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Effects of Alcohol on the Body

In our previous article, Alcohol; its Relationship with New Zealanders we discussed alcohol and how it may influence us as a nation. We considered how much we may be drinking, our attitudes towards alcohol and our drinking culture or if there was indeed one. Those of us who choose not to drink alcohol may have experienced peer pressure to do so at times, we looked at why people may insist that we drink from a social standpoint.

Lastly, some figures were presented that implicated alcohol as a contributing factor towards poor outcomes in our health, our road toll, crime rates and national budget. In this article we will explore some of the ways our body responds to alcohol with some interesting ideas about how alcohol may influence the way we feel and behave.

What alcohol does to the body.

Have you ever thought about what happens to alcohol in the body when we have a drink and the different processes that occur? When we swallow the first drink of an alcoholic beverage the alcohol contained is absorbed rapidly by the blood. The stomach absorbs 20% and the intestines absorbs the other 80%. The effect of alcohol can be felt within 5 to 10 minutes after being consumed and usually peaks after 30-90 minutes.

After the alcohol is absorbed into the bloodstream by the digestive system it enters the liver to be metabolised, the liver is also considered part of the digestive system.  We can think of the process of the liver metabolising alcohol as simply breaking it down into a manageable compound or inactive state, so it can then be excreted by the body. We can also picture the liver as a filter which removes harmful toxins from the bloodstream through a process called ‘detoxification’

The Liver

The metabolising of alcohol by the liver is a process of breaking down alcohol from a toxic type substance to water and carbon dioxide. Approximately 90% of the metabolising of alcohol is performed by the liver. The rest is excreted by the lungs (allowing alcohol breath tests) and through the kidneys in the form of urine.

Blood alcohol concentration (BAC) rises when we are drinking faster than the liver can break the alcohol down, we then experience the intoxicating effect of alcohol or ‘drunkenness’. However, the BAC level does not exactly correlate to how a person will react to alcohol, the response will be different depending on different factors such as bodyweight, presence of food in the stomach, how quickly somebody drinks and so on. Genetics is also a determining factor in how people will respond to alcohol, the ability of the enzymes in the liver that break down alcohol differ from person to person because of genetic variance.

Heavy drinking over extended periods of time has been associated with liver disease or alcohol-related liver disease (ALD). For most people, moderate drinking will not lead to ALD, it is excessive consumption that is prolonged over time that may cause ALD. The first stage of ALD is known as ‘fatty liver’ and will usually go away when somebody stops drinking. The accumulation of fat within liver cells inhibits function so therefore the livers’ ability to metabolise alcohol is compromised. Ten to twenty percent of heavy regular drinkers may develop cirrhosis of the liver, usually after a period of 10 or more years drinking. With cirrhosis some of the livers’ cells are replaced by scar tissue which is non-living, the damaged cells no longer function. Initially the early stages of ALD is referred to as fibrosis as the scarring with be less prevalent, but when scar tissue encapsulates a lot of the liver the term used is cirrhosis.

The Brain 

One common adverse effect experienced by many alcoholics from drinking is thiamine deficiency in the brain. Thiamine is another term for vitamin B1 which is found in many foods such as yeast, cereal grains, beans, nuts and meat. All B vitamins are water soluble and are needed for healthy skin, hair, eyes and liver. Thiamine is an essential nutrient needed in all tissues and therefore must be supplied to the brain, thiamine is not made by the body so must be obtained from our diet. Heavy sustained drinking can lead to reduced thiamine uptake by the body which can lead to impairment of brain function. Wernicke’s encephalopathy is a nervous system disease experienced by many alcoholics, it characterised by confusion, unsteady gait or walking and paralysis of the eye muscles. It is estimated that 85% of people with Wernicke’s encephalopathy who continue to drink and remain untreated will go on to develop Wernicke-Korsakoff syndrome, this is characterised by severe impairment of memory, language (aphasia), movement (apraxia) and the ability to process sensory information (agnosia).

Alcohol can profoundly affect our mood, arousal, neuropsychological functioning and the way we behave. Drugs are classified by the chemicals they target within the brain. Stimulants may influence the amount of excitatory neurotransmitters dopamine and norepinephrine produced by the brain. Depressants are considered drugs that target the neurotransmitter GABA in the brain which produces an inhibitory or ‘relaxed’ feeling. Traditionally, alcohol has been considered a depressant, but early research failed to show that alcohol targeted a specific receptor. We can think of a receptor as a lock, and a neurotransmitter as a key specific to that lock. Neurotransmitters are the messengers that communicate between neurons in the brain to respond in a certain manner. Drugs can mimic neurotransmitters because of their similar structure and ‘fool’ the receptor into allowing that drug to attach to it. Although drugs can mimic the brain’s own chemicals, they don’t activate the brain in the same way the natural neurotransmitter does. What happens is abnormal messengers get sent throughout the brains communication network. The person who uses cocaine will experience intense euphoria in way that is not our “normal” experience, the same goes for all the other types of drugs that are used to ‘get high’.

Now, when considering the idea that alcohol is a ‘depressant’ and slows us down or makes us feel ‘mellow’, why do people have a few drinks to feel energetic, so they can ‘liven up the party’ rather than to slow down or ‘mellow out’? Maybe alcohol is more than simply a depressant. Research has shown that the specific effects of alcohol depend on whether blood alcohol content (BAC) is rising or falling not just on how much is consumed. The interesting thing is that while in the process of drinking, alcohol acts as a stimulant, but as drinking tapers off and BAC is falling it acts as a sedative. Drinkers report that as BAC rises they feel elated, excited and can become extraverted while feeling less fatigue, restlessness, tension and depression. Accordingly, drinkers report feeling lethargic, unmotivated, melancholy, tired, tense and confused when the rate they are drinking slows down and BAC falls.

A group of researchers have found that drinking increases the levels of norepinephrine, the neurotransmitter responsible for heightened arousal, which would account for the feeling of elation that some drinkers experience when they begin to drink. This finding is certainly contrary to the belief that alcohol is simply a depressant, norepinephrine is the neurotransmitter that is targeted by many stimulants. Higher levels of epinephrine increase impulsivity or the tendency to react without thinking, this would account for why we can lose our inhibitions when drinking. Intoxicated brains are more likely to seek pleasure without considering the consequences, hence why coupling off with the opposite sex at parties or at a bar is common place. Understanding that norepinephrine is increased when we drink explains some of the effects of alcohol on our behaviour, but not what part of the brain is experiencing changes because of alcohol.

Research shows through brain scans that alcohol decreases activity in the pre-frontal cortex and the temporal cortex. The pre-frontal cortex is responsible for decision making and rational thought, this further explains why alcohol can make us act without thinking. The pre-frontal cortex is also involved in suppressing violent behaviour, many drinkers can become aggressive when drinking and alcohol can be implicated in many acts of violence. The temporal cortex houses the hippocampus which is responsible for forming new memories, decreased activity in this region because of alcohol would account for why many people ‘blackout’ from drinking. Brain scans also reveal that activity in the cerebellum is reduced, this region of the brain is responsible for coordination of motor activity or movement. A cerebellum operating at half speed would make driving heavy machinery hazardous and walking a straight line more difficult. The argument of whether alcohol should be considered as simply a depressant or not is a little complicated because alcohol has been found to affect over 100 unique receptors in the brain. What also needs to be considered is that many systems in the brain are interrelated. It is not clear if alcohol acts directly on those receptors or if or if it is a downstream cascade from it action somewhere else in the brain.

If alcohol is to be considered a depressant it would act on GABBA receptors which were discussed earlier on in this article. Alcohol does indeed act on GABBA receptors but not until alcohol concentrations reached .33ML/L as discovered when GABBA was first isolated. For the average person, concentrations of alcohol over .3ml/L are enough to cause them to vomit and pass out. How then can we explain the euphoria that can be experienced when after the first few drinks? The way alcohol influences other neurotransmitters like norepinephrine would explain this, and the way alcohol effects different people in different ways. 

Other organs and functions of the body that alcohol effects

The heart can also suffer from prolonged heavy drinking. High blood pressure can eventuate leading to stress on the heart and other vital organs. The heart is a muscle and the tissue itself can become damaged leading to stretching and drooping altering its ability to function properly. Over time alcohol can cause the pancreas to produce toxic substances which may lead to pancreatitis, this involves dangerous swelling and inflammation of the blood vessels in the pancreas that prevents proper digestion. Cancer of the mouth, oesophagus, throat, liver and breast have been associated with problem drinking. The immune system will also be compromised from heavy drinking, when this occurs our body becomes an easier target for disease. Research shows that after one single occasion of heavy drinking our immune system can become slower at warding off infections, even up to 24 hours after drinking. All the major organs of our body can be affected by alcohol since they are all interrelated. When we consider the influence, alcohol has over our physical health, the amount of alcohol consumed over time will ultimately be the determining factor, as we know many people drink alcohol without experiencing much in the way of adverse effects or other problems.


We have discussed some of the ways alcohol interacts with human physiology in this article, investigating all the ways in which alcohol can have an impact on our body is a vast topic and beyond the scope of our discussion, but hopefully you have found it informative. This discussion has attempted to be unbiased in its presentation but rather increase awareness of the way alcohol can potentially influence the way we function. We hope that you have come to a better understanding of the body and the amazing way it is able to function, while being aware of how alcohol can have significant and detrimental effects on the way it does function.

Alcohol Addiction if left to run its progressive and destructive course ruins people’s lives, not only the individual suffering the Addiction, also those people who love and care for them. 

Capri Sanctuary provides an environment that has a focus on our Guest’s ‘Wellbeing’. Our clinical programme is evidence-informed and underpinned by our philosophy based in ‘Transformation through Partnership and Relationship’. It is delivered to you by our highly qualified and experienced team and directed to meet our Guest’s specific individual needs. 

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