Alcohol is a substance called ethanol or ethyl alcohol. Alcohol is not made in the body, thus alcohol circulating in the blood has been derived from drinking alcohol-containing beverages. Many tissues throughout the body can break down alcohol, but the liver handles the majority of the task by far. In liver cells, alcohol can be used to make a substance called acetate (a short-chain fatty acid), which then leaves the liver and circulates to other tissue for further energy production.
Alcohol is the only substance that is both a drug affecting brain function and a nutrient (sometimes providing 5–10% of people’s calorie intake). It is dispensed with food, not in a pharmacy. Alcohol is associated with happy times—weddings and celebrations; it is also a cause of misery. The dose determines the effect.
Alcohol is normally consumed not pure (‘neat’) but in aqueous solution in alcoholic beverages that were first developed thousands of years ago. Beer was first drunk by the Sumerians and Babylonians, around 4000 years ago and has been brewed ever since. Wine is mentioned occasionally in the Old Testament (in Genesis 9, Noah planted a vineyard and got drunk), and was important in the life of classical Greece and Rome. It featured in Jesus’ first miracle at the marriage feast in Cana and at his last supper, and passed into the central part of the Christian mass. Alcoholic beverages were also developed in prehistoric times in East Asia, e.g. sake fermented from rice, and in Africa beers from fermented millet or maize. Alcoholic beverages were thus independently discovered in different parts of the world by prehistoric sedentary agriculturalists who were growing barley, rice, or grapes. But the indigenous peoples of Oceania (Polynesians and Australian Aborigines) and of America (American Indians) did not know alcohol until the arrival of the Europeans and had not established ways of using and controlling it.
From the basic fermented beverages alcohol can be concentrated by the process of distillation (which was brought to Europe by the Arabs). Brandy and whisky first appeared in the fifteenth century.
Production of alcoholic beverages
Alcohol is produced by alcoholic fermentation of glucose. The specific enzymes are provided by certain yeasts, Saccharomyces. The biochemical pathway first follows the usual 10 steps of anaerobic glycolysis to pyruvate, as in animal metabolism. Yeast contains the enzyme, pyruvate decarboxylase, not present in animals. This converts pyruvate to acetaldehyde, and then alcohol dehydrogenase converts acetaldehyde to ethanol. The overall reaction is:
C6H12O6 + cofactors + ATP → 2 C2H5OH + 2CO2
Grapes are unusual among fruits in containing a lot of sugar, nearly all glucose (around 16%), so providing an excellent substrate for alcoholic fermentation. Starch is a polymer of glucose. Before it can ferment to alcohol it has to be hydrolysed to its constituent glucose units. Beers are made by malting the starch in barley. To do this the barley is spread out, moist and warm, and allowed to germinate for several days. Enzymes are generated in the sprouting grain that breaks down the stored starch into glucose. The barley is then heated and dried. This kills the embryo, which stops using sugar. For sake the starch is in rice. It is first treated with a mould, Aspergillus oryzae, that grows on the rice and secretes an amylase to yield glucose.
Beer contains around 5% alcohol (unless alcohol reduced), wines contain around 10% alcohol (unless fortified) and spirits are about 30% alcohol. Alcoholic beverages also contain variable amounts of unfermented sugars and dextrins (in beers), small amounts of alcohols other than ethyl (e.g. propyl alcohol), moderate amounts of potassium, almost no sodium, small amounts of riboflavin and niacin but no thiamin, and sometimes vitamin C.
They also contain a complex array of flavour compounds, colours (natural anthocyanins in red wines), phenolic compounds, a preservative (e.g. sodium metabisulphite), and sometimes additives. A standard drink (e.g. ½ pint beer) provides 10 g of ethanol.
History of Using Alcohol
Alcohol has had a prominent role throughout history. Old religious and medical writings frequently recommend its use, although with warnings for moderation. Thanks to alcohol’s antiseptic properties, fermented drinks were safer than water during the centuries before modern sanitation, especially as people moved to towns and villages where water supplies were contaminated. Even mixing alcohol with dirty water afforded some protection from bacteria.
At a time when life was filled with physical and emotional hardships, people valued alcohol for its analgesic and euphoric qualities. People relied on it to lift spirits, ease boredom, numb hunger, and dull the discomfort, even pain, of daily routine. Before the twentieth century, it was one of the few painkillers available in the Western world.
In sharp contrast to what is allowed today, drinking was often encouraged at the work site. Workers might be given alcohol as an inducement to do boring, painful, or dangerous jobs. Distilled spirits, beer, and wine accompanied sailors and passengers on all long voyages, supplying relatively pathogenfree fluid and calories. Legend has it that even the Puritans, a group known for rigid morality, disembarked at Plymouth Rock because their beer supply was depleted.
Sources of Alcohol
|Food name||Weight (g)||Alcohol (g)|
Health Benefits of Alcohol
Let’s discuss on the health benefits with moderate intake of alcohol:
- Increase HDL cholesterol
Moderate alcohol consumption can raise HDL cholesterol and help protect against heart disease. People who consume one to two “drinks” per day (a drink is a mediumsized glass of beer or wine or 45 ml of spirits, all containing about 10 g of ethanol) have less risk of heart disease than those who abstain. Red wine may also be beneficial because it contains natural antioxidants that can protect against oxidation of blood fats.
- Promote longevity
People who drink occasionally promote longevity of life. Study has shown that intake of less than four or two drinks per day for men and women respectively could lower the chances of death by 18 percent. Low amounts are preferred during meals which are termed to be the right way.
- Good mood
Research concluded that moderate intake of alcohol prevents erectile dysfunction similar to red wine intake being beneficial for heart disease. Studies conducted in 2009 shows that risk of erectile dysfunction were lowered by 25 to 30 percent in alcohol drinkers.
- Prevent common cold
Moderate intake of alcohol showed low chances of cold in case of nonsmokers. Study was carried out in 391 adults. Research also showed that intake of 8 to 14 glasses of wine per week showed 60% reduction in chances of developing cold. It is considered to be related with antioxidant properties of wine.
- Lowers risk of dementia
Study conducted in more than 365000 participants found that moderate drinkers have 23 percent less likely to develop cognitive impairment, dementia and Alzheimer’s disease. In moderate amounts, alcohol stresses cells and toughens them to manage the stresses which could lead to dementia.
- Prevent chances of gallstones
Study shows that intake of two units of alcohol per day lowered the chances of developing gallstones by one third.
- Diabetes prevention
Study has shown that healthy adults when consumed one to two glasses per day have low chances of developing type 2 diabetes. Investigated results shows that moderate intake of alcohol has a part in healthy lifestyle to lower the chances of developing type 2 diabetes.
Effect of alcohol on the brain
Pharmacologists classify ethanol as a central nervous system depressant, in the same group as volatile anaesthetic agents. With increasing levels of blood alcohol people pass through successive stages of alcohol intoxication. At the biochemical level alcohol affects a number of neurochemical processes simultaneously. γAminobutyric (GABA) systems (inhibitory) are more active. Activity of the stimulatory glutamate Nmethyldaspartate receptor system is reduced. Dopamine is released and contributes to the reward effects of alcohol. The serotonergic system is stimulated. Reversal of all these effects occurs in the alcohol withdrawn syndrome. Ingestion of alcohol has effects in other systems of the body. There is peripheral vasodilation and increased heart rate. The imbiber may feel warm but be losing more heat than usual. Alcohol inhibits hypothalamic osmoreceptors, hence there is reduced pituitary antidiuretic hormone secretion so there is diuresis (an increased urine output) which can lead to dehydration, especially after drinking spirits.
Effect on Gastrointestinal System
Years of heavy drinking and ongoing contact with alcohol and acetaldehyde eventually damage the gastrointestinal system, which, in turn, discourages eating, affects absorption of protective nutrients, and leaves the digestive lining even more vulnerable to damage as the vicious cycle continues.
Chronic irritation from alcohol and acetaldehyde erodes protective mucosal linings, causing inflammation and release of destructive free radicals. Esophagitis (inflammation of the esophagus), esophageal stricture (closing), and swallowing difficulties are common among alcoholics. When the stomach is exposed repeatedly to alcohol at high concentrations, gastritis (inflammation of the stomach) often develops. Alcoholics frequently have diarrhea and malabsorption, evidence of intestinal damage. Cancer of the upper aerodigestive tract (mouth, pharynx, esophagus to larynx) is common, and consumption of both alcohol and cigarettes further increases the risk of these types of cancers.
Effect on Liver
Metabolizing and detoxifying alcohol is almost entirely the responsibility of the liver. So it’s not surprising that too much drinking hurts the liver more than any other site in the body. In the United States, heavy alcohol use is considered the most important risk factor for chronic liver disease. According to the Centers for Disease Control and Prevention, over 29,000 people die annually in the United States as a result of chronic liver disease and cirrhosis (nearly 10 deaths per 100,000).
The earliest evidence of liver damage is fat accumulation, which can appear after only a few days of heavy drinking. Fatty liver recedes with abstinence but persists with continued drinking. Studies show that 5 to 15 percent of people with alcoholic fatty liver who continue to drink develop liver fibrosis (excessive fibrous tissue) or cirrhosis (scarring) in as soon as 5 to 10 years.
Direct Consequences of Alcohol intake
- Acute intoxication
Acute intoxication can lead to road and other accidents, or domestic and other violence. Intoxicated people can suffer and inflict a range of injuries. Occasionally people consume such a large dose of alcohol that they die with lethal blood levels. The breathalyser was developed to reduce road traffic accidents. In many countries, a driver stopped at random by a police check that has a breathalyser reading corresponding to a blood level of 0.05 g/dL (0.02 to 0.08 in different countries) has his driver’s licence suspended. This measure has reduced traffic accidents and contributed to the decline of alcohol consumption in a number of developed countries.
The excess intake of alcohol the night before may not yet have all been cleared from the blood. Dehydration may be present from diuresis and, with some drinks (e.g. brandy), toxic effects of small amounts of methanol and higher alcohols contribute to the symptoms.
What causes hangover?
Scientists have identified several causes of the painful symptoms of a hangover. Alcohol causes dehydration, which leads to headache and dry mouth. Alcohol directly irritates the stomach and intestines, contributing to stomach pain and vomiting. The sweating, vomiting, and diarrhea that can accompany a hangover cause additional fluid loss and electrolyte imbalance. Alcohol’s hijack of the metabolic process diverts liver activity away from glucose production and can lead to low blood glucose (hypoglycemia), causing lightheadedness and lack of energy. Alcohol also disrupts sleep patterns, interfering with the dream state and contributing to fatigue. The symptoms of a hangover are largely due to inflammation. In general, the greater the amount of alcohol consumed, the more likely a hangover will strike. However, some people experience a hangover after only one drink, whereas some heavy drinkers do not experience hangovers at all.
In addition, factors other than alcohol may contribute to the hangover. A person with a family history of alcoholism has increased vulnerability to hangovers. Mixing alcohol and drugs also is suspected of increasing the likelihood of a hangover. The congeners in most alcoholic beverages can contribute to more vicious hangovers.
Few treatments have undergone rigorous, scientific investigation. Time is the most effective treatment—symptoms usually disappear in 8 to 24 hours. Eating bland foods that contain complex carbohydrates, such as toast or crackers, can combat low blood glucose and possibly nausea. Sleep can ease fatigue, and drinking nonalcoholic beverages can alleviate dehydration. Limited research suggests that taking vitamin B6 or an extract from Optunia ficus indica (a type of prickly pear cactus) before drinking may reduce the severity of hangover symptoms. The prickly pear cactus extract may reduce three symptoms of hangover—nausea, dry mouth, and loss of appetite. The best way to prevent a hangover, of course, is to abstain from drinking alcohol.
Certain medications also can relieve some symptoms. Antacids, for example, may relieve nausea and stomach pains. Aspirin may reduce headache and muscle aches, but could increase stomach irritation. Avoid acetaminophen, because alcohol metabolism enhances its toxicity to the liver. In fact, people who drink three or more alcoholic beverages per day should avoid all over the counter pain relievers and fever reducers. These heavy drinkers may have an increased risk of liver damage and stomach bleeding from medicines that contain aspirin, acetaminophen.
- Chronic alcoholism
Some people become dependent or addicted to alcohol and cannot face the world unless they have some alcohol in their blood throughout the day. Thus they maintain an intake of alcohol per day larger than their liver’s capacity to metabolize it.
- Alcohol withdrawal syndrome
Alcohol addicts who have maintained some alcohol in their blood continuously for weeks or even longer suffer withdrawal symptoms if an accident or illness abruptly removes them from their alcohol supply. There are tremors of the hands, anxiety, insomnia, and tachycardia. Epileptic convulsions can occur and, in severe cases there is agitation, mental confusion, and hallucinations. This is delirium tremens, a severe illness.
- Binge drinkers
Onenight binge drinkers expect to get drunk. Men imbibe 80 g of alcohol (4 pints of beer) or more and women somewhat less. The other pattern of alcohol excess is that a person drinks heavily for weeks. Consequently, as alcohol displaces much of the usual food intake there can be an acute deficiency of micronutrients with the smallest reserve in the body, usually thiamin.
Medical consequences of excess consumption
- Liver disease
Alcohol causes liver damage in three stages. The least severe is fatty liver. Metabolisms of large amounts of ethanol in the liver produce an increased ratio of NADH/NAD; this depresses the citric acid cycle and oxidation of fatty acids, and favours triglyceride synthesis in the liver cells. It used to be thought that the fatty liver was due to an associated nutritional deficiency, but fatty liver has been observed (using needle biopsy of the liver) in volunteers who took a moderately large intake of alcohol but with all nutrients provided under strictly controlled conditions in hospital. The symptoms of fatty liver are not striking. On abdominal examination a doctor can feel that the liver is somewhat enlarged, and this shows with ultrasound; biochemical changes can be seen in a blood sample.
- Metabolic effects
Moderate regular drinkers who are apparently well may have increased plasma triglycerides (an over flow from the overproduction of fat in the liver). Plasma urate is raised because of reduced renal excretion probably due to increased blood lactate, which follows alcohol ingestion.
- Fetal alcohol syndrome
Women who drink alcohol heavily during early pregnancy can give birth to a baby with an unusual facial appearance (small eyes, absent philtrum, thin upper lip), prenatal and postnatal growth impairment, central nervous system dysfunction, and often other physical abnormalities. Mothers of children with the fetal alcohol syndrome were heavy drinkers during their pregnancy and most were socially deprived. More moderate drinkers may have babies that are small for dates but otherwise normal. Some authorities insist that pregnant women should avoid all alcohol, but in a careful prospective study in Dundee, Scotland, Florey’s group found that, after adjustment for the effect of smoking, social class, and mother’s size, there was no detectable effect on pregnancy of alcohol consumption below 100 g/week (i.e. one standard drink a day).
- Wernicke–Korsakoff syndrome
In heavy drinkers who consume large amounts of alcohol and virtually stop eating for 3 or more weeks, brain function can be affected by acute thiamin deficiency. Ethanol uses up thiamin for its metabolism, yet alcoholic beverages provide no thiamin; there is no rich food source of thiamin and body stores are very small. In Wernicke’s encepha lopathy, the patient is quietly confused—not an easy state to recognize in an alcoholic. The diagnostic feature, if the sufferer is brought to medical attention, is that the eyes cannot move properly (ophthalmople gia). When Wernicke’s encephalopathy is treated with thiamin, the ophthalmoplegia and confusion clear but the patient may be left with a loss of recent memory, the inability to recall what has happened recently (Korsakoff’s syndrome). It has been suggested that when an alcoholic has a partner who pro vides food, containing some thiamin, Wernicke– Korsakoff syndrome (WKS) is less likely. The incidence has been high in Australia. Korsakoff’s psy chosis can be permanent. It is one cause of alcoholrelated brain damage. As preventive measure bread is fortified with thiamin since 1991, as it had been for a long time (for other reasons) in the USA, UK, and most other developed countries. WKS has become uncommon in Australia. Wernicke’s encephalopathy uncommonly occurs in people who have not taken alcohol, e.g. with persistent vomiting of pregnancy, hyperemesis gravidarum.
- Other nutritional deﬁciencies in alcoholics
In societies with adequate food supply, vitamin deficiencies are rare but do occur in heavy drinkers. Chronic thiamin or other B vitamin deficiency may be responsible for a peripheral neuropathy in the legs, with reduced function of the motor and sensory nerves and diminished ankle jerks. Folate metabolism is commonly impaired in alcoholics, and megaloblastic anaemia may be seen. Vitamin A metabolism is abnormal where there is alcoholic liver disease: the liver does not store retinol normally or synthesize retinol binding protein adequately. There can, consequently, be reduced plasma retinol and night blindness. Among inorganic nutrients, plasma magnesium and zinc can be subnormal in alcoholics.
- Predisposition to some types of cancer
The risk of cancer of the mouth and pharynx is increased, especially when high alcohol intakes are combined with smoking. Other cancers associated with high alcohol consumption are those of the oesophagus or liver (primary cancer of the liver is a complication of cirrhosis), the rectum (in some beer drinkers), and possibly breast cancer.
- Gastrointestinal complications
Chronic gastritis and gastric or duodenal ulcers may be associated with excessive alcohol consumption. Acute pancreatitis is a severe complication.
- Impaired immunity
Heavy alcohol consumption impairs immunity and increases susceptibility to pneumonia and tuberculosis.
The prevalence of raised arterial blood pressure increases with usual alcohol intakes above three or four drinks per day. Prompt falls of moderately elevated blood pressures have been well documented in heavy drinkers admitted to hospital for detoxication. Increased prevalence of hypertension explains the greater risk of stroke from cerebral haemorrhage in heavy alcohol drinkers. Heavy intakes of alcohol simulate secretion of corticotrophin releasing hormone. Increased cortisol and sympathetic activity may explain the increased blood pressure. Limiting alcohol consumption is a standard part of lifestyle modification recommended for people with hypertension.
Recommendation on Alcohol Intake
In the UK the Department of Health recommends that men consume no more than 3–4 units of alcohol/day and women no more than 2–3 units. It is also recommended that 2 day/week should be alcohol free. As women have lower rates of metabolizing alcohol, advice on safe drinking levels has to be different for men and women. Recommendations are expressed in standard drinks that (in many countries) contain 10 g of pure alcohol. Note that standard drinks are normally served in the pub, but at home people tend to be more generous. In men, two or three standard drinks per day (20–30 g alcohol) (i.e. 140–210 g alcohol/week), are usually biologically safe, but no more than two drinks before driving and a minority of men should not take this much, or even any alcohol (e.g. people with liver disease, taking other sedative drugs, with a history of alcohol dependence). In women, the biologically safe intake is one or two drinks (10–20 g alcohol) per day (i.e. 70–140 g alcohol/week). In pregnancy, intake should be one drink or less, likewise if a woman thinks she might be pregnant. Children should not take alcohol, but in some cultures they are offered a small drink of wine with the family’s main meal and some believe this can be a good training in moderation in consumption of alcohol.
Risks associated with Alcohol intake
Too much alcohol may impair judgment, which can lead to accidents and injury. Drinking beyond moderation is linked to many health problems, including high blood pressure, stroke, heart disease, certain cancers, and diseases of the liver and pancreas. And it’s linked to social problems, too, including violence and suicide. Drinking during pregnancy increases the chances of birth defects. And even one drink a day slightly increases a woman’s risk for breast cancer. Another potential problem: over time some people become dependent on alcohol.