Leaky gut syndrome — or increased intestinal permeability — is a digestive disorder that allows bacterial fragments, endotoxin, and undigested protein to leak through the intestinal wall.
Although many medical professionals do not recognize leaky gut as a genuine health condition, there is a body of scientific evidence to suggest that this condition exists and is associated with several other health conditions. (Mu et al., 2017)
What is Leaky Gut Syndrome?
One of the roles of the digestive system is to protect your body from harmful substances.
The intestinal walls act as barriers and control which substances can enter the bloodstream. The intestinal wall has small gaps, known as tight junctions. These allow nutrients and water to pass through while preventing the passage of harmful substances such as pathogens, bacterial fragments and undigested proteins.
When the tight junctions loosen, the intestinal walls become more permeable, which can enable toxins and harmful bacteria to enter the bloodstream.
When toxins enter the bloodstream, your body will send a signal to your immune system to protect it from these invaders. Your immune system will react rapidly and aggressively. Each time it responds to invaders, your immune system triggers systemic inflammation.
Chronic inflammation is one of the primary symptoms of leaky gut syndrome. It stops your body from healing itself naturally and can be a precursor to many diseases.
Possible symptoms of leaky gut syndrome include:
- Chronic diarrhea
- Gas or bloating
- Compromised immune system
- Nutritional deficiencies
- Skin complaints such as rashes, eczema, psoriasis and acne
- Joint pain
- Autoimmune diseases
Causes and Risk Factors
Experts in the medical field have not been able to determine the exact cause of leaky gut syndrome. The protein zonulin is known to regulate intestinal permeability. (Fasano, 2012)
Bacteria in the intestines and gluten trigger the release of zonulin. In people who have a genetic susceptibility, this can lead to leaky gut syndrome. (Fasano, 2012)
Other factors which are believed to play a role in leaky gut syndrome include:
- Excessive sugar intake
- Excessive alcohol intake
- Non-steroidal anti-inflammatory drugs (NSAIDs)
- Vitamin A and D deficiency
- Chronic inflammation
- An imbalance of gut bacteria (dysbiosis)
Health Conditions Associated with Leaky Gut
Some medical studies have associated increased intestinal permeability with several chronic diseases. These include:
This is an autoimmune disease caused by extreme sensitivity to gluten — a substance found in wheat and other cereal grains. Intestinal permeability is known to be higher in people who have celiac disease. (Sander et al., 2005)
Crohn’s disease causes chronic inflammation of the intestinal tract. Intestinal permeability plays a significant role in this condition.
Leaky gut may also play a role in the genetic aspect of Crohn’s disease. (Hollander et al., 1986)
Type 1 diabetes is a result of the autoimmune destruction of insulin-producing pancreatic beta cells. It is possible that toxins leaking through the intestinal wall trigger this. (de Kort et al., 2011)
Irritable Bowel Syndrome
IBS is a digestive disorder which can cause both chronic diarrhea and chronic constipation. Increased intestinal permeability is common in people who suffer from diarrhea-predominant IBS. (Dunlop et al., 2006)
Food Allergies and Intolerances
A leaky gut can result in the passage of food proteins through the intestinal barrier, which stimulates an immune response. This is a form of food allergy. (Ventura et al., 2006)
Food intolerances are also linked to leaky gut by non-IgE mechanisms.
Diagnosing Leaky Gut
There are several leaky gut tests. These include:
The Lactulose/Mannitol test analyzes urine for the presence of the two sugars — lactulose and mannitol. If there are elevations or a problem with the ratio between the two, it is suggestive of leaky gut.
Excessive production of zonulin causes the intestine’s tight junctions to stretch inappropriately, causing toxins and bacteria to leak into the bloodstream. The accuracy of zonulin testing has been called in to question, so the Lactulose/Mannitol test is the best option.
Stool Test for Dysbiosis
A weakened gastrointestinal system associated with leaky gut syndrome can lead to an imbalance between pathogenic and beneficial intestinal bacteria. A stool test is used to diagnose this problem, although it is not a direct measure of leaky gut.
Learn more about dysbiosis here.
Breath Test for SIBO
A breath test can diagnose SIBO which is often associated with leaky gut, although this test is not a direct measure of leaky gut.
Learn more about SIBO here.
Elimination diets can be used to determine food sensitivities or intolerances. An elimination diet requires you to avoid eating suspected problem foods for several weeks or until symptoms have subsided.
Each food is then gradually reintroduced to determine which one is causing an adverse reaction. These reactions are often associated with leaky gut.
Learn more about elimination diets here.
Healing Leaky Gut
The first step often recommended to healing a leaky gut is to eliminate toxins and other damaging factors which may be contributing to the condition. This means avoiding:
- Food allergens, such as gluten
- Excessive use of NSAIDs
- Chronic stress
- Excessive exercise
There are other dietary and lifestyle changes you can make to help heal a leaky gut.
The following probiotic strains have evidence behind them for restoring integrity of the tight junctions:
- Lactobacillus rhamnosus GG
- Lactobacillus salivarius UCC118 and CCUUG38008
- Saccharomyces cerevisiae var boulardii
- E. coli Nissle 1917 (Mutaflor)
- Lactobacilus casei Shirota (Yakult)
- Lactobacillus casei DN-114 001
(Hechtman et al., 2018)
Adding foods rich in digestive enzymes to your diet may reduce the amount of partially undigested, toxic substances that can adversely affect your intestinal lining. Foods containing digestive enzymes include avocados, bananas, pineapples, papaya, and sauerkraut.
Glutamine is an amino acid that can help leaky gut syndrome by protecting the lining of your gut and intestines. Foods which are rich in glutamine include chicken, bone broth, eggs, seafood, nuts, and beans.
Glutamine can also be taken as a daily supplement of up to 20 grams per day divided between meals.
Vitamins A and D
These two vitamins help with the body’s production of immunoglobulin A, which is vital for the health of your mucous membranes and the functioning of your immune system.
- The recommended daily dose of vitamin A is 700 - 900 mcg for adults.
- The recommended daily dose of vitamin D is 600 IU for ages 1 to 70 years, and 800 IU for people over 70 years.
Both zinc sulfate and zinc carnosine are useful for leaky gut.
Other Nutrients/Plant Compounds
Other beneficial compounds include quercetin, curcumin, EGCG (found in green tea), myricetin and kaempferol.
The Leaky Gut Diet
The leaky gut diet involves eliminating foods which may trigger widespread inflammation and adding foods which encourage the growth of beneficial bacteria throughout your gastrointestinal tract. Such foods include gluten, dairy and alcohol.
Foods to Add
- Vegetables: Arugula, Brussels sprouts, broccoli, beets, spinach, ginger, zucchini, kale, eggplant, Swiss chard, and cabbage.
- Fermented vegetables: Tempeh, miso, sauerkraut, and kimchi.
- Tubers and roots: Sweet potatoes, potatoes, carrots, yams, turnips, and squash.
- Sprouted seeds: Flax seeds, chia seeds, and sunflower seeds.
- Gluten-free grains: White and brown rice, buckwheat, sorghum, amaranth, and teff.
- Fruit: Bananas, grapes, coconut, raspberries, blueberries, papaya, passion fruit, kiwi, pineapple, lemons, limes, and oranges.
- Meat and fish: Lean beef, chicken, turkey, tuna, salmon, herring, and mackerel.
- Healthy fats: Extra virgin olive oil, coconut oil, and avocado oil.
- Cultured dairy products: Greek yogurt, kefir, and buttermilk.
- Nuts: Almonds, peanuts, and nut milks.
Foods to Avoid
- Wheat-based foods: Pasta, bread, wheat flour, couscous, and cereals.
- Grains containing gluten: Bulgur, rye, barley, oats, and seitan.
- Processed meats: Deli cuts, hot dogs, and bacon.
- Junk food: Fries, sugary cereals, fast foods, and candy bars.
- Dairy products: Ice cream, milk, and cheeses.
- Snack foods: Potato chips, pretzels, popcorn, crackers, and muesli bars.
- Baked goods: Muffins, pies, cakes, pizza, and pastries.
- Refined oils: Sunflower, canola, soybean, and safflower oils.
- Artificial sweeteners: Saccharin, aspartame, and sucralose.
- Beverages: Soda, alcohol, and sugary drinks.
The best thing to do is to pay attention to your body. A gut-healthy diet can support your digestive and immune systems, even if you don’t notice symptoms of leaky gut syndrome.
The state of your gastrointestinal tract can make an incredible difference in how you feel — it makes sense to take care of it daily.