What Causes Leaky Gut? + What To Eat & Avoid To Help Manage It, From Experts

The terms leaky gut and leaky gut syndrome (sometimes called intestinal permeability) are used with a lot more frequency these days—especially in reference to patients who suffer from painful digestive conditions, like irritable bowel syndrome (IBS) or celiac disease.

At the most basic level, a leaky gut means your intestines aren't quite as secure as they should be.

Here's a quick biology lesson: The walls of the intestines are supposed to be permeable to a degree. This is how the nutrients from the food we eat make it into the body, while other parts of food we can't use continue through the intestines and eventually leave as waste. Ideally, the barrier of the intestines would only allow tiny nutrients to absorb into the bloodstream, and excrete unwanted particles.

The problem occurs when the intestinal tight junctions1—the spaces between the single layer of cells that regulate what enters the bloodstream—are injured (which can happen for a variety of reasons like poor diet and stress). This allows unwanted microbes and undigested food particles to "leak" into the bloodstream, where the immune system often marks them as foreign invaders and attacks. This is considered leaky gut, or increased intestinal permeability2.

Increased intestinal permeability is known to play a role in some gastrointestinal conditions, like celiac disease, Crohn's disease3, and irritable bowel syndrome (IBS)4. While scientists are in agreement that increased intestinal permeability is related to these gastrointestinal issues, it's not clear whether leaky gut is the cause or a side effect of them.

Other studies suggest leaky gut may be connected to autoimmune diseases5, such as arthritis and thyroid disorders.

So, what causes increased intestinal permeability? A 2013 study points toward zonulin6, a human protein that researchers described as "the only known...modulator of intercellular [tight junctions] described so far." When zonulin is released, the tight junctions of the intestines can break apart.

According to research, bacteria and gluten6 have been shown to trigger the release of zonulin in the small intestine. This is why many functional nutrition experts suggest dietary changes, like a gluten-free diet, to help manage the symptoms.

If you think you may have leaky gut, mbg Collective member and gut health expert Vincent Pedre, M.D., recommends working with a registered dietitian or gastroenterologist to begin limiting the following foods from your diet.

Because gluten is linked to the release of zonulin, it's suspected to trigger leaky gut. Gluten is protein found in wheat, barley, and rye, and common sources include pastas, noodles, breads, pastries, cereal, and granola, not specifically labeled "gluten-free."

Now that you know what not to eat, you might be thinking: so, what's left? Don't worry, there's plenty!

The gelatin in bone broth protects the mucosal lining of the digestive tract and helps aid in the digestion of nutrients. Some research suggests collagen peptides may have a similar benefit. Bone broth is also a rich source of glutamine, an amino acid that's a preferred source of energy for the cells of the small bowel, along with other immune cells. It's also been shown to regulate intestinal permeability13.

Foods like kimchi, unpasteurized sauerkraut, and lacto-fermented pickles are all rich sources of probiotics that help keep your immune system strong, fend off pathogens, and protect the gut lining.

Altering your dietary intake should be the first step after visiting a doctor. To further support your gut, consider the following:

Add a probiotic supplement: Good gut bacteria, which are crucial in supporting a healthy microbiome, can become depleted or disrupted by a number of things, and fermented foods may not deliver the amount you need. So, taking a highly concentrated probiotic daily may provide additional support.*

Reduce your use of NSAIDs: When taken too frequently, this class of anti-inflammatory pain relievers may increase the risk14 of intestinal permeability, research says.

This sample menu incorporates the gut-friendly foods from the list of "what to eat." It's not hard and fast, though—feel free to swap in foods from the list above if you don't have some of these ingredients on hand. The goal is to avoid possibly aggravating foods from the "foods to avoid" list.

Breakfast: A couple of scrambled eggs with a side of sautéed kale. Pro tip: Cooked veggies are gentler on the gut and may be a better choice than raw.

Alternative breakfast option: Go for a bowl of oatmeal with almond milk, berries, and walnuts if you're craving something sweet.

Lunch: A salad with lentils and lean protein will provide sustained energy and a good dose of prebiotic fiber. Add some kimchi or sauerkraut for a probiotic boost.

Alternative lunch: Not a fan of salads? Scoop some tuna or chicken salad (made with an avocado-oil-based mayo) into romaine lettuce and eat it like a taco.

Snack: Carrot slices with hummus, apple slices with almond butter, or crunchy roasted chickpeas. The possibilities are endless, but leaky-gut-friendly snacks should include a form of fiber, along with a bit of fat and protein to help balance blood sugar and keep you fuller, longer.

Dinner: Pan-seared salmon, roasted sweet potato, and Brussels sprouts cooked in olive oil is a delicious, gut-friendly dinner. Whatever you choose to make, keep this simple formula in mind: quality protein source + non-starchy veggie + starchy veggie (optional) + healthy fat.

Leaky gut syndrome is a condition in which the cellular junctions of the intestinal wall become damaged, allowing undigested food and bacteria to "leak" into the bloodstream. Leaky gut has been implicated in many autoimmune disorders like IBS and celiac disease. However, it is not yet a widely recognized medical condition and more research is needed to understand the cause and proper treatment methods.