This week I wanted to talk about a crucial topic: intestinal permeability, a.k.a. leaky gut syndrome. You may have heard of this oddly named medical condition. It’s an incredibly common issue correlated with many other diseases. It’s important because when you heal your gut, so many other symptoms and conditions are healed.
Leaky gut has long been diagnosed and treated in naturopathic and functional medicine, and it’s finally starting to gain more recognition in the general population and even in the conventional medical system (just a little). Before the last couple of years, many conventional health care practitioners considered leaky gut “woo woo” (as I’m sure many still do), but the scientific evidence to support intestinal permeability and its role in many chronic inflammatory diseases is overwhelming. And the number of diseases recognized to involve changes in the permeability of the intestinal barrier is rapidly growing. Conditions associated with leaky gut include:
Autoimmune diseases like celiac, inflammatory bowel disease, rheumatoid arthritis and multiple sclerosis (1). To my knowledge, autoimmune diseases are the most well studied and treated group of diseases associated with leaky gut. I have seen countless patients with autoimmune disease who either achieve remission or significant control of their autoimmune disease when leaky gut is addressed.
Allergies, both food and environmental (2)
Some cancers (3)
Leaky gut is also thought to be associated with asthma (4), infections, and diseases of the nervous system such as schizophrenia (5)
So what is leaky gut?
First, you need to understand what the intestinal barrier is. The intestinal barrier, or epithelium, is the largest and most significant barrier we have against the external environment. It’s composed of a single layer of cells bound together by tight junctions that line the gut lumen (the innermost layer of the intestine, the part that is closest to our food). It functions to allow your body to absorb the things you take in through your diet like nutrients, water, electrolytes, etc., and keep out things that shouldn’t be absorbed such as pathogens (bacteria, fungi, viruses and parasites), toxins and even your probiotics (6).
The reason the role of the intestinal barrier is so important is that every time we eat, we are exposing our body to the outside world. The intestinal barrier is essentially that, a barrier - it keeps things out that shouldn’t be absorbed and brings things in that should. Intestinal permeability is when the gut barrier’s ability to do this function properly is compromised, which can then lead to a myriad of inflammatory and immune issues.
What causes leaky gut?
Some of the most well-understood causes of leaky gut include:
Dysbiosis: SIBO, candida, parasites, dysbiotic bacteria
A diet that is low in the fiber that feeds gut-friendly probiotics and high in foods that promotes inflammation (i.e., the Standard America Diet)
High levels of stress (6)
Certain medications, most notably, antibiotics and acid blockers
Allergens and toxins
As you can see, there are a lot of things that contribute to leaky gut syndrome, and most of us at some point in time are exposed to one of these if not all. It’s not at all a surprise to me that so many people in developed countries suffer from digestive issues and chronic inflammatory diseases.
Testing for leaky gut syndrome:
Zonulin in the blood or stool: Zonulin is a protein that controls the permeability of the tight junctions (TJs) between the epithelial cells of the digestive tract. We talked about the epithelial cells above, but the TJs are a new concept. Think of them as the links that connect the epithelial cells (8).
Lactulose and mannitol: This test involves drinking a solution of lactulose and mannitol, followed by a urine collection. The lab then evaluates to see if there is a higher than the standard rate of these solutions in the urine indicating hyperabsorption and therefore compromised intestinal barrier.
These are two tests that are unique to leaky gut. However, it’s important to mention that I don’t always start by ordering these tests because the presence of a positive leaky gut test alone doesn’t explain the root cause. For example, if a test came back positive, I would then need to investigate the causes of leaky gut mentioned above. If I suspect a patient has leaky gut, I will often start by testing for dysbiosis, markers of intestinal inflammation, and/or SIBO because I'll need this information to treat adequately.
Treatment: the first step is to uncover and address the root cause of the inflammation and resolve that. I’ll discuss foods, herbs, and nutrients that help strengthen the intestinal barrier in a future post.