“Excess alcohol intake can disrupt your gut’s balance and function” Dr Megan Rossi

Drinking alcohol will affect your body’s systems ^[1], and the extent of the impact depends on many factors. Here’s what you need to know.

One of the first organs to be affected by your drinking is the brain

No two people will experience exactly the same effect from drinking alcohol but will usually feel its impact within minutes. As ethanol passes into your brain, it interacts with the chemicals and pathways that determine your emotions and mood, how you respond to pleasure and pain, and regulate your coordination, movement and even your breathing ^[2].

Drinking moderately can make you less inhibited and more relaxed, but the more you drink, the more alcohol depresses your ability to function. If you drink very heavily in a short amount of time, you may risk passing out. In extreme cases, people who become severely intoxicated can fall into a coma and even stop breathing ^[3]. These responses all involve your brain.

Studies have shown that heavy and abusive drinking over long periods can also change the brain’s structure ^[4]. Unlike some other organs, the brain doesn’t regenerate, so any damage is irreversible. This is also one reason why drinking at an early age is not a good idea at all. As adolescent brains are still developing, drinking may disrupt how brain connections are formed, particularly those involved in learning and memory ^{[5, 6]}.

Some scientific studies have shown that for some older people, moderate drinking may have a positive effect on how the brain functions, improve cognition and memory, and slow the mental decline often seen with ageing ^[7-9].

However, these effects don’t apply to everyone, and you shouldn’t begin to drink for health reasons. Only a qualified health professional can give you advice based on your drinking pattern, health, and lifestyle. Older adults may need specialised advice about drinking and its effects.

It is important to remember that the health impact of drinking alcohol is the same whether you choose beer, wine, or distilled spirits. They all have the same effect on your brain and on the other organs and systems in your body, depending on how much you drink. For the purposes of health, alcohol is alcohol.

The liver is your body’s main clearinghouse for alcohol

The liver is part of your digestive system and has primary responsibility for breaking down most of the alcohol you drink ^[21]. The ethanol in your drink is first converted into a compound called acetaldehyde, which is toxic to your body, so it’s quickly broken down further and eliminated in urine.

Drinking too much will seriously affect your liver ^[22]. The enzymes in the liver can process roughly one drink every hour; drinking more and at a faster rate means that acetaldehyde builds up and lingers, causing damage. People who drink heavily over long periods of time develop inflammation of the liver and a condition called cirrhosis where scar tissue builds up and stops the liver from functioning normally.

How alcohol affects your liver also depends on other factors ^[23]. Research shows that being obese and taking certain medications can damage your liver, increasing inflammation and susceptibility to acetaldehyde. If you’re concerned about the effect of your drinking on the health of your liver, or how it may interact with medications, consulting your health professional is the best course of action to get accurate advice that’s appropriate for you.

Drinking alcohol has different effects on your heart depending on how you drink and who you are

Excessive drinking is not good for the heart ^[24]. It can cause an irregular heartbeat, known as arrhythmia ^[25] , even after a single heavy drinking session. You may have heard of ‘holiday heart syndrome’, where the synchronized beating of the heart’s chambers is disrupted after excessive drinking (and eating), often during holiday celebrations ^[26]. You may feel lightheaded, dizzy, and out of breath. Repeated heavy drinking episodes can increase risk of long-term problems like heart failure and stroke ^{[27, 28]}. People who have certain heart conditions or a family history of heart disease may be advised not to drink alcohol at all.

That said, research conducted over many decades supports the notion that for some middle-aged and older adults, drinking moderately may be good for the heart ^[28]. Compared with people who don’t drink, light and moderate drinkers have lower cholesterol levels and less buildup in their blood vessels ^[29], reducing their risk of heart disease and stroke. But this doesn’t apply equally to everyone. Other factors play a role, including age, gender and overall health. Even small amounts of alcohol may be risky for people who take certain medications or have other medical conditions.

In recent years, some scientists have questioned the benefits of moderate drinking for heart health, calling into question possible shortcomings in some key studies ^[30-32]. However, where there’s no disagreement among scientists is on the effect that excessive drinking can have on your heart. Binge drinking and drinking heavily over a long time can increase your odds of developing heart disease. Because the effects of drinking are different for everyone, it’s important that you consult a medical professional if you have questions about your drinking and its impact on your heart.

Alcohol affects your gut microbiome and excessive drinking can contribute to inflammation throughout your body

If you didn’t already know, maintaining a healthy gut not only supports proper digestion, but also impacts your immune system (with around 70% of your immune system living there), helping you to fight infection and prevent against some diseases, as well as contributing to your longevity, mental wellbeing and much more. This involves the gut ‘microbiome’, the ecosystem of trillions of microorganisms that work to keep you well and functioning, and their connection with almost every system and function in the body.

The gut microbiome has an essential role in helping to manage inflammation and disrupting your gut’s homeostasis (balance) has a knock-on effect on many aspects of your overall health.

Excessive drinking is one key cause of disruption allowing more inflammatory bacteria to thrive and suppressing bacteria known for their anti-inflammatory properties ^[11]. The short-term effects are obvious – you may experience acid reflux, nausea/vomiting, bloating or diarrhea ^{[12, 13, 14]}. Hangovers are the first and most obvious sign of inflammation after heavy drinking.

Over the longer term, drinking excessively makes your gut microbiome less diverse, increasing the risk of a leaky gut and irritable bowel syndrome ^{[15, 16]}. It has also being linked to increasing your risk of autoimmune, neurodegenerative disorders and some cancers ^{[17, 18, 19]}. All of these involve the body’s reduced ability to fight inflammation.

The good news is that the gut microbiome is resilient and can be restored to a healthy state by reducing your alcohol intake and modifying your diet by focusing on plant-based diversity across what Dr Megan Rossi (PhD, RD) calls the Super Six (fruits, vegetables, wholegrains, legumes, nuts and seeds, plus herbs and spices) to allow the gut microbiome to recover ^[20]. All types of alcohol beverages contribute to inflammation when consumed in excess and can negatively affect the gut microbiome.

Dr Megan Rossi (PhD, RD), founder of The Gut Health Doctor said: “Alcohol actively speaks to your gut microbes and can alter the unique mix of microbes in your digestive tract, meaning even just a few too many drinks can shift how your gut functions. When the balance of microbes changes, so too can gut permeability (aka gut leakiness), inflammation, digestion and even bowel habits. You don’t need to give up alcohol entirely to support your gut health, but making informed choices can make a real difference. For example, limiting overall intake, alternating with non‑alcoholic refreshers, adding frozen berries with sparkling water instead of full sugar or diet mixers to spirits, choosing higher polyphenol options (plant compounds your gut microbes enjoy) such as red wine, dark beers and whiskey with ginger, not drinking on an empty stomach, nourishing your gut microbiome with fibre‑rich plant foods before and after alcohol intake, and adequate hydration, all help. Plus, be mindful of how your body responds to alcohol by observing how your gut feels after a drink. Through this increased awareness and by taking small steps to support your gut, you can enjoy social occasions without compromising your long‑term gut health.”