Elsevier

Nutrition

Volume 27, Issue 6, June 2011, Pages 672-676
Nutrition

Applied nutritional investigation
Nutrient intake in Italian obese patients: Relationships with insulin resistance and markers of non-alcoholic fatty liver disease

https://doi.org/10.1016/j.nut.2010.07.014Get rights and content

Abstract

Objective

We investigated the prevalence of insulin resistance, elevated liver enzymes, and Non-Alcoholic Fatty Liver Disease Fibrosis Score (NFS) in obese and severely obese patients. Relations between inadequate nutrient intakes and the markers of metabolic and hepatic disorders were evaluated.

Methods

From January to September 2009, 63 consecutive obese patients (21 men and 42 women, 19–68 y old) were admitted to the study. According to the World Health Organization obesity classification, patients were categorized into three subgroups (classes I, II, and III). NFS scores lower than −1.455 were defined as NFS; higher scores were positive (NFS+). Insulin resistance (IR) was assessed by the homeostasis model assessment. Nutrient intakes and their potential role as risk factors for IR and liver damage were determined.

Results

Body mass index ranged from 30.9 to 73.7 kg/m2 and most patients (54%) were in class III (body mass index ≥40 kg/m2). Homeostasis model assessment of IR (>2.5) was recorded in 63.5%. The prevalence of NFS+ was significantly higher in class III than in classes II and I. Excessive nutrient and energy intake prevalence showed significant differences for protein, fat, and carbohydrate among the obesity classes. Animal protein (odds ratio 3.43, 95% confidence interval 1.15–10.20) and carbohydrate (odds ratio 3.83, 95% confidence interval 1.33–10.94) intakes were the risk factors for IR and NFS+.

Conclusion

Non-normal alanine aminotransferase and γ-glutamyltranspeptidase values were observed in less than one-third of patients, whereas NFS+ and IR were significantly prevalent, suggesting a close relation between the progression of liver fibrosis and metabolic derangement. An excessive intake of animal protein is associated with an increased risk of IR. Carbohydrate intake, albeit at the highest limit of the recommended dietary allowance range, is associated with an increased risk of liver fibrosis.

Introduction

Obesity could be considered a systemic disease due to its widespread effects on several organs, above all the cardiovascular system and the liver. Endogenous (genetic) and exogenous (dietary habits and decreased/absent physical activity) components play important roles in the pathogenesis of obesity and related metabolic disorders.

Insulin resistance (IR) represents the main link among obesity, metabolic syndrome, and liver disease with fat accumulation, i.e., non-alcoholic fatty liver disease (NAFLD) [1], [2]. In most obese patients, NAFLD remains stable for many years. However, in a subset of these patients, it may worsen to non-alcoholic steatohepatitis and liver cirrhosis. Progression depends on the degree of liver fibrosis. Identifying the presence and severity of liver fibrosis in patients with NAFLD is therefore of major importance for the management of such patients. In contrast, the general criterion for referral to liver units is the presence of higher than normal levels of enzymes alanine aminotransferase (ALT) and γ-glutamyltranspeptidase (GGT) [3]. However, recent studies have demonstrated that, despite normal enzyme levels, histologic hepatic features with increased risk of progression have been observed in obese patients; therefore, it is not clear whether normal ALT levels can exclude patients with NAFLD from the need for liver biopsy [4]. Although liver biopsy is widely recognized as the only reliable means for determining the severity of fibrosis, it is an invasive procedure associated with many complications. Serum markers and new technologies, such as ultrasonography-based elastography (FibroScan®, Echosens, Paris, France), have recently been reported as non-invasive procedures for monitoring NAFLD in obese patients [5]. The combination of serum and clinical markers may also be useful to predict the severity of liver fibrosis in such patients. Among the non-invasive panels of tests, a simple scoring system, the NAFLD Fibrosis Score (NFS), could be considered quite reliable for distinguishing between NAFLD with and without the probability of fibrosis [6], [7], [8].

Conversely, although dietary habits are strongly related to the development of obesity and IR, few investigations have used nutritional assessment in obese subjects to demonstrate the relations between dietary constituents and the development or progression of metabolic and liver disorders in obesity.

The aims of this study were to 1) evaluate the prevalence of IR and markers of hepatic dysfunction in an Italian cohort of obese and severely obese patients; 2) identify the characteristics of dietary habits and nutrient intakes in obese patients by detailed questioning; 3) compare IR and the suggested NAFLD markers with nutrient intakes in three subgroups according to obesity classification; and 4) investigate the possible relations among IR, hepatic markers, and inadequate dietary intakes (nutrients and energy) in our obese population.

Section snippets

Materials and methods

From January through September 2009, 63 consecutive obese (body mass index [BMI] >30 kg/m2) patients (21 men and 42 women, mean age 41.1 ± 10.5 y, age range 19–68 y) were admitted to our digestive endoscopy service for bariatric treatment of obesity.

Clinical, laboratory, and metabolic determinations were assessed for each patient, under informed consent. Exclusion criteria were a positive finding for hepatitis B or C virus, previous or current alcohol consumption higher than 30 g/d, use of

Results

Clinical, laboratory, and demographic data are presented in Table 1. The BMI ranged from 30.9 to 73.7 kg/m2 and most patients (53%) were in class III (BMI ≥40 kg/m2), i.e., severe obesity. Waist circumference ranged from 81 to 194 cm. A “bright liver” echo pattern at ultrasound investigation, consistent with liver steatosis, was observed in 63%. Impaired fasting blood glucose (≥110 mg/dL) was observed in 24%. HOMA values ranged from 0.78 to 17.6 and indicated IR (>2.5) in 63.5% of all patients.

Discussion

Insulin resistance and NAFLD are commonly observed in most obese subjects, suggesting a close relation between visceral fat and liver injury due to increased circulating insulin levels [17], [18]. The exact mechanisms underlying the progression of liver damage have not yet been sufficiently clarified. However, fat accumulation and oxidative hepatocellular injury are considered the two unavoidable steps leading to non-alcoholic steatohepatitis and advanced fibrosis [6], [7], [8]. Conflicting

Conclusions

Non-normal ALT and GGT were observed in less than one-third of all patients, although the prevalent elevation of HOMA-IR and NFS over their respective cutoffs showed the severity of metabolic and hepatic disorders in our patients. The high intake of protein, especially animal protein, was associated with an increased risk of IR. The carbohydrate intake, albeit at the highest limit of the RDA range, was associated with an increased risk of liver fibrosis.

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