Validation of Alcohol Flushing Questionnaires in Determining Inactive Aldehyde Dehydrogenase-2 and Its Clinical Implication in Alcohol-Related Diseases

Epidemiologic relationship between alcohol flushing and smoking in the Korean population: the Korea National Health and Nutrition Examination Survey

Although facial flushing after drinking alcohol (alcohol flushing response) is common in Asian populations, the epidemiological features in a large sample have been investigated in only a few studies. This study assessed the epidemiologic characteristics and associated factors for alcohol flushing in a Korean population. This study was based on data collected during the 2019 Korea National Health and Nutrition Examination Survey (KNHANES). A total of 5572 Korean adults was included in the general population group, and the alcohol flushing group consisted of 2257 participants. Smoking and physical activity were evaluated as possible associated factors for alcohol flushing. The overall prevalence of alcohol flushing was estimated at 40.56% of the general population (43.74% in males and 37.4% in females), and the prevalence was highest at 60-69 years of age and lowest in individuals older than 80 years. Occasional, frequent, and persistent alcohol flushing was reported by 11.9%, 3.7% and 15.0% of current flushers, among whom persistent flushers consumed the least amount of alcohol. Subjects who currently smoke had a higher propensity of alcohol flushing (adjusted OR 1.525, 95% CI 1.2-1.938), and subjects with smoking history of 20-29 pack-years (PYs) showed the highest association (adjusted OR 1.725, 95% CI 1.266-2.349) with alcohol flushing after adjustment for confounders. In contrast, significant association was not found between physical activity and alcohol flushing. The results demonstrated that current smoking status is shown to be significantly associated with alcohol flushing, and that current smokers with a history of smoking ≥ 20 PYs had a higher likelihood of alcohol flushing than non-smokers or ex-smokers.

Effect of alcohol consumption on risk of hypertension based on alcohol-related facial flushing response: From the health examinees study

BACKGROUND

Alcohol consumption is a significant public health concern in Korea, with many individuals engaging in risky drinking behaviors. This study aims to analyze the association between facial flushing responses and the progression of hypertension in Korean adults, stratified by gender, using a large-scale prospective cohort study.

METHODS

This study included 39,868 participants (males 10,868 and females 29,000) from the health examinees cohort. Participants were divided into two groups according to their weekly drinking patterns (moderate and heavy) and facial flushing responses (non-flusher and flusher) for statistical analysis. A multivariate Cox proportional hazards regression model was used to calculate hazard ratios and 95% confidence intervals between flushing response after alcohol consumption and hypertension risk.

RESULTS

In males, the flusher group with a moderate alcohol intake pattern had a decreased risk of incident hypertension compared with non-flushers. In females, the flusher group had relatively higher risk of pre-hypertension and hypertension compared to the non-flusher group.

CONCLUSION

The association between facial flushing and hypertension varies depending on the level of alcohol consumption and should be considered in relation to gender differences. Further research is needed to understand the relationship between facial flushing response and the risk of hypertension based on alcohol consumption levels.

Asian flush is a potential protective factor against COVID-19: a web-based retrospective survey in Japan

BACKGROUND

Coronavirus disease 2019 (COVID-19), first reported in December 2019, spread worldwide in a short period, resulting in numerous cases and associated deaths; however, the toll was relatively low in East Asia. A genetic polymorphism unique to East Asians, Aldehyde dehydrogenase 2 rs671, has been reported to confer protection against infections.

METHOD

We retrospectively investigated the association between the surrogate marker of the rs671 variant, the skin flushing phenomenon after alcohol consumption, and the timing of COVID-19 incidence using a web-based survey tool to test any protective effects of rs671 against COVID-19.

RESULTS

A total of 807 valid responses were received from 362 non-flushers and 445 flushers. During the 42 months, from 12/1/2019 to 5/31/2023, 40.6% of non-flushers and 35.7% of flushers experienced COVID-19. Flushers tended to have a later onset (Spearman's partial rank correlation test, p = 0.057, adjusted for sex and age). Similarly, 2.5% of non-flushers and 0.5% of flushers were hospitalized because of COVID-19. Survival analysis estimated lower risks of COVID-19 and associated hospitalization among flushers (p = 0.03 and <0.01, respectively; generalized Wilcoxon test). With the Cox proportional hazards model covering 21 months till 8/31/2021, when approximately half of the Japanese population had received two doses of COVID-19 vaccine, the hazard ratio (95% confidence interval) of COVID-19 incidence was estimated to be 0.21 (0.10-0.46) for flusher versus non-flusher, with adjustment for sex, age, steroid use, and area of residence.

CONCLUSIONS

Our study suggests an association between the flushing phenomenon after drinking and a decreased risk of COVID-19 morbidity and hospitalization, suggesting that the rs671 variant is a protective factor. This study provides valuable information for infection control and helps understand the unique constitutional diversity of East Asians.

Current Status of Korean Alcohol Drinking in Accordance with the Korean Alcohol Guidelines for Moderate Drinking Based on Facial Flushing

Since each person has a different ability to break down alcohol, it is inappropriate to apply a uniform standard to everyone when evaluating drinking status. In Korea, there has been a guideline for moderate drinking based not only on sex and age but Koreans' alcohol metabolism capabilities that can be predicted by presence of facial flushing response. So far, there have been no studies that have investigated drinking habits of Koreans in accordance with the guideline. This study tried to identify the current drinking status of Koreans according to the guideline. As a result, it was confirmed that about 1/3 of the total population was accompanied by facial flushing when drinking alcohol, and it was found that different drinking habits were shown even in the same age and gender groups according to the presence of facial flushing. It is difficult to accurately evaluate drinking habits because facial flushing has not yet been investigated in some large data or various medical examinations. In the future, it is necessary to ensure that the presence of facial flushing can be confirmed at the medical treatment or examination site so that accurate drinking habit evaluation and prevention and resolution of drinking problems can be achieved.

The alcohol flushing response is associated with the risk of depression

The alcohol flushing response is experienced by 36–45% of East Asians after they consume a small amount of alcohol. Because individuals with this response are unable to metabolize the toxic acetaldehyde derived from alcohol effectively, the response offers a potential indicator of the health risks associated with alcohol intake. Depression is a major health problem linked to alcohol consumption; it might also be associated with the alcohol flushing response. Therefore, we examined the association between the alcohol flushing response and the risk of depression in the general population of South Korea. Our analysis included 139,380 participants and used data from the 2019 Korean Community Health Survey. Only current drinkers were considered in the analysis. The relationship between the alcohol flushing response and depression was evaluated by logistic regression analysis using SAS 9.4. Of the participants, more than one-third were current flushers; compared to never flushers, current flushers had a significantly greater risk of depression (adjusted odds ratio [AOR] 1.23, 95% confidence interval [CI] 1.12–1.34, P < 0.001). Former flushers did not exhibit a risk of depression. The risk of depression was significantly greater among alcohol flushers who drank < 15 g alcohol/day (< 5 g alcohol/day: AOR 1.20, 95% CI 1.07–1.35, P = 0.002; 5–14.9 g alcohol/day: AOR 1.39, 95% CI 1.13–1.70, P = 0.002). In conclusion, a large number of South Koreans experience the alcohol flushing response; compared with never flushers, current flushers are more likely to develop depression with a small dose of alcohol (< 15 g alcohol/day).

Relationship between Alcohol Consumption and Testosterone Deficiency according to Facial Flushes among Middle-Aged and Older Korean Men

BACKGROUND

This study examined the relationship between alcohol consumption and total testosterone deficiency based on facial flushing among Korean men.

METHODS

A total of 314 men were included in this study and divided into non-drinkers (n=78) and drinkers (n=236). Drinkers were also divided into flushers (n=96) and non-flushers (n=140). Flushers and non-flushers were separated into two groups based on the amount of alcohol consumed: moderate drinkers (≤8 standard drinks per week) and heavy drinkers (>8 standard drinks per week). Total testosterone <3.5 ng/mL was defined as testosterone deficiency.

RESULTS

The risk of testosterone deficiency was significantly higher in heavy drinkers who flushed than in nondrinkers (odds ratio, 4.37; 95% confidence interval, 1.20-15.88; P=0.025). However, no significant difference was observed in the risk of testosterone deficiency in non-flushers, regardless of the amount of alcohol consumed.

CONCLUSION

This study suggests that the risk of testosterone deficiency increases in heavy drinkers (>8 drinks per week) who flush compared to that in non-drinkers.

Alcohol Consumption and Cigarette Smoking among Young Adults: An Instrumental Variable Analysis Using Alcohol Flushing

Association between drinking and smoking has remained controversial since the association between two studies were influenced by various confounding. Thus, our study aimed to explore the causal effect of alcohol consumption and cigarette smoking using alcohol flushing as an instrument variable, which is free from confounders. We analyzed cross-sectional survey data from 2500 Korean young adults (1600 men and 900 women). Alcohol flushing was strongly associated with log transformed alcohol consumption (F = 272). In men, alcohol non-flushers were 1.41 times (95% CI 1.28-1.55) more likely to smoke 100 cigarettes in their lifetime in logistic regression analysis. Alcohol non-flushers were also 1.3 times (95% CI 1.21-1.40) more likely to become daily smokers and 1.39 times (95% CI 1.27-1.51) more likely to be current smokers than alcohol flushers. However, in an IV analysis, no causal relationships between alcohol consumption and smoking status were found. Alcohol consumption, on the other hand, was causally associated with lowering nicotine dependence and former smoking in men. Alcohol consumption determined by alcohol flushing status does not appear to be causally linked to the smoking behavior of young adults. The relationship between alcohol consumption and nicotine dependence and smoking cessation needs further study.

Combinations of alcohol-induced flushing with genetic polymorphisms of alcohol and aldehyde dehydrogenases and the risk of alcohol dependence in Japanese men and women

OBJECTIVE

The risk of alcohol dependence (AD) in Japanese men and women was evaluated according to combinations of alcohol flushing and aldehyde dehydrogenase-2 (ALDH2, rs671) and alcohol dehydrogenase-1B (ADH1B, rs1229984) genotypes, all of which are known to determine AD susceptibility in Asians. Previous studies have focused on men, since women account for a smaller proportion of AD subjects.

METHODS

Case control studies were conducted between 3721 male and 335 female AD Japanese and 610 male and 406 female controls who were asked about their current or former tendency to experience facial flushing after drinking a glass of beer and underwent ALDH2 and ADH1B genotyping. The time at which alcohol-induced facial flushing tendencies had disappeared in former-flushing AD subjects was also evaluated.

RESULTS

Current alcohol flushing, the inactive ALDH2*1/*2 genotype, and the fast-metabolizing ADH1B*2 allele were less frequently found in the AD groups. Although alcohol flushing was strongly influenced by the ALDH2 and ADH1B genotypes, multiple logistic model showed that never or former flushing and the genotype combinations were independent strong risk factors of AD in men and women. Never or former flushing (vs. current flushing) markedly increased the odds ratios of AD in carriers of each of the ALDH2 and ADH1B genotype combinations. The temporal profiles for drinking and flushing in former-flushing AD subjects revealed that the flushing response disappeared soon after or before the start of habitual drinking during young adulthood, regardless of the ALDH2 genotype.

CONCLUSION

Although alcohol flushing is influenced by the ALDH2 and ADH1B genotypes, constitutional or acquired flushing tolerance is an independent susceptibility trait for AD. The combination of the alcohol flushing status and the ALDH2 and ADH1B genotypes can provide a better new strategy for AD risk assessment than the alcohol flushing status alone or the genotypes alone in Asian men and women.

Association between the incidence of hypertension and alcohol consumption pattern and the alcohol flushing response: A 12-year follow-up study

BACKGROUND

Alcohol consumption is associated with hypertension, and this association depends on the alcohol consumption pattern and alcohol flushing response. In this 12-year follow-up study, we investigated the relationship between the alcohol consumption pattern and incidence of hypertension in the Korean population.

METHODS

We analyzed 1,366 Korean participants in the Ansung-Ansan cohort study without hypertension at baseline. The subjects were classified into four alcohol consumption patterns: never-drinking, light alcohol consumption, moderate alcohol consumption, and heavy alcohol consumption, and as flushers or non-flushers in response to alcohol.

RESULTS

In flushers, moderate and heavy alcohol consumption patterns increased the risk of incident hypertension compared with never-drinkers [moderate: HR 1.811 (95% CI 1.084-3.028); heavy: HR 2.494 (95% CI 1.185-5.247)], but non-flushers were not associated with increased risk of incident hypertension according to the alcohol consumption pattern. In addition, a heavy alcohol consumption pattern increased the risk of hypertension among flushers compared with non-flushers [HR 2.232 (95% CI 1.054-4.728)].

CONCLUSION

In this 12-year follow-up study, we observed that moderate and heavy alcohol consumption was associated with an increased risk of hypertension in flushers. Especially, a heavy alcohol consumption pattern in flushers markedly increased the risk of hypertension.

Association Between ALDH2 Polymorphism and Gastric Cancer Risk in Terms of Alcohol Consumption: A Meta-Analysis

BACKGROUND

Alcohol may increase gastric cancer risk. Alcohol can be more carcinogenic in persons who possess inactive ALDH2. The aim of this meta-analysis was to evaluate whether ALDH2 polymorphism can affect alcohol-induced gastric carcinogenesis.

METHODS

We searched the PubMed, EMBASE, and Cochrane databases to identify relevant articles published between January 2000 and September 2019. Eligible articles were selected according to inclusion and exclusion criteria. The data were analyzed using Review Manager 5.3.

RESULTS

A total of 7 case-control studies on ALDH2 rs671 polymorphism consisting of 3,251 gastric cancer cases and 4,943 controls were included in the analysis. Inactive ALDH2 genotypes (G/A or A/A) were associated with an increased risk of gastric cancer (odds ratio [OR] = 1.26, 95% confidence interval [CI]: 1.04 to 1.52, p = 0.02, I²  = 64%), compared with active ALDH2 (G/G genotype). Subgroup analysis by alcohol consumption showed that inactive ALDH2 increased risk for gastric cancer in moderate to heavy drinkers (OR = 1.85, 95% CI: 1.52 to 2.25, p < 0.01, I² = 6%) more than in nondrinkers or mild drinkers (OR = 1.19; 95% CI: 1.05 to 1.36, p < 0.01, I²  = 6%). Moderate/heavy alcohol consumption increased gastric cancer risk in individuals with inactive ALDH2 (OR = 2.23, 95% CI: 1.63 to 3.05, p < 0.01, I² = 30%) more than those with active ALDH2 (OR = 1.40, 95% CI: 0.98 to 2.01, p = 0.07, I² = 85%).

CONCLUSIONS

The ALDH2 polymorphism modifies the risk of gastric cancer. Moderate/heavy drinkers are more susceptible to gastric cancer than non-drinkers or light drinkers with inactive ALDH2.

Aldehyde Dehydrogenase, Liver Disease and Cancer

Acetaldehyde dehydrogenase 2 (ALDH2) is the key enzyme responsible for metabolism of the alcohol metabolite acetaldehyde in the liver. In addition to conversion of the acetaldehyde molecule, ALDH is also involved in other cellular functions. Recently, many studies have investigated the involvement of ALDH expression in viral hepatitis, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), liver fibrosis, and liver cancer. Notably, ALDH2 expression has been linked with liver cancer risk, as well as pathogenesis and prognosis, and has emerged as a promising therapeutic target. Of note, approximately 8% of the world's population, and approximately 30-40% of the population in East Asia carry an inactive ALDH2 gene. This review summarizes new progress in understanding tissue-specific acetaldehyde metabolism by ALDH2 as well as the association of ALDH2 gene polymorphisms with liver disease and cancer. New research directions emerging in the field are also briefly discussed.

Korean Alcohol Guidelines for Moderate Drinking Based on Facial Flushing

This study investigated advantages and potential risks associated with drinking alcohol in Koreans based on the alcohol flush reaction. Our investigation reviewed published studies and examined moderate-drinking levels for Koreans based on modified National Institute on Alcohol Abuse and Alcoholism guidelines. Fourteen articles out of a total 198 publications were searched using PubMed, EMBASE, KoreaMed, and RISS (Research Information Sharing Service) databases and selected for review. Individuals without alcohol flush reaction (non-flushers) exhibited lower risks associated with insulin resistance, metabolic syndrome, and hyperhomocysteinemia and their 10-year cardiovascular disease risk when alcohol consumption was ≤8 drinks/wk. Conversely, risks associated with insulin resistance, metabolic syndrome, high blood pressure, prediabetes or type-2 diabetes, and high intraocular pressure and increases in carbohydrate-deficient transferrin, gamma glutamyl transferase, and blood glucose levels were present when >8 drinks were consumed. For individuals with flushing reaction (flushers), advantages were reported in relation to risks of hyperhomocysteinemia when alcohol consumption was ≤4 drinks/wk, whereas consumption of >4 drinks/wk increased the risk of insulin resistance, metabolic syndrome, high blood pressure, pre-diabetes or type-2 diabetes, high-risk colorectal adenoma, and high intraocular pressure and increased carbohydrate-deficient transferrin, gamma glutamyl transferase, and blood glucose levels. The moderate drinking level for Koreans is ≤8 drinks/wk for men aged ≤65 years and ≤4 drinks/wk for men aged over 65. For women, these limits should be half of those for men. Furthermore, individuals with flushing reaction should maintain an alcohol consumption level half of that for non-flushers.

Validation of Alcohol Flushing Questionnaire to Identify ALDH2 Status in a Case-Control Study of Head and Neck Cancer

BACKGROUND

Carriers of the ALDH2*2 allele have impaired alcohol metabolism and are more susceptible to the development of alcohol-related cancers, including head and neck cancer (HNC). Screening for ALDH2*2 allele may identify high-risk individuals for alcohol health education. Although genotyping of ALDH2 is the most accurate way to identify ALDH2 deficiency, it may not be practical due to the cost and requirement for genotyping service.

METHODS

This study evaluated the accuracy of the alcohol flushing questionnaire to identify ALDH2 deficiency in a case-control study of HNC conducted in Taiwan using data collected from 904 patients with HNC and 1,078 controls.

RESULTS

Overall, alcohol flushing questionnaire had a high sensitivity (89%) of identifying ALDH2*2 carriers among the control subjects and a good sensitivity (79%) among the patients with HNC. The sensitivity of the alcohol flushing questionnaire in identifying ALDH2*2 carriers was affected by alcohol use, with a lower sensitivity among individuals who consumed alcohol, particularly among current regular (drinking alcohol once per week or more) alcohol drinkers.

CONCLUSIONS

The current validation study showed that the alcohol flushing questionnaire may be a reasonable method to identify ALDH2-deficient individuals. However, current regular users of alcohol who reported no alcohol flushing may need to undergo genotyping of ALDH2 for a more accurate assessment of the ALDH2 status.

Primary Reason for Drinking Among Current, Former, and Never Flushing College Students

Alcohol consumption among individuals who experience a flushing response (reddening of the face, nausea, dizziness, headache, anxiety, and increased heartbeat) can result in serious health problems. However, studies on reasons for drinking among flushers, especially in the college context, are limited. Thus, this study investigated the association between primary reason for drinking and alcohol use among a nationally representative sample of current, former, and never flushing college students. The aim was to measure whether college students with current or former experience of facial flushing have different primary reasons for drinking compared to students with no experience of facial flushing. We surveyed and analyzed the data of 4590 students in a nationally representative sample of 82 colleges in South Korea. Multiple regression analysis was used to identify the association between primary reason for drinking and alcohol intake. Alcohol intake was measured using the Alcohol Use Disorders Identification Test (AUDIT). Among 1537 current (33.5%), 152 former (3.3%), and 2901 (63.2%) never flushers, mean AUDIT scores were 7.715 ± 5.434, 11.039 ± 6.405, and 10.465 ± 5.779, respectively. Current flushers had significantly higher AUDIT scores when drinking for pleasure (β = 2.696, p < 0.0001) or stress/depression (β = 2.578, p < 0.0001). Primary reasons for drinking were not associated with alcohol intake for former flushers. Never flushers had significantly higher AUDIT scores when drinking for pleasure (β = 2.696, p < 0.0001), stress/depression (β = 2.578, p < 0.0001), or boredom (β = 0.740, p = 0.029) than peer pressure. Our results suggest that former and never flushers consume higher amounts of alcohol on average than never flushers. For current flushers, drinking for pleasure or stress/depression may increase alcohol intake, while for never flushers, drinking for pleasure, stress/depression, as well as boredom may have the same effect.