Hashimoto's thyroid disease is one of the most common types of hypothyroidism in the United States. Most commonly occurring in middle-aged women, this endocrine disorder is caused by the immune system attacking the thyroid gland. After diagnosis, medication is given to regulate thyroid levels in the body. Certain foods should be limited to enhance the effectiveness of thyroid medications.

Limit Fiber

A diet rich in fiber may increase the transit time in the intestines, allowing a greater excretion of thyroid medication in the stool. Fiber in the diet should be limited to enhance the effectiveness of thyroid medication. Fresh fruits, vegetables, legumes, nuts and whole grains are considered good sources of fiber.

Limit Soy Foods

Soy foods have also been associated with a negative interaction with thyroid medications and may lead to goiter in some individuals, according to Dr. Mike Fitzpatrick, an environmental scientist and soy expert. Sources of soy include edamame, soy milk, tofu, tempeh and processed foods with soy isolates. These foods should be limited in the diet.

Other Considerations

Certain foods and supplements may be helpful when taking thyroxine to treat Hashimoto's thyroid disease. Research published in the "Journal of Clinical Endocrinology and Metabolism" indicates that taking selenium supplements or eating foods rich in selenium may help to increase the uptake of thyroxine. Nuts, breads, cereal, rice, oatmeal, turkey and tuna are all sources of selenium in the diet.