Hyperthyroidism is a condition where the thyroid gland produces and releases excessive amounts of thyroid hormones. These hormones, primarily thyroxine (T4) and triiodothyronine (T3), regulate the body’s metabolism, influencing nearly every organ and bodily function, including heart rate and energy use. Selenium is an essential trace mineral, meaning the body requires it in small quantities for proper functioning. This article explores the relationship between selenium and hyperthyroidism, how this mineral influences thyroid health, and considerations for individuals with an overactive thyroid.
Selenium’s Role in Thyroid Health
The thyroid gland contains the highest concentration of selenium in the body. Selenium is incorporated into selenoproteins, which are involved in various bodily processes, including DNA synthesis and protection against cell damage. These selenoproteins also play a direct role in the synthesis and metabolism of thyroid hormones.
Deiodinase enzymes are a group of selenoproteins responsible for converting the inactive thyroid hormone T4 into the more active form, T3, by removing an iodine atom. This conversion is important for the proper utilization of thyroid hormones by cells and tissues throughout the body.
Selenium is also a component of glutathione peroxidases. These enzymes act as antioxidants, protecting the thyroid gland from oxidative stress. During thyroid hormone production, reactive oxygen species (ROS) are generated, which can cause cellular damage. Glutathione peroxidases help neutralize these harmful free radicals, safeguarding thyroid tissue.
Selenium’s Influence on Hyperthyroidism
In hyperthyroidism, especially in Graves’ disease, the most common cause of an overactive thyroid, there is often increased oxidative stress and inflammation within the thyroid gland. Selenium’s antioxidant properties, through its role in glutathione peroxidases, may help mitigate this damage and inflammation.
Research has explored selenium supplementation in individuals with Graves’ disease. Some studies suggest that selenium, when combined with anti-thyroid medications like methimazole, can lead to a faster normalization of thyroid hormone levels, specifically lowering free T3 and free T4. This quicker response may reduce the overall period of exposure to the heightened oxidative stress associated with hyperthyroidism.
While some studies indicate that selenium supplementation can lower levels of certain antibodies characteristic of autoimmune thyroid conditions, the overall scientific consensus on selenium as a standalone treatment for hyperthyroidism remains mixed. It is generally considered a supportive nutrient that may enhance the effectiveness of conventional treatments, rather than a primary treatment itself. Effectiveness can vary depending on factors such as baseline selenium status, the specific form of selenium used, and the duration of supplementation.
Obtaining Selenium and Supplementation Guidelines
Individuals can obtain selenium through various dietary sources. Foods rich in selenium include Brazil nuts, which are exceptionally high in the mineral, containing around 544 micrograms per ounce (about six to eight nuts). Seafood such as yellowfin tuna, sardines, shrimp, cod, halibut, and salmon are also good sources.
Other dietary sources include:
Meats like ham, pork, beef, turkey, and chicken
Eggs
Cottage cheese
Brown rice
Sunflower seeds
Baked beans
Mushrooms
Oatmeal
Spinach
Milk
Yogurt
Lentils
The selenium content in plant-based foods can vary significantly based on the mineral content of the soil where they were grown.
When considering selenium supplementation, be aware of the recommended daily allowance (RDA) for adults, which is 55 micrograms per day. Some studies related to thyroid health have used dosages in the range of 75 to 200 micrograms per day. However, avoid excessive intake, as high doses of selenium can lead to toxicity, a condition known as selenosis.
Symptoms of selenium toxicity can include a garlic odor in the breath, a metallic taste in the mouth, hair loss, brittle nails, skin rash, nausea, diarrhea, fatigue, irritability, and nervous system abnormalities. Extremely high doses, typically above 900 micrograms per day, can lead to more severe outcomes, including organ failure.
Consult a healthcare professional before starting any selenium supplementation, especially if diagnosed with hyperthyroidism. This ensures appropriate dosage and helps avoid potential adverse effects or interactions with medications.