Eliminating gluten is necessary for some people. But for others it can be useless and even harmful.

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On Nutrition

Gluten-free diets are as trendy as ever, with many people seeking them out for weight loss or health, even though avoiding gluten is unlikely to provide the solutions they’re seeking. While eliminating gluten is both healthy and necessary for some people, for most people it’s useless, and could even be harmful, according to Peter Green, MD, director of the Celiac Disease Center at Columbia University.

“The gluten-free diet is a trendy diet. It will save someone’s life if they have celiac disease, but its role in the general public is nonexistent,” said Green, co-author of the excellent, very detailed book “Gluten Exposed: The Science Behind the Hype and How to Navigate to a Healthy, Symptom-Free Life.” He said that many people who go on a gluten-free diet do so for “bogus reasons,” giving the example of a recent patient in his clinic with Hashimoto’s thyroiditis. “They were told they should go on a gluten-free diet to reduce inflammation in the thyroid, but there’s no evidence for that.”

Green notes that the number of people in the United States who have adopted a gluten-free diet has increased significantly, for reasons that aren’t quite clear. “Maybe some of them have celiac disease, but most people aren’t tested for celiac.”

That’s a problem, because celiac disease — an autoimmune disease in which the body’s immune system inappropriately reacts to gluten, the protein in wheat, rye and barley — is serious business. The small intestine takes the brunt of the attack because that’s where the immune system encounters gluten, but the resulting damage interferes with absorption of nutrients, so celiac disease can affect the entire body.

Out of 100 people, one or two have celiac disease. To develop it, people first need to be genetically at risk. Then, the theory is, comes the “double hit”: an infection, illness or other health condition that triggers the immune system to start responding inappropriately to gluten. Testing for celiac disease starts with a blood test for the enzyme IgA tissue transglutaminase (tTG) and a few other indicators while still eating gluten. If the results are positive, then an intestinal biopsy can confirm the diagnosis. Testing while gluten-free can lead to false results.

Why self-diagnosis isn’t a good idea

Does that mean that only people with celiac disease need to avoid gluten? No. It’s clear that some people have what is properly called non-celiac gluten sensitivity (NCGS). However, it’s not currently possible to test for NCGS in this country. Many people think that testing for the IgG anti-gliadin antibody (gliadin is one component in gluten) is sufficient to diagnose NCGS, but Green said it’s not, because that antibody can also be elevated in people with many other disorders, as well as in healthy people.

The good news is that an accurate test for NCGS may be on the horizon. A study Green co-authored last year in the journal Gut found that there are a few substances that are noticeably elevated in the blood of people with NCGS compared with people with celiac disease and with healthy individuals. “We’re very excited with that study that we identified some potential biomarkers,” he said, adding that, unfortunately, no commercial labs in the U.S. test for these biomarkers yet.

For now NCGS is largely a self-diagnosed condition. I often hear from patients, “I have a problem with gluten but I know I don’t have celiac disease because my symptoms aren’t that bad and I don’t have intestinal issues.” That’s a dangerous assumption. Green said that fewer than half of adults who have celiac disease have gastrointestinal symptoms. In fact, the biggest source of referrals to his celiac center comes from neurology. Other common symptoms, related largely to poor absorption of nutrients, include anemia, osteoporosis, fatigue and deficiencies of specific nutrients. It’s important to note that these symptoms could be due to other causes, which is why proper diagnosis is so critical.

Celiac disease without obvious symptoms is known as “silent celiac,” and Green said it’s unclear how may people have it. About half of people with celiac disease have not been diagnosed (on average, someone has celiac disease for 12 years before diagnosis), and Green said there’s no way to know whether the other 50 percent has silent celiac, or if their doctors simply don’t know to test for it.

Self-diagnosis is risky for a few reasons. If you don’t know if you have celiac disease, and you go off gluten and feel better, you may not want to reintroduce gluten (a “gluten challenge”) in order to be properly tested for celiac. Also, the real culprit of your symptoms could be another intestinal disorder, like irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) or small intestine bacterial overgrowth (SIBO).

The pitfalls of a gluten-free diet

Finally, despite the health halo attached to the gluten-free diet, it can be unhealthy — even for people who truly need to be on one. Green said what you do eat is just as important as what you don’t. “We refer our patients to a dietitian for two reasons. One, to make sure that you are actually on a gluten-free diet, and two, to make sure that what you’re eating is healthy,” he said.

Unless carefully planned, gluten-free diets may contain hidden gluten, which is dangerous for someone with celiac disease, because even trace amounts can cause intestinal damage. Gluten-free diets tend to be lower in the B-vitamins and iron, and higher in heavy metals and food additives. They may also be low in fiber, which can harm both intestinal and overall health. “There’s a suggestion that people who eat less whole grains have a higher rate of heart disease,” Green said. “And people who eat whole grains live longer.”

For some, going gluten free can be a gateway to orthorexia, an unhealthy obsession with eating healthfully. “When people restrict gluten, they often restrict other foods, especially soy, dairy and corn, so their diet becomes more and more limited,” Green said. “We just don’t think that’s very healthy.”