An estimated 20 million Americans have some form of thyroid disease. Approximately 90% of hypothyroid cases and 80% of hyperthyroid cases are autoimmune. Several studies show a strong link between autoimmune thyroid disease (AITD) and gluten intolerance (1, 2, 3). Identifying gluten intolerance as a player in the development of AITD can be a vital component of the diagnosis and management of AITD.

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What is Thyroid Disease?

The thyroid is an endocrine gland located in the neck responsible for making thyroid hormones. Every cell in the body has receptors for thyroid hormones, which regulate the ongoing biochemical and physiological processes required to maintain a living state.

• ‍Thyroid disease :is the general term for any condition that interferes with the thyroid gland's ability to maintain a balanced level of thyroid hormones.  ‍
• Hypothyroidism: is one of the most common forms of thyroid disease and occurs when the gland cannot make sufficient thyroid hormone. ‍
• Hyperthyroidism: occurs secondary to an overproduction of thyroid hormone.
• Autoimmunity is responsible for most cases of thyroid disease, resulting either in Hashimoto's (hypothyroid) thyroiditis or Grave's (hyperthyroid) disease.

What is Gluten?

Gluten is the general name for the group of hundreds of related storage proteins of wheat, rye, barley, and other closely related grains. Gluten comprises many different types of proteins, the two main ones being gliadins and glutenins. Within the grain, gluten stores nutrients to support germination and seedling development. In baking, gluten is helpful because it acts as a glue to hold foods together.

Proteases are the digestive enzymes that help to break down proteins in the human body. Most proteins are broken down into their smallest building blocks called amino acids; however, the body is incapable of completely digesting gluten. Gluten is, therefore, partially digested into peptide fragments, which hold the capacity to trigger an immune response.

Many healthy individuals can consume gluten with no acute symptoms. But for others, including those with Celiac disease (CD), non-Celiac gluten sensitivity (NCGS), wheat allergy, or a predisposition to autoimmune disease, gluten can trigger an aggressive immune response and undesirable consequences.

How Does Gluten Trigger Thyroid Antibodies?

What explains this connection between AITD and gluten? The answer lies largely in the gut. In a healthy digestive tract, there are small spaces between the cells that line the intestine. These tight junctions allow the absorption of small, digested particles into the bloodstream. Factors such as alcohol and food sensitivities, certain medications, intestinal dysbiosis, and stress can irritate the gut lining and increase a protein called zonulin, leading to larger spaces in the intestinal wall and absorption of larger, undigested food particles. This is known as intestinal hyperpermeability, more commonly as leaky gut.

Once leaky gut is present, gluten (and other larger molecules) enters the bloodstream, is recognized as foreign by the immune system, and triggers an immune response. Immune cells form antibodies against the protein gliadin within gluten to quickly detect and neutralize it in future exposures. Due to very similar structures in gliadin and an enzyme called transglutaminase, which is heavily concentrated in the thyroid gland, these sensitized gluten antibodies will mistakenly attack the thyroid gland at the same time it attacks gluten protein. This phenomenon in which the immune system mounts an autoimmune response due to similarities between foreign and self-proteins is called molecular mimicry.  

Note: Patients with celiac disease, an autoimmune disease triggered by the ingestion of gluten, have four times increased prevalence of AITD compared to the general population.

Functional Medicine Labs to Test for Gluten-Related Thyroid Disease

Comprehensive Thyroid Panel

To diagnose and monitor thyroid dysfunction, a comprehensive thyroid panel should include TSH, free T3, free T4, and thyroid antibodies (anti-thyroglobulin, anti-thyroid peroxidase, and thyroid stimulating immunoglobulin) at minimum.

A thyroid panel is recommended annually to monitor thyroid levels for those with stable thyroid disease. Your doctor may recommend monitoring at more frequent intervals after implementing changes to thyroid medications or treatment plans to assess how the changes impact thyroid function and autoimmunity.

Gluten Sensitivity Panel

A comprehensive wheat sensitivity panel, like Array 3X, screens for celiac disease and measures additional antibodies to gluten's smaller breakdown products, limiting the number of false negatives. These types of panels can also aid in making a diagnosis of non-celiac gluten sensitivity.

Cyrex also offers its Array 4 panel, which identifies common food sensitivities due to gluten cross-reactivity. If positive, these foods will cause similar undesirable immune responses even following a gluten-free diet.

For accuracy in either of these tests, gluten should be incorporated into your diet for at least six weeks before this blood draw.

Comprehensive Stool Test

A comprehensive stool analysis provides insight into the health and integrity of the gut and its microbiome. Adding zonulin, the protein that regulates intestinal permeability, onto your stool analysis is helpful when specifically interested in quantifying the level of intestinal permeability present.

Micronutrient Panel

A micronutrient panel can diagnose nutrient deficiencies secondary to leaky gut. These results can also guide treatment recommendations, as many vitamins and minerals are involved in the healing processes of the intestinal lining and thyroid gland.

Functional Medicine Treatment for Gluten-Related Thyroid Disease

Nutrition

The first step in addressing gluten-related AITD is a strict removal of all gluten and foods that could be cross-contaminated with gluten. This is especially true for those with concurrent celiac disease, as continued gluten exposure in even small amounts will cause irreparable damage to the small intestine.

A gluten-free diet can support the healing of the intestinal barrier, improve quality of life, and improve thyroid markers (6, 7). The most common gluten-containing grains include wheat, barley, and rye. When buying packaged foods, look for products that have certified gluten-free labels printed on their packaging.

Oats do not contain gluten, but they do have a structurally similar protein called avenin. This can cause similar gastrointestinal and autoimmune reactions for some with CD and NCGS. Doing a trial elimination of oats may be worthwhile, especially if a gluten-free diet is not delivering the expected results.

There are many research articles on gluten thyroid disease. Studies show women with Hashimotos Thyroiditis saw a reduction in thyroid antibody titers after following a strict gluten-free diet for six months.

An anti-inflammatory diet that emphasizes plenty of vitamins and minerals through whole foods, sufficient protein intake, dietary fiber, and unsaturated fats can help to prevent dysbiosis of the gut microbiome, improve thyroid function, and support the fortification of the gut lining.

Research has shown that selenium is effective in treating AITD, with outcomes that include reduction of thyroid antibodies after six months and improved quality of life. A one-ounce serving of Brazil nuts has nearly 1,000% of the recommended daily allowance of selenium and can be used as a whole food alternative to a selenium supplement.

Herbs and Supplements

Probiotics

Roles of probiotics include:

• Nutritional assistance
• Regulation of the immune system
• Protection of gut barrier function

They can also prevent the overgrowth of unwanted bacteria in the gut, a common contributor to intestinal inflammation and permeability. Stool analysis results can help to guide which probiotic formulation is best for individual cases, but VSL#3 is a well-documented probiotic specific to treating Celiac disease.

Glutamine

Glutamine is an amino acid backed by a large pool of supporting evidence for its restorative properties for the gut lining. It is the preferred fuel source for small intestine cells and supports cell metabolism, division, and repair.

Zinc Carnosine

Zinc carnosine has been researched in its application for various intestinal-related disorders. Many studies support its efficacy in decreasing intestinal inflammation, healing intestinal ulcers, and healing intestinal permeability.

Deglycyrrhizinated Licorice

Deglycyrrhizinated licorice (DGL) is a demulcent herb with proven anti-inflammatory, antioxidant, and immunomodulatory effects. Demulcents create a mucilaginous "goo" that coats surfaces and are commonly utilized in gut healing protocols. The limited research on these herbs supports their efficacy in soothing irritated surfaces (4, 5).

Lifestyle Changes

Physical and emotional stressors can promote a leaky gut by shifting the gut microbiome's balance, directly triggering AITD (8, 9). Stress management techniques like cognitive behavioral therapy (CBT), meditation, yoga, and biofeedback therapy can help to modulate the body's stress response and improve digestive and thyroid health.

Summary

There is sufficient evidence to support the connection between gluten intake and autoimmune thyroid disease. The formation of leaky gut and molecular mimicry leading to misdirected immune responses can explain this gluten-thyroid connection. Proper testing for gluten intolerance and autoimmune thyroid disease can determine if eliminating gluten from the diet is appropriate for treating thyroid disease. There are many well-documented adjunctive therapies in addition to a gluten-free diet that will support the repair of the intestinal barrier and normalize the thyroid function.