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The Gut Check: Unraveling the Effects of Alcohol on Gut Health

by Valerie Polley | Aug 16, 2023 | 0 comments

While enjoying a social drink occasionally likely isn’t cause for alarm, excessive alcohol intake carries several health risks, including high blood pressure and various cancers.

But what about the effect of alcohol on the gut? While we’re still learning about the effects of alcohol on the gut in humans, animal studies provide clues about how alcohol intake could harm our gut. Excessive alcohol intake is correlated with changes in the gut microbiome, inflammation in the digestive tract, increased gut “leakiness,” and impaired nutrient absorption.

Read on to learn about the different ways excessive alcohol consumption can impact your gut, plus tips for enjoying alcohol safely and responsibly.

 

The Gut Microbiome: A Balancing Act

The gut microbiome is the community of microorganisms that live in the human intestinal tract. They have numerous important functions, including the production of vitamins and essential amino acids. They also produce short-chain fatty acids (SCFAs), which fuel the intestine's cells and can influence the immune system.

Studies have uncovered links between the composition of the intestinal microbiome and different diseases, including inflammatory bowel disease (IBD), inflammatory skin diseases, autoimmune arthritis, type 2 diabetes, obesity, and atherosclerosis. In many cases, less bacterial diversity and lower overall numbers of certain bacteria are associated with developing these diseases.

Alcohol consumption can disrupt the balance of microorganisms in the gut. This is known as gut dysbiosis. One study showed that alcohol consumption led to the overgrowth of bacteria in the small intestine, where the number of microorganisms should be low. It’s possible that this occurs because alcohol impairs gut motility (the movement of food through the digestive tract).

Other studies show that there is a correlation between alcohol and changes in the ratio of “good” bacteria to “bad” bacteria, with “bad” bacteria increasing after chronic alcohol consumption in a study on mice.

While we’re still learning about how alcohol affects specific species of bacteria in the gut, preliminary findings show that excessive alcohol consumption can negatively impact your gut microbiome. So, if you’re looking to keep your gut microbiome healthy, you may want to forego that second cocktail.

 

Alcohol Absorption and Inflammation the Digestive Tract

Once swallowed, alcohol is primarily absorbed by the small intestine into the veins that collect blood from the bowels and stomach and the portal vein that leads to the liver. Once in the bloodstream, it is carried to the liver, where it is broken down by special enzymes.

Alcohol can irritate each part of the digestive tract. For example, alcohol can impair the esophagus's motility (movement). Plus, it can cause gastroesophageal reflux resulting in damage to the esophagus.

Excessive alcohol consumption can also lead to gastritis, a condition in which the lining of the stomach becomes inflamed. This chronic inflammation is recognized to have significant tumor-promoting potential, which could increase your risk of developing stomach cancer.

In addition, the gut can become inflamed due to an inflammatory response that the immune system mounts against alcohol and its metabolites (the substances or byproducts that are produced during the metabolism of alcohol).

The inflammatory response is provoked in several ways. First, alcohol may lead to an initial decrease in immune response, increasing susceptibility to gut pathogens such as bacteria and viruses. Infection by these gut pathogens then triggers an immune response and increases the production of immune cells involved in inflammation.

Since inflammation is involved in the development and progression of numerous diseases, such as cancer, heart disease, asthma, and psoriasis, avoiding things that cause inflammation can be one way of keeping our bodies happy and healthy.

 

Alcohol and Gut Permeability

The “leakiness” of the gut (also known as gut permeability) is a key component of the immune system. When it’s working properly, the gut wall is semipermeable. This means that special proteins in the gut wall prevent harmful substances from entering the gut while allowing helpful substances like nutrients and immune molecules to enter.

However, different factors can make the gut “leakier” than it should be. This allows foreign substances to travel through, which can lead to inflammation. Defects in the gut barrier have been associated with several different diseases, including celiac disease and inflammatory bowel disease.

Studies have found that alcohol can increase the “leakiness” of the gut wall. It’s thought that this happens because alcohol and its metabolites disrupt the gut wall cells and the spaces between those cells, which consist of special proteins that control the “leakiness” of the gut wall. If these special proteins are disrupted, the “leakiness” of the gut wall increases.

To protect the integrity of your gut wall, be mindful of how many alcoholic beverages you consume in one sitting. If it’s more than one or two, you may want to consider cutting back to keep your gut wall healthy.

 

Alcohol and Nutrient Absorption

The main role of the small intestine is to absorb nutrients vital for human health. These nutrients are either passively absorbed or actively transported through the cells of the small intestine.

However, excessive alcohol consumption can prevent the proper absorption of many nutrients, including vitamin B1 (thiamin), vitamin B2 (riboflavin), vitamin B7 (biotin), vitamin B9 (folate), vitamin C and vitamin B12. It may also impair the absorption of the mineral zinc.

While it may be advisable to supplement these nutrients in some cases (such as in the case of thiamine deficiency in alcohol use disorder, which can cause irreversible brain damage), it’s generally best to ensure adequate absorption of these nutrients by sticking to low or moderate alcohol consumption.

 

Moderation and Gut Health

We’ve talked a lot about moderate alcohol consumption. But what does that really mean?

According to the Centers for Disease Control and Prevention (CDC), moderate alcohol consumption is a single standard drink (e.g. 12 ounces of beer, 5 ounces of wine, or 1.5 ounces of liquor) per day for women and two standard drinks per day for men. The guidelines also note that drinking less alcohol is better for health than drinking more.

For many people, cutting back on alcohol is easier said than done. After all, it’s something we use to socialize, especially during the hot summer months.

Here are a few strategies you can use to reduce your alcohol intake while remaining social:

  • Opt for a mocktail instead of a cocktail. Most restaurants have a mocktail menu; if they don’t, they can usually alter one of the alcoholic cocktails to be alcohol-free.
  • Try alcohol-free beer, wine, or spirits. More and more online retailers are starting to sell alcohol-free versions of these popular drinks. Try one, and you might be surprised by how much you enjoy it!
  • Try agua fresca. Agua fresca is one of my favorite refreshing summer drinks. Simply blend 1 cup of ice, 1 cup of fresh fruit (strawberries work well), the juice of one lime, 2-3 mint leaves, 1 tablespoon of liquid sweetener (like simple syrup or maple syrup) and enough cold water to cover all your ingredients and blend away! It’s refreshing and easy to prepare, and you get the benefits of some added fiber from the fruit!
  • Drink kombucha. Known for its fizzy, sweet-and-sour flavors, kombucha is another gut-loving drink. Since it’s a fermented food, it contains good bacteria that may contribute to better gut health.

 

Final Thoughts

There are many ways excessive alcohol consumption can negatively impact the gut, including disrupting the gut microbiome, causing inflammation in the gut, and impairing nutrient absorption.

If you’re looking to cut back your alcohol intake, try to aim for no more than one drink per day if you’re female and two drinks per day if you’re male. Better yet, opt for an alcohol-free version of your favorite drink or sip on kombucha for its tangy flavor and dose of beneficial microbes.

If you’re struggling to reduce your alcohol consumption, working with a registered dietitian can help. Here at Blue Tree Nutrition, our dietitian can help you come up with a plan for reducing your alcohol consumption while still enjoying an active social life. Click here to get in touch and book an appointment today!

Our gut microbiome (the community of trillions of microbes that live in our gut) plays a key role in maintaining metabolic and immune health. Gut dysbiosis occurs when the composition and diversity of our gut microbiome shift. This could include overgrowth of harmful bacteria or a decrease in beneficial bacteria. Gut dysbiosis has been linked to a wide range of negative health outcomes, including increased levels of inflammation and changes in metabolism.

Many people switch to non-nutritive sweeteners like sucralose, aspartame, and stevia for health reasons, and for decades, we've believed that they pass through our bodies without affecting us. But emerging research shows that these compounds interact directly with our gut microbiome and may have potential negative effects on our health. 

This article will review what we currently know about the relationship between non-nutritive sweeteners (including artificial sweeteners and calorie-free natural sweeteners) and the gut microbiome, plus practical advice for navigating sweeteners.

Sucralose

Sucralose (Splenda) is an artificial sweetener commonly used in baked goods, gums, and sugar-free beverages and is approximately 600 times sweeter than sucrose (table sugar). However, recent research has linked it to adverse health effects such as systemic inflammation, metabolic disease, and gut dysbiosis. For example, a 2022 study found that sucralose consumption increased harmful bacteria and reduced beneficial bacteria, which was associated with changes in insulin and glucose levels.

Additionally, a 2025 randomized controlled trial examining the effects of replacing added sugars with sucralose found that people with type 2 diabetes who consumed sucralose experienced reductions in both alpha diversity (the number and types of species present in a single person) and beta diversity (differences in microbial composition between people). Interestingly, the people with overweight and obesity without type 2 diabetes did not experience the same changes.

Overall, animal studies and limited human studies suggest that sucralose may trigger intestinal inflammation, likely through its effects on the gut microbiome. However, since most of the evidence we have comes from test tube or animal studies, these results should be interpreted cautiously.

Aspartame

Aspartame is another commonly used artificial sweetener that is about 200 times as sweet as sucrose. While it does contain some calories, because you don't need much of it to reach the same sweetness levels as sucrose, these calories are negligible.

Like sucralose, most of the research into the gut effects of aspartame has been done in animals. However, we do have some very small human studies. A 2022 randomized controlled trial (RCT) involving 20 healthy adults found that participants taking aspartame showed changes in both probiotic (beneficial) and pathogenic (harmful) bacteria, but the changes were specific to each individual. 

Why the differences? It's likely due to the "responder vs. non-responder" phenomenon. We all have differences in our "baseline" microbiome. While certain bacterial species are common in healthy populations, our microbiome is as unique as a fingerprint. Whether an artificial sweetener has positive or negative effects on our microbiome may depend on which species are already present in our gut, as well as on our habitual diet. This difference in responses makes it very challenging to draw firm conclusions about whether artificial sweeteners are harmful.

Stevia

Many people choose stevia because it's a "natural" zero-calorie sweetener. Studies have shown mixed results regarding the effects of stevia on the gut microbiome. For example, while some in vitro (test tube) and in vivo (animal) studies have reported potentially harmful effects of stevia on the gut microbiome, others have found no impact, and some even reported beneficial effects through inhibition of inflammatory pathways.

Additionally, a 2024 human study found that stevia had no significant effect on the gut microbiome. This highlights the importance of not forming conclusions based solely on test tube and animal studies. Overall, it appears that stevia is a potentially less-harmful alternative to artificial sweeteners like sucralose and aspartame.

Practical Advice for Navigating Sweeteners

Since the research on artificial sweeteners is still evolving, the decision to include or avoid them comes down to personal preference. Here are some tips for including them in your diet in moderation:

  • Try gradually reducing the amount you use: If you typically use two packets of sweetener in your coffee or tea, try gradually reducing to one packet. Our taste buds are highly adaptable, and you may find that one packet is sweet enough once you get used to it.
  • Check your labels: Low- or no-calorie sweeteners (such as sucralose, aspartame, and sugar alcohols like erythritol) are often hidden in low-sugar foods like protein bars, yogurt, and diet sodas. Awareness is the first step to reducing your intake.
  • Rotate your sources: If you do use artificial sweeteners, try switching up the types you use. Since different sweeteners may affect your gut microbiome in different ways, this may reduce the concentrated impact on your gut.
  • Switch to stevia: While animal and test-tube studies show mixed findings, human research indicates that stevia has a limited effect on the gut microbiome, making it a better choice for people seeking to support their gut health.

Another way to support your gut if you regularly use artificial sweeteners is to rebuild gut diversity with fiber and fermented foods, while focusing on whole-food sweeteners.

  • High fiber prebiotic foods (like legumes, whole grains, garlic, onions, asparagus, and under-ripe bananas) act as "fuel" for your healthy gut microbes. Aim to include a variety of these foods in your diet to support the microbes already in your gut.
  • Add fermented foods, like unpasteurized sauerkraut and kimchi, kefir, or kombucha, to your diet. Some fermented foods contain live, beneficial bacterial cultures, while others are rich in "postbiotics" (beneficial compounds like short-chain fatty acids, which are produced when bacteria break down prebiotics).
  • Try using whole-food sweeteners instead of artificial ones. For example, sweeten plain yogurt with vanilla extract and berries or add dates to smoothies or homemade energy bites.

Final Thoughts

Emerging research suggests that certain low- or no-calorie sweeteners, including sucralose and aspartame, may affect the gut microbiome, whereas stevia appears to have a less negative effect. While individual responses can vary with a person's unique baseline microbiome, certain artificial sweeteners may increase inflammation or reduce gut microbiome diversity.

If you need personalized support navigating sweeteners or supporting your gut health, Blue Tree Nutrition can help. Click here to get in touch!

 

 

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Hello, I am

Valerie

My name is Valerie Polley. I am a Indianapolis-based registered dietitian and owner of Blue Tree Nutrition. I consult with clients both local and far away.
I have a bachelor’s degree in nutrition from Purdue University and I have been practicing for 20 years.
I thoroughly enjoy helping clients through their gut health journey. I see a range of GI issues including, but not limited to celiac disease, IBS and SIBO. I also specialize in the FODMAP elimination diet.

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