If you’ve ever wondered whether gluten can harm your health, join the club. While one in four Americans seeks out gluten-free foods at least some of the time, a rising number also doubt that it’s a real health concern. Indeed, the gluten-free food trend is waning.

If you see your doctor about gluten concerns, such as bloating or headaches that you swear are brought on by eating pasta or bread, you may be met with similar doubts. That is especially true if you test negative for the “real” gluten disease—celiac disease, an autoimmune condition diagnosed by specific tests that’s treated by a total lifelong avoidance of gluten, a protein found in wheat, barley and rye. Celiac disease affects about 1% of the population. If you also test negative for a wheat allergy, your doctor may dismiss any concerns about gluten.

After all, there are no definitive tests for “gluten sensitivity,” which is more officially called “non-celiac gluten sensitivity” (NCGS). The symptoms can be caused by many other conditions. And some studies find that many people who think they’re gluten-sensitive aren’t.

But now a careful scientific study from Columbia University Medical Center adds to the growing evidence that NCGS is not only real but can lead to widespread body inflammation and immunological damage. It contributes to a medical condition that many integrative and complementary medical practitioners have been diagnosing and treating—and that Bottom Line has been reporting on—for years.

The condition? A weakened intestinal barrier, often referred to as leaky gut. While it starts in the gut, it can affect your entire body—and mind. Here’s what the new research has found—and how to restore healthy digestion. Hint: It’s not just about avoiding gluten.


Investigators from Columbia University Medical School in New York City tested 80 patients with confirmed NCGS (we’ll explain the best way to get diagnosed below) who were not already avoiding gluten. They compared them with 40 people with celiac disease and 40 healthy people as controls. They took blood and tissue samples looking for biomarkers that may explain how NCGS affects the body.

Results: In comparison with the healthy control group, participants with NCGS or celiac disease had higher levels of a marker of damage to the cells of the lining of the intestines (the epithelium). For patients with celiac disease, there was more damage—but patients with NCGS had uniquely unhealthy responses. Unlike subjects with celiac and healthy controls, the NCGS group had very high levels of specific markers of immune overreaction and body-wide inflammation.

Here’s what was going on: The researchers uncovered evidence that, in NCGS patients, microbes and nutrients that should stay in the gut were moving from the intestinal lining into the bloodstream where they don’t belong—causing the widespread unhealthy immune response and inflammation. This is the phenomenon called “leaky gut.”

The new research provides evidence that leaky gut is at the core of the health problems in many people who are gluten- or wheat-sensitive. Even more compelling: Removing gluten from these patients made a big difference. In the next phase of the study, the Columbia researchers put 20 of the NCGS patients on a gluten-free diet for six months. Results: Blood levels of markers of inflammation and epithelial cell damage were significantly lower during the gluten-free diet.


To better understand this phenomenon, we spoke with Seema Patel, MD, an integrative medicine physician at the Cleveland Clinic’s Center for Integrative Medicine in Ohio. Dr. Patel has no doubt that NCGS exists, and she has diagnosed the disorder in many of her patients.

A normal digestive tract with a healthy epithelium, she explains, selectively allows nutrients to pass through the digestive tract and enter the bloodstream. In a leaky gut, tiny spaces between cell junctions open up, allowing environmental toxins (including gluten) and unhealthful bacteria and microbes to pass through to the bloodstream. Wherever those errant microscopic compounds land, an inflammatory response may be launched. Result? “Eczema, headaches, joint pain and many other medical conditions can be caused by leaky gut,” says Dr. Patel. (Some of these gut compounds that go into the bloodstream even may cross the blood/brain barrier, contributing to mental health issues including anxiety and cognitive problems, although this possible mechanism is still speculative.)


While the new research provides strong new evidence that NCGS is real, it doesn’t mean that everyone who thinks gluten is causing symptoms has it. For example, some people who experience gastrointestinal distress and blame it on gluten are actually fine when they consume gluten but have symptoms when they consume foods that contain hard-to-digest fibers that are collectively called FODMAPs (see Bottom Line’s article, “Before You Give Up Gluten, Try A Low-FODMAP Diet”).

But other people complain of symptoms that extend far beyond the digestive tract when they eat gluten-containing foods. That is, they have not only bloating, abdominal pain and diarrhea but also symptoms such as headaches, fatigue, anxiety and/or brain “fog.” When they stop eating gluten-containing foods, their symptoms often get better.

They are prime candidates for a diagnosis of NCGS. While there is no lab test to diagnose NCGS, your gastroenterologist or integrative physician can help with a diagnosis. First, he/she will do tests to rule out celiac disease and wheat allergy.

Next, you’ll eliminate gluten from your diet for about one month. “When you introduce it, you have gluten-containing food twice a day for three days,” explains Dr. Patel. “If symptoms recur, remove gluten from your diet.” That worsening of symptoms is an indication that you have NCGS. Lab tests, such as an IgG test, which picks up food sensivities that are not classic allergies, also can be helpful in diagnosis, says Dr. Patel. Note: Don’t ask for the blood and tissue biomarker tests used in the Columbia study—they are very expensive, not generally available and not routinely used in clinical practice.


Non-celiac gluten sensitivity isn’t the only potential cause of a leaky gut. A weakened intestinal barrier can also be caused by frequent use of antibiotics, recurrent infections, poor nutrition, physical or mental stress, trauma or environmental toxins.

Whatever the cause, Dr. Patel treats her patients using the principle of the “five Rs”…

Remove gluten—and other potentially offending foods. Aside from gluten, several other foods can present problems for people with leaky guts, including corn, dairy, eggs, caffeine, soy and shellfish. Dr. Patel advises her patients to eliminate all potentially offending foods for at least one month before slowly introducing them back—one by one—into their diets. (To find out how to go on an elimination diet, see the Bottom Line article “How to Find Your Food Triggers.”)

Reinoculate the gut microbiome with healthful bacteria by taking a probiotic supplement. (To learn more, see Bottom Line’s article “The Right Way to Take Probiotics.”)

Replace the digestive acids that may be missing—especially if you’ve been taking a heartburn medication (such as histamine blocker or proton pump inhibitor). Digestive acids are the first line of defense in the gastrointestinal system. Over-the-counter enzyme supplements are one way to enhance these acids. Drinking one teaspoon of apple cider vinegar mixed into a glass (eight ounces) of water before meals may also help. (For more tips, see the Bottom Line article “Heartburn Remedies You’ve Never Heart Of.”)

Repair the gut epithelium and cellular junctions—by consuming bone broth, which naturally contains high quantities of the amino acid L-glutamine or by taking physician-prescribed supplemental L-glutamine (an amino acid that helps repair cellular junctions). “L-glutamine should be taken only under the advice or monitoring of an experienced physician or practitioner,” says Dr. Patel.

Rebalance your lifestyle, the foundation of good health. Learn how to manage your stress, improve your diet and incorporate physical activity into your daily life. It’s a two-way street, sometimes called the gut-brain axis—a can s your mind relaxes, the gut is bathed in fewer stress chemicals so it can better repair itself, including leaky gut. “As the gut improves its leakiness,” says Dr. Patel, “the brain functions better, too.”

Finally, be patient. Your gut didn’t become leaky overnight, and it won’t repair itself instantly. The process of strengthening the barrier takes time. “How long depends on the severity of the disease, other life circumstances and the compliance of the patient,” says Dr. Patel. “Some can take a few months, while more severe cases can take a year or two.” The earlier you start the process in the course of the leaky gut condition, she adds, “the faster you will improve.”

The good news for bread lovers: Once you’ve repaired your leaky gut, you may be able to tolerate small amounts of gluten-containing foods again, in moderation.