As mentioned in the previous Leaky Gut: The Basics post, leaky gut is when intestinal permeability occurs for prolonged periods of time and is accompanied by inflammation. Leaky gut can cause havoc not only in the digestive tract but can contribute to poor systemic health. Intestinal permeability happens when the gut cells no longer fit tightly together and cease to function as a discriminating barrier. When this happens temporarily as a normal physiologic function, there are usually no issues. When this happens in the presence of inflammation and is the rule rather than the exception, then the symptoms of leaky gut start to show up.
So what causes the cells forming the tight junctions to fail or to allow substances across the membrane that shouldn’t cross it? Lots of things can contribute to a leaky gut. It can range from the food we eat to the pathogens in our environment to certain medications we take to a variety of different stressors in our life to the genes that make us who we are. Identifying the cause (or more likely, causes) of leaky gut can help you to properly treat it and reverse damage in the body.
The 9 Causes Leaky Gut
#1 – Food
Food additives – This list includes sugar, salt, gluten, emulsifiers, organic solvents, microbial transglutaminase, and nanoparticles (1, 2). You might be looking at this list and thinking you are doing okay because your foods don’t list any of the later four on their labels. These are a bit sneaky! Organic solvents, for instance, do not necessarily need to be listed on labels because they are used in extracting “active ingredients” or cleaning. Even though they sound benign, most are actually poisons and have to labeled as such; but, again, you won’t see these listed on your food labels because they are used in the processing. To easily avoid them, choose whole and minimally processed foods. Many edible oils are extracted with solvents. Not all organic solvents are necessarily bad, some are simply antioxidants that help with food preservation.
Food sensitivities and allergies (3) – A sensitivity and an allergy are different. Allergic reactions from food tend to be more severe and easier to recognize: acute redness, swelling, and sometimes throat tightening and closing. With food sensitivities, the symptoms can be more varied and appear in pretty much any system in your body. People tend to think that if their body does not like a particular food, it will show up as digestive issues soon after eating it; lactose intolerance is an example of this. Food sensitivities are different. These can appear up to 3 days after eating the food and have symptoms as varied as eczema, brain fog, muscle aches, heartburn, and irritability—just to name a few! The degree of leaky gut correlates to the severity of symptoms (4).
Food coloring – Artificial food dyes (which are made from petroleum and are FDA-approved for consumption) can promote inflammation and cause increased permeability (5). They are not only added to food, but also to many pharmaceutical and cosmetic products.
Gluten (5, 6) – This infamous molecule causes an increase in gut permeability and leakiness by increasing a protein called zonulin. Zonulin is naturally produced by the body to open up the gut to allow small particles and nutrients to enter. When too much zonulin is present, the gaps between cells increase, and larger particles are allowed into your body. It can do this in both people who have celiac disease and those who do not.
Lack of certain nutrients – Zinc (7), glutamine (8), and fiber are a few nutrients necessary to maintain a healthy digestive tract. The bacteria in your gut metabolize fiber and produce short-chain fatty acids (SCFAs). These SCFAs help to keep the gut sealed appropriately (9).
#2 – Inflammation
Inflammation doesn’t occur on its own, but I am still listing it here because the signaling molecules and other products produced during an inflammatory process can perpetuate a leaky gut. Inflammation itself has many causes, including some already listed here like pathogens (bacteria and viruses) and certain foods and food additives.
Some bugs found to be responsible for leaky gut include giardia, entamoeba histolytica, Yersinia (13), H. pylori (14, 15), blastocysitis (16), and HIV. A few of these have been directly associated with Hashimoto’s and IBD.
#4 – NSAIDs
Many of the studies on gut permeability and NSAIDs have been done in the context of Crohn’s patients and their relatives (17, 18). However, there have also been studies showing that even short-term use of aspirin can cause changes in the gut lining of healthy people (19) and that when aspirin is taken by healthy subjects before exercise, their gut permeability will increase (20, 21). NSAIDs include aspirin products like Bayer and Excedrin, Ibuprofen products like Advil and Motrin, and naproxen products like Aleve. Sadly, these pain relievers are often used by people with rheumatological conditions such as arthritis and ankylosing spondylitis. Increases in intestinal permeability (leaky gut, as we have been calling it) have been found in people with these conditions. The authors of one study focusing on the connection say they don’t know which came first: the leaky gut or the NSAID use (22). I would say that the leaky gut likely comes first and that NSAIDs perpetuate and perhaps even worsen it. I say this because 1) we know many autoimmune diseases are linked to a leaky gut (23) and 2) clinical experience. Naturopathic medicine has long said that arthritis is related to a leaky gut and naturopathic doctors, myself included, often focus first on the gut when treating patients with arthritis. Treatment often involves removing food sensitivities and providing nutrients to heal the gut. This is successful and necessary for rheumatologic patients who do and don’t use NSAIDs on a regular basis.
#5 – Some anticancer therapies
When the chemotherapy drugs bevacizumab, oxaliplatin, 5-fluorouracil, and/or leucovorin were used in patients with cancer, there was an increase in intestinal permeability (24).
#6 – Stress
Know that butterflies-in-your-stomach feeling? We have all experienced the firsthand link between our nervous system and our guts. Both physical (25) and emotional stress (26) can cause the cells to create a space between themselves.
#7 – Changes in your normal gut flora (27)
What causes changes in the normal gut flora? Diet is a major daily contributor. Stress and infections are also to blame.
#8 – Overtraining/Exercising (28)
People are Iron Man and CrossFit crazy these days, but it may not always be the best move for your long-term health.
#9 – Genes
A study on Crohn’s disease demonstrated that mutations in a certain gene, NOD2, were common in Crohn’s disease patients and their first-degree relatives. Intestinal permeability was also commonly found in both. The authors of the study put two-and-two together and realized there was a link between the gene and intestinal permeability (31). Please remember that gene mutations don’t dictate that an issue will certainly arise, they merely tell us about areas of greater vulnerability.
Signs & Conditions of Leaky Gut
Whew! There is a lot that can cause a leaky gut! If you’re wondering if you might have it, here are some signs and conditions that may indicate leaky gut is contributing to your health:
- Allergies and asthma
- PMS and hormonal issues
- Depression and anxiety
- Autoimmunity (and any other conditions listed in this post)
- Chronic fatigue
- Food sensitivities
- Acne, eczema, psoriasis, mystery rashes
- GI symptoms: gas, bloating, belching, cramping
Many of these diseases and symptoms are multi-factorial, and the treatment is as individualized as each person. However, addressing a leaky gut is an excellent place to start. For suggestions on how to fix leaky gut as well as how to prevent leaky gut, those are the next topics in this series!