Leaky Gut - symptoms, causes and how to heal it

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What is leaky gut? 

Leaky gut syndrome, also known as ‘intestinal permeability’, is a condition where the lining of the small intestine becomes damaged. This damage allows undigested food particles, toxins, and bacteria to ‘leak’ through the intestinal wall into the bloodstream, triggering inflammation and immune reactions throughout the body.  

Surprisingly leaky gut is not recognised as an official medical diagnosis, although it is believed that most people have leaky gut to some extent. Research suggests that an increased level of gut permeability may play a role in a various conditions. 

The gut barrier 

The gut barrier is largely responsible for absorbing water and essential nutrients from the foods we eat whilst also preventing harmful substances from entering circulation. 

The gut barrier is a complex system made up of: 

• Epithelial cells: These form a tight barrier lining the intestines. 

• Tight junction proteins: These hold the epithelial cells together, controlling what passes into the bloodstream. 

• Mucus layer: This protects the gut lining and supports beneficial gut bacteria. 

• Gut microbiome: The collection of microbes in the intestines helps regulate immunity and digestion. 

When the gut barrier is weakened, it becomes less efficient at keeping out many harmful toxins, which can then enter the bloodstream and contribute to systemic inflammation and may manifest as chronic diseases. 

The gut barrier has many layers of defence that protect the body from harmful toxins. It is largely believed that increased intestinal permeability is the result of consistent and prolonged damage from common everyday factors that can eventually wear down the lining of the gut. 

Causes of leaky gut 

Whilst there is no definitive understanding on the causes of leaky gut, there are several factors that are believed to contribute to increased intestinal permeability: 

Poor diet 

A diet high in processed foods, refined sugars, and unhealthy fats can weaken the gut lining. Specific culprits include: 

• Gluten: Some studies suggest gluten can increase gut permeability, particularly in people with coeliac disease or gluten sensitivity. 

• Excess sugar and artificial sweeteners: High sugar intake promotes harmful bacteria, which can damage the gut barrier. 

• Processed foods: Processed foods can contain high levels of sugar, refined carbohydrates, industrial fats and food additives. In the UK, ultra processed foods made up 57% of the total calories consumed by adults and 65% in children. 

• Alcohol: Chronic alcohol consumption disrupts the gut microbiome and weakens the intestinal lining. 

• Food additives: Emulsifiers and preservatives found in processed foods can alter the gut microbiome and impair gut function. 

The western diet, which is high in foods that negatively impact gut health, such as alcohol, increased sugar intake, food additives and processed foods as well as a lack of fibre, is often a contributing factor. 

Chronic stress 

Ongoing stress can alter gut bacteria, increase inflammation, and weaken the integrity of the gut lining. The body’s natural stress hormone such as cortisol can alter the composition of the gut microbiome. 

Gut dysbiosis – an imbalance of bacteria 

A healthy gut microbiome consists of trillions of different types of beneficial and harmful bacteria. The beneficial bacteria prevent overgrowth of harmful bacteria and support the health of the gut lining. When harmful bacteria overgrow, causing gut dysbiosis, it can lead to inflammation and increased permeability. 

Infections 

• Bacterial infections (e.g. H. pylori) 
• Fungal overgrowth (e.g. Candida) 
• Environmental toxins, pesticides, and heavy metals 

Medications 

Certain medications have been linked to gut barrier dysfunction by altering the balance of the bacteria within the gut microbiome: 

• Non-steroidal anti-inflammatory drugs (NSAIDs) (naproxen, ibuprofen) are known to damage the lining of the gut. 

• Antibiotics cannot differentiate between beneficial and harmful bacteria, so when consumed, they destroy both harmful and beneficial gut bacteria. This can lead to gut dysbiosis and increased intestinal permeability.  

• Proton pump inhibitors (PPIs) reduce stomach acid, affecting digestion and microbial balance. 

Chronic inflammation and autoimmune diseases 

• Conditions like coeliac disease, Crohn’s disease, and irritable bowel syndrome (IBS) are associated with increased gut permeability. 

• Autoimmune diseases such as rheumatoid arthritis, type 1 diabetes, and multiple sclerosis may be linked to leaky gut. 

Symptoms of leaky gut 

We know that the gut microbiome plays a vital role in our overall health and wellness, so the symptoms linked to leaky gut can span much wider than digestive issues and, in some cases, can manifest into chronic conditions if not addressed. 

Since leaky gut affects multiple body systems, symptoms can vary widely, including: 

Digestive symptoms 

• Bloating 

• Diarrhoea or constipation 

• Gas and indigestion 

• Food intolerances 

• Stomach ache 

Other symptoms 

• Fatigue and brain fog 

• Joint pain 

• Skin issues (eczema, acne, psoriasis) 

• Frequent headaches 

Immune and inflammatory symptoms 

• Autoimmune flare-ups 

• Allergies and asthma 

• Chronic inflammation 

These conditions are characterised by inflammation, which can be caused by the movement of unwanted substances into the bloodstream. If left untreated, leaky gut may contribute to more serious conditions such as chronic fatigue syndrome, metabolic disorders, and mood disorders like anxiety and depression. 

What conditions are linked to leaky gut? 

Emerging research suggests that leaky gut is associated with several health conditions, including: 

• Gastrointestinal symptoms – bloating, diarrhoea, abdominal pain, constipation, excess gas. 
• Irritable bowel syndrome (IBS) and Irritable bowel disease (IBD). 
• Inflammation 
• Food sensitivities and allergies 
• Autoimmune diseases such as rheumatoid arthritis and multiple sclerosis 
• Skin conditions like eczema, psoriasis, and acne 
• Mood disorders such as anxiety, chronic fatigue, depression, and brain fog 
• Joint pain 
• Metabolic disorders – such as obesity and type 2 diabetes 

Why addressing leaky gut is essential 

If you suffer from leaky gut this can indicate that your gut health has been compromised. Since gut health is vital to various aspects of our overall wellbeing, ignoring symptoms can lead to long-term complications. This imbalance can create a cycle of inflammation, immune dysfunction, and ultimately contribute to chronic diseases. 

Addressing gut health through diet and lifestyle changes can help to repair your gut lining, balance any bacteria imbalances and reduce your risk of developing many of the conditions that leaky gut is linked to. 

How to test for leaky gut

There's is no definitive way to diagnose leaky gut, but some diagnostic tools and tests may be able to paint a picture of your overall gut health to help pinpoint causes of symptoms. Some of these tests include: 

Urine test 

This involves drinking two different types of solutions containing different sizes molecules. If any of the larger molecules have made it into your urine it can indicate increased intestinal permeability. 

Zonulin test 

Zonulin is a protein linked to gut permeability; elevated levels can suggest increased leaky gut. 

Microbiome test 

A gut microbiome test can provide a complete picture of your gut health, identifying gut dysbiosis and bacterial overgrowth. A microbiome test it can also give you the tools needed to improve your gut health through correct nutrition and supplementing.

Regardless of the testing method used, testing for leaky gut is likely to be multi-faceted and will involve a combination of testing, symptom assessment and dietary and lifestyle changes.

How to heal leaky gut naturally 

Adopt a gut friendly diet 

Focus on gut friendly foods that can help to repair your gut microbiome. 

Foods to include 

• Bone broth: Rich in collagen and amino acids that support gut healing. 

• Fermented foods (kefir, sauerkraut, kimchi, yoghurt, miso) contain beneficial probiotics that help boost the numbers of beneficial bacteria like Bifidobacterium and restore balance, promoting a healthy microbiome. 

• Omega-3-rich foods: (e.g. oily fish, flaxseeds, chia seeds) reduce inflammation. 

• Leafy greens and colourful vegetables: High in antioxidants and fibre to nourish gut bacteria. 

• Prebiotic foods: (e.g., garlic, onions, bananas) feed good bacteria. 

Foods to avoid 

• Processed foods and refined sugars 

• Gluten (if sensitive) 

• Dairy (if lactose intolerant) 

• Alcohol and caffeine in excess 

Lifestyle changes 

• Reduce stress 
• Chronic stress impacts gut health. Practices that help manage stress include: 
  • Mindfulness and meditation 
  • Gentle exercise (e.g. yoga, walking) 
  • Adequate sleep 
  • Spending time outdoors 
  • Socialising 

Limit antibiotic use 

Although not always avoidable, where possible you should limit the use of gut disrupting medicines such as antibiotics and NSAID’s. 

Saskia's thoughts

Leaky gut is a growing area of interest in gut health research, and we believe that it is only a matter of time before it is officially classified as a recognised condition. It’s clear that leaky gut is not caused by one thing, instead it appears to be a multifaceted condition that arises after years of prolonged damage to the gut. 

While more studies are needed, addressing gut permeability through diet, lifestyle changes, and targeted supplementation can support overall health. If you suspect leaky gut, working with a healthcare provider or gut health specialist can help tailor a healing plan to your needs.