**1. Introduction**

Alcohol abuse and alcoholism represent substantial problems that affect a large portion of individuals throughout the world. More than 200 disease and injury conditions are caused by alcohol consumption due to liver cirrhosis, cancer and various injuries [1]. According to Organization for Economic Cooperation and Development (OECD) report released in May 2015, alcoholism has been increased by about 55% between 1992 and 2012. It is a quickly rising concern among the youth of the country. According to WHO [2], alcohol per capita consumption increased in China and India (China: 4.1, 7.1 and 7.2 liters in 2005, 2010 and 2016 respectively; India: 2.4, 4.3 and 5.7 liters in 2005, 2010 and 2016 respectively). By 2025, the highest increase in per capita alcohol consumption is expected in India and China covering largest population of South-East Asia and Western Pacific region. **Table 1** indicates Indian scenario of alcohol consumption.

Approximately 80% of the college students consume alcohol which can have short- and long-term consequences including increased risk of accidental injury, risky sexual behavior, and lower education attainment. Alcohol use stimulates the Hypothalamic-Pituitary-Adrenal (HPA) axis and causes stress-like cortisol responses [3, 4]. Frequent stimulation of the HPA by alcohol may alter the function of the system, setting the stage for reduced activity to stressors and increased likelihood of alcohol use disorder. Moreover, abnormal stress physiology is related to greater addiction severity, cravings, and poor treatment outcome alcohol use disorder [5]. More than 90% of people who drink heavily develop fatty liver, a type of liver disease. Yet only 20% will go on to develop the more severe alcoholic liver disease and liver cirrhosis [6]. Environmental factors and genetic differences in the


#### **Table 1.**

*State-wise alcohol consumption per capita per week in India [7].*

way alcohol is metabolized, also contribute to the development of alcoholic pancreatitis [8]. Genetic factors, for example, variation in enzyme activity that metabolize alcohol and environmental factors, for example, quantity of alcohol and overall nutrition a person consume play an important role in the etiology of alcoholic liver disorders including liver cancer. It has been reported that in the population of Central India who consume alcohol are at risk for liver disorders due to ALDH2, GSTM1 and GSTT1 gene polymorphism [9, 10].

This article mainly focuses on the consequences of alcohol consumption at genetic level that ultimately affect alcohol metabolism resulting in various health disorders.

## **2. Alcohol types and components**

There are two categories of alcoholic beverages, fermented (beer and wine) and distilled (whiskey, rum, gin, vodka etc.) and the concentration of ethanol differs across preparation. Yeast fermented alcoholic drinks generally contain less concentration of alcohol since yeast stops growing at about 15% ethanol concentration while strong alcoholic drinks/liquors are prepared through distillation [11].

**125**

*Genetic Polymorphism and Alcohol Metabolism DOI: http://dx.doi.org/10.5772/intechopen.88907*

organometals [12].

individual [17].

alcohol-related problems [23].

**3. Alcohol metabolism**

**4. Oxidative metabolism**

Most alcoholic beverages mainly contain ethanol and water. Some beverages like beer, wine, spirit contain volatile and non-volatile substances along with ethanol. Volatile compounds include hydrocarbons, aliphatic carbon compounds, monocarboxylic acids esters, compounds having sulfur and nitrogen, benzene etc. Dibasic carboxylic acids, tribasic carboxylic acids, coloring agents, inorganic salts polyphenols, tannic acid etc. are the non-volatile substances [12]. Contaminants and toxins found are nitrosamines, mycotoxins, ethyl carbamate, pesticides, thermal processing contaminants, benzene, and inorganic contaminants include lead, cadmium, arsenic, copper, chromium, inorganic anions, and

Regardless of how much a person consume, the body can only metabolize a certain amount of alcohol every hour. That amount varies widely among individuals and depending on liver size and body mass [13]. The effects of alcohol on various tissues depend on blood alcohol concentration (BAC) over time. The time of alcohol absorption, distribution, metabolism and excretion determines BAC [14]. After absorption from small intestine, alcohol reaches liver for metabolism. The rate of BAC rise depends on how quickly alcohol is emptied from the stomach and its metabolism during first pass through stomach and liver [15, 16]. BAC depends on various factors viz. the presence of food in the stomach, alcoholic beverages, the rate of alcohol drinking and genetic polymorphism of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Depending upon age, diet, alcohol consumption and smoking, the rate of alcohol elimination varies from individual to

In the developing world, alcohol use is one of the prevalent habit and is responsible for liver cancer [18–20]. Heavy drinking along with smoking increase the risk of developing cancers [21]. Observations suggest that some people develop cancer even at moderate daily alcohol consumption indicating that alcohol metabolism is genetically determined [22]. Also, those who typically consumed more than two drinks per drinking day were at increased risk of high blood pressure, high triglycerides, increased abdominal girth, and elevated blood glucose. Further, excessive per-occasion consumption is the primary risk factor for both acute and chronic

The pharmacologic and potentially pathologic effects of alcohol depend on the concentration of ethanol and its metabolites in the body, and on the duration of exposure to these substances. Alcohol is metabolized in the body by various mechanisms, that is, oxidative pathways involving alcohol dehydrogenase (ADH), aldehyde dehydrogenase (ALDH), cytochrome P450, and catalase enzymes (which

Most of the alcohol that people drink is metabolized in the liver. First, alcohol is oxidized to acetaldehyde by alcohol dehydrogenase (ADH). Acetaldehyde is highly toxic to the body, even in low concentrations. In the second step, acetaldehyde is further metabolized by ALDH to acetate and eventually to acetyl CoA, which then is broken down into water and carbon dioxide for easy elimination (**Figure 1**). Thus depending on the nutritional, hormonal, energetic status, the acetyl CoA is con-

either add oxygen or remove hydrogen) and non-oxidative pathways.

verted to CO2, ketone bodies, fatty acid and Cholesterol [14].

*Genetic Polymorphism and Alcohol Metabolism DOI: http://dx.doi.org/10.5772/intechopen.88907*

*The Recent Topics in Genetic Polymorphisms*

**country liquor (ml)** **Beer, imported alcohol, wine (ml)**

Andhra Pradesh 561 104 Madhya Pradesh 133 12

Assam 304 19 Manipur 155 6 Bihar 266 17 Meghalaya 74 49 Chandigarh 37 42 Mizoram 29 2 Chhattisgarh 120 27 Nagaland 159 23

Daman and Diu 252 1079 Pondicherry 154 144 Delhi 55 86 Punjab 141 50 Goa 47 108 Rajasthan 80 43 Gujarat 53 3 Sikkim 41 307 Haryana 89 43 Tamil Nadu 20 85

**State/UT Toddy and** 

656 532 Lakshadweep 0 0

749 346 Maharashtra 65 19

2533 498 Orissa 146 20

149 73 Tripura 163 2

32 7 Uttar Pradesh 34 5

**country liquor (ml)** **Beer, imported alcohol, wine (ml)**

**State/UT Toddy and** 

Andaman and Nicobar Island

Arunachal Pradesh

Dadra and Nagar Haveli

Himachal Pradesh

Jammu and Kashmir

**Table 1.**

way alcohol is metabolized, also contribute to the development of alcoholic pancreatitis [8]. Genetic factors, for example, variation in enzyme activity that metabolize alcohol and environmental factors, for example, quantity of alcohol and overall nutrition a person consume play an important role in the etiology of alcoholic liver disorders including liver cancer. It has been reported that in the population of Central India who consume alcohol are at risk for liver disorders due to ALDH2,

Jharkhand 320 14 Uttarakhand 38 43 Karnataka 23 102 West Bengal 74 12

This article mainly focuses on the consequences of alcohol consumption at genetic level that ultimately affect alcohol metabolism resulting in various health

There are two categories of alcoholic beverages, fermented (beer and wine) and distilled (whiskey, rum, gin, vodka etc.) and the concentration of ethanol differs across preparation. Yeast fermented alcoholic drinks generally contain less concentration of alcohol since yeast stops growing at about 15% ethanol concentration while strong alcoholic drinks/liquors are prepared through distillation [11].

GSTM1 and GSTT1 gene polymorphism [9, 10].

*State-wise alcohol consumption per capita per week in India [7].*

**2. Alcohol types and components**

Kerala 94 102

**124**

disorders.

Most alcoholic beverages mainly contain ethanol and water. Some beverages like beer, wine, spirit contain volatile and non-volatile substances along with ethanol. Volatile compounds include hydrocarbons, aliphatic carbon compounds, monocarboxylic acids esters, compounds having sulfur and nitrogen, benzene etc. Dibasic carboxylic acids, tribasic carboxylic acids, coloring agents, inorganic salts polyphenols, tannic acid etc. are the non-volatile substances [12]. Contaminants and toxins found are nitrosamines, mycotoxins, ethyl carbamate, pesticides, thermal processing contaminants, benzene, and inorganic contaminants include lead, cadmium, arsenic, copper, chromium, inorganic anions, and organometals [12].

Regardless of how much a person consume, the body can only metabolize a certain amount of alcohol every hour. That amount varies widely among individuals and depending on liver size and body mass [13]. The effects of alcohol on various tissues depend on blood alcohol concentration (BAC) over time. The time of alcohol absorption, distribution, metabolism and excretion determines BAC [14]. After absorption from small intestine, alcohol reaches liver for metabolism. The rate of BAC rise depends on how quickly alcohol is emptied from the stomach and its metabolism during first pass through stomach and liver [15, 16]. BAC depends on various factors viz. the presence of food in the stomach, alcoholic beverages, the rate of alcohol drinking and genetic polymorphism of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Depending upon age, diet, alcohol consumption and smoking, the rate of alcohol elimination varies from individual to individual [17].

In the developing world, alcohol use is one of the prevalent habit and is responsible for liver cancer [18–20]. Heavy drinking along with smoking increase the risk of developing cancers [21]. Observations suggest that some people develop cancer even at moderate daily alcohol consumption indicating that alcohol metabolism is genetically determined [22]. Also, those who typically consumed more than two drinks per drinking day were at increased risk of high blood pressure, high triglycerides, increased abdominal girth, and elevated blood glucose. Further, excessive per-occasion consumption is the primary risk factor for both acute and chronic alcohol-related problems [23].
