Beneficios de la fibra dietética y poder antioxidante del salvado de arroz en ratas deficientes en Vitamina E / Benefits of fiber and antioxidant power of rice bran in Vitamin E deficient rats / Beneficios da fibra alimentar e poder antioxidante do farelo de arroz em ratos deficientes em Vitamina E

Las recomendaciones de consumo de fibra no se cumplen y hay una necesidad por alimentos con fibra. El salvado de arroz (SA) tiene fibra y propiedades antioxidantes. Aquí se evaluaron estas propiedades en ratas suficientes (+) y deficientes (-) en Vitamina E (VitE) con o sin SA. Las ratas fueron divididas en cuatro grupos. Dos consumieron dietas +VitE y uno tenía SA. Los restantes consumieron dietas -VitE y uno tenía SA. El consumo de alimento, su eficiencia y el crecimiento, fueron similares entre los 4 grupos pero la masa fecal húmeda o seca fue 3 veces superior en los SA+. La hemoglobina en sangre y el hierro hepático fueron similares entre grupos, pero en los grupos (SA-) la VitE hepática fue 10 veces menor en las ratas -VitE que en las +VitE. Sin embargo, en las ratas -VitE/SA+, la VitE hepática fue sólo 2,6 veces menor. Este efecto del SA también se detectó en los eritrocitos, ya que la catalasa y la glutatión reductasa aumentaron en el grupo -VitE/SA-pero no en el grupo -VitE/SA+. El estudio muestra que SA no interfirió con el crecimiento y el metabolismo del hierro, sino que tuvo un efecto laxante y previno parcialmente la deficiencia de VitE.

Dietary fiber requirements are met by only a small fraction of the population. There is need for supplemented foods to fill this gap. Rice bran (RB) is high in fiber and has antioxidant properties. The effects of rice bran fiber on several metabolic indicators and the antioxidant capacity of rice bran in rats was reported. Rats were divided into 4 dietary groups: Vitamin E-sufficient with (+VitE/RB+) or without (+VitE/RB-) rice bran; Vitamin E-deficient with (-VitE/RB+) or without (-VitE/RB-) rice bran. Food intake, growth and feed efficiency were similar in all groups but wet and dry fecal mass of the RB+ groups were 3 times higher than the RB- groups. Blood hemoglobin and liver iron were also similar among all groups. However, the liver VitE concentration of the rats of (-VitE/RB-) group was 10x lower than the (+VitE/RB-) group. In contrast, liver VitE of the rats (-VitE/RB+) was only 2.6x lower. This effect of RB was also seen in erythrocytes since, catalase and glutathione reductase increased in the VitE deficient rats but RB prevented this increase. This study shows that dietary RB did not interfere with growth, feed efficiency and iron metabolism, it provided dietary fiber and laxation and partially prevented VitE deficiency.

As recomendações de ingestão de fibras não são cumpridos e existe uma necessidade de alimentos ricos em fibras. Farelo de arroz (FA) tem fibra e propriedades antioxidantes. Aqui, estas propriedades foram avaliadas em ratos suficientes (+) e pobres (-) em Vitamina E (VitE) com ou sem FA. Os ratos foram divididos em 4 grupos. Dois consumiram dietas +VitE e um tinha FA. Os restantes consumiram dietas -ViteE e um tinha FA. O consumo de alimento, sua eficiência e crescimento foram semelhantes entre os 4 grupos, mas nos grupos (FA-) a VitE hepática foi 10 vezes menor nos ratos -VitE que nos +VitE. Entretanto, nos ratos -VitE/FA+, a VitE hepática foi apenas 2,6 vezes menor. Este efeito do FA também foi detectado nos eritrócitos, visto que catalase e glutationa redutase aumentaram no grupo -VitE/FA-, mas não no grupo -VitE/FA+. O estudo mostra que FA não interferiu no crescimento ou no metabolismo do ferro, porém teve um efeito laxante e impediu parcialmente a deficiência de VitE.

Prolonged QT interval and lipid alterations beyond ß-oxidation in very long-chain acyl-CoA dehydrogenase null mouse hearts.

Patients with very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency frequently present cardiomyopathy and heartbeat disorders. However, the underlying factors, which may be of cardiac or extra cardiac origins, remain to be elucidated. In this study, we tested for metabolic and functional alterations in the heart from 3- and 7-mo-old VLCAD null mice and their littermate counterparts, using validated experimental paradigms, namely, 1) ex vivo perfusion in working mode, with concomitant evaluation of myocardial contractility and metabolic fluxes using (13)C-labeled substrates under various conditions; as well as 2) in vivo targeted lipidomics, gene expression analysis as well as electrocardiogram monitoring by telemetry in mice fed various diets. Unexpectedly, when perfused ex vivo, working VLCAD null mouse hearts maintained values similar to those of the controls for functional parameters and for the contribution of exogenous palmitate to ß-oxidation (energy production), even at high palmitate concentration (1 mM) and increased energy demand (with 1 µM epinephrine) or after fasting. However, in vivo, these hearts displayed a prolonged rate-corrected QT (QTc) interval under all conditions examined, as well as the following lipid alterations: 1) age- and condition-dependent accumulation of triglycerides, and 2) 20% lower docosahexaenoic acid (an omega-3 polyunsaturated fatty acid) in membrane phospholipids. The latter was independent of liver but affected by feeding a diet enriched in saturated fat (exacerbated) or fish oil (attenuated). Our finding of a longer QTc interval in VLCAD null mice appears to be most relevant given that such condition increases the risk of sudden cardiac death.

Is obesity related to the type of dietary fatty acids? An ecological study.

BACKGROUND: Animal studies and a few clinical trials lend credibility to the hypothesis that not all types of fatty acids carry the same potential for weight gain. Only a few epidemiological studies concerning this issue are currently available and results are conflicting. AIM: The purpose of the present ecological study was to test the existence of an association between obesity prevalence and the types of fat available in 168 countries. METHODS: Data on the prevalence of obesity (BMI >or= 30 kg/m2) for women over 15 years of age were obtained from the WHO Global InfoBase. Food balance sheets for the years 1998 to 2002 were obtained from the FAOSTAT database. Five-year means for energy, total fat, MUFA, PUFA, SFA and 'other fat' per capita were calculated, with their standard deviations, for each country. Bivariate correlations and a multiple linear regression model were used to test for the association between prevalence of obesity and types of fat available in these countries. RESULTS: Not surprisingly, dietary energy supply, SFA, PUFA and 'other fat' were positively associated with the prevalence of obesity. We also found, however, a strong negative association between MUFA availability and obesity prevalence (beta= -0.68, P<0.0001). CONCLUSION: Populations with a lower prevalence of obesity seem to consume a greater amount of MUFA. Considering the partial correlations between variables, our results suggest that in countries with higher obesity prevalence, it is the shift from MUFA to PUFA that particularly appears to be associated with the risk of obesity.

Could the quality of dietary fat, and not just its quantity, be related to risk of obesity?

This review focuses on the possible association between types of fatty acids and weight change. It examines the biological plausibility underlining these associations and the evidence obtained to date from clinical trials and epidemiological studies. Animal studies have shown that dietary short- and medium-chain fatty acids compared to long-chain fatty acids appear to promote weight loss. Similarly, monounsaturated fatty acids (MUFAs) appear to favor weight loss compared to saturated fatty acids (SFAs) in human studies. The structure of fatty acids seems to affect their degree of oxidation and deposition. Although results are conflicting, human studies follow the general trend reported in animal studies. These trials suggest that some fatty acids are prone to oxidation and some others lead to fat storage when comparing isocaloric diets. For instance, n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic and docosahexaenoic acids are preferentially oxidizied to other PUFA but results remain inconsistent. Epidemiological studies concerning this issue reported that total dietary fat, which includes MUFA, PUFA, and SFA could increase the risk of obesity, but results are few and conflicting. The rising biological plausibility linking dietary fat quality and risk of obesity, together with the rather recent addition of fatty acids content in food composition tables, support the need for major epidemiological studies in that area.

Docosahexaenoic acid level of the breast milk of some Filipino women.

This study was conducted to determine the docosahexaenoic acid (DHA) level of the breast milk of 100 Filipino women as affected by diet. The subject distribution was patterned after the 1997 Family and Income Expenditure Survey of the National Statistics Office regarding the total number of families, and the total and average family income and expenditures by income class in an urban area. The subjects were asked to complete a 3-day food record and food frequency questionnaire to ascertain the nutrient content of their food intake and approximate eating habits. Hind milk was drawn manually by means of a fabricated glass breast pump and collected in polypropylene vials. The milk samples were stored in a freezer maintained at -25+/-2 degrees C until they were transported to the University of Montreal for fatty acid composition. The milk was methylated using the Lepage and Roy method. The obtained fatty acid methyl esters were analyzed by gas chromatography. Results showed that the milk samples contain an average of 188.34 microg DHA/ml milk, while %DHA of the samples is 0.65%. Regression analysis revealed that mean protein intake of the subjects was a determinant of the DHA level in the milk samples.

Kinetic analysis of the selectivity of acylcarnitine synthesis in rat mitochondria.

Mitochondrial acylcarnitine synthesis is an obligatory step in the transport of cytosolic long-chain FA into the mitochondria. It is an important control point in the partitioning of cytosolic fatty acids to synthetic pathways or to mitochondrial beta-oxidation. Mitochondrial carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) is the enzyme that catalyzes the transformation of long-chain fatty acylCoA esters to acylcarnitine. Additionally, the isoform of acylCoA synthetase (EC 6.2.1.3) found in mitochondria, which is in close proximity to CPT I on the outer membrane, may act in concert with CPT I to form acylcarnitines from cytosolic nonesterified FA (NEFA). The mitochondrial acylcarnitine synthesis pathway is exposed to multiple fatty acid substrates present simultaneously in the cell milieu, with each fatty acid present at varying pool sizes. The selectivity of this pathway for any particular fatty acid substrate under conditions of multisubstrate availability has not yet been tested experimentally. Our objective was to develop mathematical equations that make use of kinetic constants derived from single-substrate experiments to predict the selectivity of the acylcarnitine synthesis pathway under conditions in which two or more substrates are present simultaneously. In addition, the derived equations must be verifiable by experiment. Our approach was to begin with a Michaelis-Menten model that describes the initial rates of an enzyme system acting on multiple and mutually competitive substrates. From this, we derived equations expressing ratios of reaction rates and fractional turnover rates for pairs of substrates. The derived equations do not require assumptions concerning the degree of enzyme saturation. Using rat mitochondrial preparations and the NEFA substrate pairs, linolenic-oleic acids and palmitic-linoleic acids, we showed that the shape of the experimentally derived data on acylcarnitine synthesis fits the predictions of the derived model equations. We further validated the derived equations by showing that their predictions calculated from previously published kinetic constants were consistent with data from actual experiments. Thus, we are able to conclude that with respect to acylcarnitine synthesis, the fractional turnover rate of the linolenic acid pool would always be 2.9-fold faster than that of the oleate pool regardless of the pool size of either fatty acid. Similarly, the fractional turnover rate of the palmitate pool would always be 1.8-fold faster than that of the linoleate pool regardless of pool size. We extended our kinetic model to more than two mutually competitive substrates. Using previously published rate constants for eight physiologically relevant fatty acids, the derived model predicts that regardless of pool size of any of the fatty acids, the linolenate pool, whether as NEFA or as a CoA ester, would always have the highest fractional turnover rate with respect to acylcarnitine synthesis. Conversely, the stearate pool whether as NEFA or as CoA ester will have the lowest fractional turnover rate relative to all the other fatty acids.

Effects of dietary soybean lecithin on plasma lipid transport and hepatic cholesterol metabolism in rats.

Dietary lecithin can stimulate bile formation and biliary lipid secretion, particularly cholesterol output in bile. Studies also suggested that the lecithin-rich diet might modify hepatic cholesterol homeostasis and lipoprotein metabolism. Therefore, we examined hepatic activities of 3-hydroxy-3 methylglutaryl coenzyme A reductase "HMG -CoA reductase", cholesterol 7 alpha-hydroxylase and acyl-CoA: cholesterol acyltransferase "ACAT" as well as plasma lipids and lipoprotein composition in rats fed diets enriched with 20% of soybean lecithin during 14 days. We also evaluated the content of hepatic canalicular membrane proteins involved in lipid transport to the bile (all P-glycoproteins as detected by the C 219 antibody and the sister of P-glycoprotein "spgp" or bile acid export pump) by Western blotting. As predicted, lecithin diet modified hepatic cholesterol homeostasis. The activity of hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase was enhanced by 30 and 12% respectively, while microsomal ACAT activity showed a dramatic decrease of 75%. As previously reported from ACAT inhibition, the plasma level and size of very low-density lipoprotein (VLDL) were significantly decreased and bile acid pool size and biliary lipid output were significantly increased. The canalicular membrane content of lipid transporters was not significantly affected by dietary lecithin. The current data on inhibition of ACAT activity and related metabolic effects by lecithin mimic the previously reported effects following drug-induced inhibition of ACAT activity, suggesting potential beneficial effects of dietary lecithin supplementation in vascular disease.