The term “leaky gut” has gained a lot of attention in recent years.

Also known as increased intestinal permeability, it’s a condition in which gaps in your intestinal walls start to loosen. This makes it easier for larger substances, such as bacteria, toxins, and undigested food particles, to pass across the intestinal walls into your bloodstream.

Studies have associated increased intestinal permeability with several chronic and autoimmune diseases, including type 1 diabetes and celiac disease.

This article takes a close look at leaky gut and its causes. It also includes a list of foods that aid digestive health and a 1-week sample meal plan.

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Leaky gut syndrome is a proposed condition caused by increased intestinal permeability.

The digestive system consists of many organs that collectively break down food, absorb nutrients and water, and remove waste products. Your intestinal lining acts as a barrier between your gut and bloodstream to prevent potentially harmful substances from entering your body (1, 2).

Nutrient and water absorption mostly occurs in your intestines. Your intestines have tight junctions, or small gaps, that allow nutrients and water to pass into your bloodstream.

How easily substances pass across the intestinal walls is known as intestinal permeability.

Certain health conditions cause these tight junctions to loosen, potentially allowing harmful substances like bacteria, toxins, and undigested food particles to enter your bloodstream.

Alternative health practitioners claim that leaky gut triggers widespread inflammation and stimulates an immune reaction, causing various health problems that are collectively known as leaky gut syndrome (3).

They believe leaky gut leads to various conditions, including autoimmune diseases, migraines, autism, food sensitivities, skin conditions, brain fog, and chronic fatigue.

Yet, there is little evidence to prove that leaky gut syndrome exists. As a result, mainstream physicians do not recognize it as a medical diagnosis.

Although increased intestinal permeability exists and occurs alongside many diseases, it’s not clear if it’s a symptom or underlying cause of chronic disease (4).

Summary Leaky gut, or increased intestinal permeability, occurs when the tight junctions of your intestinal walls loosen. This may allow harmful substances, such as bacteria, toxins, and undigested food particles, to pass into your bloodstream.

The exact cause of leaky gut is a mystery.

However, increased intestinal permeability is well known and occurs alongside several chronic diseases, including celiac disease and type 1 diabetes (5).

Zonulin is a protein that regulates tight junctions. Research has shown that higher levels of this protein may loosen tight junctions and increase intestinal permeability (6, 7).

Two factors are known to stimulate higher zonulin levels in certain individuals — bacteria and gluten (8).

There is consistent evidence that gluten increases intestinal permeability in people with celiac disease (9, 10).

However, research in healthy adults and those with non-celiac gluten sensitivity shows mixed results. While test-tube studies have found that gluten can increase intestinal permeability, human-based studies have not observed the same effect (10, 11, 12).

Aside from zonulin, other factors can also increase intestinal permeability.

Research shows that higher levels of inflammatory mediators, such as tumor necrosis factor (TNF) and interleukin 13 (IL-13), or the long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, may increase intestinal permeability (13, 14, 15, 16).

Furthermore, low levels of healthy gut bacteria may have the same effect. This is called gut dysbiosis (17).

Summary The exact cause of leaky gut remains a mystery, but certain proteins like zonulin and markers of inflammation provide some clues. Other potential causes include long-term NSAID use and an imbalance of gut bacteria known as gut dysbiosis.

As leaky gut syndrome isn’t an official medical diagnosis, there is no recommended treatment.

Yet, you can do plenty of things to improve your general digestive health.

One is to eat a diet rich in foods that aid the growth of beneficial gut bacteria. An unhealthy collection of gut bacteria has been linked to poor health outcomes, including chronic inflammation, cancers, heart disease, and type 2 diabetes (18).

The following foods are great options for improving your digestive health:

  • Vegetables: broccoli, Brussels sprouts, cabbage, arugula, carrots, kale, eggplant, beetroot, Swiss chard, spinach, ginger, mushrooms, and zucchini
  • Roots and tubers: potatoes, sweet potatoes, yams, carrots, squash, and turnips
  • Fermented vegetables: kimchi, sauerkraut, tempeh, and miso
  • Fruit: coconut, grapes, bananas, blueberries, raspberries, strawberries, kiwi, pineapple, oranges, mandarin, lemon, limes, passionfruit, and papaya
  • Sprouted seeds: chia seeds, flax seeds, sunflower seeds, and more
  • Gluten-free grains: buckwheat, amaranth, rice (brown and white), sorghum, teff, and gluten-free oats
  • Healthy fats: avocado, avocado oil, coconut oil, and extra virgin olive oil
  • Fish: salmon, tuna, herring, and other omega-3-rich fish
  • Meats and eggs: lean cuts of chicken, beef, lamb, turkey, and eggs
  • Herbs and spices: all herbs and spices
  • Cultured dairy products: kefir, yogurt, Greek yogurt, and traditional buttermilk
  • Beverages: bone broth, teas, coconut milk, nut milk, water, and kombucha
  • Nuts: raw nuts, including peanuts, almonds, and nut-based products, such as nut milks
Summary A diet that promotes digestive health should focus on fibrous vegetables, fruits, fermented vegetables, cultured dairy products, healthy fats, and lean, unprocessed meats.

Avoiding certain foods is equally important for improving your gut health.

Some foods have been shown to cause inflammation in your body, which may promote the growth of unhealthy gut bacteria that are linked to many chronic diseases (19).

The following list contains foods that may harm healthy gut bacteria, as well as some that are believed to trigger digestive symptoms, such as bloating, constipation, and diarrhea:

  • Wheat-based products: bread, pasta, cereals, wheat flour, couscous, etc.
  • Gluten-containing grains: barley, rye, bulgur, seitan, triticale, and oats
  • Processed meats: cold cuts, deli meats, bacon, hot dogs, etc.
  • Baked goods: cakes, muffins, cookies, pies, pastries, and pizza
  • Snack foods: crackers, muesli bars, popcorn, pretzels, etc.
  • Junk food: fast foods, potato chips, sugary cereals, candy bars, etc.
  • Dairy products: milk, cheeses, and ice cream
  • Refined oils: canola, sunflower, soybean, and safflower oils
  • Artificial sweeteners: aspartame, sucralose, and saccharin
  • Sauces: salad dressings, as well as soy, teriyaki, and hoisin sauce
  • Beverages: alcohol, carbonated beverages, and other sugary drinks
Summary Avoiding processed junk foods, alcohol, sugary beverages, refined oils, and artificial sweeteners may aid the growth of healthy gut bacteria. Cutting out foods containing gluten or common stimulants of digestive symptoms may also help.

Below is a healthy 1-week sample menu for improving your digestive health.

It focuses on incorporating foods that promote the growth of healthy gut bacteria while removing foods that are notorious for causing uncomfortable digestive symptoms.

Some menu items contain sauerkraut, a type of fermented cabbage that is easy, simple, and inexpensive to prepare.

Monday

  • Breakfast: blueberry, banana, and Greek yogurt smoothie
  • Lunch: mixed green salad with sliced hard-boiled eggs
  • Dinner: beef and broccoli stir-fry with zucchini noodles and sauerkraut

Tuesday

  • Breakfast: omelet with veggies of your choice
  • Lunch: leftovers from Monday’s dinner
  • Dinner: seared salmon served with a fresh garden salad

Wednesday

  • Breakfast: blueberry, Greek yogurt, and unsweetened almond milk smoothie
  • Lunch: salmon, egg, and veggie frittata
  • Dinner: grilled lemon chicken salad with a side of sauerkraut

Thursday

  • Breakfast: gluten-free oatmeal with 1/4 cup of raspberries
  • Lunch: leftovers from Wednesday’s dinner
  • Dinner: broiled steak with Brussels sprouts and sweet potatoes

Friday

  • Breakfast: kale, pineapple, and unsweetened almond milk smoothie
  • Lunch: beet, carrot, kale, spinach, and brown rice salad
  • Dinner: baked chicken served with roasted carrots, beans, and broccoli

Saturday

  • Breakfast: coconut-papaya chia pudding — 1/4 cup of chia seeds, 1 cup of unsweetened coconut milk, and 1/4 cup of diced papaya
  • Lunch: chicken salad with olive oil
  • Dinner: roasted tempeh with Brussels sprouts and brown rice

Sunday

  • Breakfast: mushroom, spinach, and zucchini frittata
  • Lunch: sweet potato halves stuffed with spinach, turkey, and fresh cranberries
  • Dinner: grilled chicken wings with a side of fresh spinach and sauerkraut
Summary A healthy gut menu should be rich in fruits, vegetables, and lean protein. Fermented vegetables like sauerkraut or cultured dairy products like Greek yogurt are also excellent additions, as they’re a great source of healthy gut bacteria.

Although diet is key to improving gut health, there are plenty of other steps you can take.

Here are some more ways to improve your gut health:

  • Take a probiotic supplement. Probiotics contain beneficial bacteria that are naturally present in fermented foods. Taking a probiotic supplement, which you can find online, may improve gut health if you don’t get enough probiotics through your diet (20).
  • Reduce stress. Chronic stress has been shown to harm beneficial gut bacteria. Activities like meditation or yoga can help (21).
  • Avoid smoking. Cigarette smoke is a risk factor for several bowel conditions and may increase inflammation in the digestive tract. Quitting smoking can raise your count of healthy bacteria and reduce your count of harmful gut bacteria (22).
  • Sleep more. Lack of sleep can cause a poor distribution of healthy gut bacteria, possibly resulting in increased intestinal permeability (23).
  • Limit alcohol intake. Research has shown that excessive alcohol intake may increase intestinal permeability by interacting with certain proteins (24, 25, 26).

If you think you have leaky gut syndrome, consider getting tested for celiac disease.

The two disorders can have overlapping symptoms.

Some people also find that diets like the Gut and Psychology Syndrome (GAPS) diet may ease leaky gut symptoms. However, this diet is incredibly restrictive, and no scientific studies support its health claims.

Summary Aside from diet, try taking a probiotic supplement, reducing your stress levels, sleeping more, avoiding smoking, and limiting alcohol intake to improve your gut health.

Leaky gut syndrome is a hypothetical condition caused by increased intestinal permeability.

It’s associated with increased intestinal permeability – microscopic gaps in the intestinal walls that make it easier for bacteria, toxins, and undigested food particles to pass through the intestinal walls into your bloodstream.

However, mainstream physicians do not recognize leaky gut syndrome as a medical diagnosis, as there is currently little evidence that increased intestinal permeability is a serious health problem in and of itself.

Increased intestinal permeability occurs alongside chronic diseases like celiac disease and type 1 diabetes. However, it’s more likely to be a symptom of these diseases, rather than a cause.

That said, there are plenty of steps you can take to improve your digestive health.

To combat leaky gut, eat foods that promote the growth of healthy gut bacteria, including fruits, cultured dairy products, healthy fats, lean meats, and fibrous and fermented vegetables.

Avoid processed and refined junk foods.

You can also take probiotic supplements, reduce stress, limit NSAID use, avoid alcohol, and get more sleep.