How does alcohol affect the body?

April 24, 2023


Anne Carroll, MS, RDN

A look at the science behind alcohol metabolism and the health effects of drinking


When focusing on your health and nutrition goals, you may wonder how alcohol fits into the picture. How is alcohol processed in the body? How does alcohol affect overall health? What are the effects of alcohol on nutrition?

In this article, we will address these questions and more. Keep reading to learn more about the science behind alcohol and nutrition.


What is alcohol? Is alcohol a carbohydrate?

Alcohol is known in the science world as ethanol or ethyl alcohol, formed through a process called fermentation. Fermentation is when microorganisms, like yeast, break down sugars. Therefore, all alcoholic drinks originate from a carbohydrate.

For example, wine is made from grapes, beer is made from barley, and vodka is made from potatoes. While alcohol itself is not a carbohydrate, alcoholic drinks can contain varying levels of sugars and carbohydrates.


Alcohol Metabolism: How does the body process alcohol?

Alcohol, or ethanol, is metabolized differently than proteins, fats, and carbohydrates. Because it is a toxin, your organs work hard to eliminate it and its byproducts. There are many factors that play into the individual metabolism of alcohol, including body size, age, sex, ethnicity, and genetics. (2)

First, alcohol moves through the GI tract into the stomach. Then, an enzyme called alcohol dehydrogenase (ADH) starts to break down alcohol before it hits the bloodstream.

Food in the stomach helps give your body more time to break down alcohol in the stomach. Therefore, drinking on a full stomach helps to mitigate blood alcohol concentrations (BAC) and the overall effects of alcohol on other parts of the body. (2)

While some alcohol is broken down in the stomach, the primary site of alcohol metabolism is the liver. The liver breaks down 80-90% of alcohol, converting it into alcohol substrates that can then be eliminated from the body. Two key enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), breakdown alcohol into acetaldehyde, a toxic substance that is associated with carcinogenic effects and organ damage when circulating at high levels.

With low to moderate drinking, our body can typically convert acetaldehyde to acetate, carbon dioxide, and water for elimination. Keep in mind that the liver can only effectively breakdown about one drink per hour (however, this varies based on individual factors). Drinking beyond that can cause a build-up of alcohol in the body’s blood, organs, and tissues. (2)

Once alcohol is absorbed into the bloodstream, it is distributed to different organs in the body, including the brain. This causes mood changes and impaired cognition that can lead to memory disruption. High levels of alcohol impair sensory perception and movement coordination. Very high levels of alcohol will slow breathing and result in lost consciousness or even death. (3)


What is considered excessive alcohol use?

In the United States, moderate alcohol consumption is defined as up to 1 drink per day for women and up to 2 drinks per day for men. (10) Excessive drinking includes 8 drinks per week or more for women and 15 drinking per week or more for men. Additionally, 4 drinks or more for women and 5 or more for men consumed on one occasion is considered excessive binge drinking. (4) If you think you are drinking in excess, we recommend seeking care from a healthcare professional to help address any misuse of alcohol.


How does drinking alcohol affect our health?

We know that excessive, chronic alcohol use can cause a variety of negative health outcomes, including heart, liver, kidney, and pancreatic diseases, as well as increased risk of certain cancers, diabetes, brain damage, inflammation, gastrointestinal issues, and fertility and pregnancy complications. (2,3) Excessive drinking can also deplete a variety of vitamins and minerals, impair nutrient absorption, and potentially lead to malnutrition. (9)

But what about low to moderate drinking? Here is a look at the potential effects of low to moderate drinking on certain health conditions:


Heart Health:

Some data suggests that low to moderate alcohol consumption may help reduce the risk of heart disease. There are a few proposed mechanisms by which this may occur, including increasing “good” HDL cholesterol, lowering blood pressure, and reducing stress and anxiety. (12)(5)

However, even moderate drinking can increase our resting heart rate, which can be potentially dangerous for those with pre-existing heart conditions. Rises in resting heart rate can also impair sleep, leading to less deep and restorative sleep. (6)


Brain Health:

The research on low to moderate drinking and brain health is conflicting. Some evidence shows that low to moderate drinking can have protective cognitive effects, while others show either no effect or potentially damaging effects. (7,8) A large-scale study looked at the correlation between moderate drinking and cognitive decline and found that consumption of more than 7 drinks per week was associated with higher levels of iron in the brain, which can lead to alcohol-related cognitive decline. (13)


Gut Health:

Low to moderate alcohol consumption does not appear to have negative consequences on gut health. However, the amount of alcohol exposure to the gut that can cause damaging effects is not well understood.

For example, even a single episode of heavy drinking can irritate the gastric lining, increase inflammation and digestive issues, and cause disruption to the gut microbiome, as well as acid reflux. (14) (16) Those with IBS may be more susceptible to gastrointestinal side effects of drinking, particularly when consuming high FODMAP drinks. (15)


Nutritional Status:

According to the NIH, moderate drinkers seem to have a low risk of developing nutrient deficiencies. If you have a night where you drink beyond the recommended moderate dosages, you may lose some vitamins and minerals through increased urination, including potassium, magnesium, zinc, and vitamin C.

Additionally, B vitamins play a role in alcohol metabolism, so a night of heavier drinking may leave you depleted in some B vitamins, including thiamine and folic acid. Aim to eat balanced meals the next day, including a variety of fruits, vegetables, whole grains, proteins, and healthy fats. If you take a daily multivitamin, that can also help to replenish your stores. (9)


Hydration Status:

Alcohol is a diuretic, so it can lead to dehydration and electrolyte losses. It’s important to hydrate both before, during, and after drinking to avoid dehydration. Those that have alcohol-induced dehydration may benefit from an electrolyte powder or oral rehydration solution to help accelerate rehydration and replenish electrolyte stores lost through urine.


How does alcohol affect blood sugar?

Some studies show that moderate drinking can actually enhance insulin sensitivity and lower the risk of type-2 diabetes. (17) As far as the immediate effects, alcohol intake can lead to hypoglycemia (or low blood sugar) because our liver prioritizes breaking down alcohol over stabilizing blood sugar. Additionally, those with diabetes taking insulin or insulin secretion medications are more at risk of hypoglycemia when drinking.

The type of alcoholic drink also matters. While pure alcohol is not a carbohydrate, drinks can contain varying levels of carbohydrates. For example, mixed beverages made with fruit juices, sugar, sweeteners like agave, and some beers can cause a sharp rise in blood sugar because they contain quick-releasing carbohydrates.

On the other hand, there are only about 4 grams of carbs in a 5-ounce glass of wine and 0 grams in a vodka club soda. Make sure to have a meal before or during drinking that contains protein, healthy fats, and fiber. This will help slow the release of alcohol and glucose into your bloodstream. (18)


The bottom line on alcohol and nutrition

While there is some conflicting research on the health risks and potential benefits of consuming alcohol, one thing remains clear – if you are consuming alcohol, it is best to do so in moderation.

Your best bet is to listen to the U.S. Dietary Guidelines recommendations: If you aren’t currently drinking, there is no reason for you to start. If you do choose to drink, do so moderately. Moderate alcohol consumption is defined as up to 1 drink per day for women and up to 2 drinks per day for men. (14) Remember: one alcoholic beverage is equivalent to 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of a spirit.

The long-term effects of excess alcohol on overall health may include heart, liver, kidney, and pancreatic diseases, as well as increased risk of certain cancers, diabetes, brain damage, inflammation, gastrointestinal issues, and fertility and pregnancy complications. We need more research on the risk versus benefits of low to moderate alcohol intake on certain health conditions.


Have more questions about alcohol and nutrition? Work with a Culina Health Registered Dietitian Nutritionist to get personalized virtual nutrition care that is covered by insurance. Schedule a free intro call to get started!

Any general advice posted on our blog, website, or application is intended for reference and educational purposes only and is not intended to replace or substitute for any professional medical advice, diagnosis, treatment, or other professional advice. If you have specific concerns or a situation arises in which you require medical advice, you should consult with an appropriately qualified and licensed medical services provider.

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