Browsing by Subject "Fatty liver"

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    The effect of viscous and fermentable dietary fiber consumption on adiposity, insulin resistance and fuel utilization in rats
    (2013-05) Brockman, David Andrew
    The incidence of obesity continues to be a major public health problem in the United States and comorbidities such as type 2 diabetes, cardiovascular disease and fatty liver that accompany obesity have dramatically increased over the last several decades. The health costs associated with the diagnosis and treatment of obesity-related disorders, particularly type 2 diabetes, are extraordinary and will be an enormous financial burden on the economy. Due to these dire circumstances, there is great interest in identifying foods that reduce the accumulation of adipose tissue and decrease the progression of insulin resistance. The consumption of dietary fibers that decrease the postprandial glucose curve is associated with decreased adiposity and a reduced incidence of type 2 diabetes, but it is controversial as to which property of dietary fiber is responsible for these effects. The objective of this research was to investigate the effect of increasing the small intestinal contents viscosity on the progression of obesity and type 2 diabetes. In the first study, non-fermentable hydroxypropyl methylcellulose (HPMC) was used to increase the small intestinal contents viscosity in a model of obesity with type 2 diabetes, the Zucker Diabetic Fatty rat. Rats fed HPMC showed improvements in insulin resistance and fatty liver but only a modest effect on reducing obesity. There was also a decrease in diabetic wasting as there was a greater food efficiency ratio and less urinary glucose excretion. In the second study, it was shown that adding barley flour containing a high concentration of viscous fermentable β-glucans had similar outcomes to those observed in the first study, including decreased insulin resistance and fatty liver, and a greater concentration of plasma adiponectin. In the third study, a model of diet-induced obesity was used to determine differences in fuel utilization when consuming viscous dietary fibers. Adding non-fermentable HPMC and fermentable guar gum to a high fat diet significantly decreased adiposity and fatty liver, yet there was no difference in insulin resistance. Consumption of both HPMC and guar gum increased the postprandial respiratory quotient compared to cellulose and also increased metabolic flexibility. There was no added effect of fermentability on any measure of adiposity, glucose control or fatty liver disease, indicating that SCFAs produced from fermentation had little or no effect on metabolic disease. In summary, the consumption of soluble dietary fibers that increase the viscosity of the small intestinal contents reduces the progression of obesity, insulin resistance and fatty liver, while the property of fermentation appears to have little discernable effect.
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    The effect of whole wheat and wheat milling fractions on metabolic parameters of adiposity, glucose control, and lipid metabolism using a rat model of obesity with type 2 diabetes
    (2014-01) Dos Santos, Ana
    Obesity prevalence is at an all-time high, with 1 in 3 Americans now classified as obese (1). Obesity is a debilitating condition that is associated with various co-morbidities, including type 2 diabetes (T2D), cardiovascular disease, pulmonary dysfunction, gastrointestinal disease, various cancers, and osteoarthritis. T2D is one of the most significant co-morbidities of obesity, as it often leads to other diseases such as non-alcoholic fatty liver disease (NAFLD) and hyperlipidemia. There are now 347 million people worldwide with T2D (2).The incidence of newly diagnosed cases of T2D in America is at its highest of 1.9 million per year and, according to the American Diabetes Association, and if the trend continues, 1 in 3 Americans will have diabetes by the year 2050 (3). There are many factors that increase the risk of developing T2D, some which include being overweight and physically inactive, having a genetic predisposition, and high blood pressure. In addition, there are complications that develop gradually over a period of time during T2D if blood glucose sugar levels are not properly controlled. Long-term poor glucose control puts patients at a higher risk for complications such as cardiovascular disease (CVD), neuropathy, nephropathy, and retinopathy.Obesity and diabetes are having a substantial impact on the economic state of the health care system. The total estimated cost of diagnosed diabetes in 2012 was $245 billion. This includes $176 billion in direct medical costs and $69 billion in reduced productivity, encompassing lower labor force participation from chronic disability and premature mortality (4). In addition to the economic burden, there are substantial intangible costs, such as a reduced quality of life for those people with diabetes, and often for their families and friends as well. Several epidemiological studies suggest that whole grain consumption is associated with a lower risk of obesity and T2D. Whole grain consumption has been found to have an inverse association with fat mass and insulin resistance in both humans and rats, possibly through several different mechanisms, involving mechanical, hormonal, and anti-inflammatory processes. The mechanical mechanism focuses on alterations in caloric density and absorption of nutrients, the hormonal mechanism on changes in hormone synthesis and secretion due to nutrient availability, and lastly, anti-inflammatory and anti-oxidative components in the whole grain. However, it is unclear which milling fraction of the whole grain, the bran, germ, or endosperm, may be responsible for these health benefits. Therefore, the aim of this study was to examine the effects of whole wheat and wheat milling fractions, specifically bran, germ, and endosperm, on glucose control, insulin resistance, fatty liver, and adiposity using an animal model of obesity with T2D, the Zucker Diabetic Fatty (ZDF) rat. Male ZDF rats were fed either a cornstarch-based diet (AIN-93G; obese control ), or diets containing 64% whole wheat flour, 54% refined wheat, 9.4 % wheat bran, 1.6% normal wheat germ, or high 15% wheat germ for 5 weeks. Lean ZDF littermates fed a standard AIN-93G diet served as a negative control. All animals were fed ad libitum. The refined wheat, wheat bran, and wheat germ were present in the diets in the same concentration as would be found in the whole wheat diet. The high wheat germ diet had amounts of germ 10 times that of the normal wheat germ diet. It was found that after 5 weeks, the whole wheat, refined wheat, and high and normal wheat germ groups all showed a significant improvement (p<0.05) in area under the curve during glucose and insulin tolerance tests. There were no differences in body weight or fat pad weight among the ZDF groups; however, there was a significant difference (p=0.031) in fat mass % between the whole wheat group and the obese control. The whole wheat group and all wheat fraction groups decreased the concentration of liver lipids compared to the obese control, and the bran and germ groups also had lower liver cholesterol concentration. Only the whole wheat group had a significantly lower cecum pH (p<0.0001) and greater cecal weight (p<0.0001) compared to the obese control, indicating greater fermentation of the diet. There were no significant differences in plasma adiponectin and resistin levels among the ZDF diet groups. In conclusion, the results of this study suggests that none of the wheat milling fractions stand out as responsible for the metabolic effects seen with consumption of whole wheat and that individual milling fractions of wheat are just as effective in improving insulin resistance and fatty liver as whole wheat.
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    Prebiotic Dietary Fibers Must Achieve a Threshold of Beneficial Gut Bacteria in Order to Prevent Adiposity and Fatty Liver in Rats Fed High Fat Diets.
    (2020-08) Abernathy, Breann
    Introduction Prebiotic dietary fibers are dietary fibers that are highly fermented in the large intestine, produce beneficial changes in the gut microbiome, and impart a health benefit to the host. Using reactive extrusion, we have synthesized a novel dietary fiber that is an oligosaccharide of polymerized lactose, which we term polylactose. Here we report on two studies feeding polylactose to rats to determine its prebiotic potential. Methods In Exp. 1, the polylactose preparation contained 51% dietary fiber, 20% free lactose, 5% glucose, and 24% other materials. Rats were fed high fat diets containing 9% total dietary fiber, including cellulose (C, 9%), polylactose (PL, 6%), polydextrose (PD, 6%), and fructooligosaccharide (FOS, 6%). In Exp. 2, the polylactose preparation contained 75% dietary fiber, 9% lactose, 3% glucose, and 13% other materials. Rats were again fed high fat diets containing 9% total dietary fiber, including C (9%), polylactose (6% or 3%), PD (6%), and galactooligosaccharides (GOS, 6%). In both experiments, rats were fed for 10 weeks, then ceca (empty), cecal contents, livers, and epididymal fat pads were collected. Results In both experiments, final body weight and daily energy intake did not differ among the groups. In Exp. 1, feeding PL greatly increased cecum weight (an indicator of fermentation), cecal Bifidobacterium and Lactobacillus species abundance, increased cecal acetate and propionate, and reduced liver lipids and fat pad weight, compared to the HFC group. PD and FOS increased probiotic species and short chain fatty acids slightly (compared to HFC), but not to the same extent as PL, and neither PD or FOS reduced fatty liver or adiposity. In Exp. 2, 6% PL increased cecum weight relative to 3% PL, PD and GOS, all of which were greater than HFC. The cecal microbiome was similar among PL (both 3 and 6%), PD, and GOS, all of which differed from HFC. Liver lipids, fat pad weight, and body composition did not differ among any of the groups in Exp. 2. Conclusions The prebiotic activity of polylactose differed depending on the preparation, for unknown reasons. However, our results suggest there is a threshold of probiotic bacteria abundance that must be attained before beneficial effects are imparted on the host by prebiotics.