Quick answer: “Leaky gut” is a simple name for increased intestinal permeability, when the gut lining lets through more than it should. Think of a garden hose with tiny holes: water still flows, but some leaks out. Common contributors include a highly processed diet, stress, infections, some medications, alcohol and environmental toxins. Signs can include bloating, food sensitivities, skin issues, fatigue and brain fog.
Key takeaways
Leaky gut is a plain-language name for increased intestinal permeability, when the gut lining lets through more than it should.
A garden hose with tiny holes is a helpful picture, because the gut still works but some contents leak where they should not.
Processed food, stress, infections, some medications, alcohol and everyday exposures are common contributors, and first steps start with diet and stress.
The garden-hose analogy
Imagine your intestines as a long hose. When the hose is intact, water flows from one end to the other. Add tiny holes and some water leaks out along the way. Your gut lining works as a selective barrier: it lets nutrients and water in while keeping larger food particles, microbes and toxins out. When the tight junctions between lining cells loosen, more gets through, and the immune system reacts.
Possible signs
Possible signs include bloating, abdominal pain, diarrhea or constipation, new or growing food sensitivities, and skin rashes or eczema. Joint aches, fatigue, brain fog, anxiety or low mood can also show up, and there is an association with autoimmune conditions.
These symptoms overlap with many other conditions, so they are a reason for evaluation rather than a diagnosis.
Common contributors
Common contributors include a diet high in processed foods and added sugar, psychological stress, and gut infections, including SIBO and yeast overgrowth. Medications such as NSAIDs, antibiotics and acid blockers can contribute, as can alcohol.
Environmental exposures such as pesticides and mold play a part too, along with age, since the gut barrier can change over time.
First steps
Start by learning the basics in what is leaky gut?, then follow a step-by-step support plan: how to support leaky gut naturally. Eat more fiber-rich plants and fewer ultra-processed foods, manage stress and sleep, and ask your provider before stopping any medication.
Leaky gut and healthy aging
A leakier gut lets bacterial fragments reach the bloodstream, which may contribute to low-grade chronic inflammation (often called inflammaging) and disrupts communication between the gut, immune system and brain. Supporting the gut barrier is one way to calm that background inflammation.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have ongoing bloating, irregular bowels or food reactions, or skin, joint or mood symptoms along with gut symptoms. The same is true if you have an autoimmune condition and want to support gut health, or if you want a structured plan instead of guessing.
See a medical provider promptly for blood in the stool, black stools, unexplained weight loss, persistent vomiting, or severe abdominal pain.
What the research shows
One of the first studies to measure gut permeability in people was a 1984 Lancet study by Bjarnason and colleagues. Using a sugar-like tracer test, they compared 24 people with rheumatoid arthritis and 34 controls. Permeability was normal in people not taking anti-inflammatory painkillers (NSAIDs) but almost always raised in those who were, and bowel scans showed inflammation near the end of the small intestine in 6 of 9 people on or recently on NSAIDs. The authors concluded that the arthritis itself did not seem to cause the leak, but the medicines did.
Age may matter too. In a 2015 study by Man and colleagues, researchers examined small intestine biopsies from children, adults aged 20 to 40 and older adults aged 67 to 77 without digestive symptoms. Older tissue had more of the inflammatory signal IL-6 and more of a protein (claudin-2) that loosens the seal between cells, but overall leakiness to large molecules did not change. These were lab measurements on tissue samples, so they do not tell us how much this matters for symptoms.
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Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Which first step, such as diet changes or stress care, would be most useful for my gut right now?
Which of my symptoms might point to an issue with my gut lining?
Which first steps for gut health would be the gentlest for me?
When would testing be worth considering for my gut?
Frequently asked questions
Is leaky gut a real diagnosis?
Increased intestinal permeability is well documented in research. “Leaky gut syndrome” is not a formal diagnosis, but the barrier problem is real.
What causes leaky gut?
Common contributors include diet, stress, infections, certain medications, alcohol and environmental exposures.
Can food sensitivities come from leaky gut?
They are often associated. When the barrier is more permeable, the immune system may react to more foods.
How do I know if I have leaky gut?
Symptoms and history guide the picture. Testing is optional and can help in complex cases.
Sources
- Bjarnason I, Williams P, So A, et al. Intestinal permeability and inflammation in rheumatoid arthritis: effects of non-steroidal anti-inflammatory drugs. Lancet 1984. PMID: 6150232. https://pubmed.ncbi.nlm.nih.gov/6150232/
- Man AL, Bertelli E, Rentini S, et al. Age-associated modifications of intestinal permeability and innate immunity in human small intestine. Clin Sci (Lond) 2015. PMID: 25948052. https://pubmed.ncbi.nlm.nih.gov/25948052/
- Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in humans. Gut 2019. PMID: 31076401. https://pmc.ncbi.nlm.nih.gov/articles/PMC6790068/
- Fasano A. Leaky gut and autoimmune diseases. Clin Rev Allergy Immunol 2012. PMID: 22109896. https://pubmed.ncbi.nlm.nih.gov/22109896/
- Vanuytsel T, et al. Psychological stress and corticotropin-releasing hormone increase intestinal permeability in humans by a mast cell-dependent mechanism. Gut 2014. PMID: 24153250. https://pubmed.ncbi.nlm.nih.gov/24153250/
- Bjarnason I, et al. Mechanisms of Damage to the Gastrointestinal Tract From Nonsteroidal Anti-Inflammatory Drugs. Gastroenterology 2018. PMID: 29221664. https://pubmed.ncbi.nlm.nih.gov/29221664/
- MedlinePlus: Digestive Diseases
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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