top of page

Alcohol and your health

Alcohol, chemically known as ethanol (ETOH), is the product produced when yeast breaks down sugar, otherwise known as fermentation. Alcohol provides energy (calories) whilst also being a sedative-hypnotic drug that affects our mental judgement and physical abilities. We all know that alcohol is not that great for us, but why is this, and how might it be affecting your overall health? As ‘dry July’ is coming to an end, I thought it may be an appropriate time to discuss the latest evidence-based information regarding alcohol, some of which you may know, but hopefully you will learn something interesting too.

Topics covered:

1) Nutritional impact of alcohol

(a) Table 1 Energy density of macronutrients and alcohol

(b) Table 2 Nutritional composition of common alcoholic beverages

2) Types of alcoholic beverages

3) How does my body metabolise the alcohol I drink?

4) Why may alcohol be detrimental to my health?

5) How alcohol is becoming a public health problem

6) Realistic tips to keep your alcohol consumption in check

7) Summary

Nutritional impact of alcohol

Like fat, carbohydrate, and protein, alcohol also provides energy. In fact, alcohol is the second most energy-dense after fat, providing 7 calories per gram! In 2016, the worldwide consumption per person over the age of 15 years was 6.4 litres of pure alcohol in one year. This equates to 44,800 calories, which is about 18 days of food for the average person. This is before it is even added into the drink you consume it with, which is often sugar-dense, and therefore even higher in energy.

Table 1 Energy density of macronutrients and alcohol

*One standard drink = 10g alcohol.

Table 2 Nutritional composition of different alcoholic beverages

Note: it was very difficult to find nutritional information for various RTD’s. Did you know, under the rules of Food Standards Australia New Zealand (FSANZ), alcoholic beverages are exempt from having to include a nutrition information panel. This makes it pretty difficult for the general public to be informed of exactly what they are drinking, especially with the higher sugar brews, like RTDs.


Types of alcoholic beverages

Beer: made most commonly from barley, this beverage is no good for those suffering Coeliac disease. Beer can be either an ale or lager depending on the different fermentation process. Both beer and red wine contain phenolic compounds which add the specific tastes and colours.

Wines: New Zealand is world renown for its production of wine. Wine is made from grapes which are crushed and then fermented. However, wine can also be made from sources other than grapes, for example, sake is made from rice. Different production processes will affect the final colour, strength and quality of the wine. Wine is often quite high in sugar, and red wine has antioxidant activity and polyphenols (especially Pinot Noir).

Spirits: these are distilled to produce drinks with higher alcohol concentration. Different spirits may have different herbs and ingredients added to give them their specific quality or flavour. Some examples of where spirits come from include: brandy (distilled wine), whiskey and gin (distilled from grains), rum (from molasses), vodka (from grain or potatoes), and tequila (from agave and cacti plants).

Ready to drink (RTDs): this is a general term for pre-mixed drinks which come in a range of flavours, strengths, and volumes. Some examples include KGB’s, Vodka cruisers, and Smirnoff Ice. These are often very high in sugar per drink and mask the taste of alcohol well, which means they can be easy to over-consume unintentionally.


How does my body metabolise the alcohol I drink?

Alcohol metabolism is relatively complicated, but to briefly explain it, alcohol is metabolised primarily in the liver with a small proportion metabolised in the stomach. Within minutes of taking your first sip, alcohol starts travelling all around the body and its effects are almost instant. Alcohol absorption depends on the gastric emptying rate and the concentration of the alcohol consumed. The gastric emptying rate is affected by the composition of the foods you have eaten (carbohydrates, fats, protein) as these will slow the rate of gastric emptying, compared to if you have been fasting which will increase the rate of gastric emptying. This is why you often feel the effects of alcohol more markedly if you haven’t eaten prior to drinking.

From the stomach and small intestine, alcohol travels to the liver where it is metabolised by an enzyme called alcohol dehydrogenase which produces a toxic compound called acetaldehyde. Acetaldehyde is the primary culprit in the symptoms of a hangover (alongside dehydration). When we talk about the ‘alcohol flush’ this is due to a deficiency in the enzyme which reduces the amount of acetaldehyde. This is typically seen in people of Asian descent (genetic factor). Acetaldehyde is then reduced to acetate via another enzyme before being released back into the bloodstream.

I like to explain to people that when we drink, our liver has to put aside all its other jobs to urgently get rid of the toxic alcohol, thus, the rest of the processes associated with good metabolism have to be put on hold.

Peak blood concentration levels of alcohol occur 30-60 minutes after drinking, and it takes the average person about one hour to metabolise one standard drink (10-15g alcohol/hour). Blood alcohol concentration of 0.4% can be fatal. Peak blood concentration time varies from person to person, even if drinking the same amount of alcohol. Such factors include: the liver's ability to break down the alcohol (people who drink more regularly are more efficient at metabolising it, thus can often drink more), how much food a person has eaten (if any), how quickly the alcohol is consumed, and a person’s body type, as well as their age, gender, and ethnicity.

Myth buster: there is no way to actually ‘aid’ your hangover or speed up the process of alcohol leaving your body. Forget the Powerade, cold shower or black coffee. The only method that helps your hangover truly is time. In other words, the time your liver takes to metabolise and excrete the toxin that it has been faced with.


Why may alcohol be detrimental to my health?

The 2018 World Cancer Research Fund report stated there is strong evidence that drinking alcohol:

  • Increases the risk of mouth, pharynx, larynx, oesophageal and breast cancers;

  • >2 alcoholic drinks per day increases the risk of colorectal cancer; and

  • >3 alcoholic drinks per day increases the risk of stomach and liver cancers.

Liver: as the liver is the primary organ involved in metabolising alcohol, long term consumption of alcohol, especially heavy drinking patterns, can take their toll. For example, liver cirrhosis (when liver cells get damaged and produce scar tissue), alcoholic hepatitis and even liver cancer.

Brain: as we all know, alcohol is a sedative-hypnotic drug that alters our mood, judgement, and concentration which is often the main reason people drink in the first place. However, large amounts can lead to drowsiness and even coma. Long term effects of alcohol can damage nerve pathways in the brain which affect memory and increase the risk of dementia.

Pancreas: heavy drinking can cause acute or chronic pancreatitis. As the pancreas is involved in regulating our blood glucose levels, heavy drinking can cause dangerously low blood glucose levels (hypoglycaemia).

Sexual health and fertility: consumption of alcohol can lead to unsafe sex, or sexual encounters later regretted. This can increase risk of sexually transmitted diseases, sexual assault and negatively affect one’s mental health. Long-term heavy alcohol consumption can reduce fertility in men and women.

Stomach and dentition: drinking too much alcohol can lead to nausea, vomiting, and diarrhoea. If someone is regularly binge-drinking on the weekend, vomiting, and going to bed with acidic contents residing in their mouth this can also seriously affect dental health.

Special note for athletes: celebrating after a game with alcohol interferes with recovery, injury treatment and sleep patterns. It exacerbates dehydration and slows the recovery process, such as interfering with the body’s ability to replenish carbohydrate stores. As alcohol dilates blood vessels, it increases bleeding and swelling, thus slowing injury recovery. For athletes in weight-orientated sports, it is also important to consider the nutritional impact as discussed previously.


How alcohol is becoming a public health problem

Every week, New Zealand as a country spends a total of $85 million on alcohol, with one in five drinkers having a dangerous drinking pattern. The New Zealand Police estimate that 50% of all crimes involve alcohol. Furthermore, in 2010, alcohol was involved in 105 fatal car accidents, 385 serious crash accidents and 991 minor crash incidents. A lot of the data around the world of drinking patterns is highly variable between availability, culture, religion, and dependency. Previously, women were much less likely to drink than men, but this theme is changing, particularly in younger population groups. In many countries, including New Zealand, alcohol consumption is a major health problem. Countries with the highest daily intake of alcohol include Lithuania (3.32 drinks/day per person >15 years), Belarus, Russia, Romania, Czech Republic and Croatia (2.48 drinks/day per person >15 years).

Fun fact: alcoholic drinks are illegal in Islamic countries.

Many people use alcohol as a way to unwind after a hard day at work, or include it as a habitual part of being social. When people begin to start drinking alcohol regularly and more heavily, it begins to displace food sources of nutrition whilst having potential health consequences. Alcohol has become so socially acceptable; people forget it’s a class one carcinogen, which is the same class as asbestos and tobacco (smoking and drinking are a highly toxic mix). I don’t see anyone picking up a glass of asbestos? Alcohol also introduces endless issues with relationships, money, criminal activity, depression and mental health.

As for the toll that alcohol takes on the healthcare system, including both acute and long-term, is a whole other story. Alcohol related diseases are putting more strain on an already overloaded healthcare system.


Realistic tips to keep your alcohol consumption in check

I believe a lot of New Zealanders would benefit from reducing their alcohol consumption. This is easy to say, but I understand it can be really hard to change behaviour, especially when there is dependency. Here are some helpful ideas to help reduce weekly alcohol consumption:

  1. Ask yourself why you feel the need to drink if it is becoming a daily occurrence? What is the underlying emotion, stress or anxiety? What are other strategies you could implement to feel the deal with these emotions?

  2. If you are a daily drinker, start by reducing by one drink per day for a start, or opting for a lower alcohol option, there are now many options available on the market.

  3. Reduce the number of days you drink per week, have an alcohol free day(s), and for every one alcoholic drink you consume, have one non-alcoholic beverage, preferably sugar-free and ideally water.

  4. Experiment with making non-alcoholic drinks or mocktails when holding social gatherings, so both you and your guests have the option to not drink alcohol. There are tonnes of inspiring ideas on the internet, including here:

  5. Drinking is a habit for many people, and habits take time to break, be patient with yourself and focus on how you are benefiting your health.

  6. ‘Out of sight out of mind.’ Store your alcohol away so that you are less inclined to reach for a cold drink straight form the fridge. No one likes a warm beer.

  7. If drinking out, it can be much harder to stay in control of your drinking, especially when people start buying rounds or there is peer pressure involved. If rounds are occurring, try and keep the drinks lighter or less concentrated and the group of friends you are buying for smaller (your wallet will thank you too). It is OK to say ‘I’ve had enough, thanks.’

  8. Keep drinking to special occasions or a weekend treat (without overcompensating by bingeing).



Personally, as a ‘non-diet’ dietitian I am a strong advocate for non-diet approaches and moderation in all aspects of health and food. I always ask people, if diets worked, why is everyone always starting a new one or regainging the weight they lost?

However, contrary to my beliefs, when it comes to alcohol, I believe moderation does not exist, and the less you consume the better off your health will be. Everyone has the right to choose how they will consume alcohol, but I think everyone also deserves the right to be informed on the risks that come with consuming it, particularly more frequent or heavy drinkers.

Like food, there can be many emotional reasons we reach for alcohol, and often there are issues beneath the surface as to why we drink, some of which we may not even be aware of. I will leave you with this question, if you are a regular or heavy drinker, what is it about your life that makes you feel you require alcohol?

Instagram: holdaway_dietitian


1. World Cancer Research Fund/American Institute for Cancer Research, Food, Nutrition, Physical Activity, and the prevention of Cancer: a Global Perspective. Washington DC: AICR, 2007. Available from

2. WHO. Global status report on alcohol and health 2014. 2014. World Health Organisation. Accessed 24/07/2018; available from

3. Health Promotion Agency. Alcohol and You. Facts & effects (internet). May 2016. Accessed 26 July 2018. Available from:


Related Posts

See All


bottom of page