Beneficial effects of ethanol consumption on insulin resistance are only applicable to subjects without obesity or insulin resistance; drinking is not necessarily a remedy for metabolic syndrome

Early-life exposure to alcohol and the risk of alcohol-induced liver disease in adulthood

Alcohol consumption remains prevalent among pregnant and nursing mothers despite the well-documented adverse effects this may have on the offspring. Moderate-to-high levels of alcohol consumption in pregnancy result in fetal alcohol syndrome (FAS) disorders, with brain defects being chief among the abnormalities. Recent findings indicate that while light-to-moderate levels may not cause FAS, it may contribute to epigenetic changes that make the offspring prone to adverse health outcomes including metabolic disorders and an increased propensity in the adolescent-onset of drinking alcohol. On the one hand, prenatal alcohol exposure (PAE) causes epigenetic changes that affect lipid and glucose transcript regulating genes resulting in metabolic abnormalities. On the other hand, it can program offspring for increased alcohol intake, enhance its palatability, and increase acceptance of alcohol's flavor through associative learning, making alcohol a plausible second hit for the development of alcohol-induced liver disease. Adolescent drinking results in alcohol dependence and abuse in adulthood. Adolescent drinking results in alcohol dependence and abuse in adulthood. Alterations on the opioid system, particularly, the mu-opioid system, has been implicated in the mechanism that induces increased alcohol consumption and acceptance. This review proposes a mechanism that links PAE to the development of alcoholism and eventually to alcoholic liver disease (ALD), which results from prolonged alcohol consumption. While PAE may not lead to ALD development in childhood, there are chances that it may lead to ALD in adulthood.

Impact of High Fat Diet and Ethanol Consumption on Neurocircuitry Regulating Emotional Processing and Metabolic Function

The prevalence of psychiatry disorders such as anxiety and depression has steadily increased in recent years in the United States. This increased risk for anxiety and depression is associated with excess weight gain, which is often due to over-consumption of western diets that are typically high in fat, as well as with binge eating disorders, which often overlap with overweight and obesity outcomes. This finding suggests that diet, particularly diets high in fat, may have important consequences on the neurocircuitry regulating emotional processing as well as metabolic functions. Depression and anxiety disorders are also often comorbid with alcohol and substance use disorders. It is well-characterized that many of the neurocircuits that become dysregulated by overconsumption of high fat foods are also involved in drug and alcohol use disorders, suggesting overlapping central dysfunction may be involved. Emerging preclinical data suggest that high fat diets may be an important contributor to increased susceptibility of binge drug and ethanol intake in animal models, suggesting diet could be an important aspect in the etiology of substance use disorders. Neuroinflammation in pivotal brain regions modulating metabolic function, food intake, and binge-like behaviors, such as the hypothalamus, mesolimbic dopamine circuits, and amygdala, may be a critical link between diet, ethanol, metabolic dysfunction, and neuropsychiatric conditions. This brief review will provide an overview of behavioral and physiological changes elicited by both diets high in fat and ethanol consumption, as well as some of their potential effects on neurocircuitry regulating emotional processing and metabolic function.

Access schedules mediate the impact of high fat diet on ethanol intake and insulin and glucose function in mice

Alcoholism and high fat diet (HFD)-induced obesity individually promote insulin resistance and glucose intolerance in clinical populations, increasing risk for metabolic diseases. HFD can also stimulate alcohol intake in short-term clinical studies. Unfortunately, there is currently a disconnect between animal models and the clinical findings, as animal studies typically show that HFD decreases ethanol intake while ethanol intake mitigates HFD-induced effects on insulin and glucose dysfunction. However, most previous animal studies utilized forced or continuous HFD and/or ethanol. In three experiments we sought to determine whether HFD (HFD = 60% calories from fat) vs. control diet (chow = 16% fat) alters voluntary two-bottle choice ethanol intake in male C57Bl/6J mice given differing access schedules for 6-7 weeks, and we assessed the resultant impact on metabolic function via insulin and glucose tolerance tests. Experiment 1: Unlimited Access Ethanol + HFD (UAE + HFD; n = 15; 10% ethanol v/v, ad libitum diet and ethanol) or UAE + Chow (n = 15). Experiment 2: Limited Access Ethanol + HFD (LAE + HFD; n = 15; ethanol = 4 h/day; 3 days/week, ad libitum diet) or LAE + Chow (n = 15) with increasing ethanol concentrations (10%, 15%, 20%). Experiment 3: Intermittent HFD with limited access to ethanol (iHFD-E; HFD = single 24-h session/week; ethanol = 4 h/day; 4 days/week) (n = 10). UAE + HFD mice consumed significantly less ethanol and were insulin-resistant and hyperglycemic compared with UAE + Chow mice. LAE + HFD mice consumed ethanol similarly to LAE + Chow mice, but exhibited hyperglycemia, insulin resistance, and glucose intolerance. iHFD-E mice displayed binge eating-like behaviors and consumed significantly more ethanol than mice given ad libitum chow or HFD. iHFD-E mice did not have significantly altered body composition, but developed insulin insensitivity and glucose intolerance. These findings suggest that access schedules influence HFD effects on ethanol consumption and resultant metabolic dysfunction, ethanol intake does not improve HFD-induced metabolic dysfunction, and binge eating-like behaviors can transfer to binge drinking behaviors.

PREVALENCE OF INSULIN RESISTANCE AND ASSOCIATION WITH METABOLIC RISK FACTORS AND FOOD CONSUMPTION IN ADOLESCENTS - RECIFE/BRAZIL

OBJECTIVE

To identify the prevalence of insulin resistance in adolescents and its associations with metabolic factors and food intake.

METHODS

Cross-sectional study conducted with a stratified, complex, school-based sample. The subjects were adolescents (n=1,081) who participated in the Study of Cardiovascular Risk in Adolescents in the city of Recife (Pernambuco, Brazil). We analyzed demographic, socioeconomic, behavioral, anthropometric, biochemical, and dietary variables. Insulin resistance was defined as HOMA-IR>75th percentile. A Poisson multivariate regression model with robust variance adjustment was used, and variables with p≤0.05 in the final model were considered statistically associated with insulin resistance.

RESULTS

Median age was 14 years (interquartile range: 13-16 years), and 25.3% of the sample showed insulin resistance. The variables associated with insulin resistance in the final model were age, body mass index-for-age (BMI/A), biochemical markers (triglycerides and high-density lipoprotein cholesterol) and saturated fat intake, with insulin resistance being more prevalent in individuals whose consumption of this type of fat was below the median of the sample distribution.

CONCLUSIONS

Insulin resistance was prevalent in the adolescents analyzed and was significantly associated with metabolic variables and saturated fat intake.

Effect of imidazoline-1 receptor agonists on renal dysfunction in rats associated with chronic, sequential fructose and ethanol administration

Insulin resistance and chronic alcoholism are risk factors for renal dysfunction. This study investigated the therapeutic effects of two imidazoline-1 receptor (I1R) agonists on renal dysfunction in rats after chronic, sequential fructose and ethanol administration. Daily drinking water was supplemented with fructose (10%, w/v) for 12 weeks and then with ethanol (20%, v/v) for another 8 weeks. Rats were treated with rilmenidine and clonidine in the last two weeks of the study. Blood glucose and serum insulin (sIns) levels, lipid profiles, kidney function and renal histopathology were evaluated at the end of the experiment. Additionally, renal gene expression of nischarin, phosphatidylcholine-specific phospholipase C (PC-PLC) and prostaglandin E2 (PGE2) were measured. Renal levels of superoxide dismutase (SOD), malondialdehyde (MDA), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS) and total NO (tNO) were detected, and we determined the relative renal gene expression levels of alpha smooth muscle actin (α-SMA), hydroxyproline, interleukin 10 (IL-10), tumour necrosis factor alpha (TNF-α) and caspase-3. The results showed significant deterioration of blood glucose, sIns, lipid profiles, kidney function and renal histopathology in fructose/ethanol-fed rats. Additionally, markers of inflammation, fibrosis, apoptosis and oxidative stress were upregulated. The administration of rilmenidine or clonidine significantly improved blood glucose and sIns levels and reduced renal dysfunction. Our work showed that chronic, sequential fructose and ethanol administration induced fasting hyperglycaemia and renal impairment, and these effects were ameliorated by I1R agonists.

Moderate consumption of fermented alcoholic beverages diminishes diet-induced non-alcoholic fatty liver disease through mechanisms involving hepatic adiponectin signaling in mice

PURPOSE

Results of some epidemiological studies suggest that moderate alcohol consumption may be associated with a decreased risk to develop NAFLD. Here, the effect of the consumption of moderate beer and diluted ethanol, respectively, on the development of NAFLD were assessed.

METHODS

Female C57BL/6J mice were fed a control diet (C-D) or a diet rich in fructose, fat and cholesterol (FFC) enriched isocalorically and isoalcoholically with beer (FFC + B) or plain ethanol (FFC + E) (2.5 g ethanol/kg body weight/day) for 7 weeks. Liver damage was assessed by histology using NAFLD activity score. Markers of inflammation, insulin resistance and adiponectin signaling were measured at mRNA and protein levels. Using J774A.1 cells as a model of Kupffer cells, the effect of alcoholic beverages on adiponectin receptor 1 (Adipor1) was assessed.

RESULTS

Hepatic triglyceride concentration, neutrophil granulocytes, iNOS protein concentrations and early signs of insulin resistance found in FFC-fed mice were significantly attenuated in FFC+ B-fed mice (P < 0.05 for all). These findings were associated with a super-induction of Adipor1 mRNA expression (+ ~ 18-fold compared to all other groups) and a decrease of markers of lipid peroxidation in liver tissue of FFC + B-fed mice when compared to FFC-fed animals. Similar differences were not found between FFC- and FFC+ E-fed mice. Expression of Adipor1 was also super-induced (7.5-fold) in J774A.1 cells treated with beer (equivalent to 2 mmol/L ethanol).

CONCLUSIONS

These data suggest that moderate intake of fermented alcoholic beverages such as beer at least partially attenuates NAFLD development through mechanisms associated with hepatic AdipoR1 expression.

The Relation of Light-to-Moderate Alcohol Consumption to Glucose Metabolism and Insulin Resistance in Nondiabetic Adults: the Moderating Effects of Depressive Symptom Severity, Adiposity, and Sex

PURPOSE

We examined the relation of alcohol consumption to glucose metabolism and insulin resistance (IR) as a function of depressive symptoms, adiposity, and sex.

METHOD

Healthy adults (aged 18-65 years) provided fasting blood samples and information on lifestyle factors. Alcohol intake was categorized as never, infrequent (1-3 drinks/month), occasional (1-7 drinks/week), and regular (≥2 drinks/day) drinkers. The Beck Depression Inventory (BDI) was used to assess symptom severity. Primary outcomes were fasting insulin, glucose, and IR assessed by the homeostasis model assessment (HOMA).

RESULTS

In univariate analysis, alcohol consumption was negatively associated with HOMA-IR (p = 0.03), insulin (p = 0.007), and body mass index (BMI) (p = 0.04), but not with glucose or BDI. Adjusting for potential confounders including BMI, alcohol consumption was associated with HOMA-IR (p = 0.01) and insulin (p = 0.009) as a function of BDI and sex. For women with minimal depressive symptoms, light-to-moderate alcohol consumption was associated with lower HOMA-IR and insulin. Alcohol consumption was not associated with metabolic markers in women with higher depressive symptoms and in men. In analysis using BMI as a continuous moderator, alcohol consumption was only associated with insulin (p = 0.004). Post-hoc comparisons between BMI groups (<25 vs ≥25 kg/m²⁾ revealed that light-to-moderate alcohol consumption was associated with lower insulin but only in subjects with BMI ≥ 25 kg/m².

CONCLUSIONS

The benefits of light-to-moderate alcohol consumption on fasting insulin and IR are sex dimorphic and appear to be independently moderated by adiposity and depressive symptom severity.

Chronic alcohol consumption potentiates the development of diabetes through pancreatic β-cell dysfunction

Chronic ethanol consumption is well established as a major risk factor for type-2 diabetes (T2D), which is evidenced by impaired glucose metabolism and insulin resistance. However, the relationships between alcohol consumption and the development of T2D remain controversial. In particular, the direct effects of ethanol consumption on proliferation of pancreatic β-cell and the exact mechanisms associated with ethanol-mediated β-cell dysfunction and apoptosis remain elusive. Although alcoholism and alcohol consumption are prevalent and represent crucial public health problems worldwide, many people believe that low-to-moderate ethanol consumption may protect against T2D and cardiovascular diseases. However, the J- or U-shaped curves obtained from cross-sectional and large prospective studies have not fully explained the relationship between alcohol consumption and T2D. This review provides evidence for the harmful effects of chronic ethanol consumption on the progressive development of T2D, particularly with respect to pancreatic β-cell mass and function in association with insulin synthesis and secretion. This review also discusses a conceptual framework for how ethanol-produced peroxynitrite contributes to pancreatic β-cell dysfunction and metabolic syndrome.

Flushing response modifies the association of alcohol consumption with markers of glucose metabolism in Japanese men and women

BACKGROUND

Influences of alcohol use on glucose metabolism may depend on alcohol flushing response. We investigated the effect of alcohol flushing response on the associations between alcohol consumption and markers of glucose metabolism in Japanese men and women.

METHODS

The subjects were 979 employees (885 men and 94 women), aged 18 to 69 years, of a manufacturing company in Japan. Flushing response and alcohol consumption were determined using a self-administered questionnaire. Homeostasis model assessment-insulin resistance (HOMA-IR) and homeostasis model assessment for β-cell function (HOMA-β) were computed using fasting plasma glucose and insulin. For each group of flushers and nonflushers, multiple regression analysis was used to estimate means of fasting plasma glucose, hemoglobin A1c (HbA1c), and HOMAs for each category of alcohol consumption, with adjustments for potential confounders.

RESULTS

In flushers, alcohol consumption was associated with HbA1c levels in a U-shaped manner, with the lowest HbA1c levels being observed at an alcohol consumption level of 23.0 to <34.5 g ethanol/d (p for quadratic trend = 0.002). In nonflushers, alcohol consumption was linearly and inversely associated with HbA1c levels (p for linear trend = 0.001). Decreases in HbA1c were more evident among flushers compared with nonflushers at moderate alcohol consumption levels (p for interaction = 0.049). An increase of fasting glucose associated with highest alcohol consumption was observed in both flushers and nonflushers. A statistically significant decrease in HOMA-IR with increasing alcohol consumption was observed in flushers (p for trend = 0.007), whereas HOMA-IR levels slightly decreased at higher alcohol consumption in nonflushers. HOMA-β similarly decreased with increasing alcohol consumption in both flushers and nonflushers (both p for trend < 0.001).

CONCLUSIONS

The results suggest that the alcohol flushing response may improve glucose metabolism and insulin resistance at moderate alcohol use levels in apparently healthy Japanese adults.

Moderate alcohol use and health: a consensus document

AIMS

The aim of this consensus paper is to review the available evidence on the association between moderate alcohol use, health and disease and to provide a working document to the scientific and health professional communities.

DATA SYNTHESIS

In healthy adults and in the elderly, spontaneous consumption of alcoholic beverages within 30 g ethanol/d for men and 15 g/d for women is to be considered acceptable and do not deserve intervention by the primary care physician or the health professional in charge. Patients with increased risk for specific diseases, for example, women with familiar history of breast cancer, or subjects with familiar history of early cardiovascular disease, or cardiovascular patients should discuss with their physician their drinking habits. No abstainer should be advised to drink for health reasons. Alcohol use must be discouraged in specific physiological or personal situations or in selected age classes (children and adolescents, pregnant and lactating women and recovering alcoholics). Moreover, the possible interactions between alcohol and acute or chronic drug use must be discussed with the primary care physician.

CONCLUSIONS

The choice to consume alcohol should be based on individual considerations, taking into account the influence on health and diet, the risk of alcoholism and abuse, the effect on behaviour and other factors that may vary with age and lifestyle. Moderation in drinking and development of an associated lifestyle culture should be fostered.

Alcohol use behaviors, fat intake and the function of pancreatic β-cells in non-obese, healthy Korean males: findings from 2010 Korea National Health and Nutrition Examination Survey

AIMS

In the present study, we aimed to identify dietary factors related to insulin secretion function especially in healthy, non-obese Korean males.

METHODS

Data were obtained from the Korea National Health and Nutrition Examination Survey V-1 (KNHANES V-1). Nine hundred and twenty male adults aged >30 years of normal weight were included, excluding those with type 2 diabetes mellitus and liver disease. Alcohol use disorders identification test (AUDIT) score which represents alcohol use behaviors and nutrient intakes was used, and homeostasis model assessment of β-cell function (HOMA-B score) was calculated.

RESULTS

HOMA-B score was associated with age (p < 0.001), AUDIT score (p = 0.030), and percentage of fat from total energy intake (p = 0.002). HOMA-B scores in the problematic AUDIT group were significantly lower than those in the normal AUDIT group. In addition, HOMA-B scores in the lowest fat intake group were significantly lower than those in the medium fat intake group, but similar to those in the highest fat intake group. There was an interaction between alcohol use behaviors and percentage of fat from energy intake in determining HOMA-B score (p for interaction = 0.034).

CONCLUSIONS

Alcohol use behaviors and percentage of fat from energy intake were found to be associated with HOMA-B score in healthy, non-obese Korean males.