What’s the difference between celiac disease and a gluten sensitivity?

DEAR DOCTOR K:

Many people I know are going gluten-free. When I ask them why, I hear about gluten sensitivity and celiac disease. What do these terms mean?

DEAR READER:

Gluten sensitivity and celiac disease are two separate conditions with one thing in common: gluten. Gluten is a protein found in anything made with grains such as wheat, rye or barley. Gluten is what makes breads chewy.

Celiac disease is a disorder in which the body can’t tolerate gluten. The gluten triggers an immune reaction, causing inflammation of the lining of the small intestine. In the short term, a person with celiac disease may experience gas, bloating, abdominal cramps and fatigue.

Celiac disease also can cause symptoms in parts of the body distant from the gut, including the brain, bones and kidneys. Over time, if the problem remains unchecked, celiac disease damages the small intestine so that it can’t properly absorb nutrients from food. This can result in diarrhea, weight loss, anemia, malnutrition, joint pain, osteoporosis and even infertility. Here is an illustration showing the effect of gluten on the intestines of someone with celiac disease:

Celiac disease: When the body goes against the grain

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When people with celiac disease eat foods that contain gluten, gluten proteins permeate the wall of the small intestine and are taken up by immune cells called macrophages, which digest them and send a signal to other immune cells called T cells (1). In response, T cells emit chemicals called cytokines that trigger inflammation and also notify B cells, another group of immune cells, to produce antibodies to gluten (2).

As the immune system wages war against gluten, the intestinal villi and microvilli suffer collateral damage. The villi become eroded and flatten, which leaves the small intestine less capable of absorbing nutrients. The result is diarrhea and a host of health problems related to malnutrition, including weight loss, anemia, and osteoporosis.

Diagnosing celiac disease generally requires a blood test and a biopsy. During the biopsy, a small sample is snipped from the wall of the small intestine and checked under a microscope for damage.

The treatment for celiac disease is a completely gluten-free diet. This stops the harmful immune reaction in the gut, and the symptoms the disease can have outside the gut. And it also allows the intestinal lining to heal.

We used to think of celiac disease as primarily involving children and being very severe. And it can be. Even a crumb of food with gluten can trigger such massive diarrhea that a child can die of dehydration if he or she doesn’t get prompt treatment.

But as our tests for the disease have gotten better, we’ve recognized that the disease can produce much milder symptoms and can start later in adult life.

Gluten sensitivity is a recently recognized illness that is different from celiac disease. We don’t yet understand it, and some doctors don’t believe it really exists. People with this condition have celiac disease-like symptoms but do not test positive for celiac disease. These patients are often asked to remove all gluten from their diet. If their symptoms improve, they are usually diagnosed with gluten sensitivity.

Gluten is found in foods such as pasta, bread, wheat cereals and many baked goods. It can also be in less obvious items such as sauces, soups, salad dressings, medications and candy.

Luckily, these days, more and more gluten-free foods are appearing on grocery store shelves. And there are many alternatives for foods traditionally made with grains — everything from rice pasta to millet, quinoa or chickpea flour. I used to be a skeptic. Today I encourage patients who think they may be gluten sensitive to try a gluten-free diet. And to stick with it if it makes them feel better.