What Causes Leaky Gut?

Leaky gut occurs when normally tight junctions in the gut become loose and open, allowing the passage of substances through the lining of the small intestine to leak into the bloodstream.

Gluten is the number one cause of leaky gut. Gluten upregulates a protein called zonulin produced in the small intestine. Zonulin dismantles proteins in the gut that seal the gut lining creating gaps through which other food proteins may enter the bloodstream.

These circulating substances are seen as “foreign” to the body and the immune system initiates an inflammatory immune response against them.

The most common causes of leaky gut can be classified into 3 groups: your history, your lifestyle and your diet.


  • Chronic antibiotic or NSAID (e.g. ibuprofen) use
  • Mercury filling or heavy metals
  • Traumatic brain injury
  • Chemo or radiation treatments
  • Caesarean birth
  • Gut dysbiosis/infections
  • Hormone imbalance
  • Chronic inflammation
  • Vitamin/nutrient deficiencies


  • Environmental toxins
  • Sleep deprivation
  • Alcohol
  • Chronic stress
  • Liver toxicity


  • Gluten
  • Nightshades (e.g. eggplants, tomatoes, peppers, potatoes, goji berries)
  • Sugar
  • Omega 6/Omega 3 inflammatory ratio
  • Industrial seed oils (canola, sunflower, soybean, cottonseed, grapeseed, rice bran)

More than 80% of your immune system is in your gut. If you have an autoimmune disease, then by definition you have a leaky gut that needs to be repaired, otherwise you won’t be able to reverse your condition.

Read my “Gut & Disease” article for more information on leaky gut.