Originally, the gluten-free diet was to treat celiac disease. Now, more people are following the gluten-free diet for a number of personal or health-related reasons. Some physicians even recommend it for people with non-celiac conditions, particularly thyroid disorders. Below is a closer look at the connection between these two conditions and the role of gluten.
What is gluten?
Gluten comprises three indigestible plant proteins: glutenin from wheat, secalin from rye, and hortein from barley. “Because they are structurally similar, we lump them under the same umbrella and call all of them gluten,” says Dr. Daniel Adelman, adjunct professor of medicine at University of California San Francisco. For most people, gluten goes through the intestinal tract, where it is not digested and is eliminated. In people with celiac disease, an autoimmune response is triggered by the gluten protein that results in intestinal inflammation.
The gluten/thyroid connection
Research suggests that celiac disease is more common in people with autoimmune thyroid disease. This type of thyroid disease usually refers to hypothyroidism, which is a low production of thyroid hormone. According to the National Foundation for Celiac Awareness, people with celiac are four times more likely to develop an autoimmune thyroid condition compared to those without celiac. Around two to five percent of individuals with hypothyroidism develop celiac disease. Conversely, around 10 to 20 percent of individuals with celiac disease have hypothyroidism.
Studies have also indicated an association between celiac disease and type 1 diabetes, another autoimmune disease. This pattern began emerging years ago, states Dr. Adelman, when doctors observed a number of celiac disease patients who also had hypothyroidism or type 1 diabetes, or both.
It turns out the underlying association stems from a certain genetic predisposition of a gene family characterized by the human leukocyte antigen (HLA) DQ2 or DQ8. These cell surface markers are part of the immune’s response recognition system, helping to identify certain proteins as antigens, explains Dr. Adelman. Quick refresher: An antigen is any substance (usually a protein structure) that can trigger an immune response.
Antibodies vs. proteins
The human body forms antibodies against a lot of the proteins we eat. The gut, being the first line of defense, is responsible for keeping those antigens and antibodies in the gut and not circulating through the bloodstream, explains Dr. Adelman. So, in addition to anti-chicken or anti-soy antibodies, humans can also produce anti-gliadin antibodies. Gliadin is essentially the gluten molecule.
Anti-gliadin antibodies are easily detected through a simple blood test.
However, they are not necessarily dangerous, and as Dr. Adelman states, “They are not used at all in the diagnosis and management of patients with celiac disease.” People can have elevated anti-gliadin antibodies present; however, this alone is not a usual indicator of celiac disease. Instead, doctors focus on the deamidated gliadin peptide antibodies. These antibodies are directed at the metabolized form of gluten and are useful in diagnosing and managing celiac disease.
“So part of what a lot of these alternative practitioners are doing is that they’re looking for anti-gliadin antibodies, which they will find in pretty much everybody, and then they are impugning those as being pathogenic, for which there really is no evidence of that being the case,” says Dr. Adelman.
This may explain why some people are misdiagnosed as celiac disease or gluten sensitive. But the concept of non-celiac gluten sensitivity is a controversial subject in the medical community. Its existence is widely debated.
Should everyone with hypothyroidism be on a gluten-free diet?
“There is really no evidence that going gluten-free will affect the thyroid function,” says Dr. Adelman. “There are no data to suggest that in patients, who do not have the genetic susceptibility to celiac disease, that gluten causes any problems.”
In other words, hypothyroidism is not caused by gluten consumption and going off gluten will not cure someone of their autoimmune thyroid condition. Dr. Adelman does not recommend people who do not have celiac disease follow a gluten-free diet. “There is no evidence to suggest that going gluten-free is necessarily going to be helpful for people who don’t have celiac disease.” Being gluten-free can result in a loss of fiber and other vitamins and minerals obtained through wheat, rye, and barley. Instead, he recommends eliminating or reducing high-glycemic index foods for people thinking of going gluten-free in order to lose weight. A good option is swapping out white bread for whole-wheat bread.
When to get tested for celiac disease
People diagnosed with an autoimmune thyroid disease and experiencing gastrointestinal symptoms should be screened for celiac disease. For an accurate diagnosis, a patient must undergo a biopsy of their small intestines in addition to an antibody blood test. Additionally, celiac patients should be proactive and ask their physician for an evaluation of their thyroid function. Just remember that treating one doesn’t necessarily affect the other.
Celiac disease is estimated to affect 1 out of 100 people, although the actual number may be higher since many cases either go undiagnosed or misdiagnosed. Other people who are at high risk of developing celiac disease include family members of celiac patients and people with a history of autoimmune diseases.