Effect of oral amino acid supplementation on liver disease after jejunoileal bypass for morbid obesity

The FXR agonist 6ECDCA reduces hepatic steatosis and oxidative stress induced by ethanol and low-protein diet in mice

BACKGROUND AND AIM

Excessive ethanol consumption can lead to development of hepatic steatosis. Since the FXR receptor regulates adipose cell function and liver lipid metabolism, the aim of this work was to examine the effects of the FXR agonist 6ECDCA on alcoholic liver steatosis development and on oxidative stress induced by ethanol consumption.

METHODS

Swiss mice (n=24) received a low-protein diet (6%) and a liquid diet containing 10% ethanol or water for 6weeks. In the last 15days mice received oral treatment with 6ECDCA (3mgkg(-1)) or 1% tween (vehicle). The experimental groups (n=6) were: water+tween, water+6ECDCA, ethanol+tween and ethanol+6ECDCA. Moreover, as a diet control, we used a basal group (n=6), fed by a normal-proteic diet (23%) and water. After the treatment period, the animals were anesthetized for sample collection to perform plasma biochemistry assays, hepatic oxidative stress assays, hepatic cholesterol and triglycerides measurements, liver histology and hepatic gene expression.

RESULTS

Ethanol associated with low-protein diet induced hepatic oxidative stress, increased plasma transaminases and induced hepatic lipid accumulation. Many of these parameters were reversed by the administration of 6ECDCA, including amelioration of lipid accumulation and lipoperoxidation, and reduction of reactive oxygen species. These effects were possibly mediated by regulation of Srebpf1 and FAS gene expression, both reduced by the FXR agonist.

CONCLUSIONS

Our data demonstrated that 6ECDCA reverses the accumulation of lipids in the liver and decreases the oxidative stress induced by ethanol and low-protein diet. This FXR agonist is promising as a potential therapy for alcoholic liver steatosis.

Diet macronutrients composition in nonalcoholic Fatty liver disease: a review on the related documents

CONTEXT

Non-alcoholic fatty liver disease (NAFLD) is a growing health problem in both developed and developing countries. Metabolic abnormalities, specially insulin resistance and hyperglycemia are highly correlated with NAFLD. Lifestyle modifications including physical activity and promoting nutrient intakes are critical in prevention and treatment of NAFLD. Hence, in this article we aimed to review the evidence regarding the effects of various macronutrients on fat accumulation in hepatic cells as well as the level of liver enzymes.

EVIDENCE ACQUISITIONS

The relevant English and non-English published papers were searched using online databases of PubMed, ISI Web of Science, SCOPUS, Science Direct and EMBASE from January 2000 to January 2013. We summarized the findings of 40 relevant studies in this review.

RESULTS

Although a hypocaloric diet could prevent the progression of fat accumulation in liver, the diet composition is another aspect which should be considered in diet therapy of patients with NAFLD.

CONCLUSIONS

Several studies assessed the effects of dietary composition on fat storage in liver; however, their findings are inconsistent. Most studies focused on the quantity of carbohydrate and dietary fat; whilst there is very limited information regarding the role of protein intake.

Dietary Quality Indices and Biochemical Parameters Among Patients With Non Alcoholic Fatty Liver Disease (NAFLD)

BACKGROUND

Dietary intake might have important role in non-alcoholic fatty liver diseases (NAFLD). Although, there are some reports on dietary intake and anthropometrics measurements, few studies have focused on the markers of assessing whole diet like dietary quality indices.

OBJECTIVES

Therefore, our aim was to determine the diet quality indices and biochemical parameters among patients with NAFLD and healthy individuals.

PATIENTS AND METHODS

This case-control study was performed on 100 patients with NAFLD and 100 healthy subjects who were attending to Gastrointestinal Research Center, Baqiyatallah University, Tehran, Iran during the recent years. Usual dietary intake was assessed by three dietary records (one weekend and two week days). Healthy eating index (HEI), dietary diversity score (DDS), dietary energy density (DED), mean adequacy ratio of nutrients (MAR) were assessed according to the standard methods.

RESULTS

Patients with NAFLD had higher body mass index, weight and waist circumference compared to the healthy group (P < 0.05). Serum levels of liver enzymes, triglyceride, LDL, BUN, and uric acid were higher in patients with NAFLD (P < 0.05). Although patients with NAFLD had higher energy, carbohydrate and fat intake, their values for antioxidant vitamins, calcium and vitamin D were lower than healthy subjects (P < 0.05). HEI and MAR were higher among healthy group, and DED was lower among them. Nutrient adequacy ratio for calcium, vitamin D, and antioxidant micronutrients were lower in patients with NAFLD (P < 0.05).

CONCLUSIONS

It seems that dietary quality indices may be associated with NAFLD. Calcium, vitamin D, and antioxidant micronutrients intake might be lower among patients with NAFLD based on this case-control study. Further prospective studies should be conducted in this regard.

Lifestyle Modification through Dietary Intervention: Health Promotion of Patients with Non-Alcoholic Fatty Liver Disease

BACKGROUND

Prevalence of non-alcoholic fatty liver disease (NAFLD) is more common worldwide and no certain treatment apart from lifestyle modification has been established yet. Available data consistently show that energy intake is significantly higher in patients with NAFLD than in individuals with no evidence of fatty liver. Changing nutritional behaviors seems to be the primary approach for treatment, simultaneously addressing all the clinical and biochemical defects. This study was aimed to examine the effects of two different composition of low energy diet (diet I vs. diet II) on non-alcoholic fatty liver disease patients.

METHODS

In this double-blind randomized controlled trial, 44 ultrasonography-proven overweight non-alcoholic fatty liver disease patients were divided into two groups and received two low-energy diets (-500 kcal less than energy requirement individually) inc. diet I (Carbohydrate: Fat: Protein: 55:25:20) and diet II (Carbohydrate: Fat: Protein: 40:40:20) for six weeks. Anthropometric and biochemical measures as well as liver enzymes were assessed after 12 hours fasting.

RESULTS

After diet I and diet II, weight decreased significantly (%1.82 and %2.45, respectively). Liver enzymes and echogenicity decreased significantly by both diet I and diet II. Mean of triglyceride concentration decreased (%18.09) after diet II (P=0.023), while there was no significant change after diet I. Significant correlations were found between changes in aspartate aminotransferase with triglyceride and LDL-C diet I.

CONCLUSION

Low energy diets can decrease liver enzymes regardless of their composition, while diet II seems to be more effective than diet I in reduction of weight and triglyceride level.

Comparative review of diets for the metabolic syndrome: implications for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a significant health problem and affects 70 million adults in the United States (30% of the adult population), and an estimated 20% of these individuals have the most severe form of NAFLD-nonalcoholic steatohepatitis (NASH). The mechanisms underlying disease development and progression are awaiting clarification. Insulin resistance and obesity-related inflammation, among other possible genetic, dietary, and lifestyle factors, are thought to play a key role. A program targeting gradual weight reduction and physical exercise continues to be the gold standard of treatment for all forms of NAFLD. Even though weight loss and dietary and lifestyle changes are recommended as primary treatment for fatty liver, little to no scientific evidence is available on diet and NAFLD. This article reviews the implications of current dietary approaches, including national guidelines and popular weight-loss diets, with a focus on determining the optimal diet to prescribe for NAFLD and NASH patients. The effects of macronutrient content (carbohydrate, fat, and protein ratios) and specific food components, such as soluble fiber, n-3 fatty acids, and fructose, are discussed. The premises, effects, barriers, and issues related to current dietary guidelines and specific diets are discussed, and the question, "Will it work for the pathogenesis of NAFLD and NASH? ", is addressed.

Etiology of jejunoileal bypass-induced liver dysfunction in rats

Several recent studies suggest that jejunoileal bypass-induced liver disease results from malabsorption of essential nutrients. However, in experimental animals, resection of the defunctionalized bowel substantially reduces bypass-induced liver injury. Such models are often used to support the theory that bacteria in the defunctionalized bowel produce toxic substances which result in liver damage. We used a rat model to first explore the effects of intestinal bypass vs resection on various parameters of liver injury, and subsequently compared these findings to the effect of both bypass and resection on mucosal adaptation in the remaining intact bowel after each procedure. Bypassed animals had lower levels of hepatic cytochrome P-450, glucose-6-phosphatase, pentobarbital hydroxylase, and serum triglycerides than did animals undergoing resection of defunctionalized bowel. Concurrently, resected animals had much greater increases in mucosal weight, DNA content, and protein content in the intact bowel than did bypassed animals. We speculate that the beneficial effects of resection of bypassed bowel on liver function may be a result of increased mucosal hyperplasia in resected animals, rather than elimination of production of toxic substances in the defunctionalized bowel.

Amino acid and peptide absorption in bypassed jejunum following jejunoileal bypass in rats

The intestinal digestive and absorptive function of the excluded jejunum was evaluated 6 and 12 weeks after jejunoileal bypass in rats. Brush border and cytosol aminopeptidase activities as well as mucosal sucrase activity were measured in self-emptying excluded jejunal segments following bypass surgery. In addition, following in vivo perfusion of equimolar amounts of amino acid (L-leucine) and dipeptide (L-leucyl-L-leucine) solutions through bypassed jejunal segments, the uptake of L-leucine was determined. Mucosal weight, protein, and DNA content were reduced in the bypass segment reflecting jejunal mucosal cell hypoplasia. Hydrolytic activities for all enzymes (including the subcellular fractions of the aminopeptidase activities) and absorption rates from both the free amino acid and peptide solutions were reduced in bypassed jejunal segments. When expressed on the basis of mucosal DNA content, however, no changes were observed. This study indicates that the functional alterations in the excluded jejunum after bypass are due to the reduced mucosal cell content of this segment.

Effect of improved absorption on development of jejunoileal bypass-induced liver dysfunction in rats

Jejunoileal bypasses were performed in rats to determine the effect of improved absorption on the development of liver dysfunction occurring after this procedure. Several parameters of liver function were measured in rats 7 weeks after both the standard 85% small-bowel bypass and an 80% bypass in which an extra 5 cm of intact bowel was retained. Animals having undergone 80% bypass had a lesser degree of lowering of serum protein and triglyceride levels, hepatic cytochrome P-450 content, and hepatic glucose-6-phosphatase activity than did the animals undergoing 85% bypass. Abnormalities found in 85% bypass animals were only partially reproduced by reducing food intake in another group of 80% bypassed animals. These findings emphasize the importance of nutritional factors in the etiology of bypass-induced liver disease and militate against toxin production in the defunctionalized bowel as the sole cause of liver dysfunction following bypass.

Role of defunctionalized bowel in jejunoileal bypass-induced liver disease in rats

The pathogenesis of jejunoileal bypass-induced liver disease was investigated in the rat model. Male Sprague-Dawley rats were subjected to 90% jejunoileal bypass and compared to rats having undergone 90% jejunoileal resection, to ad libitum and pair-fed controls and to weight-matched (underfed) controls. After 8 weeks the animals were killed and selected analyses performed. Several indications of liver dysfunction were observed in the bypass rats including hepatomegaly, hypotriglyceridemia, hypoproteinemia, elevated SGOT levels, and markedly decreased levels of cytochrome P-450. All of these abnormalities with the exception of elevated SGOT levels and decreased serum proteins were not observed to the same degree in animals in which the defunctionalized bowel was resected. Rats which were underfed (weight matched) did not develop any of the abnormalities of liver injury demonstrated in the bypass rats. Multiple factors appear to be responsible for the production of bypass-induced liver disease, but the defunctionalized bowel plays an important role.