Moderate Drinking, Inflammation, and Liver Disease

Is low-level alcohol consumption really health-protective? A critical review of approaches to promote causal inference and recent applications

Heavy and disordered alcohol consumption is a known risk factor for several health conditions and is associated with considerable disease burden. However, at low-to-moderate levels, evidence suggests that drinking is associated with reduced risk for certain health outcomes. Whether these findings represent genuine protective effects or mere methodological artifacts remains unclear, but has substantial consequences for policy and practice. This critical review introduces methodological advances capable of enhancing causal inference from observational research, focusing on the 'G-methods' and Mendelian Randomization. We also present and evaluate recent research applying these methods and compare findings to the existing evidence base. Future directions are proposed for improving our causal understanding of the relationships between alcohol and long-term health outcomes.

Gut microbiota-modulating agents in alcoholic liver disease: Links between host metabolism and gut microbiota

Alcoholic liver disease (ALD) involves a wide spectrum of diseases, including asymptomatic hepatic steatosis, alcoholic hepatitis, hepatic fibrosis, and cirrhosis, which leads to morbidity and mortality and is responsible for 0.9% of global deaths. Alcohol consumption induces bacterial translocation and alteration of the gut microbiota composition. These changes in gut microbiota aggravate hepatic inflammation and fibrosis. Alteration of the gut microbiota leads to a weakened gut barrier and changes host immunity and metabolic function, especially related to bile acid metabolism. Modulation and treatment for the gut microbiota in ALD has been studied using probiotics, prebiotics, synbiotics, and fecal microbial transplantation with meaningful results. In this review, we focused on the interaction between alcohol and gut dysbiosis in ALD. Additionally, treatment approaches for gut dysbiosis, such as abstinence, diet, pro-, pre-, and synbiotics, antibiotics, and fecal microbial transplantation, are covered here under ALD. However, further research through human clinical trials is warranted to evaluate the appropriate gut microbiota-modulating agents for each condition related to ALD.

Relative protective activities of quercetin, quercetin-3-glucoside, and rutin in alcohol-induced liver injury

Alcoholic liver diseases has been known to be one of the major health risks worldwide. The purpose of this study was aimed to demonstrate the relative protective effect of quercetin, quercetin-3-glucoside, and rutin on alcohol-induced damage in hepatocytes. The hepatotoxicity, antioxidant enzymatic defense mechanisms, and pro-inflammatory mediators were examined for evaluating the hepatoprotective effects of quercetins in hepG2 cells. The results revealed that quercetin and its glucoside derivatives significantly prevented ethanol-induced hepatotoxicity by decreasing hepatic aminotransferase activities and inflammatory response in HepG2 cells. Moreover, the quercetins significantly induced detoxifying enzymes via the nuclear accumulation of the NF-E2-related factor 2 (Nrf2) and induction of antioxidant response element (ARE) gene. These hepatoprotective activities were observed to be more effective with quercetin aglycone than quercetin glucosides. From the above findings, the present study imply that quercetin aglycone may have a vital function in the therapeutic and preventive strategies of alcoholic liver diseases. PRACTICAL APPLICATIONS: Quercetin is commonly present in fruits and vegetables as aglycone and glucoside-derived forms. In the present study, quercetin and its glycosides was shown to alleviate oxidative stress, glutathione depletion, and pro-inflammatory cytokines in alcohol-induced HepG2 cells via the Nrf2/ARE antioxidant pathway. Moreover, quercetin aglycone had better protective effects against alcohol-induced liver damage in vitro, compared to its glycosylated form. The present study proposed that quercetin aglycone may be a more efficient hepatoprotective agent than its glucoside derivatives such as rutin in the amelioration of alcohol-induced liver diseases.

Association of Ambient Air Pollution with Increased Liver Enzymes in Korean Adults

An association between exposure to air pollution and liver enzymes in certain areas or older people has been reported in the literature; however, it cannot be generalized to the general population. We investigated the association between air pollution, liver enzyme levels, and alcohol consumption using nationwide data of South Korean adults. Air pollutants included particulate matter with an aerodynamic diameter ≤10 µm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon monoxide (CO). Liver enzymes included alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Exposure to air pollutants were significantly associated with elevation of log ALT and log AST, especially increases from 0.0073 IU/L (95% confidence interval (CI) = 0.0042, 0.0104) to 0.0251 IU/L (95% CI = 0.0132, 0.0371) per interquartile range (IQR) increase of each pollutant (all pollutants: p < 0.001). Association of the liver enzymes with PM₁₀ (β (95% CI) = 0.0285 IU/L (0.0201, 0.0368) for log ALT; β (95% CI) = 0.0139 IU/L (0.0079, 0.0198) for log AST) and CO (β (95% CI) = 0.0247 IU/L (0.0182, 0.0311) for log ALT; β (95% CI) = 0.0164 IU/L (0.0118, 0.0210) for log AST) were only significant among drinkers. Our findings suggest that chronic exposure to PM₁₀ and CO is a risk factor for liver enzymes increases among the general adult population who admitted to drinking alcohol.

Awareness of HCV infection among persons who inject drugs in San Diego, California

We asked persons who inject drugs questions about HCV, including past testing and diagnosis followed by HCV testing. Of 540 participants, 145 (27%) were anti-HCV positive, but of those who were positive, only 46 (32%) knew about their infection. Asking about previous HCV testing results yielded better results than did asking about prior HCV diagnosis. Factors associated with knowing about HCV infection included older age, HIV testing, and drug treatment. Comprehensive approaches to educating and screening this population for HCV need implementation.

Regulation of microRNAs and their role in liver development, regeneration and disease

Since their discovery more than a decade ago microRNAs have been demonstrated to have profound effects on almost every aspect of biology. Numerous studies in recent years have shown that microRNAs have important roles in development and in the etiology and progression of disease. This review is focused on microRNAs and the roles they play in liver development, regeneration and liver disease; particularly chronic liver diseases such as alcoholic liver disease, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, viral hepatitis and primary liver cancer. The key microRNAs identified in liver development and chronic liver disease will be discussed together with, where possible, the target messenger RNAs that these microRNAs regulate to profoundly alter these processes. This article is part of a Directed Issue entitled: The Non-coding RNA Revolution.

The use of a selective serotonin reuptake inhibitor decreases heavy alcohol exposure-induced inflammatory response and tissue damage in rats

Alcohol intoxication and psychiatric medication overdoses, including antidepressants, are common emergency room events. Heavy alcohol and antidepressant exposure are able to induce changes in cytokines disturbing normal physiology. We examined the inflammatory and physiological effects of selective serotonin reuptake inhibitor (SSRI) medication after heavy alcohol exposure. Rats were randomly divided into Alc (EtOH 5g/kg, intravenous infusion for 3 h), SSRI (paroxetine oral intake) and Alc+SSRI groups. Serum samples were collected to measure blood ethanol, aspartate transferase, alanine transferase, creatine phosphokinase, lactate dehydrogenase, amylase, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) levels. Lactate dehydrogenase levels in bronchoalveolar lavage fluid were also examined. Liver, pancreas and lungs were removed after sacrifice and any pathological changes were catalogued. Ethanol infusion resulted in blood levels of ethanol of >100 mg/dL after ethanol infusion. Serum levels of aspartate transferase, alanine transferase, creatine phosphokinase, lactate dehydrogenase, amylase, TNF-α and IL-6 in the Alc+SSRI group were lower than in the Alc group. Moreover, pathological damages to the liver, pancreas and lungs were slightly lower in the Alc+SSRI group than in the Alc group. These findings suggested that SSRI is able to decrease the release of pro-inflammatory cytokines and thereby reduce liver and pancreas damage after heavy alcohol exposure.

Calorie and alcohol consumption in nonalcoholic fatty liver disease

OBJECTIVES AND METHODS

Most definitions of nonalcoholic fatty liver disease (NAFLD) allow some intake of alcohol but little attention has been paid to the possible contribution of alcohol-derived calories in the overall daily intake. The aim of the present study was to determine whether, in a group of 144 patients referred to liver outpatients with NAFLD, a more structured questioning of dietary habits and alcohol consumption would provide better information on alcohol-derived and dietary-derived calorie intake and the relationship with the BMI.

RESULTS

Both food intake and calories resulting from alcohol ingestion were frequently underestimated as was the percentage of patients who were drinking excessively (>30 U a week), which was surprisingly high at 40%. The substantial calorie intake resulting from alcohol consumption in this group was associated with a reduction in dietary calorie intake, so that the total daily calorie intake remained similar to those with low-to-moderate or no alcohol consumption. The findings also showed that the BMI, although still elevated, was significantly reduced in those drinking heavily compared with low and nondrinkers.

CONCLUSION

Patients with NAFLD can have substantially higher levels of alcohol consumption than usually recognized. The additional calorie intake resulting from this is to some extent balanced by a reduction in dietary calorie intake with less elevation in BMI, and a clear distinction from an alcohol-induced steatosis may be difficult.

Impact of alcohol use on mortality in the elderly: results from the Korean Longitudinal Study on Health and Aging

BACKGROUND

To examine the effects of problematic drinking, amount of alcohol use and binge drinking on all-cause mortality in the elderly.

METHODS

We investigated 45-month all-cause mortality of 997 randomly sampled community-dwelling elderly Koreans aged 65 years or older who participated in the Korean Longitudinal Study on Health and Aging. Problematic drinking was defined as having alcohol use disorders according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria or having 8 or higher of the Alcohol Use Disorders Identification Test. Light drinking was defined as drinking 7 alcoholic drinks or less, and heavy drinking as having 14 alcoholic drinks more per week during past 12 months. Binge drinking was defined as having 6 or more drinks on a single occasion at least monthly.

RESULTS

One hundred and thirteen participants (11.3%) died during the 45-month follow-up period. Heavy drinking (>14 alcoholic drinks per week) increased the all-cause mortality risk when in association with problematic drinking (hazard ratio [HR]=2.604, 95% confidence interval [CI]=1.221-5.553, p=0.012) or binge drinking (HR=2.823, 95% CI=1.259-6.328, p=0.013). Light drinking (≤ 7 alcoholic drinks per week) was associated with decreased all-cause mortality (HR=0.114, 95% CI=0.015-0.833, p=0.032).

CONCLUSIONS

Problematic drinking is associated with increased all-cause mortality in elderly Koreas, particularly when it is heavy and/or combined with binge drinking.

Correlates of hazardous drinking among Veterans with and without hepatitis C

Hazardous drinking is a major barrier to antiviral treatment eligibility among hepatitis C (HCV) patients. We evaluated differences in substance-related coping, drinking-related consequences, and importance and confidence in ability to change alcohol use among hazardous drinkers with and without HCV (N = 554; 93.5% male). We examined group differences between HCV+ patients (n = 43) and their negative HCV counterparts (n = 511). Results indicate a higher percentage of HCV+ patients report using substances to cope with possible symptoms of PTSD (P < .05) and depression (P < .01), and endorse more lifetime drinking-related negative consequences than HCV patients (P < .01). Furthermore, HCV+ patients place greater importance on changing alcohol use (P < .01) but report less confidence in their ability to change (P < .01). Use of brief assessment and feedback with skills-based interventions to decrease alcohol use may be well-received by HCV+ patients.

Effects of a hepatitis C virus educational intervention or a motivational intervention on alcohol use, injection drug use, and sexual risk behaviors among injection drug users

OBJECTIVES

We compared the effects of 2 interventions on alcohol use, use of a new syringe at last injection, and condom use at last sexual encounter in a community sample of injection drug users.

METHODS

Between 2003 and 2006, 851 out-of-treatment injection drug users were recruited in Raleigh, NC, and Durham, NC, through street outreach and were randomly assigned to either a 6-session educational intervention or a 6-session motivational intervention. Intervention effects were examined at 6 and 12 months after enrollment.

RESULTS

In multiple logistic regression analyses adjusted for baseline alcohol use and HCV status, participants assigned to the motivational intervention were significantly less likely than were participants in the educational intervention to be drinking at the 6-month follow-up (odds ratio = 0.67; 95% confidence interval = 0.46, 0.97). There were no significant between-group differences in use of a new syringe at last injection or condom use at last sexual encounter at either follow-up.

CONCLUSIONS

Reducing alcohol use among persons with HCV may slow disease progression and provide important health benefits. Additional strategies are needed for slowing HCV disease progression until more effective HCV treatments are available.

Alcohol consumption: the good, the bad, and the indifferent

Dietary ethanol (alcohol) is the most widely consumed drug worldwide. High levels of mortality, morbidity, and social malaise are associated with abuse of alcohol, and increasing numbers of women and youth are abusing alcohol. However, strong epidemiological data demonstrate a U- or J-shaped relationship between volume of alcohol consumed and all-cause mortality or disease burden. Moderate alcohol consumption is associated with a lower risk of all-cause mortality and disease burden than are abstinence and immoderate drinking. A brief review of the absorption, distribution, metabolism, and excretion of ethanol is provided with a discussion of the impact of gender differences. Potential mechanisms by which ethanol, ethanol metabolites, and (or) phytochemicals, as associated with different types of ethanol-containing beverages, are discussed in regards to the beneficial and detrimental impacts they may have on physiological system functioning and mortality or disease burden. Per capita consumption of ethanol-containing beverages varies across geo-political regions worldwide. A more recent research focus is the impact of consumption patterns on consumption volumes as they relate to disease and mortality. Certain drinking patterns moderate overall volume of ethanol consumption. Thus, an emerging approach to the study of alcohol consumption in populations is to consider both the volume and pattern of consumption as they relate to mortality and disease burden. Alcohol consumption patterns among athletes are discussed; physiological implications of alcohol abuse in this population are outlined. Current guidelines for the consumption of alcohol are reviewed. Alcohol consumption guidelines reflect the current scientific understanding of both the benefits of moderate alcohol consumption and the detriments of immoderate alcohol consumption.