Should Patients with Hypothyroidism Avoid Wheat?

Map showing incidence of Celiac Disease, Wheat Consumption, and the prevalence of genetic types that correlate with higher risk of having Celiac Disease. 

Many patients with hypothyroidism or low thyroid function ask if there is anything they change in their diet to help them feel better.  Should they avoid any particular foods such as wheat or soy?  I've had many hypothyroid or patients with borderline thyroid labs tell me that they empirically feel better if they don't eat wheat and these are some of the points I share with them in terms of the science:

• It seems like there is a higher correlation between patients who have Hashimoto's Hypothyroidism (the most common form of hypothyroidism in the US where there is an antibody which attacks the thyroid gland--usually detected by positive TPO antibodies or TG antibodies) and Celiac Disease.  For example, in the general Western population, the incidence of Celiac's Disease is about 1%.   However, the incidence of Celiac Disease among people with Hashimoto's is as high as 5%-15%.  This means that persons with Hashimoto's hypothyroidism have a higher chance of being unable to digest wheat properly.
• It's not clear if one disease causes the other, or if they happen more often together because some genetic mechanism.  For example, it has been observed that persons with one type of auto-immune disease has a higher chance of having other auto-immune diseases or auto-immune antibodies.   Celiac disease and Hashimoto's hypothyroidism are both forms of auto-immune disease. 

Bottomline:   While it is unclear what the relationship between Celiac Disease or wheat and Hashimoto's Hypothyroidism is, there are some studies which show
a higher correlation.  I feel it is reasonable for someone who has Hashimoto's to do a several-month trial of wheat elimination from their diet (wheat, rye, barley and oats) to see if it makes them feel better.  Or, conversely, if they feel worse when they add wheat back into their diet after eliminating it for a few months.  This seems like a very low risk (although admittedly inconvenient) way to find out how wheat may or may not affect your health.

Should thyroid patients avoid soy?