Incorporation of orally administered glucose-U-14C and fructose-U-14C into the triglyceride of liver, plasma, and adipose tissue of rats

Temporal effect of fructose supplementation at different concentrations on hepatic metabolism of Wistar rats

INTRODUCTION

Introduction: in the last few years important changes have occurred in nutritional patterns. There has been an increase in the consumption of simple carbohydrates such as fructose, which has been associated with numerous metabolic disorders, including hepatic steatosis. Materials and methods: we sought to evaluate the impact of fructose consumption, as diluted in water at different concentrations, for two time periods, on the metabolic parameters of Wistar rats using ANOVA. Results: our data indicate that both time and fructose concentration promote variations in animal body mass, and in food, water, and caloric intake. The time variable influenced the modulation of biochemical parameters such as serum concentrations of glucose and total cholesterol. Both fructose concentration and time of exposure influenced the concentrations of serum triglycerides, creatinine, AST, TNF, and IL-6. When evaluating redox status and oxidative damage markers, we observed that fructose concentration and exposure time had an effect on total glutathione levels, which decreased with an increase in concentration and time. For superoxide dismutase, we evaluated the effects of time and interaction. A significant interaction was observed for TBARS. For carbonylated proteins, exposure time was a fundamental factor in generating an effect. Conclusions: we demonstrated that fructose modulates the parameters of triglycerides and total liver cholesterol, and that time influences the number of hepatocytes. Our data suggest that fructose concentration, exposure time, and an interaction between these two parameters have a significant effect on the metabolic parameters responsible for the development of non-alcoholic fatty liver disease.

Triose Kinase Controls the Lipogenic Potential of Fructose and Dietary Tolerance

The surge in fructose consumption is a major factor behind the rapid rise of nonalcoholic fatty liver disease in modern society. Through flux and genetic analyses, we demonstrate that fructose is catabolized at a much higher rate than glucose, and triose kinase (TK) couples fructolysis with lipogenesis metabolically and transcriptionally. In the absence of TK, fructose oxidation is accelerated through the activation of aldehyde dehydrogenase (ALDH) and serine biosynthesis, accompanied by increased oxidative stress and fructose aversion. TK is also required by the endogenous fructolysis pathway to drive lipogenesis and hepatic triglyceride accumulation under high-fat diet and leptin-deficient conditions. Intriguingly, a nonsynonymous TK allele (rs2260655_A) segregated during human migration out of Africa behaves as TK null for its inability to rescue fructose toxicity and increase hepatic triglyceride accumulation. Therefore, we posit TK as a metabolic switch controlling the lipogenic potential of fructose and its dietary tolerance.

Artemisia sphaerocephala Krasch polysaccharide prevents hepatic steatosis in high fructose-fed mice associated with changes in the gut microbiota

High fructose (HF) diet-induced liver steatosis is associated with intestinal microbiota dysbiosis.

Fructose and sugar: A major mediator of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome; its rising prevalence parallels the rise in obesity and diabetes. Historically thought to result from overnutrition and a sedentary lifestyle, recent evidence suggests that diets high in sugar (from sucrose and/or high-fructose corn syrup [HFCS]) not only increase the risk of NAFLD, but also non-alcoholic steatohepatitis (NASH). Herein, we review the experimental and clinical evidence that fructose precipitates fat accumulation in the liver, due to both increased lipogenesis and impaired fat oxidation. Recent evidence suggests that the predisposition to fatty liver is linked to the metabolism of fructose by fructokinase C, which results in ATP consumption, nucleotide turnover and uric acid generation that mediate fat accumulation. Alterations to gut permeability, the microbiome, and associated endotoxemia contribute to the risk of NAFLD and NASH. Early clinical studies suggest that reducing sugary beverages and total fructose intake, especially from added sugars, may have a significant benefit on reducing hepatic fat accumulation. We suggest larger, more definitive trials to determine if lowering sugar/HFCS intake, and/or blocking uric acid generation, may help reduce NAFLD and its downstream complications of cirrhosis and chronic liver disease.

Effect of supplementation of milk fat with peanut oil on blood lipids and lipoproteins in infants

Three different groups of infants were fed with different formulae based on milk fat. Group I received cow's milk fat formulae with 20% butter fat whereas groups II and III received a formulae which was supplemented with 50 and 33% of peanut oil supplementation in 20% milk fat respectively. Anthropometric measurements, cholesterol, triglyceride, lipoproteins and plasma fatty acids were followed up to a period of 6 months. The results indicated that cow's milk-fed infants had higher cholesterol levels (P < 0.01) than the other two groups. No significant differences with respect to high-density lipoproteins (HDLs) were found, whereas low-density lipoproteins (LDLs) and very low-density lipoproteins (VLDls (VLDls) were found to be increasing up to a period of 6 months. No significant differences were observed with respect to saturated fatty acids and oleic acid (18:1) levels whereas linoleic acid (18:2) clearly showed a proportional relationship between the intake and plasma levels, indicating a positive correlation. Arachidonic acid (20:4) did not, however, show a proprotionate relationship with respect to linoleic acid (18:2) intake. The triene/tetraene, oleic/linoleic, linoleic/arachidonic and total n6 fatty acids were all normal indicating normal activity of desaturase and elongase enzymes for the optimal utilisation of linoleic acid. Thus, the present study suggests that a vegetable oil such as peanut oil could be used in milk fat to improve the essential fatty acid (EFA) status of infants.

The effect of glycerol and other intermediates on the incorporation of 14C-fructose and 14C-glucose to hepatic triglyceride

Mature male rats were given, orally, 14C-fructose either alone or in conjunction with dihydroxyacetone, glyceraldehyde, or glycerol. Glycerol was also administered with 14C-glucose in a dose equimolar with fructose. After 2 hr the rats were killed and the liver triglyceride fraction was separated. Estimations of the degree of incorporation of 14C from the radioactive labeled carbohydrate into the glycerol and fatty acid moieties were carried out. Dihydroxyacetone and glyceraldehyde reduced the incorporation of 14C-fructose into hepatic triglyceride to approximately equal extents, suggesting that both trioses contribute equally to alpha-glycerophosphate formation. Glycerol, however, brought about a profound increase in the amount of fructose converted to triglyceride. This effect of glycerol was not apparent to any measurable extent on glucose incorporation into triglyceride and none of the intermediates affected the proportional distribution of radioactive counts between the fatty acid and glycerol moieties of the triglyceride after 14C-fructose administration.

"Added lactose" and "added sucrose" cow's milk formulae in nutrition of low birthweight babies

During the manufacture of dried milks for infant feeding the composition of cow's milk may be modified by the addition of extra carbohydrate powder to lower the relative proportions of protein and minerals, and in practice various carbohydrates are used in a largely empirical manner. In other circumstances it is known that the quality of dietary carbohydrate affects intestinal tolerance, deposition of body fat (in rats), and concentrations of plasma lipids (in man). Therefore, in this study the effects of feeding newborn infants on added lactose formula and added sucrose formula have been investigated. 29 low birthweight babies were observed throughout the first 3 months of life. The added carbohydrate achieved a satisfactory composition in terms of mineral and protein concentration of the reconstituted milk, but the "added lactose" group experienced more diarrhoea and a greater degree of metabolic acidosis during the first week of life. The added lactose group was slightly fatter and the plasma triglyceride concentration slightly higher than in the "added sucrose" group. Despite teleological evidence in favour of lactose, we found no objective contraindication to the addition of sucrose to cow's milk in the manufacture of infant feeding formulae. Both milks contained only small quantities of linoleic acid and the polyunsaturated fatty acid content of the plasma and adipose tissue lipids fell to low levels, but no clinical evidence of "essential fatty acid deficiency" was found.

Glucose, glucose-6-phosphate, lactate and pyruvate content of the retina, blood and liver of streptozotocin-diabetic rats fed sucrose- or starch-rich diets

The feeding of starch- or sucrose-rich diets to normal rats for 20 days resulted in a significant increase in lactate level and L/P ratio in the retina in the sucrose-fed animals. There was no correlation between the glucose and lactate content of the blood and retina and it was concluded that the increased lactate content of the retina was derived from the fructose moiety of the sucrose. Liver hypertrophy occurred in both normal and diabetic animals fed the sucrose diet. When streptozotocin-diabetic rats were maintained for 20 days on the same diets significant increases in the lactic acid content of the blood and liver occurred, but the high level of lactate in the retina of the sucrose-fed normal rats was not further elevated. The feeding of sucrose to diabetic rats resulted in better metabolic control of both blood glucose and lactate as compared with the maintenance of these animals on a starch diet.