How the body handles alcohol
Alcohol is absorbed from the stomach and small intestine into the bloodstream. The rate at which it is absorbed varies; it is most rapid on an empty stomach, so that a high peak level is quickly reached, and the person feels drunk quickly.
What affects the absorption of alcohol?
Food in the stomach slows down its absorption by up to 50 per cent, thus reducing the peak blood alcohol level. This also means that the same amount of alcohol stays longer in the body when the stomach is full than if it is empty.
The alcohol from wine and sherry reaches the bloodstream more quickly than that from beer, because it is more concentrated. Sugar in sweet drinks retards absorption, whereas the bubbles of carbon dioxide in champagne or gin and tonic accelerate it.
What parts of the body hold alcohol?
Alcohol is distributed throughout the body so that most tissues – the heart, brain and muscles – get the same concentration as present in the blood. The liver receives a higher concentration. Little alcohol enters fat, which has a poor blood supply.
Do women deal differently with alcohol?
Women have more of their body weight as fat and less as muscles and blood. This explains why a woman of the same weight as a man who has drunk the same amount of alcohol will have a higher level of alcohol in blood and tissue.
Women also break down less alcohol in the stomach than men. Women are therefore generally able to tolerate less alcohol than men. In pregnant women alcohol crosses the placenta into the fetus.
How does the body get rid of alcohol?
Alcohol is metabolised by the liver first to a substance called acetaldehyde which is very toxic. It is thought that acetaldehyde may be responsible for some of the physical damage caused by alcohol. Acetaldehyde is quickly changed to a non-toxic substance called acetate. The chemical processes in the liver are complex and require many enzymes, which are substances that assist chemical processes. The way that the liver deals with alcohol can be accelerated or retarded by medications that affect the enzymes. It also varies according to the amount of alcohol drunk, the amount that is normally drunk (what the enzymes are used to dealing with) and whether the liver is healthy or not. Too much alcohol is toxic to the liver, and the process of handling alcohol can be slowed when the liver is diseased, as in cirrhosis of the liver, which occurs after long-term alcohol abuse (see ‘Harm from heavy drinking’ on page 24). Only two to five per cent of alcohol is excreted without processing, either in the urine or in the breath. Although breath concentrations are low, they reflect accurately the blood alcohol level, and this forms the basis of the breathalyser test.
Why can some people ‘hold their drink’ better than others?
The amount of alcohol that people can tolerate depends on a variety of factors including whether food is taken as well.
As explained earlier, women may get a higher alcohol level in the blood than men, after drinking the same amount. The bigger a person is, the more he or she can drink without appearing intoxicated.
The liver enzymes of a person with a regular drinking habit also become more efficient at handling alcohol, and so people who are used to alcohol can burn it off slightly quicker than first-time drinkers. Children are therefore very susceptible, being smaller in size than adults, and less experienced drinkers.
It is mainly the adjustments that the brain cells make that allow regular drinkers to drink without initially showing much effect. This tolerance of the brain cells may be the beginnings of dependence on alcohol.
Tolerance fades: heavy drinkers who abstain for a few weeks rapidly get drunk if they resume their former drinking pattern.
What are the effects of alcohol on the body?
Heart and blood circulation
Alcohol causes an increase in heart rate, and dilates the skin blood vessels, producing a flush. The flush is severe in some people of Chinese or Japanese origin. This causes a feeling of warmth, although body temperature may actually fall because heat from the body is lost through the skin. Drinking brandy from the neck cask of a St Bernard dog who has rescued you in snow could lead to hypothermia!
Alcohol stimulates the release of gastric acids, and can lead to inflammation of the stomach lining. Alcohol also has a diuretic effect, causing more urine to be produced.
However, most people drink for the effects of alcohol on the brain. At blood levels of about 50 mg% most people feel relaxed and carefree. At higher concentrations more brain functions are affected. Speech becomes slurred, memory is impaired and the eyes focus with difficulty. At 100 mg% movement starts to become careless and clumsy, and emotional control and judgement may be impaired. Alcohol can cause people to take more risks. At 200–300 mg% most people are very drunk, and may become unconscious. The level at which alcohol becomes fatal varies – what a hard drinking man regularly tolerates may kill a young girl who has never had a drink before. After the level of alcohol in the blood has peaked, there is a phase when the individual may feel tired, depressed and irritable.
What are the immediate effects of alcohol on the body?
Women may get a higher blood alcohol level than men after drinking the same amount and, in general, the bigger a person the less potent the same amount of alcohol will be. The following are the immediate effects of alcohol:
- Increases the heart rate
- Dilates blood vessels in the skin
- Stimulates the release of gastric juices
- High doses irritate the stomach lining
- May have a diuretic effect – more urine is produced
- Speech may become slurred
- Memory is impaired
- Eyes focus with difficulty
- Movement and coordination may be impaired
- Affects emotional control and judgement
- High doses cause unconsciousness which puts people at grave risk of choking
- High doses may block the breathing centre in the brain
What causes a hangover?
The effects of the congeners in drinks cause the nausea, headache, tremulousness and tiredness that we recognise as a hangover. Dehydration may contribute, and drinking alcohol with sufficient water may prevent some symptoms.
However, as blood levels of alcohol fall during the night, there is a rebound wakefulness, and some of the heightened sensitivity and restlessness is caused by withdrawal. Contrary to popular myth, mixing drinks does not cause a hangover, and nor does avoiding mixing prevent one! It is more likely that, if you do mix drinks, you are taking a large dose of alcohol, which gives you more of a headache the next day.
Harm from heavy drinking
The immediate problems
A large enough dose of alcohol can kill by blocking the breathing centre in the brain. Even if the amount taken is not directly fatal, the deep unconsciousness that it causes puts people at risk of dying from exposure, or choking and suffocating on their own vomit.
Harm from alcohol
Estimates of the involvement of drinking in accidents and crime show that it is a common cause of harm. Alcohol consumption is implicated in:
- 80% of deaths from fires
- 65% of serious head injuries
- 50% of murders
- 40% of road traffic accidents
- 30% of accidents in the home
Other short-term problems include dehydration and low blood sugar, which can be dangerous for young and elderly people, and people taking treatment for diabetes.
The most common reason for drinkers seeing a doctor is an injury caused by drunkenness. When people are drunk they are a danger to themselves and to others. Alcohol is a factor in road, rail, shipping and airplane accidents. One-third of private pilots killed have alcohol in their blood. The accident rate for heavy drinkers at work is three times the normal. About 60 per cent of fatal accidents at work are alcohol related. For more information on drinking and driving, see page 100. Alcohol also leads to greater risk-taking, and may lead to a person making him- or herself vulnerable to crime and assault, both physical and sexual.
The longer-term problems of heavy drinking
Heavy drinking means more than five units per day for women or seven units per day for men. Safe limits are up to a maximum of three units per day for women and four units per day for men. Even so, the Chief Medical Officer has recommended that drinking one to two units a day confers the best health benefits without risk, and that regularly drinking up to a maximum safe limit can lead to problems. And the more the safe limit is exceeded,the more likely illness becomes.
Heart and circulation
From the age of 40, when coronary heart disease begins to affect susceptible people, one to three units a day may help prevent heart attacks and angina. Another type of heart disease occurs in people drinking over 10 units per day. It results from damage to the heart muscle and causes breathlessness and palpitations (a fluttering feeling in the heart), swelling of the ankles and accumulation of fluid in the lungs. Alcohol can cause strokes, partly as a result of high blood pressure, so people with high blood pressure should cut down their drinking.
The irritation to your stomach lining caused by alcohol can cause loss of appetite. When severe, it results in pain, vomiting and bleeding.
The pancreas lies behind your stomach and is also sensitive to alcohol. When its cells become inflamed the pain is very severe. If it becomes damaged permanently, your pancreas cannot make enough insulin, causing diabetes. Enzymes that break food down are not produced and diarrhoea and malnutrition can result.
Liver problems can be deceptive. Although a blood test from your family doctor could show that alcohol is causing harm to your liver, you may notice nothing for years. By then it can be too late. Alcohol can cause several problems with the liver. At first they are mild but as drinking continues they become more serious:
- Fat deposits cause mild symptoms
- Hepatitis and jaundice are more serious
- Cirrhosis can be life threatening
In mild cases, fat gets deposited in the liver, causing the cells to bulge. The liver increases in size, giving rise to vague abdominal discomfort and nausea. In more serious cases, alcoholic hepatitis occurs. Here, the liver cells are inflamed and damaged. The person may feel well, but more often feels ill and weak, and may be jaundiced. Jaundice is a yellowing of the skin caused by the
accumulation, in the blood, of a substance called bilirubin, which is then deposited in the skin. One of the liver’s roles is to process bilirubin to keep the level steady, but, when it is diseased, this process breaks down and the level of bilirubin starts to climb. In the final stage of alcohol damage, cirrhosis occurs. Here, the alcohol has caused permanent damage. The cells of the liver are destroyed, and scarring occurs. The liver’s function is compromised. Proteins needed to maintain muscle are not produced. A person with cirrhosis is often, but not always, jaundiced. Water swells the abdomen (‘ascites’) and the feet and legs (‘oedema’). The scarring and distortion block the flow of blood into the liver. The back pressure that this causes leads to varicose veins swelling up in the stomach and gullet and these can bleed and bleed. Cirrhosis is eventually life threatening. The only cure is liver transplantation. As a result of the shortage of donor organs, doctors may be unwilling to recommend someone who has abused alcohol for this treatment, unless an undertaking to stop drinking is agreed. If cirrhosis has not reached the life-threatening stage, stopping drinking will often halt further damage and allow a reasonable quality of life. People who have hepatitis C virus are advised to stop drinking, to reduce the risk of cirrhosis.
Alcohol can cause cancer in the mouth, throat and gullet. Smoking contributes to these too. Breast cancer is more likely in women who drink more than two units per day.
Brain and nerves
Some heavy drinkers lose mental faculties, especially the ability to remember new things and recent events. It is an exaggeration of what happens in old age.
Others damage their balance mechanism or get pins and needles in the feet and hands; combined with alcohol-induced loss of muscle, this leads to great difficulty in walking. People who drink sometimes do not take a balanced diet and this can result in vitamin deficiency. Alcohol reduces the body’s ability to absorb vitamins from food and a deficiency of vitamin B1 (thiamine) is linked to nerve and brain damage in heavy drinkers.
Alcohol causes changes in the blood cells. Your doctor may unexpectedly find an abnormal test result, due to alcohol, when your blood is taken for some other reason. Regular drinkers may have enlarged red blood cells, but this itself is not dangerous. However, a lack of platelets in the blood may lead to bleeding in the stomach or brain. Blood tests to check how the liver is functioning may show an abnormal result long before liver disease develops. Your doctor will explain whether a result indicates serious illness. Gamma-glutamyl transferase (GGT) measurement is the liver test that has the most sensitivity to drinking.
If you are planning to reduce your alcohol intake, you can ask your doctor to monitor the tests. This gives you and your doctor a way of measuring whether you are being successful in cutting down! There is now a new blood test called carbohydrate-deficient transferase (CDT) which is more accurate than older tests in showing excessive drinking and changes in drinking.
Alcohol can cause mental illness. It alters the brain chemistry to cause depressed mood. This can, of course, also harm important relationships with friends and family. It may be believed, wrongly, that a partner is having an affair and drinking can cause the situation to be blown up out of all proportion. Fortunately quite rare, there is another illness in which the brain can be so damaged that hallucinations occur which may go on for weeks or months. The ‘voices’ may say threatening or derogatory things that are frightening. This can nearly always be cured by medical treatment and avoiding all alcohol.
Regular heavy drinkers give their habit away by their red and blotchy faces, with tiny extra blood vessels in the cheeks and eyes. The bulging red nose comes only after 15 years of tippling! Some people have a condition called psoriasis in which the skin develops red patches and the surface layer is white and flaky. It comes and goes – and heavy drinking can bring on an episode.
Alcoholic drinks are calories without vitamins. A glass of wine or half a pint of lager contains about the same number of calories as a thick slice of bread and butter. Therefore drinkers can put on weight. The beer belly is well named – three pints of beer a day or twenty-one pints per week will increase your weight by about two kilograms in four weeks. Two or three single gin and tonics a day will do the same. And, of course, the same will happen in the next four weeks – and so on! Drinking a glass of sherry can stimulate your appetite, but drinking five or six units regularly without food irritates your stomach lining and causes nausea. This is why some drinkers lose weight and feel weak and easily tired.
Benefits to health
The news on alcohol is not all bad. Used in moderation, some people will actually have better health.
Introducing a ‘cocktail hour’ in old people’s homes improves mobility, memory and social interaction. Requests for sleeping tablets can go down. Small amounts of alcohol can make life seem a little more colourful.
Medical research has found that people who drink moderately – one to three units a day – have less chance than abstainers of getting heart disease. This beneficial effect is seen most in people over the age of 40, and when the alcoholic drink is taken at mealtimes. Alcohol helps to prevent blood clots forming in the arteries. As heart disease is a common cause of death in western society, it means that light/moderate drinkers have a longer life expectancy than either abstainers or heavy drinkers. We can, of course, reduce the chance that we will get heart disease in other ways – stopping smoking, losing weight, eating less animal fats and more fruit and vegetables, and taking more exercise.
Getting a job where we feel in control and achieve satisfaction helps too. People whose pattern is to drink one to three units per day tend to be in that category and often also have a sensible diet – this may contribute to why they have better health. Governments do not advise people to drink to protect their health – if we were told that one or two drinks were good for us, we could imagine that three or four would be even better!
In middle age and later, women who drink a little have stronger bones than those who are teetotal. Heavy drinking, however, can make bones thinner and may lead to more fractures. The advice, as always, is moderation.
Does alcohol improve sex? For some people, a drink can increase their desire. If tension is impeding their enjoyment of sex then relaxing with alcohol can help. Large doses of alcohol block the nerves necessary for sexual function, however, which in the man raises the fear of impotence. If this happens more than once or twice he may get seriously worried about his sexual ability – and worrying about performance is a sure way to impair erection, until confidence is re-established with a sympathetic partner.
Is there a safe limit?
For a woman, the chance of having liver disease or breast cancer begins to go up once she is drinking three units per day. Some people have more resistant bodies than others but we have no way yet of telling in advance who they are. A man’s liver can stand slightly more, but regular drinking of five units per day (35 per week) has been shown to be the start of problems for some men. The safe limit for regular drinking is two units per day for women, three units per day for men. People who drink in occasional sessions should stick to fewer than eight units (five for women) to avoid the dangers associated with being drunk. The media today commonly talk about ‘binge drinking’.
Alcohol can damage genes, leading to abnormal development in the fetus. Most pregnancies with abnormal fetuses miscarry – and pregnant women who drink heavily have twice the rate of miscarriage compared with non-drinkers. If a woman drinks heavily during pregnancy, she runs the risk of having a baby with ‘fetal alcohol syndrome’, in which the baby is mentally handicapped with abnormal facial features, and a variety of neurological, heart, bone and kidney defects. Pregnant women should abstain from alcohol, or at the very least restrict alcohol intake to the occasional drink. Early in pregnancy is the time of greatest danger. Alcohol appears in breast milk in breast-feeding mothers,but the occasional drink before breast-feeding will do no harm.
Alcohol and prescribed drugs
The effect of alcohol on prescribed drugs depends on the drug, and on whether alcohol is taken in a one-off binge, or as part of a chronic problem.
In the first instance, alcohol competes with the drug for liver enzymes, and so the drug is broken down more slowly and becomes ‘stronger’, and works for longer. This can be dangerous, because it is effectively an overdose. The drugs in this category include those in the box. The most common danger of taking alcohol while on a medication comes with any drug that has a sedative effect, however slight. The sedative effect of the alcoholic drink may double the sedative effect of the drug, resulting in accidents. Sedatives include tranquillisers, many antidepressants, antihistamines and all sleeping tablets.
When drinking is heavy and prolonged, the effect is to speed up the liver enzymes (as they get used to dealing with a big load), and so some drugs get dealt with more quickly than normal, and thus have a lesser effect than normal. Drug dosage may need to be increased by the doctor. Some drugs will interact with alcohol to produce an unpleasant flushing, for example, the anti-diabetic medication chlorpropamide and the antimicrobial metronidazole (Flagyl).
Drinking on an empty stomach means that alcohol reaches the brain in a burst
Drinking one to three units per day can reduce the chance of heart disease; more than that can harm health
One unit has the same calories as a slice of bread and butter
Alcohol is a factor in some types of cancer