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 suggest a potential link between autoimmune thyroid disease (AITD) and gluten intolerance (1, 2, 3). Identifying gluten intolerance as a factor in the development of AITD may be important for understanding and managing 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 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 may mistakenly target the thyroid gland at the same time they target 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 help understand and monitor thyroid function, a comprehensive thyroid panel may include TSH, free T3, free T4, and thyroid antibodies (anti-thyroglobulin, anti-thyroid peroxidase, and thyroid stimulating immunoglobulin) at minimum.
A thyroid panel may be recommended annually to monitor thyroid levels for those with stable thyroid function. Your doctor may suggest 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 identifying 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 may cause similar 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 may be helpful when specifically interested in quantifying the level of intestinal permeability present.
Micronutrient Panel
A micronutrient panel can help identify nutrient levels that may be affected by intestinal permeability. These results can also guide dietary considerations, as many vitamins and minerals are involved in the processes that support the intestinal lining and thyroid gland.
Functional Medicine Approaches for Gluten-Related Thyroid Health
Nutrition
One approach to addressing gluten-related thyroid health is to consider removing gluten and foods that could be cross-contaminated with gluten. This is especially important for those with concurrent celiac disease, as continued gluten exposure in even small amounts may affect the small intestine.
A gluten-free diet may support the health of the intestinal barrier, improve quality of life, and support thyroid health (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 immune responses 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 and thyroid health. Studies suggest that women with Hashimoto's Thyroiditis may see changes in thyroid antibody levels 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 may help to support gut health, thyroid function, and the integrity of the gut lining.
Research has shown that selenium may support thyroid health, with outcomes that include changes in 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 may include:
- Nutritional assistance
- Support for the immune system
- Support for gut barrier function
They may also help manage the balance of bacteria in the gut, which can contribute to intestinal health. 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 supporting gut health in Celiac disease.
Glutamine
Glutamine is an amino acid with a large pool of supporting evidence for its role in supporting 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 for its potential role in supporting intestinal health. Many studies suggest it may help manage intestinal inflammation and support intestinal health.
Deglycyrrhizinated Licorice
Deglycyrrhizinated licorice (DGL) is a demulcent herb with potential anti-inflammatory, antioxidant, and immunomodulatory effects. Demulcents create a mucilaginous "goo" that coats surfaces and are commonly utilized in gut health protocols. The limited research on these herbs suggests they may help soothe irritated surfaces (4, 5).
Lifestyle Changes
Physical and emotional stressors can affect gut health by shifting the gut microbiome's balance, potentially impacting thyroid health (8, 9). Stress management techniques like cognitive behavioral therapy (CBT), meditation, yoga, and biofeedback therapy may help to support the body's stress response and promote digestive and thyroid health.
Summary
There is evidence to suggest a connection between gluten intake and autoimmune thyroid health. The formation of leaky gut and molecular mimicry leading to immune responses may explain this gluten-thyroid connection. Proper testing for gluten intolerance and autoimmune thyroid health can help determine if adjusting gluten intake is appropriate for supporting thyroid health. There are many well-documented adjunctive approaches in addition to a gluten-free diet that may support the intestinal barrier and thyroid function.
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