What are the worst foods for a leaky gut?

January 10, 2026 •

3 min read

According to research published in the journal Nutrients, components of a Western diet, such as high-fat, high-sugar, and low-fiber foods, can negatively impact intestinal permeability. For those with leaky gut, or intestinal hyperpermeability, understanding which foods exacerbate symptoms is crucial for healing the intestinal lining.

Quick Summary

This guide details the foods and ingredients that can increase intestinal permeability and inflammation, including refined sugars, processed items, gluten, and dairy.

Key Points

Processed Foods: Additives and lack of fiber can disrupt the gut microbiome and cause inflammation, damaging the intestinal lining.
Added Sugars: Excess sugar feeds harmful bacteria and yeast, contributing to an imbalance (dysbiosis) and exacerbating inflammation.
Gluten: In sensitive individuals, this protein can trigger the release of zonulin, which loosens intestinal tight junctions and increases permeability.
Dairy Products: Lactose and casein can be problematic for many, causing inflammation and digestive distress due to common intolerances.
Unhealthy Fats: High intake of refined omega-6 vegetable oils and trans fats promotes systemic inflammation, which is detrimental to gut health.
Alcohol: Excessive alcohol consumption directly weakens the gut lining, increasing permeability and promoting inflammation.

Understanding Leaky Gut Syndrome

Leaky gut, medically known as increased intestinal permeability, occurs when the tight junctions in the intestinal wall loosen. This allows substances like undigested food, toxins, and bacteria to enter the bloodstream, potentially triggering inflammation and an immune response. A healthy gut barrier is vital for nutrient absorption and preventing harmful substances from escaping. Diet plays a significant role in gut health, and identifying and eliminating problematic foods can help reduce inflammation and support healing.

Foods and Ingredients to Avoid

Certain foods and their components are known to negatively impact the intestinal barrier and contribute to inflammation, making them detrimental for those with leaky gut.

Highly Processed and Refined Foods

Processed foods often contain additives, preservatives, emulsifiers, refined sugar, unhealthy fats, and lack the fiber necessary for a healthy gut. Emulsifiers, for instance, can disrupt the gut barrier, while low fiber starves beneficial gut bacteria. Common examples include fast food, packaged snacks, sugary cereals, and chips.

Added Sugars and Artificial Sweeteners

High sugar intake promotes an imbalance in gut bacteria (dysbiosis) and increases inflammation. This applies to both added sugars and artificial sweeteners, which can also alter the gut microbiome and cause digestive discomfort.

Glutenous Grains

Gluten, found in wheat, barley, and rye, can be problematic, particularly for individuals with Celiac disease or non-celiac gluten sensitivity. Gluten can stimulate zonulin, a protein that loosens the tight junctions in the gut lining, increasing permeability. While individual sensitivity varies, a gluten-free diet may be beneficial for those with gut issues. Foods containing gluten include bread, pasta, and barley.

Dairy Products

Dairy can cause inflammation due to lactose intolerance or sensitivity to proteins like casein. Lactose malabsorption can lead to digestive issues, while casein may trigger an immune response.

Unhealthy Fats

Inflammatory fats, such as refined vegetable oils high in omega-6 fatty acids and trans fats, can damage the gut lining and contribute to systemic inflammation.

Alcohol

Excessive alcohol weakens the gut lining and increases permeability by altering gut bacteria composition and promoting inflammation.

Comparison of Gut-Friendly vs. Gut-Damaging Fats


Feature	Healthy Fats (Gut-Friendly)	Unhealthy Fats (Gut-Damaging)
Source	Extra virgin olive oil, avocado oil, coconut oil, grass-fed butter	Refined vegetable oils (soybean, canola), trans fats, margarine
Omega Profile	Balanced, often higher in anti-inflammatory Omega-3s	High in pro-inflammatory Omega-6s
Inflammation	Anti-inflammatory properties	Promotes systemic inflammation
Processing	Minimally processed or unrefined	Highly processed and often hydrogenated
Gut Impact	Supports gut barrier integrity and microbiome health	Damages gut lining and disrupts microbiome balance

Conclusion: A Mindful Approach to Gut Healing

Addressing leaky gut involves eliminating inflammatory foods like processed items, sugars, unhealthy fats, gluten, and dairy to reduce inflammation and support gut repair. Incorporating supportive foods such as bone broth, fiber-rich vegetables, and probiotics is also beneficial. Since sensitivities vary, tracking your food intake can help identify personal triggers. Consulting a healthcare professional or dietitian can provide personalized guidance.

Practical Steps for a Gut-Friendly Diet

Embrace Whole Foods: Focus on unprocessed foods like fruits, vegetables, and lean proteins.
Read Labels: Check for hidden sugars, additives, and emulsifiers in packaged foods.
Consider a Short-Term Elimination: Temporarily removing certain foods can help identify specific sensitivities.
Prioritize Fiber: Increase intake of prebiotic fiber from foods like garlic and onions.
Incorporate Fermented Foods: Add probiotic-rich foods such as sauerkraut and kimchi.
Cook at Home: Preparing meals allows control over ingredients and helps avoid additives.

Authoritative Outbound Link

For more detailed information on how Western diet components affect intestinal permeability, you can refer to this review: Western diet components that increase intestinal permeability with potential implications for health

Final Thoughts on Leaky Gut Diet

Healing a leaky gut is a personal journey. The key is to reduce common inflammatory triggers, pay attention to your body, and focus on nourishing foods. Consistency is important, and informed choices can support gut health.

Frequently Asked Questions

Leaky gut is a condition where the intestinal lining, which acts as a barrier, becomes more permeable, allowing undigested food particles, bacteria, and toxins to pass into the bloodstream. This can trigger an inflammatory response.

For people with Celiac disease or gluten sensitivity, gluten can activate zonulin, a protein that regulates the tight junctions in the gut lining. This causes the junctions to open, increasing intestinal permeability.

Artificial sweeteners like sucralose and aspartame can disrupt the balance of gut bacteria, potentially harming beneficial microbes and contributing to intestinal discomfort and dysbiosis.

Not necessarily. While gluten-containing grains like wheat should be avoided by some, whole grains that are rich in fiber can actually support the growth of healthy gut bacteria. It's best to observe how your body reacts.

Excessive alcohol consumption directly harms the gut lining, leading to increased intestinal permeability and inflammation. It can also disrupt the balance of your gut microbiome.

Healthy fats, like extra virgin olive oil and avocado oil, have anti-inflammatory properties. Unhealthy fats, such as trans fats and refined vegetable oils high in omega-6, promote systemic inflammation, damaging the gut.

Yes, diets high in processed foods, which contain additives, low fiber, and inflammatory ingredients, are a major risk factor for increased intestinal permeability by negatively impacting gut bacteria.