Not long ago, gluten was just a little-known protein found in wheat, barley, and other grains—an ingredient that gives most breads, baked goods, and pastas their shape and serves as the glue that holds them together. It wasn’t vilified as a culprit of belly bloating, weight gain, or a host of other problems.
Back then, a gluten-free diet was reserved for the estimated 2 million Americans who have celiac disease, a digestive disorder caused by an immune reaction to gluten. Today, however, ditching gluten is a diet trend, and gluten-free foods are all over the supermarket and are highlighted on restaurant menus.
Even celebrities are promoting gluten-free lives, and terms like “gluten intolerance,” “gluten sensitivity,” and “gluten allergy” are going mainstream. What do these terms actually mean? And is it a good idea to abstain from—or limit—gluten from your diet?
Gluten intolerance spelled out
Gluten intolerance is a general term that encompasses both celiac disease and gluten sensitivity, explains Anthony Porto, MD, MPH, a Yale Medicine pediatric gastroenterologist. It means that the body has difficulty digesting gluten. So, if people with celiac or gluten sensitivity eat foods that contain gluten, they experience digestive symptoms, including diarrhea, gas, constipation, and abdominal pain.
Celiac disease, which is genetic, is an autoimmune disorder in which the body makes antibodies (infection-fighting cells) that attack normal cells by mistake. Those antibodies harm the inner lining of the small intestine, flattening the finger-like tissues (villi) that help your body absorb nutrients and thereby making it difficult for them to do their job.
For people with celiac disease, eating even the smallest amount of gluten triggers this reaction, which can also lead to problems absorbing nutrients and calories. Strictly adhering to a gluten-free diet is the only way to treat celiac disease.
The disease is typically diagnosed via a blood test, though it is important to note that if you have been following a strict gluten-free diet, the test may give a false-negative result. (So, don’t start a gluten-free diet until after you have consulted with a physician.) An upper gastrointestinal (GI) endoscopy, which is performed by inserting a flexible tube with a camera down your esophagus, can also be used to diagnose celiac disease by showing if there is damage to the intestine.
Gluten sensitivity is a little bit different
Gluten sensitivity, which is called non-celiac gluten sensitivity (NCGS), is similar to celiac disease in terms of symptoms, but it differs in other ways. There is no blood test for NCGS and there is no underlying inflammation in the intestine, Dr. Porto explains. If someone has NCGS, the blood test for celiac disease will be negative. But, if gluten is removed from the diet, their symptoms will improve, he says.
“Because we don’t have any tests for gluten sensitivity, it’s usually a diagnosis of exclusion,” Dr. Porto explains. “We evaluate for celiac and for a wheat allergy [see below], and if those come up normal and you are having GI symptoms when you eat gluten, we’ll remove gluten from the diet for about six weeks. If things are better, we might say it’s ‘gluten sensitivity.’”
A key difference between celiac and NCGS is that someone with NCGS may still be able to tolerate a small amount of gluten in their diet. “Some people may also simply outgrow gluten sensitivity,” Dr. Porto says.
Gluten allergies don’t exist, but wheat allergies do
It’s not uncommon for people to think of gluten sensitivities as being a kind of allergy—or sort of like an allergy—but that’s incorrect. If you have an allergy, your immune system considers a substance (certain foods, dust, pollen) to be a threat and overreacts to it. For people with a food allergy, even a microscopic amount of the food containing the allergen can cause a serious or life-threatening reaction. This differs from the immune response gluten causes in someone with celiac disease; as an autoimmune disease, the symptoms are a result of the body’s attack upon the small intestine.
Adding to the confusion: There is no such thing as a gluten allergy, but some people do have an allergy to wheat, which can cause symptoms similar to those of gluten intolerance, including abdominal pain. However, other, different symptoms such as itching, swelling of the lips and tongue, and trouble breathing might also occur. These reactions can happen quickly—within minutes even—after eating a product with wheat. A person who is allergic to wheat must avoid all foods that contain it, but they may be fine eating foods with gluten in it from non-wheat sources. However, it is possible to have both a wheat allergy and celiac disease or NCGS.
The good news is that wheat allergies are even less common than celiac disease. About 1 in 133 Americans have celiac disease, compared to approximately 1 out of 1,000 with a wheat allergy, Dr. Porto says. And while a wheat allergy is more common in children than it is in adults, about 65 percent of children outgrow it by age 12. (A wheat allergy can be diagnosed by a blood test.)
Is it good to stop eating gluten?
A common misconception is that a gluten-free diet is healthier in and of itself, even for people who don’t have medical reasons for following one. That’s not necessarily so, says Dr. Porto, who stresses the importance of eating a healthy, balanced diet. “I think some people may feel better being gluten-free, and a gluten-free diet can be healthy. But you need to make sure you eat a variety of foods,” he says. “Sometimes people who follow a gluten-free diet eat mostly rice and rice-based pastas, which don’t carry the same vitamins and minerals as many foods that also have gluten. You want to add a variety of gluten-free grains including amaranth, buckwheat, millet, and quinoa, for example, to make sure you are getting the vitamins you need.”
The same wisdom applies to people with celiac disease. They should find healthy substitutes for the vitamins and minerals they don’t get because they are either avoiding the gluten-containing foods that have them, or they have trouble absorbing the vitamins and minerals.
“If you have celiac disease, you have irritation in your intestines and that irritation might make it hard for you to absorb iron, zinc, or vitamin B well. If you can’t absorb them, you might be deficient in those vitamins and minerals,” Dr. Porto explains. “And now if you are eating gluten-free breads—most of which are not fortified with these same vitamins and minerals—you may still be deficient.”
Essentially, people with celiac need to avoid gluten, but that does not apply to those without the disease. “I personally think that if you can tolerate gluten, you should eat it. It has a place in the diet,” he says.
A booming industry
The popularity of gluten-free foods and diets, Dr. Porto says, is a good thing for people who have celiac disease or NCGS. “It’s great that we are seeing general pediatricians think about a celiac disease or gluten sensitivity diagnosis. It’s really helped awareness,” he says. “It’s also helpful that companies are making foods that are gluten-free, so the accessibility is there.”
But, Dr. Porto says, gluten-free products—which have grown to a $2.6 billion industry—appear out of sync with the demand. “We hear about the gluten-free diet a lot,” he says, “but only about 1 percent of the American population has celiac disease.”