Many websites have posted warnings about a condition called “leaky gut”, claiming it can cause depression, anxiety, autoimmune disorders such as chronic fatigue, eczema, Hashimoto’s thyroiditis , joint pain, multiple sclerosis, rheumatoid arthritis and other disorders.
But is it real? And if so, is it dangerous? And can you prevent it?
This pathology is real, but doctors and scientists call it “intestinal hyperpermeability” and so far research does not show that it is the cause of all these pathologies. On the contrary, it seems to be the opposite. Various health conditions can make the intestine more porous and release more harmful substances than it should.
“It’s a myth that all of these diseases start with a leaky gut,” says Michael Camilleri, a gastroenterologist and professor at the Mayo Clinic College of Medicine and Science in Rochester, Minnesota. “What we do know is that some diseases cause intestinal hyperpermeability,” he says. Examples are celiac disease, irritable bowel syndrome, Crohn’s disease, obesity, intestinal damage due to the use of NSAIDs (non-steroidal anti-inflammatory drugs), among others.
One of these conditions, irritable bowel syndrome (IBS), is the most commonly diagnosed digestive disorder, affecting between 6 and 15 percent of American adults. Besides abdominal pain and bloating, this disorder causes chronically abnormal bowel movements. A Mayo Clinic study found that up to 62% of people with diarrhea-prone IBS and up to 25% of people with constipation-predominant IBS had intestinal hyperpermeability.
“But it remains unclear whether hyperpermeability is a cause of IBS,” wrote Andrea Shin, a gastroenterologist and associate clinical professor at the Geffen School of Medicine at the University of California, Los Angeles, in an e- email.
A little leakage is good, a lot is not.
To understand leaky gut, it helps to understand the life-or-death function of your digestive tract: bringing nutrients into the body and keeping bad things out.
To do this, “the intestinal tract must be at least somewhat porous and permeable. It must allow the absorption of water and nutrients contained in digested foods such as sodium and small molecules such as glucose,” explains Camilleri. Once nutrients are absorbed by intestinal cells, they migrate into the bloodstream and nourish the rest of the body.
To achieve this absorption trick, the specialized cells lining the intestine have semi-permeable walls. And even though they stand side by side, locked together by what are called “tight junctions,” there’s still some space for small molecules to squeeze in. It’s normal. Tight junction proteins are the glue that holds cells together.
“But if the junctions loosen and the intestinal tract becomes too leaky, your health is at risk because substances that should not have access, such as not fully digested proteins or bacteria, pass through. These can pass into your general circulation and possibly damage organs,” says Camilleri.
No one wonders if intestinal hyperpermeability is dangerous – it is. But where the medical establishment parts ways with some in the wellness industry is in cause, diagnosis, and treatment.
Intestinal hyperpermeability test
So how do you know if you have an abnormally leaky gut? Experts doubt the test kits available on the web.
“There is no well-established non-invasive test that is scientifically and clinically valid. “That’s why most research on intestinal permeability has been done in animals and cell cultures, so scientists can study the gut and its function more closely,” says Hannah D. Holscher, registered dietitian and associate professor of nutrition at the University of Illinois Urbana-Champagne.
Shin agrees: “My patients ask if they can have a leaky gut test, and I tell them that even though different tools and methods are used in research, there is still no clear reference. »
“I don’t know of any commercially available gut test kits that can diagnose leaky gut,” says Camilleri of the Mayo Clinic. However, he and his colleagues may have developed a diagnostic test that may soon be available. (He says he has no financial interest in the new test.) It involves drinking a liquid spiked with specific types of sugars, then collecting urine throughout the day to see how much is excreted . The more these sugars are found in the urine, the more permeable the intestine is. It’s not exactly an easy test, but it’s proven to be accurate.
The link between diet and intestinal permeability
There is little data revealing specific lifestyle factors that contribute to dangerous leaky gut. But new research indicates that diet can affect intestinal permeability in several ways. Here are some:
Dietary fiber (fiber). Foods high in fiber, including fruits, vegetables, legumes and whole grains, help prevent constipation and maintain the mucus layer in the intestines, a defensive barrier that helps prevent bacteria and other harmful substances from infiltrate into intestinal cells and degrade the tight junctions between them.
“We have billions of microorganisms in our digestive tract; many of them use fiber from our diet as fuel. Without enough fiber, some of these bacteria feed on the mucus layer, thinning it and making it less protective. This could lead to increased intestinal permeability,” says Holscher.
High-fiber diets also increase populations of gut bacteria that produce short-chain fatty acids, which both serve as healthy fuel for intestinal cells and decrease inflammation, which is essential for maintaining healthy intestinal cells and their tissues. tight junctions.
Alimentary fat. Nuts, seeds, seafood and olive oil – staples of the Mediterranean diet – are rich in “good” unsaturated fats, which help decrease inflammation, while lowering blood cholesterol and possibly the risk of chronic diseases.
(Learn more about why The Mediterranean diet has stood the test of time.)
But foods high in saturated fats—butter, chicken skin, coconut oil, cream, and fatty meats—that are common in the American diet have the opposite effect.
“Eating too much saturated fat increases populations of gut microbes that can loosen tight junctions,” says Holscher.
Diets high in saturated fat promote the growth of microbes with certain types of lipopolysaccharides (LPS) embedded in their cell walls. The gut’s immune cells attack these microbes, releasing LPS that is toxic to the gut, making it more permeable. Worse yet: LPS can pass through leaky junctions and enter the bloodstream, leading to inflammation and other complications: diabetes, atherosclerosis (narrowed arteries leading to the heart), and other chronic diseases. Unsaturated fats have the opposite effect, reducing LPS.
Supplementing their diet with just 1.5 ounces of nuts per day for three weeks led to more anti-inflammatory gut microbes and fewer inflammatory bacteria in 18 men and women in Holscher’s research.
“Nuts are rich in unsaturated fats, fiber, and phytonutrients, which work in different ways to support gut health,” she says. His lab is currently conducting a similar experiment with avocados.
(Find out why olive oil is the healthiest cooking fat.)
Alcohol. Like saturated fats, alcohol promotes the growth of LPS-containing gut microbes. Chronic alcohol abuse or even a single binge can directly damage cells and loosen tight junctions.
Polyphenols. Fruits, vegetables, herbs, legumes and whole grains contain many phytonutrients (antioxidant and anti-inflammatory plant compounds) and help prevent disease. One main type, polyphenols, has been shown to accelerate the production of tight junction proteins, preventing excessive leakage.
Supplements. Experts interviewed for this story were skeptical that there are specific supplements that correct leaky gut, as some manufacturers claim. They cited only a few supplements that normalize intestinal permeability.
Preliminary research suggests that glutamine supplements may help restore normal permeability in people with IBS.
“Glutamine is an amino acid that is the primary fuel source for intestinal cells that absorb nutrients, as well as the immune cells in the gut. Glutamine deficiency can lead to shrinkage of these cells or a reduction in tight junction proteins. The result: increased intestinal permeability,” explains Shin.
Shin cautions that larger studies need to be done before glutamine is prescribed as standard treatment and that it has not yet been studied as a preventative agent.
“There is also evidence that supplementation with vitamin D, short-chain fatty acids, and fiber may also be important for maintaining and improving the intestinal barrier,” says Shin.
Until more is known about intestinal hyperpermeability (both its causes and treatments), it is best to avoid websites and head to the produce aisle for a safe and delicious intestinal health: the Mediterranean diet.