ORIGINAL ARTICLE Coffee consumption and nonalcoholic fatty liver onset: a prospective study in the general population SHIRA ZELBER-SAGI, FEDERICO SALOMONE, MURIEL WEBB, RONI LOTAN, HANNY YESHUA, ZAMIR HALPERN, ERWIN SANTO, RAN OREN, and OREN SHIBOLET TEL AVIV, HAIFA, JERUSALEM, ISRAEL; AND CATANIA, ITALY
Retrospective studies suggest that coffee consumption may exert beneficial effects in patients with nonalcoholic fatty liver; however, prospective data supporting a protective role on liver steatosis development are lacking. In this study, we aimed to evaluate the association between coffee consumption and fatty liver onset in the general population. The analysis was performed both in a cross-sectional cohort (n 5 347) and, prospectively, in a subcohort of patients without fatty liver at baseline and followed-up for 7 years (n 5 147). Fatty liver was diagnosed with abdominal ultrasound and liver steatosis was quantified noninvasively by hepatorenal index (HRI) and SteatoTest, whereas FibroTest was used to assess fibrosis degree. A structured questionnaire on coffee consumption was administrated during a face-toface interview. Neither the incidence nor the prevalence of fatty liver according to ultrasonography, SteatoTest, and the HRI was associated with coffee consumption. In the cross-sectional study, high coffee consumption was associated with a lower proportion of clinically significant fibrosis $F2 (8.8% vs 16.3%; P 5 0.038); consistently, in multivariate logistic regression analysis, high coffee consumption was associated with lower odds for significant fibrosis (odds ratio 5 0.49, 95% confidence interval, 0.25–0.97; P 5 0.041) and was the strongest predictor for significant fibrosis. No association was demonstrated between coffee consumption and the new onset of nonalcoholic fatty liver, but coffee intake may exert beneficial effects on fibrosis progression. (Translational Research 2014;-:1–9) Abbreviations: ALT ¼ alanine aminotransferase; BMI ¼ body mass index; FFQ ¼ food-frequency questionnaire; HOMA ¼ homeostasis model assessment; HRI ¼ hepatorenal index; NAFLD ¼ nonalcoholic fatty liver disease; NASH ¼ nonalcoholic steatohepatitis; US ¼ ultrasonography
From the Liver Unit, Department of Gastroenterology, Tel Aviv Medical Center, Tel Aviv, Israel; School of Public Health, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel; Division of Gastroenterology, Ospedale di Acireale, Azienda Sanitaria Provinciale di Catania, Catania, Italy; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Gastroenterology, Hadassah University Hospital, Jerusalem, Israel.
Reprint requests: Federico Salomone, UOC di Gastroenterologia, Ospedale di Acireale, Azienda Sanitaria Provinciale di Catania, Catania, Italy; e-mail: [email protected]. 1931-5244/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.trsl.2014.10.008
Submitted for publication August 27, 2014; revision submitted October 9, 2014; accepted for publication October 13, 2014.
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AT A GLANCE COMMENTARY Zelber-Sagi S, et al. Background
Coffee is the most consumed beverage worldwide and prospective data have shown that its consumption is inversely associated with all-cause mortality; prospective evidence supporting the consumption of coffee for the prevention of fatty liver is lacking. Translational Significance
In our prospective cohort from the general population no association was found between coffee intake and fatty liver onset; however, coffee consumption was inversely associated with the degree of liver fibrosis. Thus, although it is not possible to recommend coffee consumption for fatty liver prevention, coffee may be included in the diet of patients with established steatohepatitis to counteract fibrosis progression.
INTRODUCTION
Nonalcoholic fatty liver disease (NAFLD) is a common metabolic disorder that ranges from liver steatosis to nonalcoholic steatohepatitis (NASH).1 Steatogenesis in NAFLD is caused by an increased supply of free fatty acids to the liver and increased de novo lipogenesis.2 In some patients, metabolic free fatty acid handling triggers hepatocyte damage and activation of inflammation and fibrogenesis through multiple cellular events resulting in NASH.3 Both genetic and environmental factors have been implicated in modulating this complex network of molecular signals.4 Among the environmental factors, dietary habits seem to be tightly related to the fibrogenic progression of liver injury.5 Coffee is the most consumed beverage worldwide6 and is produced from the bean of an evergreen shrub belonging to the family of Rubiaceae, genus coffee. Different epidemiologic studies have considered the association between coffee drinking and liver diseases. In patients with chronic hepatitis C virus infection, coffee consumption appeared to be associated with lower fibrosis and a sustained virological response.7 Several studies, including prospective cohorts, have indicated an inverse association between coffee consumption and liver cirrhosis and cancer development independently of etiology.7 Recently, cross-sectional and casecontrol studies have suggested an inverse association of coffee consumption with liver damage in patients
with NAFLD.8-11 However, these study designs raise concerns regarding the possibility of inverse causality if persons with liver disease reduce or quit coffee drinking, thus spuriously presenting an inverse association. Solid evidence coming from prospective studies is currently lacking. Therefore, in this study, we tested the association between coffee consumption and NAFLD onset in a prospective cohort from the general population. METHODS Study design. The analysis was performed both in a cross-sectional manner on the entire sample and in a prospective manner on a subsample that were included in a follow-up study. The cross-sectional data were collected from January 2003 to March 2004. The study population consisted of 799 participants, a subgroup of Israeli adults (aged 24– 70 years) who were randomly sampled from the national population registry and interviewed in the First Israeli National Health and Nutrition Survey (the MABAT Survey).12 Individuals with any of the following were excluded from the study: alcohol consumption $30 g/d in men or 20 g/d in women,13-15 the presence of hepatitis B surface antigen or anti– hepatitis C virus antibodies, and fatty liver suspected to be secondary to hepatotoxic drugs. As described elsewhere,16,17 the final study population consisted of 375 subjects who were located and agreed to participate before the application of exclusion criteria. Participants from the baseline survey were invited to participate in a follow-up evaluation during 2010. The participants that took part in the follow-up evaluation did not differ from those who did not in any demographic, anthropometric, or biochemical parameters including age, gender, body mass index, prevalence of NAFLD, and coffee consumption (P $ 0.2 for all comparisons). The follow-up evaluation was performed by the same radiologist, and same equipment was used for the diagnosis of NAFLD using the same uniform protocol. Alcohol consumption was re-evaluated during the follow-up interview using the same questionnaire to rule out new excessive alcohol consumption and none were detected. Fasting biochemical testing in the cross-sectional study included liver enzymes, lipid profile, glucose, insulin, leptin, and adiponectin, FibroMax including FibroTest, SteatoTest, and NashTest (BioPredictive, Paris, France).18,19 Two subjects had hemolysis and thus were omitted from analysis, leaving a sample size of 347 subjects. A face-to-face interview was carried out in all participants. The questionnaire was developed by the
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Ministry of Health and included demographic data, health status, and a detailed structured questionnaire on current alcohol intake and physical activity used in national surveys as previously described.20 Evaluation of coffee consumption. During a face-toface interview, coffee consumption was evaluated by a specific questionnaire assessing the regular consumption of all types of caffeinated coffee (presented here) and separately decaffeinated coffee (data not presented because of low consumption in the study sample). Consumption categories were less than once a month, less than once a week, 1–2 times a week, 3–6 times a week, 1–2 times a day, 3–5 times a day, and more than 5 times a day. To avoid information bias, both the subject and the interviewer were unaware of the results of the ultrasonography (US) and serum examination. The second questionnaire was a detailed semiquantitative foodfrequency questionnaire (FFQ) adapted to the Israeli population that also included evaluation of coffee consumption. Both the coffee questionnaire and the FFQ were assembled by the Food and Nutrition Administration, Ministry of Health.21 The kappa measure of agreement between the coffee consumption evaluated by the FFQ and the specific questionnaire was 0.76 (60.04 standard error) indicating an excellent agreement. Ultrasonographic examination. Fatty liver was assessed by abdominal ultrasonography using the standardized criteria.22 Ultrasonography was performed in all subjects both at baseline and at follow-up with the same equipment (EUB-8500 scanner; Hitachi Medical Corporation, Tokyo, Japan) and by the same experienced radiologist (W.M.) as described previously.17,21 The ratio between the median brightness level of the liver and the right kidney cortex was calculated to determine the hepatorenal index (HRI). The HRI has been previously demonstrated to be highly reproducible and was validated against liver biopsy (r 5 0.82, P , 0.001, kappa 5 0.75)23 and against proton magnetic resonance spectroscopy, demonstrating high correlation.24,25 The study protocol was approved by the Institutional Review Board (0439-08-TLV), and all participants provided written informed consent. All authors had reviewed and approved the final manuscript. Statistical analysis. Statistical analyses were performed using Statistical Package for the Social Sciences version 21 (SPSS Inc, Chicago, Illinois) software. Continuous variables are presented as means 6 standard deviation. To test differences in continuous variables between 2 groups the independent samples’ t
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test and, if necessary, the nonparametric MannWhitney U test were performed. The associations between nominal variables were performed with the Pearson chi-square test. The evaluation of the independent association between coffee consumption and NAFLD, SteatoTest, NashTest, and FibroTest, categorized as dichotomic variables was performed with a multivariate logistic regression analysis. The associations between NAFLD and liver damage were tested as crude and with adjustment for variables that were significantly different between the high and the low coffee drinkers and can be considered as potential confounders. The stepwise (Forward Stepwise Likelihood Ratio) multivariate logistic regression model was performed to identify the strongest predictors for advanced fibrosis. P , 0.05 was considered statistically significant for all analyses.
RESULTS Characteristics of the study population. The flow chart of the study population is depicted in Fig 1. The crosssectional study included 347 subjects with mean age of 50.68 6 10.34, 53.3% were men; the body mass index of the study population is similar to that of the general population12 (Table I). FibroMax results were available for 338 subjects. FibroTest predicted significant fibrosis ($F2, borderline F1–F2 included) in 43 subjects (12.7%) and advanced fibrosis (F3–F4) in 3 subjects (0.9%). The NashTest predicted definite NASH in 3 subjects (0.9%) and borderline NASH in 106 subjects (31.4%). SteatoTest predicted the presence of clinically significant steatosis ($5%, S1–S2 and greater) in 69 subjects (20.4%). The prevalence of NAFLD according to US in the crosssectional sample was 30.8% (n 5 107). The prospective cohort included 147 subjects. The incidence rate of NAFLD according to US in the prospective cohort was 19.0% (n 5 28). Comparison between subjects who drink 3 and more cups of coffee per day and those who drink less. In both
the cross-sectional and prospective analysis, those with high ($3 cups per day) coffee consumption had higher proportion of current smoking, higher sugar consumption, and lower physical activity performance. Only on conducting the cross-sectional analysis, those with high coffee consumption had significantly higher serum cholesterol levels and dietary fat intake, but similar trends were also observed in the prospective cohort. No difference was noted between the groups in anthropometric parameters: serum ALT, glucose, insulin, lipids, ferritin, and adipocytokines levels (Table II).
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Fig 1. Flow chart of the study participants. NAFLD, nonalcoholic fatty liver disease; NASH, nonalcoholic steatohepatitis; US, ultrasonography.
Table I. Characteristics of the study sample (mean 6 SD, unless otherwise stated) Characteristics
Age (y) Male (%) BMI (kg/m2) Country of birth (%) Israel Asia Africa FSU Europe America ALT (U/L) (5–39) Glucose (mg/dL) (70–110) Cholesterol (mg/dL) (150–200) Triglycerides (mg/dL) (50–175) Insulin (mU/mL) (5–25) HOMA score* Diabetes† (%)
Total study sample n 5 347
50.68 6 10.34 53.3 27.21 6 4.55 63.7 8.6 8.1 7.8 9.2 2.6 22.15 6 9.97 90.73 6 19.52 218.12 6 40.05 116.86 6 60.86 22.27 6 11.83 5.28 6 5.21 6.6
Abbreviations: ALT, alanine aminotransferase; BMI, body mass index; FSU, former Soviet Union; HOMA, homeostasis model assessment; SD, standard deviation. *HOMA was calculated as fasting serum insulin (mU/mL) 3 fasting plasma glucose (mmol/L)/22.5. † Diabetes was defined by fasting serum glucose .126 mg/dL and/ or antidiabetic medications.
Univariate and multivariate analysis of the association between coffee consumption and NAFLD on US or according to the SteatoTest. Both the prevalence of
NAFLD according to US in the cross-sectional analysis and the incidence of NAFLD in the
prospective cohort were similar between those with high or low coffee consumption (30.1% vs 31.5%; P 5 0.769 and 18.9% vs 19.2%; P 5 0.968, respectively). Further refinement of coffee consumption into 4 categories of consumption demonstrated no association with either prevalence or incidence of NAFLD (Fig 2, A). No differences were noted between groups in HRI levels in both crosssectional and follow-up comparisons (Fig 2, B and C). In both the cross-sectional and the prospective cohort, coffee consumption was not associated with NAFLD on US, in the crude and the adjusted models with P $ 0.5 in all (Table III). In the cross-sectional cohort, analysis was also made for significant steatosis as predicted by the SteatoTest and no association was observed in any of the models with P $ 0.6 for all. Univariate and multivariate analysis of the association between coffee consumption and significant fibrosis according to the FibroTest or borderline NASH-NASH according to the NashTest. High coffee consumption
was significantly associated with a lower proportion of significant fibrosis (8.8% vs 16.3%; P 5 0.038) (Fig 3, A). High coffee consumption was strongly associated with lower odds for significant fibrosis in the crude model (odds ratio [OR] 5 0.49, 95% confidence interval [CI], 0.25–0.97; P 5 0.041). This association did not reach statistical significance with adjustment for current smoking, sugar intake, and physical activity (OR 5 0.50, 95% CI, 0.25–1.01; P 5 0.054). A third model included all potential confounders of the previous model plus other
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Table II. Comparison between subjects who drank 3 and more cups of coffee a day and those who drank less among the cross-sectional and the prospective cohorts (mean 6 SD, unless otherwise stated) Cross-sectional analysis, n 5 347 Parameter
$3/d (n 5 163)
$3/d (n 5 74)
,3/d (n 5 73)
Age (y) Gender (% males) BMI (kg/m2) Waist circumference (cm) ALT (U/L) (5–39) Glucose (mg/dL) (70–100) HbA1c % (3.9–6.0) Insulin (mU/mL) (5–25) Triglycerides (mg/dL) Total cholesterol (mg/dL) Ferritin (ng/mL) (7.1–151) Leptin (ng/mL) Adiponectin (mg/mL) Smoking % (current) Calories (kcal) Fat (g) Carbohydrates (g) Sugar (tea spoons/d) Carbohydrates from soft drinks (g/d) Physical activity (min/wk)
49.87 6 9.16 52.8 27.24 6 4.55 92.06 6 13.38
51.40 6 11.27 53.8 27.18 6 4.55 92.56 6 13.35
0.166 0.846 0.896 0.729
50.21 6 9.34 44.6 25.94 6 3.88 88.52 6 12.39
51.82 6 10.33 50.7 26.00 6 3.46 89.16 6 10.87
0.322 0.460 0.911 0.738
22.69 6 10.62 90.26 6 20.05
21.67 6 9.36 91.16 6 19.08
0.343 0.669
20.24 6 6.58 87.85 6 16.64
19.41 6 6.43 87.25 6 12.43
0.439 0.803
5.46 6 0.92 22.21 6 13.30 117.59 6 64.88 224.50 6 43.07
5.33 6 0.77 22.32 6 10.40 116.22 6 57.24 212.46 6 36.35
0.155 0.930 0.835 0.005
5.42 6 0.96 19.18 6 7.41 108.89 6 67.08 222.28 6 45.70
5.20 6 0.53 19.92 6 6.68 103.26 6 42.02 212.07 6 35.07
0.082 0.525 0.543 0.130
73.60 6 57.83
73.31 6 63.61
0.966
61.88 6 45.20
74.03 6 68.78
0.215
18.89 6 18.27 12.56 6 10.75 33.1 2529.01 6 1105.94 109.49 6 56.03 289.57 6 133.72 2.41 6 3.00 15.75 6 29.62
19.69 6 18.87 11.57 6 7.65 15.8 2319.83 6 915.28 94.43 6 40.59 283.68 6 127.31 1.43 6 2.02 15.61 6 32.56
0.693 0.331 ,0.001 0.055 0.005 0.674 ,0.001 0.967
15.67 6 13.14 13.50 6 10.06 32.4 2472.32 6 953.32 105.58 6 41.97 290.47 6 134.53 2.29 6 2.87 13.41 6 29.12
17.66 6 18.07 12.83 6 8.78 5.5 2240.65 6 781.00 93.96 6 37.29 267.71 6 104.32 1.49 6 2.13 9.53 6 16.01
0.453 0.677 ,0.001 0.109 0.078 0.254 0.057 0.318
72.15 6 142.71
0.007
90.00 6 142.85
0.063
39.29 6 76.24
,3/d (n 5 184)
Prospective analysis, n 5 147 (baseline values) P
52.26 6 95.62
P
Abbreviations: ALT, alanine aminotransferase; BMI, body mass index; HbA1c, hemoglobin A1c; SD, standard deviation.
variables that were different between the high and low coffee drinkers only in the cross-sectional cohort (serum cholesterol levels and dietary fat and calories intake). To detect the strongest predictors for significant fibrosis, a stepwise regression was performed with all variables. Coffee consumption was the strongest and only significant predictor left in the model (Fig 3, B). No association was observed between coffee consumption and presumed borderline NASH or (definite) NASH (Table III). DISCUSSION
This is the first prospective study testing the association between coffee consumption and the new onset of NAFLD. In the present study, no association was demonstrated between coffee drinking and the development of steatosis as assessed by ultrasonographic methods (regular US and HRI) and serum biomarkers (SteatoTest). However, the cross-sectional cohort results do suggest a protective effect on fibrosis progression as assessed by the FibroTest. Prospective studies have indicated a beneficial effect of coffee consumption in several diseases26 and a reduction in all-cause mortality for patients with increased lifetime intake of both
caffeinated and decaffeinated coffee.27 The effects of coffee and caffeine on liver diseases of different etiology have been reported for several years.7 Recently, clinical studies have evaluated the association of coffee consumption with the degree of liver injury in NAFLD by using different methodological approaches, leading to equivocal results. A case-control study by Catalano et al8 first evaluated the possible link between coffee intake and NAFLD, showing that espresso coffee drinkers displayed milder liver steatosis, detected by US, as compared with nondrinkers. However, a case-control study is susceptible to bias because of different recall of coffee consumption among patients and controls. Two successive crosssectional studies have considered histologic endpoints. The study by Molloy et al9 focused on the relationship between the amount of coffee-derived caffeine and liver histology and revealed an inverse relationship of fibrosis but not steatosis with caffeine intake. A French study conducted in morbidly obese subjects undergoing bariatric surgery demonstrated that the intake of regular coffee, but not espresso, may be protective from fibrosis.10 However, an important limitation in that study is that it was conducted in a selected population
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Fig 2. Fatty liver diagnosis in the prospective and in the cross-sectional cohorts. (A) New onset of nonalcoholic fatty liver (P 5 0.47 by the chi-square test) in the prospective cohort (n 5 147) and prevalence (P 5 0.93) in the cross-sectional cohort (n 5 347) by coffee consumption categories. n 5 23, 50, 55, and 19 in the prospective cohort and 52, 132, 118, and 45 in the cross-sectional study in the coffee consumption categories, respectively. (B) HRI levels by coffee consumption in the cross-sectional cohort. (C) HRI levels by coffee consumption in the prospective cohort. HRI, hepatorenal index; NAFLD, nonalcoholic fatty liver disease.
Table III. Multivariate analysis of the association between coffee consumption and NAFLD on US or according to the SteatoTest $S1–S2 and borderline NASH-NASH according to the NashTest [OR (95% CI)] NAFLD on US Cohort
Cross-sectional cohort $3/d cups/d P Prospective cohort $3/d cups/d P
SteatoTest*
NashTest*
Model 1
Model 2
Model 1
Model 2
Model 1
Model 2
0.93 (0.59–1.48) 0.769
0.92 (0.57–1.50) 0.749
1.02 (0.65–1.87) 0.718
1.05 (0.60–1.84) 0.857
1.20 (0.76–1.90) 0.428
1.22 (0.75–1.96) 0.424
0.98 (0.43–2.24) 0.968
0.72 (0.28–1.85) 0.501
— —
— —
— —
— —
Abbreviations: CI, confidence interval; NASH, nonalcoholic steatohepatitis; NAFLD, nonalcoholic fatty liver disease; OR, odds ratio; US, ultrasonography. Model 1: crude. Model 2: the forced multivariate logistic regression model adjusted for current smoking, sugar, and physical activity (minutes per week). *Steatosis and NASH according to the FibroMax were not evaluated in the follow-up cohort.
and it cannot be assumed that the results can be generalized to other populations. More recently, a study from the Nonalcoholic Steatohepatitis Clinical Research Network showed an inverse association of coffee intake with advanced fibrosis among patients with NAFLD with lower homeostasis model
assessment–insulin resistance, thus suggesting that coffee may differently impact on liver injury with respect to the metabolic background of patients.11 The previously mentioned studies could not establish any cause-effect relationship. In our study, the prospective cohort design excludes a preventive effect of the
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Fig 3. Significant fibrosis according to the FibroTest by coffee consumption. (A) Prevalence of significant fibrosis by coffee consumption. (B) Multivariate analysis of the association between coffee consumption and significant fibrosis [odds ratio (95% confidence interval)], n 5 338, 12.7% with significant fibrosis. Model 1: crude. Model 2: the forced multivariate logistic regression model adjusted for current smoking, sugar, and physical activity (minutes per week). Model 3: the stepwise multivariate logistic regression model included only the strongest predictors and excluded all the other variables listed in model 2 plus serum cholesterol levels, dietary fat, and calorie intake.
consumption of 3 or more cups of coffee on the incidence of NAFLD as assessed both by regular qualitative US and by the quantitative HRI. Coffee drinkers had worse lifestyle habits, but adjusting for lifestyle parameters (smoking, diet, and physical activity) did not uncover an association with NAFLD. In the crosssectional cohort, we confirmed that coffee consumption is independently associated with decreased liver fibrosis, assessed by the Fibrotest. This was also true when adjusting for dietary fat and sugar (usually added to the coffee), which were higher among the coffee drinkers and are well established risk factors for steatosis and fibrosis5,28 and for smoking, which was demonstrated to be associated with advanced liver fibrosis in a cohort of patients with NAFLD.29 Our data suggest that although coffee is not able to counteract steatogenesis, it may inhibit fibrogenesis that is the more important determinant of clinical outcomes in NAFLD. This is in agreement with the effects of other foods containing polyphenols, such as wine or grapevine, whose modest consumption is not protective from steatosis but from fibrosis.30 Recently, in a randomized crossover trial, coffee consumption was shown to blunt hepatic insulin resistance but not the increase in liver triglycerides induced by fructose overfeeding in 10 healthy volunteers.31 Thus, overall results from previous cross-sectional cohort and from our study suggest a protective effect from fibrosis progression, whereas effects on insulin resistance and steatogenesis need to be further explored. The specific components of coffee exerting beneficial effects have been partially elucidated. Coffee contains hundreds of chemical ingredients including several polyphenols, chlorogenic acids, melanoidins, and
caffeine. Recently, caffeine was shown to inhibit hepatic stellate cell proliferation in vitro.32 Nonetheless, some experimental studies indicate that the antifibrogenic effects of coffee may be independent of caffeine content and may depend on the polyphenolic compounds33,34; in fact, natural polyphenols have been shown to exert inhibitory effects on fibrogenesis and are promising candidates in the treatment of NASH and related metabolic disorders.35,36 Our study has some limitations. The major limitation stems from the absence of liver histology; however, it was deemed unethical to perform liver biopsy in healthy volunteers. We therefore opted to use a battery of noninvasive tests. These have shortcomings including imperfect diagnostic accuracy to define NASH and fibrosis.37,38 However, FibroTest has been recently proposed as a noninvasive marker of fibrosis in a large population39 and was used to screen fibrosis in subjects from the general population40 and in diabetics.41 Similarly, steatosis was not quantified histologically. However, HRI has been validated vs liver biopsy,23 and proton magnetic resonance spectroscopy24,25 providing a highly sensitive and quantitative tool for liver fat evaluation. Next, NASH and advanced fibrosis were not represented in this relatively healthy study population, and thus we could mainly discuss the association of coffee consumption with early histologic damage. Lastly, a limitation may lie in the accuracy of dietary assessment of coffee consumption because of a recall or reporting bias. The coffee consumption obtained from the specific coffee questionnaire was compared with the consumption obtained from the FFQ and the agreement was very high.
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CONCLUSIONS
This study provides the first prospective evidence in a sample of the general population for a lack of protective effect of coffee intake on the development of steatosis, whereas an inverse association of coffee intake with liver fibrosis was confirmed in the cross-sectional cohort. Further studies in other populations with a larger sample size, and possibly long-term randomized controlled trials, would be needed to establish possible different effects of coffee at different stages in the natural history of NAFLD. ACKNOWLEDGMENTS
Conflicts of Interest: All authors have read the journal’s policy on disclosure of potential conflicts of interest and have none to declare. All authors have read the journal’s authorship agreement. The manuscript has been reviewed and approved by all named authors. Financial support: None. REFERENCES
1. Vernon G, Baranova A, Younossi ZM. Systematic review: the epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults. Aliment Pharmacol Ther 2011;34:274–85. 2. Trauner M, Arrese M, Wagner M. Fatty liver and lipotoxicity. Biochim Biophys Acta 2010;1801:299–310. 3. Gambino R, Musso G, Cassader M. Redox balance in the pathogenesis of nonalcoholic fatty liver disease: mechanisms and therapeutic opportunities. Antioxid Redox Signal 2011;15: 1325–65. 4. Dongiovanni P, Anstee QM, Valenti L. Genetic predisposition in NAFLD and NASH: impact on severity of liver disease and response to treatment. Curr Pharm Des 2013;19:5219–38. 5. Zelber-Sagi S, Ratziu V, Oren R. Nutrition and physical activity in NAFLD: an overview of the epidemiological evidence. World J Gastroenterol 2011;17:3377–89. 6. Drewnowski A, Rehm CD, Constant F. Water and beverage consumption among adults in the United States: cross-sectional study using data from NHANES 2005-2010. BMC Public Health 2013; 13:1068. 7. Saab S, Mallam D, Cox Ii GA, et al. Impact of coffee on liver diseases: a systematic review. Liver Int 2014;34:495–504. 8. Catalano D, Martines GF, Tonzuso A, et al. Protective role of coffee in non-alcoholic fatty liver disease (NAFLD). Dig Dis Sci 2010;55:3200–6. 9. Molloy JW, Calcagno CJ, Williams CD, et al. Association of coffee and caffeine consumption with fatty liver disease, nonalcoholic steatohepatitis, and degree of hepatic fibrosis. Hepatology 2012;55:429–36. 10. Anty R, Marjoux S, Iannelli A, et al. Regular coffee but not espresso drinking is protective against fibrosis in a cohort mainly composed of morbidly obese European women with NAFLD undergoing bariatric surgery. J Hepatol 2012;57:1090–6. 11. Bambha K, Wilson LA, Unalp A, et al. Coffee consumption in NAFLD patients with lower insulin resistance is associated with lower risk of severe fibrosis. Liver Int 2013;34:1250–8.
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12. Nitzan Kaluski D, Goldsmith R, Chinitz A, et al. First National Health and Nutrition Survey, Part 2 1999-2001: Israel Center for Disease Control; 2004 October 2004. Report no.: Publication 218. 13. Neuschwander-Tetri BA, Caldwell SH. Nonalcoholic steatohepatitis: summary of an AASLD Single Topic Conference. Hepatology 2003;37:1202–19. 14. Ratziu V, Giral P, Charlotte F, et al. Liver fibrosis in overweight patients. Gastroenterology 2000;118:1117–23. 15. Angulo P. Nonalcoholic fatty liver disease. N Engl J Med 2002; 346:1221–31. 16. Zelber-Sagi S, Nitzan-Kaluski D, Halpern Z, et al. Prevalence of primary non-alcoholic fatty liver disease in a population-based study and its association with biochemical and anthropometric measures. Liver Int 2006;26:856–63. 17. Zelber-Sagi S, Nitzan-Kaluski D, Halpern Z, et al. NAFLD and hyperinsulinemia are major determinants of serum ferritin levels. J Hepatol 2007;46:700–7. 18. Ratziu V, Giral P, Munteanu M, et al. Screening for liver disease using non-invasive biomarkers (FibroTest, SteatoTest and NashTest) in patients with hyperlipidaemia. Aliment Pharmacol Ther 2007;25:207–18. 19. Kleiner DE, Brunt EM, Van Natta M, et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease. Hepatology 2005;41:1313–21. 20. Zelber-Sagi S, Nitzan-Kaluski D, Goldsmith R, et al. Role of leisure-time physical activity in nonalcoholic fatty liver disease: a population-based study. Hepatology 2008;48:1791–8. 21. Zelber-Sagi S, Nitzan-Kaluski D, Goldsmith R, et al. Long term nutritional intake and the risk for non-alcoholic fatty liver disease (NAFLD): a population based study. J Hepatol 2007;47:711–7. 22. Gore R. Diffuse liver disease. In: Gore R, Levine M, Laufer I, et al., eds. Textbook of gastrointestinal radiology. Philadelphia: Saunders, 1994:1968–2017. 23. Webb M, Yeshua H, Zelber-Sagi S, et al. Diagnostic value of a computerized hepatorenal index for sonographic quantification of liver steatosis. AJR Am J Roentgenol 2009;192:909–14. 24. Mancini M, Prinster A, Annuzzi G, et al. Sonographic hepaticrenal ratio as indicator of hepatic steatosis: comparison with (1) H magnetic resonance spectroscopy. Metabolism 2009;58: 1724–30. 25. Martin-Rodriguez JL, Arrebola JP, Jimenez-Moleon JJ, et al. Sonographic quantification of a hepato-renal index for the assessment of hepatic steatosis in comparison with 3T proton magnetic resonance spectroscopy. Eur J Gastroenterol Hepatol 2014;26: 88–94. 26. Lopez-Garcia E. Coffee consumption and risk of chronic diseases: changing our views. Am J Clin Nutr 2012;95:787–8. 27. Freedman ND, Park Y, Abnet CC, et al. Association of coffee drinking with total and cause-specific mortality. N Engl J Med 2012;366:1891–904. 28. Abdelmalek MF, Suzuki A, Guy C, et al. Increased fructose consumption is associated with fibrosis severity in patients with nonalcoholic fatty liver disease. Hepatology 2010;51:1961–71. 29. Zein CO, Unalp A, Colvin R, et al. Smoking and severity of hepatic fibrosis in nonalcoholic fatty liver disease. J Hepatol 2011;54: 753–9. 30. Dunn W, Sanyal AJ, Brunt EM, et al. Modest alcohol consumption is associated with decreased prevalence of steatohepatitis in patients with non-alcoholic fatty liver disease (NAFLD). J Hepatol 2012;57:384–91. 31. Lecoultre V, Carrel G, Egli L, et al. Coffee consumption attenuates short-term fructose-induced liver insulin resistance in healthy men. Am J Clin Nutr 2014;99:268–75.
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32. Shim SG, Jun DW, Kim EK, et al. Caffeine attenuates liver fibrosis via defective adhesion of hepatic stellate cells in cirrhotic model. J Gastroenterol Hepatol 2013;28:1877–84. 33. Vitaglione P, Morisco F, Mazzone G, et al. Coffee reduces liver damage in a rat model of steatohepatitis: the underlying mechanisms and the role of polyphenols and melanoidins. Hepatology 2010;52:1652–61. 34. Salomone F, Li Volti G, Vitaglione P, et al. Coffee enhances the expression of chaperones and antioxidant proteins in rats with nonalcoholic fatty liver disease. Transl Res 2014;163:593–602. 35. Salamone F, Galvano F, Marino Gammazza A, et al. Silibinin improves hepatic and myocardial injury in mice with nonalcoholic steatohepatitis. Dig Liver Dis 2012;44:334–42. 36. Salamone F, Li Volti G, Titta L, et al. Moro orange juice prevents fatty liver in mice. World J Gastroenterol 2012;18:3862–8. 37. Poynard T, Ratziu V, Charlotte F, et al. Diagnostic value of biochemical markers (NashTest) for the prediction of non alco-
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holo steato hepatitis in patients with non-alcoholic fatty liver disease. BMC Gastroenterol 2006;6:34. Musso G, Gambino R, Cassader M, et al. Meta-analysis: natural history of non-alcoholic fatty liver disease (NAFLD) and diagnostic accuracy of non-invasive tests for liver disease severity. Ann Med 2011;43:617–49. Poynard T, Munteanu M, Deckmyn O, et al. Validation of liver fibrosis biomarker (FibroTest) for assessing liver fibrosis progression: proof of concept and first application in a large population. J Hepatol 2012;57:541–8. Poynard T, Lebray P, Ingiliz P, et al. Prevalence of liver fibrosis and risk factors in a general population using noninvasive biomarkers (FibroTest). BMC Gastroenterol 2010; 10:40. Jacqueminet S, Lebray P, Morra R, et al. Screening for liver fibrosis by using a noninvasive biomarker in patients with diabetes. Clin Gastroenterol Hepatol 2008;6:828–31.
Retrospective studies suggest that coffee consumption may exert beneficial effects in patients with nonalcoholic fatty liver; however, prospective data supporting a protective role on liver steatosis development are lacking. In this study, we aimed to evaluate the association between coffee consumption and fatty liver onset in the general population. The analysis was performed both in a cross-sectional cohort (n 5 347) and, prospectively, in a subcohort of patients without fatty liver at baseline and followed-up for 7 years (n 5 147). Fatty liver was diagnosed with abdominal ultrasound and liver steatosis was quantified noninvasively by hepatorenal index (HRI) and SteatoTest, whereas FibroTest was used to assess fibrosis degree. A structured questionnaire on coffee consumption was administrated during a face-toface interview. Neither the incidence nor the prevalence of fatty liver according to ultrasonography, SteatoTest, and the HRI was associated with coffee consumption. In the cross-sectional study, high coffee consumption was associated with a lower proportion of clinically significant fibrosis $F2 (8.8% vs 16.3%; P 5 0.038); consistently, in multivariate logistic regression analysis, high coffee consumption was associated with lower odds for significant fibrosis (odds ratio 5 0.49, 95% confidence interval, 0.25–0.97; P 5 0.041) and was the strongest predictor for significant fibrosis. No association was demonstrated between coffee consumption and the new onset of nonalcoholic fatty liver, but coffee intake may exert beneficial effects on fibrosis progression. (Translational Research 2014;-:1–9) Abbreviations: ALT ¼ alanine aminotransferase; BMI ¼ body mass index; FFQ ¼ food-frequency questionnaire; HOMA ¼ homeostasis model assessment; HRI ¼ hepatorenal index; NAFLD ¼ nonalcoholic fatty liver disease; NASH ¼ nonalcoholic steatohepatitis; US ¼ ultrasonography
From the Liver Unit, Department of Gastroenterology, Tel Aviv Medical Center, Tel Aviv, Israel; School of Public Health, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel; Division of Gastroenterology, Ospedale di Acireale, Azienda Sanitaria Provinciale di Catania, Catania, Italy; Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel; Department of Gastroenterology, Hadassah University Hospital, Jerusalem, Israel.
Reprint requests: Federico Salomone, UOC di Gastroenterologia, Ospedale di Acireale, Azienda Sanitaria Provinciale di Catania, Catania, Italy; e-mail: [email protected]. 1931-5244/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.trsl.2014.10.008
Submitted for publication August 27, 2014; revision submitted October 9, 2014; accepted for publication October 13, 2014.
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AT A GLANCE COMMENTARY Zelber-Sagi S, et al. Background
Coffee is the most consumed beverage worldwide and prospective data have shown that its consumption is inversely associated with all-cause mortality; prospective evidence supporting the consumption of coffee for the prevention of fatty liver is lacking. Translational Significance
In our prospective cohort from the general population no association was found between coffee intake and fatty liver onset; however, coffee consumption was inversely associated with the degree of liver fibrosis. Thus, although it is not possible to recommend coffee consumption for fatty liver prevention, coffee may be included in the diet of patients with established steatohepatitis to counteract fibrosis progression.
INTRODUCTION
Nonalcoholic fatty liver disease (NAFLD) is a common metabolic disorder that ranges from liver steatosis to nonalcoholic steatohepatitis (NASH).1 Steatogenesis in NAFLD is caused by an increased supply of free fatty acids to the liver and increased de novo lipogenesis.2 In some patients, metabolic free fatty acid handling triggers hepatocyte damage and activation of inflammation and fibrogenesis through multiple cellular events resulting in NASH.3 Both genetic and environmental factors have been implicated in modulating this complex network of molecular signals.4 Among the environmental factors, dietary habits seem to be tightly related to the fibrogenic progression of liver injury.5 Coffee is the most consumed beverage worldwide6 and is produced from the bean of an evergreen shrub belonging to the family of Rubiaceae, genus coffee. Different epidemiologic studies have considered the association between coffee drinking and liver diseases. In patients with chronic hepatitis C virus infection, coffee consumption appeared to be associated with lower fibrosis and a sustained virological response.7 Several studies, including prospective cohorts, have indicated an inverse association between coffee consumption and liver cirrhosis and cancer development independently of etiology.7 Recently, cross-sectional and casecontrol studies have suggested an inverse association of coffee consumption with liver damage in patients
with NAFLD.8-11 However, these study designs raise concerns regarding the possibility of inverse causality if persons with liver disease reduce or quit coffee drinking, thus spuriously presenting an inverse association. Solid evidence coming from prospective studies is currently lacking. Therefore, in this study, we tested the association between coffee consumption and NAFLD onset in a prospective cohort from the general population. METHODS Study design. The analysis was performed both in a cross-sectional manner on the entire sample and in a prospective manner on a subsample that were included in a follow-up study. The cross-sectional data were collected from January 2003 to March 2004. The study population consisted of 799 participants, a subgroup of Israeli adults (aged 24– 70 years) who were randomly sampled from the national population registry and interviewed in the First Israeli National Health and Nutrition Survey (the MABAT Survey).12 Individuals with any of the following were excluded from the study: alcohol consumption $30 g/d in men or 20 g/d in women,13-15 the presence of hepatitis B surface antigen or anti– hepatitis C virus antibodies, and fatty liver suspected to be secondary to hepatotoxic drugs. As described elsewhere,16,17 the final study population consisted of 375 subjects who were located and agreed to participate before the application of exclusion criteria. Participants from the baseline survey were invited to participate in a follow-up evaluation during 2010. The participants that took part in the follow-up evaluation did not differ from those who did not in any demographic, anthropometric, or biochemical parameters including age, gender, body mass index, prevalence of NAFLD, and coffee consumption (P $ 0.2 for all comparisons). The follow-up evaluation was performed by the same radiologist, and same equipment was used for the diagnosis of NAFLD using the same uniform protocol. Alcohol consumption was re-evaluated during the follow-up interview using the same questionnaire to rule out new excessive alcohol consumption and none were detected. Fasting biochemical testing in the cross-sectional study included liver enzymes, lipid profile, glucose, insulin, leptin, and adiponectin, FibroMax including FibroTest, SteatoTest, and NashTest (BioPredictive, Paris, France).18,19 Two subjects had hemolysis and thus were omitted from analysis, leaving a sample size of 347 subjects. A face-to-face interview was carried out in all participants. The questionnaire was developed by the
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Ministry of Health and included demographic data, health status, and a detailed structured questionnaire on current alcohol intake and physical activity used in national surveys as previously described.20 Evaluation of coffee consumption. During a face-toface interview, coffee consumption was evaluated by a specific questionnaire assessing the regular consumption of all types of caffeinated coffee (presented here) and separately decaffeinated coffee (data not presented because of low consumption in the study sample). Consumption categories were less than once a month, less than once a week, 1–2 times a week, 3–6 times a week, 1–2 times a day, 3–5 times a day, and more than 5 times a day. To avoid information bias, both the subject and the interviewer were unaware of the results of the ultrasonography (US) and serum examination. The second questionnaire was a detailed semiquantitative foodfrequency questionnaire (FFQ) adapted to the Israeli population that also included evaluation of coffee consumption. Both the coffee questionnaire and the FFQ were assembled by the Food and Nutrition Administration, Ministry of Health.21 The kappa measure of agreement between the coffee consumption evaluated by the FFQ and the specific questionnaire was 0.76 (60.04 standard error) indicating an excellent agreement. Ultrasonographic examination. Fatty liver was assessed by abdominal ultrasonography using the standardized criteria.22 Ultrasonography was performed in all subjects both at baseline and at follow-up with the same equipment (EUB-8500 scanner; Hitachi Medical Corporation, Tokyo, Japan) and by the same experienced radiologist (W.M.) as described previously.17,21 The ratio between the median brightness level of the liver and the right kidney cortex was calculated to determine the hepatorenal index (HRI). The HRI has been previously demonstrated to be highly reproducible and was validated against liver biopsy (r 5 0.82, P , 0.001, kappa 5 0.75)23 and against proton magnetic resonance spectroscopy, demonstrating high correlation.24,25 The study protocol was approved by the Institutional Review Board (0439-08-TLV), and all participants provided written informed consent. All authors had reviewed and approved the final manuscript. Statistical analysis. Statistical analyses were performed using Statistical Package for the Social Sciences version 21 (SPSS Inc, Chicago, Illinois) software. Continuous variables are presented as means 6 standard deviation. To test differences in continuous variables between 2 groups the independent samples’ t
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test and, if necessary, the nonparametric MannWhitney U test were performed. The associations between nominal variables were performed with the Pearson chi-square test. The evaluation of the independent association between coffee consumption and NAFLD, SteatoTest, NashTest, and FibroTest, categorized as dichotomic variables was performed with a multivariate logistic regression analysis. The associations between NAFLD and liver damage were tested as crude and with adjustment for variables that were significantly different between the high and the low coffee drinkers and can be considered as potential confounders. The stepwise (Forward Stepwise Likelihood Ratio) multivariate logistic regression model was performed to identify the strongest predictors for advanced fibrosis. P , 0.05 was considered statistically significant for all analyses.
RESULTS Characteristics of the study population. The flow chart of the study population is depicted in Fig 1. The crosssectional study included 347 subjects with mean age of 50.68 6 10.34, 53.3% were men; the body mass index of the study population is similar to that of the general population12 (Table I). FibroMax results were available for 338 subjects. FibroTest predicted significant fibrosis ($F2, borderline F1–F2 included) in 43 subjects (12.7%) and advanced fibrosis (F3–F4) in 3 subjects (0.9%). The NashTest predicted definite NASH in 3 subjects (0.9%) and borderline NASH in 106 subjects (31.4%). SteatoTest predicted the presence of clinically significant steatosis ($5%, S1–S2 and greater) in 69 subjects (20.4%). The prevalence of NAFLD according to US in the crosssectional sample was 30.8% (n 5 107). The prospective cohort included 147 subjects. The incidence rate of NAFLD according to US in the prospective cohort was 19.0% (n 5 28). Comparison between subjects who drink 3 and more cups of coffee per day and those who drink less. In both
the cross-sectional and prospective analysis, those with high ($3 cups per day) coffee consumption had higher proportion of current smoking, higher sugar consumption, and lower physical activity performance. Only on conducting the cross-sectional analysis, those with high coffee consumption had significantly higher serum cholesterol levels and dietary fat intake, but similar trends were also observed in the prospective cohort. No difference was noted between the groups in anthropometric parameters: serum ALT, glucose, insulin, lipids, ferritin, and adipocytokines levels (Table II).
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Fig 1. Flow chart of the study participants. NAFLD, nonalcoholic fatty liver disease; NASH, nonalcoholic steatohepatitis; US, ultrasonography.
Table I. Characteristics of the study sample (mean 6 SD, unless otherwise stated) Characteristics
Age (y) Male (%) BMI (kg/m2) Country of birth (%) Israel Asia Africa FSU Europe America ALT (U/L) (5–39) Glucose (mg/dL) (70–110) Cholesterol (mg/dL) (150–200) Triglycerides (mg/dL) (50–175) Insulin (mU/mL) (5–25) HOMA score* Diabetes† (%)
Total study sample n 5 347
50.68 6 10.34 53.3 27.21 6 4.55 63.7 8.6 8.1 7.8 9.2 2.6 22.15 6 9.97 90.73 6 19.52 218.12 6 40.05 116.86 6 60.86 22.27 6 11.83 5.28 6 5.21 6.6
Abbreviations: ALT, alanine aminotransferase; BMI, body mass index; FSU, former Soviet Union; HOMA, homeostasis model assessment; SD, standard deviation. *HOMA was calculated as fasting serum insulin (mU/mL) 3 fasting plasma glucose (mmol/L)/22.5. † Diabetes was defined by fasting serum glucose .126 mg/dL and/ or antidiabetic medications.
Univariate and multivariate analysis of the association between coffee consumption and NAFLD on US or according to the SteatoTest. Both the prevalence of
NAFLD according to US in the cross-sectional analysis and the incidence of NAFLD in the
prospective cohort were similar between those with high or low coffee consumption (30.1% vs 31.5%; P 5 0.769 and 18.9% vs 19.2%; P 5 0.968, respectively). Further refinement of coffee consumption into 4 categories of consumption demonstrated no association with either prevalence or incidence of NAFLD (Fig 2, A). No differences were noted between groups in HRI levels in both crosssectional and follow-up comparisons (Fig 2, B and C). In both the cross-sectional and the prospective cohort, coffee consumption was not associated with NAFLD on US, in the crude and the adjusted models with P $ 0.5 in all (Table III). In the cross-sectional cohort, analysis was also made for significant steatosis as predicted by the SteatoTest and no association was observed in any of the models with P $ 0.6 for all. Univariate and multivariate analysis of the association between coffee consumption and significant fibrosis according to the FibroTest or borderline NASH-NASH according to the NashTest. High coffee consumption
was significantly associated with a lower proportion of significant fibrosis (8.8% vs 16.3%; P 5 0.038) (Fig 3, A). High coffee consumption was strongly associated with lower odds for significant fibrosis in the crude model (odds ratio [OR] 5 0.49, 95% confidence interval [CI], 0.25–0.97; P 5 0.041). This association did not reach statistical significance with adjustment for current smoking, sugar intake, and physical activity (OR 5 0.50, 95% CI, 0.25–1.01; P 5 0.054). A third model included all potential confounders of the previous model plus other
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Table II. Comparison between subjects who drank 3 and more cups of coffee a day and those who drank less among the cross-sectional and the prospective cohorts (mean 6 SD, unless otherwise stated) Cross-sectional analysis, n 5 347 Parameter
$3/d (n 5 163)
$3/d (n 5 74)
,3/d (n 5 73)
Age (y) Gender (% males) BMI (kg/m2) Waist circumference (cm) ALT (U/L) (5–39) Glucose (mg/dL) (70–100) HbA1c % (3.9–6.0) Insulin (mU/mL) (5–25) Triglycerides (mg/dL) Total cholesterol (mg/dL) Ferritin (ng/mL) (7.1–151) Leptin (ng/mL) Adiponectin (mg/mL) Smoking % (current) Calories (kcal) Fat (g) Carbohydrates (g) Sugar (tea spoons/d) Carbohydrates from soft drinks (g/d) Physical activity (min/wk)
49.87 6 9.16 52.8 27.24 6 4.55 92.06 6 13.38
51.40 6 11.27 53.8 27.18 6 4.55 92.56 6 13.35
0.166 0.846 0.896 0.729
50.21 6 9.34 44.6 25.94 6 3.88 88.52 6 12.39
51.82 6 10.33 50.7 26.00 6 3.46 89.16 6 10.87
0.322 0.460 0.911 0.738
22.69 6 10.62 90.26 6 20.05
21.67 6 9.36 91.16 6 19.08
0.343 0.669
20.24 6 6.58 87.85 6 16.64
19.41 6 6.43 87.25 6 12.43
0.439 0.803
5.46 6 0.92 22.21 6 13.30 117.59 6 64.88 224.50 6 43.07
5.33 6 0.77 22.32 6 10.40 116.22 6 57.24 212.46 6 36.35
0.155 0.930 0.835 0.005
5.42 6 0.96 19.18 6 7.41 108.89 6 67.08 222.28 6 45.70
5.20 6 0.53 19.92 6 6.68 103.26 6 42.02 212.07 6 35.07
0.082 0.525 0.543 0.130
73.60 6 57.83
73.31 6 63.61
0.966
61.88 6 45.20
74.03 6 68.78
0.215
18.89 6 18.27 12.56 6 10.75 33.1 2529.01 6 1105.94 109.49 6 56.03 289.57 6 133.72 2.41 6 3.00 15.75 6 29.62
19.69 6 18.87 11.57 6 7.65 15.8 2319.83 6 915.28 94.43 6 40.59 283.68 6 127.31 1.43 6 2.02 15.61 6 32.56
0.693 0.331 ,0.001 0.055 0.005 0.674 ,0.001 0.967
15.67 6 13.14 13.50 6 10.06 32.4 2472.32 6 953.32 105.58 6 41.97 290.47 6 134.53 2.29 6 2.87 13.41 6 29.12
17.66 6 18.07 12.83 6 8.78 5.5 2240.65 6 781.00 93.96 6 37.29 267.71 6 104.32 1.49 6 2.13 9.53 6 16.01
0.453 0.677 ,0.001 0.109 0.078 0.254 0.057 0.318
72.15 6 142.71
0.007
90.00 6 142.85
0.063
39.29 6 76.24
,3/d (n 5 184)
Prospective analysis, n 5 147 (baseline values) P
52.26 6 95.62
P
Abbreviations: ALT, alanine aminotransferase; BMI, body mass index; HbA1c, hemoglobin A1c; SD, standard deviation.
variables that were different between the high and low coffee drinkers only in the cross-sectional cohort (serum cholesterol levels and dietary fat and calories intake). To detect the strongest predictors for significant fibrosis, a stepwise regression was performed with all variables. Coffee consumption was the strongest and only significant predictor left in the model (Fig 3, B). No association was observed between coffee consumption and presumed borderline NASH or (definite) NASH (Table III). DISCUSSION
This is the first prospective study testing the association between coffee consumption and the new onset of NAFLD. In the present study, no association was demonstrated between coffee drinking and the development of steatosis as assessed by ultrasonographic methods (regular US and HRI) and serum biomarkers (SteatoTest). However, the cross-sectional cohort results do suggest a protective effect on fibrosis progression as assessed by the FibroTest. Prospective studies have indicated a beneficial effect of coffee consumption in several diseases26 and a reduction in all-cause mortality for patients with increased lifetime intake of both
caffeinated and decaffeinated coffee.27 The effects of coffee and caffeine on liver diseases of different etiology have been reported for several years.7 Recently, clinical studies have evaluated the association of coffee consumption with the degree of liver injury in NAFLD by using different methodological approaches, leading to equivocal results. A case-control study by Catalano et al8 first evaluated the possible link between coffee intake and NAFLD, showing that espresso coffee drinkers displayed milder liver steatosis, detected by US, as compared with nondrinkers. However, a case-control study is susceptible to bias because of different recall of coffee consumption among patients and controls. Two successive crosssectional studies have considered histologic endpoints. The study by Molloy et al9 focused on the relationship between the amount of coffee-derived caffeine and liver histology and revealed an inverse relationship of fibrosis but not steatosis with caffeine intake. A French study conducted in morbidly obese subjects undergoing bariatric surgery demonstrated that the intake of regular coffee, but not espresso, may be protective from fibrosis.10 However, an important limitation in that study is that it was conducted in a selected population
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Fig 2. Fatty liver diagnosis in the prospective and in the cross-sectional cohorts. (A) New onset of nonalcoholic fatty liver (P 5 0.47 by the chi-square test) in the prospective cohort (n 5 147) and prevalence (P 5 0.93) in the cross-sectional cohort (n 5 347) by coffee consumption categories. n 5 23, 50, 55, and 19 in the prospective cohort and 52, 132, 118, and 45 in the cross-sectional study in the coffee consumption categories, respectively. (B) HRI levels by coffee consumption in the cross-sectional cohort. (C) HRI levels by coffee consumption in the prospective cohort. HRI, hepatorenal index; NAFLD, nonalcoholic fatty liver disease.
Table III. Multivariate analysis of the association between coffee consumption and NAFLD on US or according to the SteatoTest $S1–S2 and borderline NASH-NASH according to the NashTest [OR (95% CI)] NAFLD on US Cohort
Cross-sectional cohort $3/d cups/d P Prospective cohort $3/d cups/d P
SteatoTest*
NashTest*
Model 1
Model 2
Model 1
Model 2
Model 1
Model 2
0.93 (0.59–1.48) 0.769
0.92 (0.57–1.50) 0.749
1.02 (0.65–1.87) 0.718
1.05 (0.60–1.84) 0.857
1.20 (0.76–1.90) 0.428
1.22 (0.75–1.96) 0.424
0.98 (0.43–2.24) 0.968
0.72 (0.28–1.85) 0.501
— —
— —
— —
— —
Abbreviations: CI, confidence interval; NASH, nonalcoholic steatohepatitis; NAFLD, nonalcoholic fatty liver disease; OR, odds ratio; US, ultrasonography. Model 1: crude. Model 2: the forced multivariate logistic regression model adjusted for current smoking, sugar, and physical activity (minutes per week). *Steatosis and NASH according to the FibroMax were not evaluated in the follow-up cohort.
and it cannot be assumed that the results can be generalized to other populations. More recently, a study from the Nonalcoholic Steatohepatitis Clinical Research Network showed an inverse association of coffee intake with advanced fibrosis among patients with NAFLD with lower homeostasis model
assessment–insulin resistance, thus suggesting that coffee may differently impact on liver injury with respect to the metabolic background of patients.11 The previously mentioned studies could not establish any cause-effect relationship. In our study, the prospective cohort design excludes a preventive effect of the
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Fig 3. Significant fibrosis according to the FibroTest by coffee consumption. (A) Prevalence of significant fibrosis by coffee consumption. (B) Multivariate analysis of the association between coffee consumption and significant fibrosis [odds ratio (95% confidence interval)], n 5 338, 12.7% with significant fibrosis. Model 1: crude. Model 2: the forced multivariate logistic regression model adjusted for current smoking, sugar, and physical activity (minutes per week). Model 3: the stepwise multivariate logistic regression model included only the strongest predictors and excluded all the other variables listed in model 2 plus serum cholesterol levels, dietary fat, and calorie intake.
consumption of 3 or more cups of coffee on the incidence of NAFLD as assessed both by regular qualitative US and by the quantitative HRI. Coffee drinkers had worse lifestyle habits, but adjusting for lifestyle parameters (smoking, diet, and physical activity) did not uncover an association with NAFLD. In the crosssectional cohort, we confirmed that coffee consumption is independently associated with decreased liver fibrosis, assessed by the Fibrotest. This was also true when adjusting for dietary fat and sugar (usually added to the coffee), which were higher among the coffee drinkers and are well established risk factors for steatosis and fibrosis5,28 and for smoking, which was demonstrated to be associated with advanced liver fibrosis in a cohort of patients with NAFLD.29 Our data suggest that although coffee is not able to counteract steatogenesis, it may inhibit fibrogenesis that is the more important determinant of clinical outcomes in NAFLD. This is in agreement with the effects of other foods containing polyphenols, such as wine or grapevine, whose modest consumption is not protective from steatosis but from fibrosis.30 Recently, in a randomized crossover trial, coffee consumption was shown to blunt hepatic insulin resistance but not the increase in liver triglycerides induced by fructose overfeeding in 10 healthy volunteers.31 Thus, overall results from previous cross-sectional cohort and from our study suggest a protective effect from fibrosis progression, whereas effects on insulin resistance and steatogenesis need to be further explored. The specific components of coffee exerting beneficial effects have been partially elucidated. Coffee contains hundreds of chemical ingredients including several polyphenols, chlorogenic acids, melanoidins, and
caffeine. Recently, caffeine was shown to inhibit hepatic stellate cell proliferation in vitro.32 Nonetheless, some experimental studies indicate that the antifibrogenic effects of coffee may be independent of caffeine content and may depend on the polyphenolic compounds33,34; in fact, natural polyphenols have been shown to exert inhibitory effects on fibrogenesis and are promising candidates in the treatment of NASH and related metabolic disorders.35,36 Our study has some limitations. The major limitation stems from the absence of liver histology; however, it was deemed unethical to perform liver biopsy in healthy volunteers. We therefore opted to use a battery of noninvasive tests. These have shortcomings including imperfect diagnostic accuracy to define NASH and fibrosis.37,38 However, FibroTest has been recently proposed as a noninvasive marker of fibrosis in a large population39 and was used to screen fibrosis in subjects from the general population40 and in diabetics.41 Similarly, steatosis was not quantified histologically. However, HRI has been validated vs liver biopsy,23 and proton magnetic resonance spectroscopy24,25 providing a highly sensitive and quantitative tool for liver fat evaluation. Next, NASH and advanced fibrosis were not represented in this relatively healthy study population, and thus we could mainly discuss the association of coffee consumption with early histologic damage. Lastly, a limitation may lie in the accuracy of dietary assessment of coffee consumption because of a recall or reporting bias. The coffee consumption obtained from the specific coffee questionnaire was compared with the consumption obtained from the FFQ and the agreement was very high.
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CONCLUSIONS
This study provides the first prospective evidence in a sample of the general population for a lack of protective effect of coffee intake on the development of steatosis, whereas an inverse association of coffee intake with liver fibrosis was confirmed in the cross-sectional cohort. Further studies in other populations with a larger sample size, and possibly long-term randomized controlled trials, would be needed to establish possible different effects of coffee at different stages in the natural history of NAFLD. ACKNOWLEDGMENTS
Conflicts of Interest: All authors have read the journal’s policy on disclosure of potential conflicts of interest and have none to declare. All authors have read the journal’s authorship agreement. The manuscript has been reviewed and approved by all named authors. Financial support: None. REFERENCES
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