Understanding Gut Health: Is Pepsi Bad for Your Gut?

October 21, 2025 •

4 min read

Recent research from the Biocodex Microbiota Institute suggests that regular consumption of sugary drinks can have serious consequences for the gut microbiota. This raises the critical question for consumers everywhere: Is Pepsi bad for your gut, and what specific ingredients might be contributing to digestive issues?

Quick Summary

Pepsi, both regular and diet, can negatively affect gut health due to its carbonation, high sugar or artificial sweetener content, and acidity. Ingredients disrupt the gut microbiome, cause inflammation, and can exacerbate existing digestive conditions.

Key Points

Microbiome Disruption: Both regular and diet Pepsi can harm the gut microbiome by either feeding harmful bacteria with high sugar content or altering microbial balance with artificial sweeteners.
Bloating and Irritation: The high carbonation and phosphoric acid in Pepsi can cause bloating, gas, and gastric irritation, especially for individuals with sensitive digestive systems or existing conditions like IBS or acid reflux.
Increased Inflammation: Excessive sugar intake from regular Pepsi is linked to increased gut and systemic inflammation, while some artificial sweeteners may also contribute to inflammatory responses.
Nutrient Absorption Issues: Phosphoric acid can act as an anti-nutrient, potentially inhibiting the absorption of vital minerals like calcium and magnesium, which are crucial for overall health.
Consider Healthier Alternatives: To protect and improve gut health, opt for water, kombucha, flavored seltzer, or herbal teas instead of soft drinks to avoid sugars, artificial sweeteners, and excess acidity.
Personalized Responses: The effects of soda on gut health can be highly individualized, depending on a person's unique microbiome composition and any pre-existing sensitivities.

The Core Components of Pepsi and Their Gut Impact

Pepsi and other soft drinks contain a combination of carbonation, acids, and either high-fructose corn syrup or artificial sweeteners. Each of these components can play a distinct, often negative, role in digestive health. For individuals with a sensitive digestive system, the effects can be immediate and uncomfortable, while long-term, chronic consumption can lead to more significant changes in the gut's delicate ecosystem.

Carbonation: The Source of Bloating and Gas

One of the most noticeable effects of drinking any carbonated beverage, including Pepsi, is the feeling of gas and bloating. This is due to the dissolved carbon dioxide (CO2) that creates the bubbles. When you consume a carbonated drink, you are essentially swallowing gas, which can get trapped in your digestive system. For most people, this results in harmless belching, but for those with digestive sensitivities, it can lead to pain and distension. The discomfort is often temporary, but it can be particularly bothersome for individuals with conditions like Irritable Bowel Syndrome (IBS).

High Fructose Corn Syrup: Feeding the Wrong Bacteria

Regular Pepsi contains a significant amount of high-fructose corn syrup, a key ingredient shown to have detrimental effects on the gut microbiome. Research indicates that diets high in fructose can:

Reduce Beneficial Bacteria: Excessive sugar intake, particularly fructose, can lead to a decrease in the diversity of beneficial bacteria in the gut, such as those that produce protective short-chain fatty acids (SCFAs).
Promote Harmful Bacteria: Meanwhile, bacteria that thrive on sugar, like Bacteroides, can multiply excessively, contributing to an imbalanced microbial community known as dysbiosis.
Increase Inflammation: Some studies suggest that high-fructose corn syrup can induce inflammatory damage in the liver and intestines by altering gut microbiota and related metabolic processes.

Artificial Sweeteners: The Gut Microbiome Under Scrutiny

Pepsi Max and Diet Pepsi replace sugar with artificial sweeteners like sucralose and aspartame. While marketed as a healthier alternative, these substitutes are not without gut-related concerns. The long-term effects on the gut microbiome are still under investigation, but studies suggest potential issues:

Microbial Disruption: Some research indicates that artificial sweeteners like sucralose and saccharin can significantly alter the composition and function of the gut microbiome, potentially impacting glucose tolerance.
Conflicting Evidence: The impact of aspartame is less consistent in human studies, though some animal research shows alterations in gut diversity. Individual responses can vary widely depending on the person's existing microbiome.
Increased Inflammation: Some findings suggest artificial sweeteners may worsen gut inflammation and contribute to an overgrowth of pathogenic strains, though more human trials are needed.

Phosphoric Acid: Irritation and Nutrient Absorption Issues

Another significant ingredient in Pepsi and other colas is phosphoric acid, which provides the tangy flavor. This high level of acidity is a major concern for gut health:

Gastric Irritation: The acid can irritate the stomach lining, especially for those with existing conditions like gastritis, ulcers, or acid reflux, and can aggravate symptoms like heartburn and discomfort.
Nutrient Interference: Phosphoric acid can be considered an anti-nutrient, as excessive consumption may interfere with the body's ability to absorb essential minerals like calcium, iron, and magnesium.

Regular Pepsi vs. Diet Pepsi: A Comparison of Gut Impact

To better understand the differences, here is a comparison table outlining the specific gut health concerns for both regular and diet versions of Pepsi.


Feature	Regular Pepsi (High Fructose Corn Syrup)	Diet/Zero Sugar Pepsi (Artificial Sweeteners)
Sweetener	High Fructose Corn Syrup	Sucralose, Aspartame, Acesulfame K
Gut Microbiome	Can cause dysbiosis by promoting sugar-loving bacteria and reducing beneficial ones. May increase inflammation.	Research suggests potential disruption of the microbiome and alterations in glucose metabolism.
Digestion	High sugar content can cause cramping and diarrhea due to osmotic effects, especially with excessive intake.	Some artificial sweeteners, particularly polyols (though not typically in Pepsi), can have a laxative effect.
Inflammation	Linked to increased systemic inflammation.	Potentially linked to increased gut inflammation, though evidence is less conclusive and individual-specific.
Acidity	High phosphoric acid content, which can irritate the stomach lining and potentially disrupt nutrient absorption.	Contains phosphoric acid, carrying the same risks of gastric irritation and mineral absorption interference.
Bloating/Gas	High carbonation leads to gas and bloating for many individuals.	High carbonation causes bloating and gas, similar to regular Pepsi.

Healthier Alternatives for Gut-Friendly Beverages

If you're seeking to improve your gut health by reducing or eliminating soft drinks like Pepsi, several delicious and gut-friendly alternatives exist:

Kombucha: A fermented tea rich in probiotics, which can help replenish and diversify beneficial gut bacteria.
Flavored Seltzer: Offers the satisfying fizziness of a soda without the sugar or artificial sweeteners. Add a squeeze of lemon, lime, or cucumber for natural flavor.
Herbal Teas: Teas like peppermint or ginger can naturally soothe an upset stomach and support digestion.
Water with Add-ins: Infuse water with fresh fruit, herbs, or cucumber for a refreshing and hydrating option that promotes a healthy gut environment.
Bone Broth: Rich in amino acids and collagen, it can help heal and soothe the gut lining.

Conclusion: Making Informed Choices for a Healthier Gut

While an occasional Pepsi is unlikely to cause serious harm for a healthy individual, chronic and excessive consumption can have real, negative consequences for gut health. The combination of carbonation, high sugar or questionable artificial sweeteners, and phosphoric acid can disrupt the gut microbiome, cause uncomfortable digestive symptoms, and potentially increase inflammation over time. Understanding these potential effects allows you to make informed decisions about your beverage choices. Replacing soft drinks with healthier alternatives like water, herbal tea, or kombucha can be a simple yet effective step toward nurturing a healthier, more balanced digestive system and improving overall well-being. Ultimately, your gut and overall health will thank you for it. For more information on gut-brain connections and the impact of the microbiome, explore resources from reputable health institutions like Cedars-Sinai.

Frequently Asked Questions

The carbonation in Pepsi introduces dissolved carbon dioxide gas into your stomach. For some people, particularly those with sensitive digestive systems, this can cause a feeling of fullness, bloating, or discomfort as the gas builds up.

Yes, it can. Pepsi Max and Diet Pepsi contain artificial sweeteners like sucralose and aspartame. Some studies suggest these sweeteners may alter the balance of bacteria in your gut microbiome, though individual responses vary.

Drinking Pepsi can aggravate the symptoms of acid reflux, though it may not cause the condition itself. The high acidity from phosphoric acid and the carbonation can irritate the stomach and increase pressure, potentially worsening reflux for those with GERD.

Both regular and diet Pepsi have distinct negative impacts. Regular Pepsi's high sugar content can promote harmful bacteria and increase inflammation, while diet Pepsi's artificial sweeteners can also disrupt the microbiome. The 'worse' option depends on an individual's specific sensitivities.

Yes. The phosphoric acid in Pepsi can lead to gastric irritation. In excess, it is known to interfere with the absorption of essential minerals like calcium, which is important for overall health.

Healthier alternatives include kombucha (for probiotics), flavored seltzer with natural fruit juice, herbal teas, or simply water infused with fresh fruits and herbs. These options provide flavor without the negative gut impacts of sugar, artificial sweeteners, and acids.

If you have a digestive condition like IBS, you should consider avoiding or significantly limiting Pepsi. The carbonation, high sugar or artificial sweeteners, and acidity can all trigger or worsen symptoms like bloating, gas, and pain.