Diet Quality and its Association With Nonalcoholic Fatty Liver Disease and All-cause and Cause-specific Mortality

Eric R. Yoo; Donghee Kim; Luis M. Vazquez-Montesino; Jessica A. Escober; Andrew A. Li; Sean P. Tighe; Christopher T. Fernandes; George Cholankeril; Aijaz Ahmed

Disclosures

Liver International. 2020;40(4):815-824. 

In This Article

Abstract and Introduction

Abstract

Background & Aims: Healthy diet has been recommended for nonalcoholic fatty liver disease (NAFLD), although it is not clear whether improving diet quality can prevent mortality. We aim to assess the impact of quality of diet on NAFLD and mortality in subjects with and without NAFLD.

Methods: We performed cohort study using the Third National Health and Nutrition Examination Survey from 1988 to 1994 and linked mortality data through 2015. We used the Healthy Eating Index (HEI) scores to define diet quality, with higher HEI scores (Q4) indicating better adherence to dietary recommendations. NAFLD was defined as ultrasonographic hepatic steatosis.

Results: Multivariate analysis showed that subjects with higher diet quality were inversely associated with NAFLD in a dose-dependent manner. During the median follow-up of 23 years, having a higher diet quality was associated with reduction in risk of all-cause mortality in the age, sex, Race/ethnicity-adjusted hazard ratio (HR) (Q4, HR: 0.60, 95% CI: 0.52–0.68) and the multivariate model (Q4, HR: 0.81, 95% CI: 0.71–0.92). Higher diet quality was associated with a lower risk for all-cause mortality in subjects without NAFLD; however, this protective association with diet quality was not noted in those with NAFLD. Furthermore, a high diet quality was associated with a lower risk for cancer-related mortality in the total population and among those without NAFLD. This association was not noted in those with NAFLD.

Conclusions: High diet quality was inversely associated with NAFLD and was positively associated with a lower risk for cancer-related and all-cause mortality in those without NAFLD.

Introduction

Nonalcoholic fatty liver disease (NAFLD) is a major cause of chronic liver disease and has an estimated prevalence of approximately 25% worldwide.[1] NAFLD is considered to be a consequence of the unhealthy dietary habits and sedentary lifestyle common in Western societies, which has been adopted all across the world in urban areas. The prevalence of NAFLD is dependent on a multitude of factors including the diagnostic modality and studied population, with a wide range from 4.5% in individuals without diabetes in Africa to 99% in patients undergoing bariatric surgery.[2] The highest prevalence was observed in the Middle East (20%-30%)[1] and South America (30%),[1] whereas the lowest prevalence of NAFLD was noted in Africa (13%).[3–5] The prevalence of NAFLD is estimated to be 24% in Europe[2] and 23.5% in the United States.[1,6] The prevalence of NAFLD has been surging in tandem with the obesity epidemic,[7] with regional prevalence of obesity among patients with NAFLD around 64% in Asia, 57% in North America and 37% in Europe.[1] The presence of metabolic syndrome highlighted by obesity and insulin resistance can increase the prevalence of hepatic fibrosis in individuals with NAFLD and lead to complications including cirrhosis, hepatocellular carcinoma (HCC) or higher risk of mortality.[5] In the United States, NAFLD has become the third most common cause of hepatocellular carcinoma (HCC), with an estimated increments of 9% on an annual basis.[8,9] Not surprisingly, NAFLD-related advanced fibrosis is on the rise at an accelerated pace in American adults,[10] which translates to an increase in overall and cause-specific mortality.[11,12] A study using the national US mortality database reported an increase in the mortality of NAFLD from an annual rate of 6.1% in 2007–2013 to 11.3% in 2013–2016.[13] Globally, liver-specific mortality among patients with NAFLD was 0.77 per 1000 person-years with an overall mortality of 15.44 per 1000 persons-years.[3] Given the current global landscape of NAFLD, concerted efforts to better understand the modifiable predictors of NAFLD globally and regionally are warranted to retard and hopefully reverse the currently rising rates of disease burden and increase in healthcare utilization.

Currently, the management of NAFLD is primarily conducted through lifestyle modifications in diet, exercise and weight loss.[14] Dietary intervention, particularly in the context of metabolic conditions, has been a topic of interest around the world. This is reflected in part by the development of various diet-related scores, such as the Dietary Approaches to Stop Hypertension (DASH), which is associated with reduced risk of cardiovascular disease and diabetes mellitus,[15,16] and studies evaluating associations between healthy dietary patterns and risk of chronic diseases.[17–19] Studies have also looked into the association between mortality risk and adherence to diets, such as DASH, Healthy Eating Index (HEI) and Mediterranean diet in patients with and without unfavorable metabolic dysfunctions.[20,21] These studies support the idea that healthy dietary patterns can be helpful for patients with metabolic risk factors. Recently published data have identified sex-based influence on NAFLD and therefore, NAFLD is a sexually dimorphic disease.[22,23] In addition, there may be a difference in diet quality between men and women, an epiphenomenon. In general, women had better diet quality than men.[24] Globally, the epidemic of obesity and type 2 diabetes mellitus have been increasing and the prevalence of NAFLD has also been increasing in tandem.[5] While we have not fully understood mechanism of pathogenesis and factors contributory to the risk of NAFLD and related disease progression, current guidelines for the management of NAFLD set by reputable scientific societies independently agree on the importance of lifestyle modifications with weight loss by physical activity and diet modification.[25] Despite the rapidly growing interest in managing NAFLD, data addressing the effects of diet quality and individual dietary components on NAFLD and all-cause and cause-specific mortality in patients with and without NAFLD are scant. We hypothesized that higher quality of diet and individual dietary components are inversely associated with the risk of NAFLD and positively associated with a lower risk for mortality in those with or without NAFLD. In this context, we aimed to assess how diet quality is associated with NAFLD and mortality in those with and without NAFLD.

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