least 44% of the overall fluorescence of wild-type HPL. Moreover, we found that the long-lived fluorescence lifetime (6.77 ns) of wild-type HPL could be specifically attributed to Trp30, a feature that enables selective monitoring of its environmental changes. Additionally, Trp residues at positions 17 and 402 strongly contributed to the 1.61 ns lifetime of HPL, while Trp residues at positions 86 and 252 contributed to the 0.29 ns lifetime.

Human digestive and metabolic lipases—a brief review

The major human lipases include the gastric, pancreatic and bile-salt-stimulated lipase that aid in the digestion and assimilation of dietary fats, and the hepatic, lipoprotein and endothelial lipase that function in the metabolism of lipoproteins. The triacylglycerol and phopholipase activities of these enzymes enable these varied functions. The lipase enzymes exhibit a high degree of sequence homology not only within but also across species. This and the diverse chromosomal location of their genes point to a multigenic family of enzymes involved in absorption and transport of lipids. Inactivation of lipolytic activity of microorganisms to control infection, inhibition of digestive lipase to control obesity, stimulation of metabolic lipase to reduce hyperlipidemia or procoagulant state, or use of pancreatic lipase supplement in the management of cystic fibrosis are examples of how lipase activity modulation can impact human health.

Anesthetic Considerations for Bariatric Surgery

According to the National Institutes of Health, obesity is a major health problem with clearly established health implications, including an increased risk for coronary artery disease, hypertension, dyslipidemia, diabetes mellitus, gallbladder disease, degenerative joint disease, obstructive sleep apnea, and socioeconomic and psychosocial impairment (1). The risk of developing one or more of these obesityrelated conditions is based on body mass index (BMI), with 25–30 kg/m 2 being low risk and 40 kg/m 2 being very high risk (2). The prevalence of obesity in the 18- to 29-yr-old group increased from 12% in 1991 to 18.9% in 1999 (3). Bariatric surgery encompasses a variety of surgical weight loss procedures used to treat morbid obesity. Obesity is clinically expressed in terms of BMI or Quetelet’s index (4), which is derived by dividing weight by the square of height to estimate the degree of obesity. Thus, BMI body weight (kg)/height 2 (m 2 ). Morbid obesity is a BMI more than 35 kg/m 2 , and super morbid obesity is BMI more than 55 kg/m 2 . The indications for surgical treatment of severe obesity, as outlined in the 1991 National Institutes of Health Consensus Development Conference Panel, include an absolute BMI more than 40 kg/m 2 or BMI more than 35 kg/m 2 in combination with lifethreatening cardiopulmonary problems or severe diabetes mellitus (1). Patients seeking surgical weight loss must have proven attempts at medically supervised weight loss. Documentation of loss of 5% to 10% excess body weight or weight gain after at least 6 mo of diet modification, exercise, and medical therapy or nonimprovement in comorbid conditions during this period indicates failure. Studies have shown that weight loss of 5%–10% of initial body weight improves glucose intolerance and Type II diabetes, hypertension, and dyslipidemia (5–7). The average expenditure is approximately $7000 per year per patient on weight loss programs and equipment. Unfortunately, long-term weight loss is the exception, and most patients regain weight, sometimes more than they initially lost.

The Lipase C-terminal Domain: A NOVEL UNUSUAL INHIBITOR OF PANCREATIC LIPASE ACTIVITY

In vertebrates, dietary fat digestion mainly results from the combined effect of pancreatic lipase, colipase, and bile. It has been proposed that in vivo lipase adsorption on oil-water emulsion is mediated by a preformed lipase-colipase-mixed micelle complex. The main lipase-colipase binding site is located on the C-terminal domain of the enzyme. We report here that in vitro the isolated C-terminal domain behaves as a potent noncovalent inhibitor of lipase and that the inhibitory effect is triggered by the presence of micelles. Lipase inhibition results from the formation of a nonproductive C-terminal domain-colipase-micelle ternary complex, which competes for colipase with the active lipase-colipase-micelle ternary complex, thus diverting colipase from its lipase-anchoring function. The formation of such a complex has been evidenced by molecular sieving experiments. This nonproductive complex lowers the amount of active lipase thus reducing lipolysis. Preliminary experiments performed in rats show that the C-terminal domain also behaves as an inhibitor in vivo and thus could be considered a potential new tool for specifically reducing intestinal lipolysis.

Effect of triacylglycerols containing medium- and long-chain fatty acids on body fat accumulation in rats.

Effect of triacylglycerols containing medium- and long-chain fatty acids (TML) on body fat accumulation was studied in rats. Male Wistar rats were fed an experimental diet containing 25% soybean oil or TML for 6 weeks. The food intake for 6 weeks did not significantly differ between the two diet groups. However, the perirenal and mesenteric adipose tissue weight and carcass fat content were significantly lower in the TML diet group than in the soybean oil diet group. The epididymal adipose tissue weight and liver triacylglycerol content did not significantly differ between the two diet groups. The digestibility of dietary fat did not significantly differ between the two diet groups. These results suggest that an intake of TML decreases body fat accumulation compared to an intake of soybean oil in rats.

Defective dietary fat processing in transgenic mice lacking aquaporin-1 water channels.

Immunocytochemistry showed expression of aquaporin-1 (AQP1) water channels at sites involved in dietary fat processing, including intrahepatic cholangiocytes, gallbladder, pancreatic microvascular endothelium, and intestinal lacteals. To determine whether AQP1 has a role in dietary fat digestion and/or absorption, mice were placed on a diet that contained 50% fat. Whereas wild-type mice (3-3.5 wk of age, 10-12 g) gained 49 +/- 5% (SE, n = 50) body weight in 8 days, and heterozygous mice gained 46 +/- 4%, AQP1 null mice gained only 4 +/- 3%; weights became similar after return to a 6% fat diet after 6 days. The null mice on a high-fat diet acquired an oily appearance, developed steatorrhea with increased stool triglyceride content, and manifested serum hypotriglyceridemia. Supplementation of the high-fat diet with pancreatic enzymes partially corrected the decreased weight gain in null mice. Absorption of [(14)C]oleic acid from small intestine was not affected by AQP1 deletion, as determined by blood radioactivity after duodenal infusion. Lipase activity in feces and small intestine was remarkably greater in AQP1 null than wild-type mice on low- and high-fat diets. Fluid collections done in older mice (that are less sensitive to a high-fat diet) by ductal cannulation showed threefold increased pancreatic fluid flow in response to secretin/cholecystokinin, but volumes, pH, and amylase activities were affected little by AQP1 deletion, nor were bile flow rates and bile salt concentrations. Together, these results establish a dietary fat misprocessing defect in AQP1 null mice.

The inhibitory effect of a highly viscous carboxymethylcellulose on dietary fat digestibility in the growing chicken is dependent on the type of fat

SummaryThe aim of the study was to determine whether there is an interaction between type of fat and lipid digestibility, for diets which induce an increased digesta viscosity. Pairs of semi‐synthetic diets were formulated which contained either tallow, soyabean oil or coconut oil as the main source of fat. To one diet of each pair, carboxymethylcelullose (CMC) was added. CMC is a soluble, viscous nonfermentable fibre. The fat fraction of the tallow diet comprised mainly C16 : 0, C18 : 0 and C18 : 1 fatty acids, whereas for the soyabean oil diet C18 : 1 and C18 : 2 fatty acids predominated and for the coconut oil diet C12 : 0 and C14 : 0 fatty acids were predominant. The diets were fed to broiler chickens (7–21 days of age) in a conventional digestibility study using chromium oxide as an indigestible marker. CMC significantly raised the viscosity of the liquid phase of the small intestinal digesta and increased the ratio of liquid to solids. CMC depressed apparent faecal lipid digestibility for chickens fed the tallow diet (76.1 versus 66.0% ) but not for the birds given the soyabean oil or coconut oil diets. The apparent digestibility of C16 : 0 was significantly depressed by CMC in the birds fed the tallow diet (62.7 versus 52.3% ) and the digestibility of C18 : 0 tended to be lower. There was no significant effect of CMC on the digestibility of C18 : 1 and C18 : 2 in the soyabean oil diet nor on the digestibility of C12 : 0 or C14 : 0 in the coconut oil diet. The effect of CMC‐induced digesta viscosity on lipid digestibility in chickens is dependent on the lipid source and its fatty acid composition.

Site directed mutagenesis of colipase reveals specific residues that control the digestion of dietary fat by pancreatic triglyceride lipase

Site directed mutagenesis of colipase reveals specific residues that control the digestion of dietary fat by pancreatic triglyceride lipase

Growth and lipid metabolism responses in rats fed different dietary fat sources

An experiment with male albino rats was conducted to examine the effect of dietary fat sources on growth performance and apparent digestibility of total fat and fatty acids. The effect on plasma and organ cholesterol concentrations as well as lipoproteins cholesterol and fatty acid profile of hepatic phospholipids was also examined. Forty 3 week old rats were fed purified diets containing 0.041% cholesterol and 7% fat (wt/wt) from soy oil (SO), or cow ghee (GH), or 25% fish oil (FO) plus soy oil (SF) or 25% fish oil plus 75% ghee (GF), or 50% soy oil plus 50% ghee (SG) for a period of 35 days. Final body weight, weight gain, organ weights and feed efficiency ratio showed no significant differences (P < 0.05) among the dietary treatments. The apparent digestibility of total dietary fat and saturated fatty acids in the animals fed diet containing cow ghee only or in combination with fish oil or soy oil was significantly lower than the other dietary groups. Consumption of ghee with combination of fish oil or soy oil lead to significant improvement in the fat apparent digestibility of dietary fat. Total cholesterol and triglyceride concentrations of plasma and organs as well as lipoprotein cholesterol levels were higher in animals fed diets containing ghee. For rats fed diet containing cow ghee in combination with fish oil or soy oil, the cholesterol content of total plasma, lipoprotein fractions (VLDL, LDL and HDL) and organs was decreased significantly. Furthermore, dietary fats altered the fatty acids composition of hepatic phosphlipid fatty acids composition. Feeding dietary fish oil reduced arachidonic acid (20:4) and increased linoleic acid (18:2) and eicosapentaenoic acid (20:5) contents. The reduction in the arachidonic acid was being more pronounced in animals fed dietary ghee with combination of fish oil.