No description available.

To examine the effect of diet fat type on rates of cholesterol synthesis and esterification during feeding and fasting, nine healthy male subjects were fed solid-food diets of 40% fat as predominantly either olive oil (MONO), safflower-oil margarine (POLY), or butter (SAT). At the end of each two-week diet trial, subjects were given deuterium (D) oxide orally and de novo synthesis was measured from D incorporation into cholesterol and interpreted as rates of fractional synthesis (FSR) (pools/day) into the rapidly exchangeable free cholesterol (FC) pool. Absolute synthesis rates (ASR) were calculated as the product of FSR and the FC pool. Pool size for each subject was obtained from analysis of the specific activity decay curve of an intravenous injection of 4-14C-cholesterol over nine months. Synthesis was measured over two consecutive 12-h fed periods followed by two consecutive 12-h fasted periods. Serum samples were also assayed for lathosterol concentration, an index of cholesterol synthesis. Serum cholesterol and non-HDL cholesterol concentrations were highest on the SAT diet, lowest (P<0.001) on the POLY diet and intermediate on the MONO diet, triglyceride levels were greater (P<0.03) on the SAT diet than on the POLY diet, and HDL levels were lowest (P<0.05) on the SAT diet and highest on the MONO diet. Cholesterol D enrichment and FSR during each 12-h period were greater (P<0.014) on the POLY diet than on the SAT diet; MONO enrichment and FSR were not significantly different from those on the other two diets. Similar results were obtained for rates of cholesterol esterification (P<0.001). Deuterium enrichment data suggested, and lathosterol data confirmed, that free cholesterol synthesis was greater during the fed period than during the fasted period (P<0.01); however, this could not be confirmed for rates of cholesterol esterification. Results suggest that POLY fat feeding augments de novo cholesterol synthesis without adverse effects on total serum cholesterol concentrations, and that the deleterious effects of SAT fat on serum cholesterol are not brought about by augmented de novo synthesis. Finally, the combination of deuterium incorporation and mathematical modelling produces estimates of daily cholesterol synthesis which are compatible with those invoked by more laborious techniques.

Our first objective was to compare deuterium incorporation and mass isotopomer distribution analysis in the measurement of in vivo cholesterol biosynthesis in humans. Twelve healthy subjects were recruited to participate in a 24 h stable isotope infusion study which mimicked temporal conditions typical of both deuterium incorporation and mass isotopomer distribution analysis techniques. Data suggest both deuterium incorporation and mass isotopomer distribution analysis accurately define cholesterol synthesis in humans when measured over a period of 24 h. / Our second objective was to examine the effects of weight loss through energy restriction upon human in vivo circulating cholesterol concentrations and synthesis using the deuterium incorporation methodology. Seven overweight subjects with a mean BMI of 30.6 +/- 1.6 kg&middot;m-2 were recruited into a 2-phase prospective clinical trial including 3 mo on a weight stable American Heart Association Step I diet and 6 mo on an energy-reduced American Heart Association Step I diet. Data suggest that deuterium incorporation and mass isotopomer distribution analysis are equally effective methods for measuring cholesterol biosynthesis in humans, and that energy restriction resulting in modest weight loss effectively reduces endogenous cholesterol synthesis thus decreasing the risk of CVD development in obese and overweight men. (Abstract shortened by UMI.)

Dietary fats and animal proteins have been shown to exert different lipidemic responses in many animals, including humans. Oxidative stress has been associated with the development of several diseases including atherosclerosis. The hypotheses of this study were that: (1) the degree and type of dietary fatty acid unsaturation will influence the type of cholesterolemic responses via the induction of differential levels of oxidative stress; and (2) hyperlipidemia induced by casein in a butterfat-based diet is related to increased tissue lipid peroxidation. Male Golden Syrian hamsters were fed diets containing butterfat/casein (BF/CAS), butterfat/egg white (BF/EGG), safflower oil/egg white (SAFF/EGG) or menhaden oil/egg white (MHO/EGG) for 27 days. In comparison to the BF/EGG and SAFF/EGG diet groups, the MHO/EGG hamsters exhibited higher levels of total serum cholesterol, serum triglyceride, serum apolipoprotein B and serum lipid peroxides. These results suggest that MHO induced-hyperlipidemia could be exerted through increased concentrations of serum apolipoprotein B and increased serum lipid peroxidation. The BF/CAS diet, in comparison to the BF/EGG diet, increased serum total cholesterol and increased serum and hepatic levels of lipid peroxides. These results suggest that dietary casein-induced hypercholesterolemia could be related to increased oxidative stress. The protective effect of dietary egg white on lipid peroxidation may involve sulfur amino acids which are found in greater amounts in egg white than casein.

No description available.

Two feeding trials were conducted with 30-week-old single comb white leghorns fed two basal diets containing 8% of hydrogenated coconut oil or safflower oil. These basal diets were fed with or without supplements of \% cholesterol (ch), 2-fo soysterols (st) or in combination (ch+st). Trial 1 was designed to study the sensitivity of laying hens in response to dietary lipid factors and to compare the mode of changes in serum and egg yolk concentrations by weekly determination of their sterol levels during a feeding period with no soysterol supplementation followed by a period with soysterol supplementation. Objectives of trial 2 were to study the effects of dietary lipid factors on the serum and egg yolk levels and to delineate their roles or mechanisms. Changes in egg yolk sterol levels caused by dietary lipid factors were generally parallel to, and preceded by, those in serum sterol levels. This indicated that the egg sterols originated from the circulating labile sterol pool. Safflower oil suppressed and hydrogenated coconut oil elevated the sterol levels in both serum and egg yolk. Cholesterol feeding with dietary safflower oil increased the absorption of cholesterol, resulting in an increase of serum and egg sterol levels as compared to sterol levels of hens fed Hydrogenated coconut oil. Dietary soysterols supplementation resulted in a decrease in both serum and egg yolk sterols which was demonstrated in the presence of dietary cholesterol as well as cholesterol-free treatments. The apparent absorption of cholesterol was not retarded by the simultaneous feeding of cholesterol and soysterols. However, soysterol feeding accelerated the fecal excretion of bile acids and catabolic products of neutral sterols. The apparent absorption of plant sterols was 11%. Absorbability Of plant sterols in laying hens was further supported by detection of these sterols in tissue and egg yolk. The absorption of the plant sterols was, however,. Slightly decreased when cholesterol was fed simultaneously. Cholesterol feeding increased total lipid content in liver and serum, whereas soysterol feeding reduced or diminished lipid accumulation caused by the cholesterol treatment. Both dietary cholesterol and soysterols altered the fatty acid composition of liver, serum and egg yolk lipids by increasing oleic acid and decreasing palmitic and/or stearic acids. These changes were significantly greater upon feeding cholesterol than soysterols. However, the simultaneous feeding of cholesterol with soysterols exerted the least effect on the fatty acid composition in liver. The possibility that soysterols affected biosynthesis and/or oxidative catabolism of fatty acids in the liver of laying hens in a similar fashion as cholesterol was discussed. / Land and Food Systems, Faculty of / Graduate

To examine the effect of diet fat type on rates of cholesterol synthesis and esterification during feeding and fasting, nine healthy male subjects were fed solid-food diets of 40% fat as predominantly either olive oil (MONO), safflower-oil margarine (POLY), or butter (SAT). At the end of each two-week diet trial, subjects were given deuterium (D) oxide orally and de novo synthesis was measured from D incorporation into cholesterol and interpreted as rates of fractional synthesis (FSR) (pools/day) into the rapidly exchangeable free cholesterol (FC) pool. Absolute synthesis rates (ASR) were calculated as the product of FSR and the FC pool. Pool size for each subject was obtained from analysis of the specific activity decay curve of an intravenous injection of 4-14C-cholesterol over nine months. Synthesis was measured over two consecutive 12-h fed periods followed by two consecutive 12-h fasted periods. Serum samples were also assayed for lathosterol concentration, an index of cholesterol synthesis. Serum cholesterol and non-HDL cholesterol concentrations were highest on the SAT diet, lowest (P<0.001) on the POLY diet and intermediate on the MONO diet, triglyceride levels were greater (P<0.03) on the SAT diet than on the POLY diet, and HDL levels were lowest (P<0.05) on the SAT diet and highest on the MONO diet. Cholesterol D enrichment and FSR during each 12-h period were greater (P<0.014) on the POLY diet than on the SAT diet; MONO enrichment and FSR were not significantly different from those on the other two diets. Similar results were obtained for rates of cholesterol esterification (P<0.001). Deuterium enrichment data suggested, and lathosterol data confirmed, that free cholesterol synthesis was greater during the fed period than during the fasted period (P<0.01); however, this could not be confirmed for rates of cholesterol esterification. Results suggest that POLY fat feeding augments de novo cholesterol synthesis without adverse effects on total serum cholesterol concentrations, and that the deleterious effects of SAT fat on serum cholesterol are not brought about by augmented de novo synthesis. Finally, the combination of deuterium incorporation and mathematical modelling produces estimates of daily cholesterol synthesis which are compatible with those invoked by more laborious techniques. / Land and Food Systems, Faculty of / Graduate

No description available.

No description available.

With the increased marketing and popularity of a range of dairy products in recent years, research has become widespread concerning the influence of dairy on human health. It is also becoming evident that an individual’s genetic make-up contributes to shaping their health responses to dietary intakes. This research was primarily designed to investigate the impact of genetic variability on responsiveness of cholesterol metabolism, a classic biomarker of cardiovascular health, to the recommended level of dairy consumption in Canada. A secondary objective was to assess the influence of dairy intake on systemic inflammation as an emerging risk factor for cardiovascular disease. In a multicentre, randomized, free-living crossover design, 124 healthy individuals consumed 3 servings/day of conventional low-fat and regular milk, yogurt, and cheese (DAIRY diet) or dairy-free control products (CONTROL diet), each for 28 days as part of a prudent background dietary protocol. At the end of the study, DAIRY was associated with increased plasma concentrations of two established fatty acid biomarkers of dairy fat, pentadecanoic acid (C15:0) and heptadecanoic acid (C17:0), as well as with small increases in serum total cholesterol (TC) and LDL-cholesterol (LDL-C) concentrations. Inter-individual variability in the cholesterol transport gene ABCG5, bile acid synthesis gene CYP7A1, and cholesterol synthesis gene DHCR7 contributed to shaping the degree of TC and LDL-C responsiveness to DAIRY; with higher cholesterol concentrations observed among ABCG5 rs6720173-G/G homozygotes, CYP7A1 rs3808607-G allele carriers, and DHCR7 rs760241-A allele carriers, relative to the C allele, T/T, and G/G carriers of these genes, respectively. Also, after DAIRY, the major allele T homozygosity of CYP7A1 rs3808607 and the minor allele A of DHCR7 rs760241 were associated with reduced plasma [3,4]13C cholesterol enrichment and deuterium incorporation, respectively, suggesting reduced cholesterol absorption and synthesis rates. DAIRY intake did not influence the inflammatory status. Overall, this research has provided evidence of a potential impact of the genomic architecture on responsiveness of cholesterol metabolism to dairy consumption. The novel findings are expected to advance knowledge of the inherited basis by which health biomarkers may be modified in response to whole foods, hence launching an important step towards an era of personalized nutrition. / February 2016