The Mediterranean diet improves hepatic steatosis and insulin sensitivity in individuals with non-alcoholic fatty liver disease

The effects of diet and lifestyle interventions on insulin resistance in patients with nonalcoholic fatty liver disease: a systematic review

Nonalcoholic fatty liver disease (NAFLD) results from excessive fat accumulation in the liver in the absence of excessive alcohol consumption. Insulin resistance (IR) is proposed to be an underlying pathogenic factor in the development and progression of disease. There are currently no proven pharmacotherapies and weight loss is the only prescribed treatment despite a lack of evidence to support a specific diet or lifestyle therapy. The aim of this review is to evaluate the efficacy of dietary lifestyle interventions on IR measured by Homeostasis model assessment in patients with NAFLD. A systematic electronic search of Medline, Scopus, The Cochrane Library, CINAHL and PubMed databases (1999-2015) was performed by two independent reviewers. Randomized control trials evaluating the efficacy of diet and lifestyle interventions on IR in adults diagnosed with NAFLD were included. A total of 6441 articles were identified; eight randomized control trials fulfilled the inclusion criteria. Three studies involved dietary interventions and five incorporated diet and exercise. The majority of intervention groups resulted in significant reductions in IR, with no significant changes observed in the control groups. Lifestyle interventions compared with controls reduced IR measured by homeostasis model assessment. All diet and diet and lifestyle intervention trials were efficient in reducing IR in participants with NAFLD. A lack of literature and variation across interventions warrants the need for extensive research to establish firm dietary lifestyle recommendations.

Dietary Composition Independent of Weight Loss in the Management of Non-Alcoholic Fatty Liver Disease

Poor dietary composition is an important factor in the progression of non-alcoholic fatty liver disease (NAFLD). The majority of NAFLD patients follow diets with overconsumption of simple carbohydrates, total and saturated fat, with reduced intake of dietary fiber and omega-3 rich foods. Although lifestyle modifications including weight loss and exercise remain the keystone of NAFLD management, modifying dietary composition with or without a calorie-restricted diet may also be a feasible and sustainable strategy for NAFLD treatment. In the present review article, we highlight the potential therapeutic role of a “high quality healthy diet” to improve hepatic steatosis and metabolic dysfunction in patients with NAFLD, independent of caloric restriction and weight loss. We provide a literature review evaluating the evidence behind dietary components including fiber-, meat- and omega-3-rich diets and, pending further evidence, we concur with the EASL-EASD-EASO Clinical Guidelines recommendation of the Mediterranean diet as the diet of choice in these patients.

The Mediterranean dietary pattern as the diet of choice for non-alcoholic fatty liver disease: Evidence and plausible mechanisms

Non-alcoholic fatty liver disease (NAFLD) has become a major global health burden, leading to increased risk for cirrhosis, hepatocellular carcinoma, type-2 diabetes and cardiovascular disease. Lifestyle intervention aiming at weight reduction is the most established treatment. However, changing the dietary composition even without weight loss can also reduce steatosis and improve metabolic alterations as insulin resistance and lipid profile. The Mediterranean diet (MD) pattern has been proposed as appropriate for this goal, and was recommended as the diet of choice for the treatment of NAFLD by the EASL-EASD-EASO Clinical Practice Guidelines. The MD has an established superiority in long term weight reduction over low fat diet, but it improves metabolic status and steatosis even without it. However, the effect on liver inflammation and fibrosis was tested only in few observational studies with positive results. Furthermore, considering the strong association between NAFLD and diabetes and CVD, the MD has a highly established advantage in prevention of these diseases, demonstrated in randomized clinical trials. The individual components of the MD such as olive oil, fish, nuts, whole grains, fruits, and vegetables, have been shown to beneficially effect or negatively correlate with NAFLD, while consumption of components that characterize a Western dietary pattern as soft drinks, fructose, meat and saturated fatty acids have been shown to have detrimental association with NAFLD. In this review we will cover the epidemiological evidence and the plausible molecular mechanisms by which the MD as a whole and each of its components can be of benefit in NAFLD.

Effect of a counseling-supported treatment with the Mediterranean diet and physical activity on the severity of the non-alcoholic fatty liver disease

AIM

To determine the clinical effectiveness of nutritional counseling on reduction of non-alcoholic fatty liver disease (NAFLD) severity, weight loss, metabolic and anthropometric indexes and liver enzymes.

METHODS

Forty-six adults with NAFLD received a 6-mo clinical and a dietary intervention (based on Mediterranean diet) carried out respectively by a gastroenterologist and a nutritionist with counseling license. The counseling process consisted of monthly meeting (about 45 min each). The effect of the treatment was evaluated monitoring liver enzymes, metabolic parameters, cardiovascular risk indexes, NAFLD severity [assessed by ultrasound (US)] and related indexes. All parameters were assessed at baseline. Biochemistry was also assessed at mid- and end-interventions and US was repeated at end-intervention.

RESULTS

The percentage of patients with steatosis grade equal or higher than 2 was reduced from 93% to 48% and steatosis regressed in 9 patients (20%). At the end of the treatment the end-point concerning the weight (i.e., a 7% weight reduction or achievement/maintenance of normal weight) was accomplished by 25 out of 46 patients (i.e., 54.3%). As far as the liver enzymes is concerned, all three liver enzymes significantly decrease during the treatment the normalization was particularly evident for the ALT enzyme (altered values reduced from 67% down to 11%). Several parameters, i.e., BMI, waist circumference, waist-to-hip ratio, AST, ALT, GGT, HDL, serum glucose, Tot-Chol/HDL, LDL/HDL, TG/HDL, AIP, HOMA, FLI, Kotronen index, VAI, NAFLD liver fat score and LAP, showed a significant improvement (P < 0.01) between baseline and end-treatment.

CONCLUSION

Outcomes of this study further strengthen the hypothesis that MedDiet and more active lifestyle can be considered a safe therapeutic approach for reducing risk and severity of NAFLD and related disease states. The proposed approach may be proposed as a valid and recommended approach for improving the clinical profile of NAFLD patients.

Randomized Controlled Trial of a MUFA or Fiber-Rich Diet on Hepatic Fat in Prediabetes

CONTEXT

Increased prevalence of type 2 diabetes mellitus and prediabetes worldwide is attributed in part to an unhealthy diet.

OBJECTIVE

To evaluate whether 12 weeks of high monounsaturated fatty acid (MUFA) or fiber-rich weight-maintenance diet lowers hepatic fat and improves glucose tolerance in people with prediabetes.

DESIGN

Subjects underwent a [6, 6-2H2]-labeled 75-g oral glucose tolerance test to estimate hepatic insulin sensitivity and liver fat fraction (LFF) using magnetic resonance spectroscopy before and after intervention.

SETTING

Mayo Clinic Clinical Research Trials Unit.

PARTICIPANTS

43 subjects with prediabetes.

INTERVENTION

Subjects were randomized into three isocaloric weight-maintaining diets containing MUFA (olive oil), extra fiber, and standard US food (control-habitual diet).

OUTCOME MEASURES

LFF, glucose tolerance, and indices of insulin action and secretion.

RESULTS

Body weight was maintained constant in all groups during the intervention. Glucose and hormonal concentrations were similar in all groups before, and unchanged after, 12 weeks of intervention. LFF was significantly lower after intervention in the MUFA group (P < 0.0003) but remained unchanged in the fiber (P = 0.25) and control groups (P = 0.45). After 12 weeks, LFF was significantly lower in the MUFA than in the control group (P = 0.01), but fiber and control groups did not differ (P = 0.41). Indices of insulin action and secretion were not significantly different between the MUFA and control groups after intervention (P ≥ 0.11), but within-group comparison showed higher hepatic (P = 0.01) and total insulin sensitivity (P < 0.04) with MUFA.

CONCLUSIONS

Twelve weeks of a MUFA diet decreases hepatic fat and improves both hepatic and total insulin sensitivity.

AISF position paper on nonalcoholic fatty liver disease (NAFLD): Updates and future directions

This review summarizes our current understanding of nonalcoholic fatty liver disease (NAFLD), a multi-factorial systemic disease resulting from a complex interaction between a specific genetic background and multiple environmental/metabolic "hits". The role of gut microbiota, lipotoxicity, inflammation and their molecular pathways is reviewed in-depth. We also discuss the epidemiology and natural history of NAFLD by pinpointing the remarkably high prevalence of NAFLD worldwide and its inherent systemic complications: hepatic (steatohepatitis, advanced fibrosis and cirrhosis), cardio-metabolic (cardiovascular disease, cardiomyopathy, arrhythmias and type 2 diabetes) and neoplastic (primary liver cancers and extra-hepatic cancers). Moreover, we critically report on the diagnostic role of non-invasive biomarkers, imaging techniques and liver biopsy, which remains the reference standard for diagnosing the disease, but cannot be proposed to all patients with suspected NAFLD. Finally, the management of NAFLD is also reviewed, by highlighting the lifestyle changes and the pharmacological options, with a focus on the innovative drugs. We conclude that the results of ongoing studies are eagerly expected to lead to introduce into the clinical arena new diagnostic and prognostic biomarkers, prevention and surveillance strategies as well as to new drugs for a tailored approach to the management of NAFLD in the individual patient.

Current and future treatment options in non-alcoholic steatohepatitis (NASH)

Non-alcoholic steatohepatitis (NASH) is a chronic liver disease that can progress to cirrhosis and hepatocellular carcinoma. Diagnosis of NASH requires a liver biopsy and is defined as presence of hepatic steatosis, ballooning and lobular inflammation with or without fibrosis. Although NASH is the most common cause of liver disease in the west world and among the top three indications for liver transplantation, there are no universally accepted pharmacological therapies and therapeutic advances have been slow. Areas covered: Current evidence about lifestyle interventions, bariatric surgery and pharmacotherapy is reviewed. Dietary recommendations and lifestyle interventions have shown promising results but are difficult to maintain. At the moment, there is no universally approved medical treatment for NASH. Pioglitazone and vitamin E are recommended by guidelines in selected patients. An increasing number of phase II and III trials in non-cirrhotic NASH are currently recruiting and their preliminary results discussed. Expert commentary: As NASH is classified as a medical condition of an unmet therapeutic need, it has gained an accelerated access pathway for drug approval based on surrogate endpoints. It is therefore expected that within the next five years, there will be at least one approved agent for the pharmacological treatment of pre-cirrhotic NASH.

Nutritional Approaches to Achieve Weight Loss in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) can range in spectrum from simple hepatic steatosis to nonalcoholic steatohepatitis (NASH), which is characterized by lipotoxicity, hepatocellular ballooning, and inflammation and can progress to cirrhosis. Weight loss is the cornerstone treatment for NAFLD and NASH. Various randomized controlled trials have shown that weight loss of ≥5-10% leads to significant improvements in hepatic steatosis. Diets high in sodium and fructose have been implicated in the pathogenesis of NAFLD. Although some clinical studies suggest that an isocaloric high-fructose diet does not worsen NAFLD, these clinical studies are often short in duration. More recently, the Dietary Approaches to Stop Hypertension diet, a sodium-restricted diet, has been associated with less prevalence of NAFLD and has been shown to improve NAFLD. In addition, the Mediterranean diet has been promising in improving hepatic steatosis, and a larger randomized controlled trial is currently enrolling subjects. For those who are unable to pursue weight loss through dietary approaches, bariatric surgery has been shown to improve hepatic steatosis and steatohepatitis. This method has been variable in improving hepatic fibrosis. In conclusion, weight loss is crucial to the improvement of NAFLD and NASH, and patients should attempt various diets in an attempt to achieve weight loss.

Pharmacological management of nonalcoholic fatty liver disease in type 2 diabetes

INTRODUCTION

The prevalence of nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes (T2D) is high and it is associated with poor prognosis. Hepatic steatosis results as a consequence of excessive hepatic lipid accumulation which correlates with insulin resistance and lipotoxicity, with subsequent oxidative stress, inflammation, apoptosis and fibrosis. Areas covered: This article presents the main pathophysiologic mechanisms and currently available drugs evaluated for their therapeutic effects on NAFLD/nonalcoholic steatohepatitis (NASH) and drugs under development that target relevant pathogenetic pathways. However, to date there is no particular drug approved for treatment of NAFLD in patients with T2D. Expert commentary: Early recognition and intervention are essential to ameliorate disease progression. Specific recommendations are still needed for NAFLD/NASH screening and diagnosis and therapeutic algorithm in patients with T2D. Lifestyle optimization with significant weight loss is a key intervention in patients with NAFLD and T2D. Pioglitazone, liraglutide, vitamin E, OCA and pentoxifylline have proven some histological improvements in NASH and omega 3-PUFAs were shown to decrease liver fat, but no specific recommendation can be made for treatment of NASH. Perhaps a combination of agents that target different pathogenic pathways are needed to better control disease progression, but more robust evidence for these agents is still needed.

Fructose and NAFLD: The Multifaceted Aspects of Fructose Metabolism

Among various factors, such as an unhealthy diet or a sedentarity lifestyle, excessive fructose consumption is known to favor nonalcoholic fatty liver disease (NAFLD), as fructose is both a substrate and an inducer of hepatic de novo lipogenesis. The present review presents some well-established mechanisms and new clues to better understand the pathophysiology of fructose-induced NAFLD. Beyond its lipogenic effect, fructose intake is also at the onset of hepatic inflammation and cellular stress, such as oxidative and endoplasmic stress, that are key factors contributing to the progression of simple steatosis to nonalcoholic steatohepatitis (NASH). Beyond its hepatic effects, this carbohydrate may exert direct and indirect effects at the peripheral level. Excessive fructose consumption is associated, for example, with the release by the liver of several key mediators leading to alterations in the communication between the liver and the gut, muscles, and adipose tissue and to disease aggravation. These multifaceted aspects of fructose properties are in part specific to fructose, but are also shared in part with sucrose and glucose present in energy–dense beverages and foods. All these aspects must be taken into account in the development of new therapeutic strategies and thereby to better prevent NAFLD.

Effects of lifestyle interventions on clinical characteristics of patients with non-alcoholic fatty liver disease: A meta-analysis

BACKGROUND/OBJECTIVES

Although lifestyle modifications remain the cornerstone therapy for non-alcoholic fatty liver disease (NAFLD), the optimal lifestyle intervention is still controversial. The aim of this meta-analysis was to evaluate the effect of exercise and/or dietary interventions, type or intensity of exercise and type of diet, on liver function outcomes (liver enzymes, intrahepatic fat and liver histology), as well as on anthropometric and glucose metabolism parameters in NAFLD patients.

SUBJECTS/METHODS

Literature search was performed in Scopus and US National Library of Medicine databases to identify all randomized controlled clinical trials (RCTs) in adult patients with NAFLD, diagnosed through imaging techniques or liver biopsy, published in English between January 2005 and August 2016. Studies' quality was evaluated using the Cochrane Risk of Bias Tool. Heterogeneity was tested using the Cochran's Q test and measured inconsistency by I². Effect size was calculated as the standardized mean difference (SMD). The meta-analysis was performed in accordance with PRISMA guidelines.

RESULTS

Twenty RCTs with 1073 NAFLD patients were included. Compared to standard care, exercise improved serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) (all P<0.05). Ιntrahepatic fat also improved, irrespectively of weight change (SMD=-0.98, 95% CI: -1.30 to -0.66). Regarding the type of exercise, aerobic compared to resistance exercise did not yield any superior improvements on liver parameters, whereas moderate-to-high volume moderate-intensity continuous training was more beneficial compared to continuous low-to-moderate-volume moderate-intensity training or high intensity interval training. Interventions combining exercise and diet showed decreases in ALT (P<0.01) and improvement in NAFLD activity score (SMD=-0.61, 95% CI: -1.09 to -0.13). Moderate-carbohydrate diets yielded similar changes in liver enzymes compared to low/moderate-fat diets.

CONCLUSIONS

Exercise alone or combined with dietary intervention improves serum levels of liver enzymes and liver fat or histology. Exercise exerts beneficial effects on intrahepatic triglycerides even in the absence of weight loss.

Good adherence to the Mediterranean diet reduces the risk for NASH and diabetes in pediatric patients with obesity: The results of an Italian Study

OBJECTIVE

In the last decade, it was demonstrated that the Mediterranean diet (MD) represents an ideal diet for all age groups and has an important role in the prevention of metabolic and cardiovascular diseases, as well as nonalcoholic fatty liver disease (NAFLD). The aim of the present study was to analyze the association between adherence to the MD and NAFLD, with laboratory and histologic evaluation, in a group of children and adolescents with obesity.

METHODS

We enrolled 243 patients with obesity referred to our department from March 2014 to November 2015. In all patients, we performed abdominal ultrasound and laboratory assays. In selected cases (100 patients) liver biopsy was performed. Level of adherence to the MD was evaluated by a clinical questionnaire, the Mediterranean Diet Quality Index for children and adolescents (KIDMED).

RESULTS

The prevalence of low KIDMED score was significantly higher in patients with nonalcoholic steatohepatitis compared with other groups; poor adherence to the MD correlated with liver damage, the NAFLD activity score >5, and grade 2 fibrosis. Moreover, in patients with poor adherence to the MD, higher values of C-reactive protein, fasting insulin, homeostatic model assessment of insulin resistance, and homeostatic model assessment of β cell function were observed.

CONCLUSION

The MD could be a safe and inexpensive therapeutic option for children with obesity and NAFLD.

Short- and Long-Term Reproducibility of Intrahepatic Lipid Quantification by 1H-MR Spectroscopy and CT in Obesity

OBJECTIVE

This study aimed to assess short- and long-term reproducibility of intrahepatic lipid (IHL) quantification by proton magnetic resonance spectroscopy (H-MRS) and computed tomography (CT).

METHODS

Sixteen obese subjects underwent H-MRS using a single-voxel point-resolved single-voxel spectroscopy sequence at 3 T and noncontrast single-slice CT of the liver. Measurements were repeated after 6 weeks and 6 months. Clinical parameters (weight, activity, serum lipids) were collected. Short-term (baseline to 6 weeks) and long-term (baseline to 6 months) reproducibility of IHL was assessed by coefficient of variance (CV), SD, and intraclass correlation coefficient (ICC).

RESULTS

Short-term reproducibility and long-term reproducibility of H-MRS were as follows: CV, 5.9% to 18.8%; SD, 0.7 to 1.9; and ICC, 0.998 to 0.995 (95% confidence interval, 0.942-0.999). Short-term reproducibility and long-term reproducibility of CT were as follows: CV, 4.4% to 14.2%; SD, 2.4 to 8.7; and ICC, 0.766 to 0.982 (95% confidence interval, 0.271-0.994). There was no significant change in clinical parameters (P > 0.3).

CONCLUSIONS

Proton magnetic resonance spectroscopy and CT are reproducible methods for short- and long-term quantification of IHL content. Our results can guide sample size calculations for interventional and longitudinal studies.

Non-pharmacological interventions in non-alcoholic fatty liver disease patients

Patients with non-alcoholic fatty liver disease have unhealthy diets, sedentary behaviour and not enough physical activity. This lifestyle triggers liver disease and probably favours its progression. It also has significant deleterious effects on health and longevity and should therefore be corrected by first-line therapy at all stages of the disease. However, important questions remain: is weight loss alone beneficial or do particular diets have beneficial effects beyond weight loss? Which specific micro- or macronutrients are clearly harmful? Does exercise without weight loss improve hepatic histology and what type of exercise is optimal? Does moderate or only vigorous exercise have metabolic and hepatic benefits? What is the efficacy of lifestyle measures outside of clinical trials? And most importantly, what is the turning point in the natural history of liver disease when non-pharmacological measures should be combined with drug therapy?

Polyphenol-rich virgin olive oil reduces insulin resistance and liver inflammation and improves mitochondrial dysfunction in high-fat diet fed rats

SCOPE

Virgin olive oil is an essential component of the Mediterranean diet. Its antioxidant and anti-inflammatory properties are mainly linked to phenolic contents. This study aims to evaluate the beneficial effects of a polyphenol-rich virgin olive oil (HPCOO) or olive oil without polyphenols (WPOO) in rats fed high-fat diet (HFD).

METHODS AND RESULTS

Male Sprague-Dawley rats were divided into four groups based on the different types of diet: (I) standard diet (STD); (II) HFD; (III) HFD containing WPOO, and (IV) HFD containing HPCOO. HPCOO and WPOO induced a significant improvement of HFD-induced impaired glucose homeostasis (by hyperglycemia, altered oral glucose tolerance, and HOMA-IR) and inflammatory status modulating pro- and anti-inflammatory cytokines (TNF-α, IL-1, and IL-10) and adipokines. Moreover, HPCOO and less extensively WPOO, limited HFD-induced liver oxidative and nitrosative stress and increased hepatic fatty acid oxidation. To study mitochondrial performance, oxidative capacity and energy efficiency were also evaluated in isolated liver mitochondria. HPCOO, but not WPOO, reduced H₂ O₂ release and aconitase activity by decreasing degree of coupling, which plays a major role in the control of mitochondrial reactive oxygen species emission.

CONCLUSION

HPCOO limits HFD-induced insulin resistance, inflammation, and hepatic oxidative stress, preventing nonalcoholic fatty liver disease progression.

A "healthy diet-optimal sleep" lifestyle pattern is inversely associated with liver stiffness and insulin resistance in patients with nonalcoholic fatty liver disease

Several lifestyle habits have been described as risk factors for nonalcoholic fatty liver disease (NAFLD). Given that both healthy and unhealthy habits tend to cluster, the aim of this study was to identify lifestyle patterns and explore their potential associations with clinical characteristics of individuals with NAFLD. One hundred and thirty-six consecutive patients with ultrasound-proven NAFLD were included. Diet and physical activity level were assessed through appropriate questionnaires. Habitual night sleep hours and duration of midday naps were recorded. Optimal sleep duration was defined as sleep hours ≥ 7 and ≤ 9 h/day. Lifestyle patterns were identified using principal component analysis. Eight components were derived explaining 67% of total variation of lifestyle characteristics. Lifestyle pattern 3, namely high consumption of low-fat dairy products, vegetables, fish, and optimal sleep duration was negatively associated with insulin resistance (β = -1.66, P = 0.008) and liver stiffness (β = -1.62, P = 0.05) after controlling for age, sex, body mass index, energy intake, smoking habits, adiponectin, and tumor necrosis factor-α. Lifestyle pattern 1, namely high consumption of full-fat dairy products, refined cereals, potatoes, red meat, and high television viewing time was positively associated with insulin resistance (β = 1.66, P = 0.005), although this association was weakened after adjusting for adiponectin and tumor necrosis factor-α. A "healthy diet-optimal sleep" lifestyle pattern was beneficially associated with insulin resistance and liver stiffness in NAFLD patients independent of body weight status and energy intake.

Nutrition Interventions for Chronic Liver Diseases and Nonalcoholic Fatty Liver Disease

The progressively increasing rates of obesity have led to a worldwide epidemic of nonalcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome. It is currently the most common cause of liver disease worldwide and projected to be the leading indication for liver transplantation in the United States by 2020. NAFLD is associated with both liver-related and overall mortality. Undoubtedly, nutrition interventions are key in the treatment of NAFLD, to reverse the disease, and prevent disease progression, complications, and associated comorbidities, including cardiovascular disease and diabetes.

Tomato Juice Consumption Modifies the Urinary Peptide Profile in Sprague-Dawley Rats with Induced Hepatic Steatosis

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in Western countries, with a high prevalence, and has been shown to increase the risk of type 2 diabetes, cardiovascular disease (CVD), etc. Tomato products contain several natural antioxidants, including lycopene—which has displayed a preventive effect on the development of steatosis and CVD. Accordingly, the aim of the present work was to evaluate the effect of tomato juice consumption on the urinary peptide profile in rats with NAFLD induced by an atherogenic diet and to identify potential peptide biomarkers for diagnosis. Urine samples, collected weekly for four weeks, were analyzed by capillary electrophoresis (CE) coupled to a mass spectrometer (MS). A partial least squares-discriminant analysis (PLS-DA) was carried out to explore the association between differential peptides and treatments. Among the 888 peptides initially identified, a total of 55 were obtained as potential biomarkers. Rats with steatosis after tomato juice intake showed a profile intermediate between that of healthy rats and that of rats with induced hepatic steatosis. Accordingly, tomato products could be considered as a dietary strategy for the impairment of NAFLD, although further research should be carried out to develop a specific biomarkers panel for NAFLD.

A Simple Dietary Questionnaire Correlates With Formal Dietitian Evaluation and Frequently Identifies Specific Clinical Interventions in an Outpatient Gastroenterology Clinic

BACKGROUND

The spectrum of gastroenterology-related diseases related to obesity is growing. Few clinical tools exist to aid in clinician-guided dietary counseling.

GOALS

(1) Develop and validate a 1-page diet history form that would provide information on dietary factors that can contribute to gastrointestinal (GI) illness and to assess adherence to the Mediterranean diet; and (2) evaluate the form in a general GI clinic to determine its potential utility as a clinical tool.

STUDY

A 1-page diet history form was developed and underwent qualitative and quantitative validation in comparison to a formal diet evaluation by a registered dietitian. The form was then evaluated in consecutive patients attending a general GI clinic, and analyzed for overall diet content, compliance with a Mediterranean diet, and presence of high-risk (red flag) dietary behaviors.

RESULTS

The form was evaluated in 134 patients. In a validation cohort (n=30) the qualitative dietary components measured were highly concordant with a formal dietary interview. Total daily calorie intake correlated with formal dietary review (R=0.61), but tended to underestimate total calories due to less precision in portion size. The prospective cohort (n=104) patients had a mean body mass index of 29.8. Overall, 52.9% were obese, 50% had metabolic syndrome, and 51% had a primary GI illness directly impacted by dietary factors (gastroesophageal reflux, irritable bowel, fatty liver). Overall, 85.6% of patients documented red flag behaviors. Patients with obesity trended for more red flags than overweight or normal body mass index groups.

CONCLUSION

A 1-page diet questionnaire correlated well with formal dietary assessment and identified clinically relevant dietary interventions in a high percentage of GI patients.

Impact of Hypocaloric Hyperproteic Diet on Gut Microbiota in Overweight or Obese Patients with Nonalcoholic Fatty Liver Disease: A Pilot Study

BACKGROUND

NAFLD is likely to become the most common cause of chronic liver disease. The first-line treatment includes weight loss.

AIMS

To analyze the impact of a hypocaloric hyperproteic diet (HHD) on gut microbiota in NAFLD patients.

METHODS

Fifteen overweight/obese patients with NAFLD were included. At baseline and after a 3-week HHD (Eurodiets(®), ~1000 kcal/day, ~125 g protein/day), we measured gut microbiota composition and function by shotgun metagenomics; body weight; body composition by bioelectrical impedance analysis; liver and visceral fat by magnetic resonance imaging; plasma C-reactive protein (CRP); and liver tests. Results between both time points, expressed as median (first and third quartile), were compared by Wilcoxon signed-rank tests.

RESULTS

At baseline, age was 50 (47-55) years and body mass index 34.6 (32.4, 36.7) kg/m(2). HDD decreased body weight by 3.6 % (p < 0.001), percent liver fat by 65 % (p < 0.001), and CRP by 19 % (p = 0.014). HDD was associated with a decrease in Lachnospira (p = 0.019), an increase in Blautia (p = 0.026), Butyricicoccus (p = 0.024), and changes in several operational taxonomic units (OTUs) of Bacteroidales and Clostridiales. The reduced liver fat was negatively correlated with bacteria belonging to the Firmicutes and Bacteroidetes phyla (a Ruminococcaceae OTU, r = -0.83; Bacteroides, r = -0.73). The associated metabolic changes concerned mostly enzymes involved in amino acid and carbohydrate metabolism.

CONCLUSIONS

In this pilot study, HHD changes gut microbiota composition and function in overweight/obese NAFLD patients, in parallel with decreased body weight, liver fat, and systemic inflammation. Future studies should aim to confirm these bacterial changes and understand their mode of action.

TRAIL REGISTRATION

Under clinicaltrials.gov: NCT01477307.

Associations between Dietary Nutrient Intakes and Hepatic Lipid Contents in NAFLD Patients Quantified by ¹H-MRS and Dual-Echo MRI

Dietary habits are crucial in the progression of hepatic lipid accumulation and nonalcoholic fatty liver disease (NAFLD). However, there are limited studies using ¹H-magnetic resonance spectroscopy (¹H-MRS) and dual-echo in-phase and out-phase magnetic resonance spectroscopy imaging (dual-echo MRI) to assess the effects of dietary nutrient intakes on hepatic lipid contents. In the present study, we recruited 36 female adults (NAFLD:control = 19:17) to receive questionnaires and medical examinations, including dietary intakes, anthropometric and biochemical measurements, and ¹H-MRS and dual-echo MRI examinations. NAFLD patients were found to consume diets higher in energy, protein, fat, saturated fatty acid (SFA), and polyunsaturated fatty acid (PUFA). Total energy intake was positively associated with hepatic fat fraction (HFF) and intrahepatic lipid (IHL) after adjustment for age and body-mass index (BMI) (HFF: β = 0.24, p = 0.02; IHL: β = 0.38, p = 0.02). Total fat intake was positively associated with HFF and IHL after adjustment for age, BMI and total energy intake (HFF: β = 0.36, p = 0.03; IHL: β = 0.42, p = 0.01). SFA intake was positively associated with HFF and IHL after adjustments (HFF: β = 0.45, p = 0.003; IHL: β = 1.16, p = 0.03). In conclusion, hepatic fat content was associated with high energy, high fat and high SFA intakes, quantified by ¹H-MRS and dual-echo MRI in our population. Our findings are useful to provide dietary targets to prevent the hepatic lipid accumulation and NAFLD.

Mediterranean diet and nonalcoholic fatty liver disease: molecular mechanisms of protection

Nutritional habits modifications have shown an important impact in preventing and ameliorating metabolic alterations, such as nonalcoholic fatty liver disease (NAFLD). Among several dietary approaches that exert positive effects in NAFLD patients, the Mediterranean dietary pattern has shown notable benefits. This review explores the molecular mechanisms through which the Mediterranean diet would improve risk factors associated with metabolic syndrome and NAFLD. The main features of the Mediterranean diet acting on metabolism are represented by its whole-grain and low glycemic index cereal-based items, its fatty acid profile, and its content in phytochemical compounds. Carbohydrate-rich foods high in dietary fiber inducing low glycemic response are able to interact with glucose and insulin metabolism. Unsaturated fatty acids are associated with better hepatic lipid metabolism. Finally, phytochemical compounds, such as dietary polyphenols, are thought to ameliorate inflammation, which is considered one of the mechanisms through which NALFD may evolve into nonalcoholic steatohepatitis (NASH).

Exercise and diet in the management of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver condition worldwide, and is projected to become the leading cause for liver transplantation in the United States as early as 2020. The mainstay of treatment remains lifestyle modification with diet and exercise recommendations, as although some pharmacological treatments such as glitazones and Vitamin E have shown benefit, there are concerns regarding long term safety. The evidence base for dietary interventions in NAFLD such as the Mediterranean diet, omega-3 polyunsaturated fatty acids and coffee is mainly derived from observational data with questionable validity. Where trials exist, they have shown benefit for surrogate outcomes such as hepatic steatosis and insulin resistance, but no trials have been conducted with salient clinical outcomes such as reduction in progression to chronic liver disease. Benefit in surrogate outcomes has also been seen for aerobic, anaerobic and combined modality exercise but it remains unclear if one type is superior. Furthermore, a reduction in sedentary time appears equally important. To provide a sound evidence base for lifestyle recommendations to people with NAFLD, longer duration trials of standardized dietary or exercise interventions, and testing various doses, types and with liver related outcomes, are essential.

The multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and represents a growing challenge in terms of prevention and treatment. Despite its high prevalence, only a small minority of affected patients develops inflammation and subsequently fibrosis and chronic liver disease, while most of them only exhibit simple steatosis. In this context, the full understanding of the mechanisms underlying the development of NAFLD and non-alcoholic steatohepatitis (NASH) is of extreme importance; despite advances in this field, knowledge on the pathogenesis of NAFLD is still incomplete. The 'two-hit' hypothesis is now obsolete, as it is inadequate to explain the several molecular and metabolic changes that take place in NAFLD. The "multiple hit" hypothesis considers multiple insults acting together on genetically predisposed subjects to induce NAFLD and provides a more accurate explanation of NAFLD pathogenesis. Such hits include insulin resistance, hormones secreted from the adipose tissue, nutritional factors, gut microbiota and genetic and epigenetic factors. In this article, we review the factors that form this hypothesis.

Association between Adherence to the Mediterranean Diet and Presence of Nonalcoholic Fatty Liver Disease in Children

OBJECTIVE

The study's objective was to analyze the association between the adherence to the Mediterranean diet (MD) and the presence of nonalcoholic fatty liver disease (NAFLD) in children.

METHODS

The study consisted of three groups of children. Group 1 included obese/overweight children with recent diagnosis of NAFLD (n = 106, 12.4 ± 2.6 years). Group 2 included obese children without NAFLD (n = 21, 11.3 ± 2.6 years). Group 3 included the healthy children (without known chronic disease) with normal BMI (n = 54, 11.8 ± 2.9 years). Compliance to the MD was assessed by the KIDMED index score.

RESULTS

KIDMED index score in obese children with NAFLD, without NAFLD, and healthy children were 2.6 ± 2.4, 4.6 ± 1.2, and 6.2 ± 1.9, respectively (p < 0.05 for group 1 versus 2, 1 versus 3, and 2 versus 3). Diet compliance was good in only 4.7% of the patients with NAFLD, whereas it was 31.5% in healthy children. KIDMED index score was negatively correlated with BMI (p < 0.05, r = -0.53), but no correlation was found with other parameters. The area under the receiver operation curve (AUROC) for predicting fatty liver disease in obese children (n = 127) with BMI and KIDMED index score was 0.78 (p < 0.05) and 0.24 (p < 0.05), respectively. BMI >26 has a sensitivity of 79.2% and specificity of 52.4%, and KIDMED index score ≤3 has a sensitivity of 66.9% and specificity of 76.1%.

CONCLUSIONS

MD is an inexpensive and nontoxic dietary regimen and may be used as a therapeutic option in obese children with NAFLD.

Non-alcoholic fatty liver disease and dyslipidemia: An update

Non-alcoholic fatty liver (NAFLD) is the most common liver disease worldwide, progressing from simple steatosis to necroinflammation and fibrosis (leading to non-alcoholic steatohepatitis, NASH), and in some cases to cirrhosis and hepatocellular carcinoma. Inflammation, oxidative stress and insulin resistance are involved in NAFLD development and progression. NAFLD has been associated with several cardiovascular (CV) risk factors including obesity, dyslipidemia, hyperglycemia, hypertension and smoking. NAFLD is also characterized by atherogenic dyslipidemia, postprandial lipemia and high-density lipoprotein (HDL) dysfunction. Most importantly, NAFLD patients have an increased risk for both liver and CV disease (CVD) morbidity and mortality. In this narrative review, the associations between NAFLD, dyslipidemia and vascular disease in NAFLD patients are discussed. NAFLD treatment is also reviewed with a focus on lipid-lowering drugs. Finally, future perspectives in terms of both NAFLD diagnostic biomarkers and therapeutic targets are considered.

The effects of low carbohydrate diets on liver function tests in nonalcoholic fatty liver disease: A systematic review and meta-analysis of clinical trials

Background:

Although several observational and experimental studies have examined the effects of low carbohydrate diets (LCDs) on nonalcoholic fatty liver disease (NAFLD), there are considerable inconsistencies among studies. We summarized the effect of LCDs on liver function tests, including intrahepatic lipid content (IHLC), alanine transaminase (ALT), aspartate aminotransferases (AST), and gamma-glutamyl transferase (GGT) in patients with NAFLD.

Materials and Methods:

PubMed, ISI Web of Science, Scopus, and Google Scholar databases were searched for relevant publications until July 2014, resulting in ten relevant papers that were included in meta-analysis. Related articles were found by searching Medical Subject Heading terms of “NAFLD” in combination with “low carbohydrate”. For this meta-analysis, we used mean differences and standard errors of liver function biomarkers. Summary effect and corresponding confidence interval (CI) were estimated using random effect models. Heterogeneity between studies was assessed using Cochran's Q- and I-squared tests.

Results:

Our search led to ten eligible papers that evaluated serum ALT levels (n = 238), nine reported serum AST levels (n = 216), five reported serum GGT concentrations (n = 91), and four assessed IHLC (n = 50). LCD decreased IHLC by −11.53% (95% CI: −18.10, −4.96; I² = 83.2%). However, the effect of LCD on liver enzymes was not significant. Mean differences for the effects of LCDs on ALT, AST, and GGT were −4.35 IU/L (95% CI: −12.91, 4.20; I² = 87.9%), −1.44 IU/L (95% CI: −4.98, 2.10; I² = 61.4%), and −7.85 IU/L (95% CI: −29.65, 13.96; I² = 99.4%), respectively.

Conclusion:

LCD consumption in subjects with NAFLD led to a significant reduction in IHLC, but did not significantly affect the concentration of liver enzymes.

Exploration of the Dietary and Lifestyle Behaviors and Weight Status and Their Self-Perceptions among Health Sciences University Students in North Lebanon

University students may experience significant environmental changes that exert a negative influence on the quality of their diet and lifestyle. There is scarcity of data concerning the dietary and lifestyle behaviors and weight status of students in the health field in North Lebanon. To investigate these data, a cross-sectional survey was conducted including 369 health sciences students aged 18-25 chosen from four public and private universities in North Lebanon. Data were collected using a standardized interview questionnaire to determine sociodemographic, dietary, and lifestyle behaviors, appetite changes, stress related dietary behaviors, and food cravings, as well as self-perceptions of dietary adequacy, physical activity levels, and weight status. Body mass index was assessed. Results had revealed significant differences in some of the dietary consumption patterns and weight status among seniors compared to juniors. However, the overall prevalence of overweight and obesity recorded 32.2% and the dietary consumption patterns fall below recommended levels. Multivariate regression analysis showed that parental obesity, comfort eating, increased appetite, food cravings, and stressful eating were associated with increased risk of obesity while a healthy diet score was associated with decreased risk. The study's findings call for tailoring culture specific intervention programs which enable students to improve their dietary and lifestyle behaviors and control stress.

Perspectives on Treatment for Nonalcoholic Steatohepatitis

It is important to provide treatment to patients with nonalcoholic steatohepatitis (NASH) because one third of patients with the metabolic syndrome die of liver disease. Basic research studies have elucidated mechanisms of NASH pathogenesis, which could lead to therapeutic targets. Health agencies have confirmed strategies for the optimal management of NASH and approved new drugs and treatments, which urgently are needed. The US Food and Drug Administration recently endorsed end points for NASH therapy. The reversal of NASH with no evidence of progression to advanced fibrosis has been defined as the end point for phase 2b and phase 3 trials in patients with NASH and early stage fibrosis. Although a decrease in the nonalcoholic fatty liver disease activity score could serve as an end point in clinical trials, it is not clear whether patients with lower scores have a lower risk of progression to advanced fibrosis. End points for clinical trials of patients with NASH cirrhosis currently are based on model for end-stage liver disease and Child-Pugh-Turcotte scores, as well as the hepatic venous pressure gradient. Different strategies are being explored to reduce liver diseases that are linked to a sedentary lifestyle, overeating, and genetic factors. In association with insulin resistance and deregulation of the lipid metabolism (accumulation of lipotoxins that promote hepatic lipogenesis, adipose tissue lipolysis, and impaired β-oxidation), these factors could increase the risk of liver steatosis with necroinflammatory lesions and fibrosis. We review the pathogenic mechanisms of NASH and therapeutic options, as well as strategies that are being developed for the treatment of injury to the liver and other organs.

Trans-Fatty Acids Aggravate Obesity, Insulin Resistance and Hepatic Steatosis in C57BL/6 Mice, Possibly by Suppressing the IRS1 Dependent Pathway

Trans-fatty acid consumption has been reported as a risk factor for metabolic disorders and targeted organ damages. Nonetheless, little is known about the roles and mechanisms of trans-fatty acids in obesity, insulin resistance (IR) and hepatic steatosis. Adult C57BL/6 male mice were fed with four different diets for 20 weeks: normal diet (ND), high fat diet (HFD), low trans-fatty acids diet (LTD) and high trans-fatty acid diet (HTD). The diet-induced metabolic disorders were assessed by evaluating body weight, glucose tolerance test, hepatic steatosis and plasma lipid profiles post 20-week diet. Histological (H&E, Oil-Red-O) staining and western blot analysis were employed to assess liver steatosis and potential signaling pathways. After 20-weeks of diet, the body weights of the four groups were 29.61 ± 1.89 g (ND), 39.04 ± 4.27 g (HFD), 34.09 ± 2.62 g (LTD) and 43.78 ± 4.27 g (HTD) (p < 0.05), respectively. HFD intake significantly impaired glucose tolerance, which was impaired further in the mice consuming the HTD diet. The effect was further exacerbated by HTD diet. Moreover, the HTD group exhibited significantly more severe liver steatosis compared with HFD group possibly through regulating adipose triglyceride lipase. The group consuming the HTD also exhibited significantly reduced levels of IRS1, phosphor-PKC and phosphor-AKT. These results support our hypothesis that consumption of a diet high in trans-fatty acids induces higher rates of obesity, IR and hepatic steatosis in male C57BL/6 mice, possibly by suppressing the IRS1dependent pathway.

Lifestyle and Dietary Interventions in the Management of Nonalcoholic Fatty Liver Disease

NAFLD is the leading cause of chronic liver disease in the Western world with an estimated prevalence of 20-30 %. Lifestyle interventions targeted at weight loss through dietary interventions and exercise are the most effective treatment, but only a minority of patients are able to achieve and sustain the necessary intervention targets. Weight loss of 3-5 % has been associated with a reduction of hepatic steatosis while weight loss of ≥5-7 % has correlated with resolution of NASH in some studies. Greater reductions in weight loss (≥10 %) may improve hepatic fibrosis. In the absence of weight loss, no specific diet has demonstrated superiority. Physical activity can improve hepatic steatosis and metabolic indices even without weight loss. Diet coupled with exercise can produce significant weight loss and may improve histologic components of the NAFLD activity score. While formal guidelines for diet and exercise in NAFLD are lacking, adherence to diet and exercise recommendations similar to those from the American Diabetes Association for diabetic care seems reasonable. Dietary supplementation with vitamin E in non-diabetics with biopsy-proven NASH has been shown to improve NAFLD activity score. The role for other macronutrients, micronutrients, antioxidants, and probiotics in the treatment of NAFLD remains limited.

Medical and Surgical Treatment Options for Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in the USA with a growing prevalence worldwide. Nonalcoholic steatohepatitis (NASH), progressive form of NAFLD, can lead to the development of cirrhosis, hepatocellular carcinoma, and the need for liver transplantation. Treatment of NASH may decrease the risk of progressive disease. Treatment for NAFLD should center around weight loss and exercise. Pharmacotherapy with vitamin E and pioglitazone should be considered for those with NASH, especially those with fibrosis. Weight loss surgery is also an effective treatment for NASH in individuals with other indications for surgery. In this review, we will discuss the currently available therapies for NASH including lifestyle, pharmacologic, and surgical options.

Lifestyle changes for the treatment of nonalcoholic fatty liver disease: a review of observational studies and intervention trials

Nonalcoholic fatty liver disease (NAFLD) is emerging as a major public health problem because of its association with increased cardiovascular and liver-related morbidity and mortality. Both genetic factors and lifestyle contribute to the pathogenesis of NAFLD. Lifestyle, including dietary habits and physical activity, is a modifiable risk factor and thus represents the main target for the prevention and treatment of NAFLD. In this review, we summarize the evidence regarding nutritional aspects (i.e. total energy intake, saturated fat and carbohydrates intake, certain foods or drinks and dietary patterns as a whole) in the treatment of NAFLD. In addition, we analyze the evidence concerning the independent effect of physical activity, including aerobic and resistance training, in the treatment of NAFLD. A therapeutic algorithm according to results from intervention trials is also provided for clinicians and other healthcare professionals involved in the management of NAFLD.

Healthy dietary pattern is inversely associated with non-alcoholic fatty liver disease in elderly

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rising, an increase that may be associated with changes in lifestyle such as unhealthy dietary patterns. Although advanced age is a risk factor for NAFLD, no studies reporting this association in the elderly population were found. In the present study, the association between dietary patterns and NAFLD in the elderly was assessed. A study including 229 older adults was conducted. NAFLD diagnosis was defined as individuals whose ultrasound examination disclosed hepatic steatosis at any stage, in the absence of excess intake of alcoholic beverages. Dietary patterns were obtained by principal components analysis. Mean scores and standard errors of each dietary pattern were calculated for the groups with and without NAFLD, and mean scores of the two groups were compared using the Mann–Whitney U test. The prevalence ratios and 95 % CI were estimated for each tertile of the dietary pattern adherence scores using Poisson multiple regression models with robust variance. A total of 103 (45 %) elderly with NAFLD and four dietary patterns were identified: traditional, regional snacks, energy dense and healthy. Mean scores for adherence to the healthy pattern in the groups with and without NAFLD differed. NAFLD was inversely associated with greater adherence to the healthy pattern and directly associated with the regional snacks, after adjustment for confounders. In conclusion, healthy dietary pattern is inversely associated with NAFLD in elderly.

Republished: Non-alcoholic fatty liver disease: a practical approach to treatment

Non-alcoholic fatty liver disease (NAFLD) affects up to a third of the population in many developed countries. Between 10% and 30% of patients with NAFLD have non-alcoholic steatohepatitis (NASH) that can progress to cirrhosis. There are metabolic risk factors common to both NAFLD and cardiovascular disease, so patients with NASH have an increased risk of liver-related and cardiovascular death. Management of patients with NAFLD depends largely on the stage of disease, emphasising the importance of careful risk stratification. There are four main areas to focus on when thinking about management strategies in NAFLD: lifestyle modification, targeting the components of the metabolic syndrome, liver-directed pharmacotherapy for high risk patients and managing the complications of cirrhosis.

Management of NAFLD: a stage-based approach

NAFLD is the most prevalent form of liver disease in the USA, affecting an estimated 30% of the population. The condition is associated with increased mortality related to cardiovascular disease, malignancy and liver disease. Identification of patients who might be at increased risk of adverse outcomes is critical as it is not feasible to screen all patients with suspected NAFLD. Patients with NASH, the progressive subtype of NAFLD, should be targeted for treatment, especially if they have concomitant fibrosis because such patients are more likely than those without fibrosis to have adverse outcomes. Treatment goals in patients with NAFLD vary depending on the disease stage owing to differential risk of progression and the particularities of an individual's comorbid disease. Lifestyle intervention is important for all patients irrespective of disease stage, but other therapies should be targeted to those most likely to benefit. In this Review, we highlight risk factors for disease progression and offer a stage-based treatment approach for patients with NAFLD.

The Effect of the Traditional Mediterranean-Style Diet on Metabolic Risk Factors: A Meta-Analysis

The Mediterranean-style diet (MedSD) has gained attention for its positive effects on health outcomes, including metabolic risk factors. However, it is unknown as to which components of MedSD interventions are most beneficial in reducing risk. The objective of this meta-analysis was to obtain effect sizes for metabolic risk factors and explain the variability across the current literature based on study design, sample, and diet characteristics. Six electronic databases were searched from inception until 9 February 2016. Data from 29 studies (N = 4133) were included. There were significant effects in favor of the MedSD for waist circumference, triglycerides, blood glucose, systolic blood pressure, and diastolic blood pressure (d+ = -0.54; d+ = -0.46; d+ = -0.50; d+ = -0.72; d+ = -0.94, respectively). The MedSD was significantly beneficial when the intervention was longer in duration, was conducted in Europe, used a behavioral technique, and was conducted using small groups. The traditional MedSD had significant beneficial effects on five of the six metabolic risk factors. Results from this study provide support for population specific dietary guideline for metabolic risk reduction.