Nutrient deficiencies are a common contributor to chronic disease states and yet they are often overlooked. Thyroid disease is no exception.

Proper thyroid function is dependent upon multiple vitamins and minerals working together. According to various sources, the following nutrients may all be involved in either initiating thyroid dysfunction or helping to manage symptoms through maintaining adequate levels: protein, vitamin D, vitamin A, thiamine (B1), riboflavin (B2), cobalamin (B12), iodine, selenium, iron, zinc, vitamin C, and magnesium.

Here we will highlight a few of these nutrients and their thyroid-related functions in the body as well as the best dietary sources or other methods of repletion.

Vitamin D

Vitamin D is known to be an “immune modulator.” Since autoimmunity is associated with an imbalance between the two parts of our immune system known as Th-1 (cell-mediated) and Th-2 (humoral), it makes sense that vitamin D deficiency has been found to be more prevalent among those with autoimmune thyroid conditions compared to healthy individuals.

But even most healthy individuals have sub-optimal vitamin D levels, especially those who live further from the equator and spend most of their time indoors. Other risk factors for deficiency include darker skin, not having much skin exposed when spending time outdoors, and history of a digestive disorders (leading to fat malabsorption).

Fatty fish, egg yolks, and fortified foods like milk and cereals are the best food sources of vitamin D. While getting more natural sunlight and food sources of vitamin D can help, vitamin D supplementation is often necessary for those who are deficient.

Ask your integrative healthcare practitioner to test and monitor your vitamin D levels. They can help guide you on supplementation. In those with autoimmune thyroid disease, many clinicians report the best outcomes for patients who maintain vitamin D levels between 60 and 80 ng/L.

Vitamin B12

It is estimated that up to 40% of hypothyroid patients are deficient in B12. Low B12 status can result in fatigue, cognitive issues, and depression – all of which are also frequently reported symptoms of hypothyroidism. Since B12 is necessary for cellular and metabolic processes, not having enough can certainly contribute to a sluggish thyroid.

Deficiency may also be associated with hypothyroidism through the autoimmune link. Poor dietary habits, digestive dysfunction, and gut infections may also be involved.

The best food sources of vitamin B12 are meat, organ meats, eggs, fish, and dairy. Sublingual is the most absorbable form of supplemental B12 (next to injections) and thyroid patients should aim for B12 levels that fall somewhere between 700-900 pg/ml.

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Iodine is a trace mineral and the nutrient most often associated with thyroid dysfunction since it is necessary for the production of thyroid hormone, T4. 70-80% of the iodine in the body is found within the thyroid gland. Iodine deficiency can cause sluggishness, weight gain, and other symptoms of hypothyroidism, and in extreme cases a goiter may occur (enlarged thyroid).

Good sources of iodine in foods include iodized salt, sea vegetables such as seaweed, spinach, Swiss chard, and lima beans.

Supplementation should only be initiated after having your iodine levels tested and with the help of an experienced thyroid practitioner since too much iodine can also be problematic.

Especially use caution in autoimmune thyroid conditions, as iodine can sometimes cause a flare-up of symptoms.


Selenium, another trace mineral, is important when it comes to thyroid function because it is necessary for the conversion of T4 to T3 – inactive to active form of thyroid hormone.

Some of the research on selenium has found that supplementation may help lower thyroid antibodies in those with Graves’ Disease and Hashimoto’s thyroiditis. In fact, in some studies, 200 mcg of selenium daily has been found to decrease TPO antibodies by 50% within 3 months. Other research is not as clear in regards to supplementation in thyroid patients.

Regardless, having adequate levels of selenium is important for overall health due to its role in immune function. Brazil nuts, wheat germ, whole grains, and sardines are all excellent dietary sources of selenium.


Iron is another mineral required for thyroid hormone synthesis. When iron levels are depleted, the activity of heme-dependent thyroid peroxidase is reduced.

Low iron is associated with Hashimoto’s thyroiditis and symptoms of fatigue, hair loss, and difficulty breathing, just to name a few.

Additionally, iron supplementation has been shown to make iodine supplementation more effective. Therefore it is important for thyroid patients to have their ferritin levels checked. The best range for thyroid patients to stay within is 90-110 ng/ml. It is also worth noting that ferritin is not normally the first test doctors run to rule out iron deficiency (and these tests may be normal despite low ferritin), so it is often necessary to ask specifically for a ferritin test.

Iron in its most highly absorbable form is found in animal sources such as red meat, poultry, and fish. Good plant sources of dietary iron include green leafy vegetables, legumes, nuts, and blackstrap molasses.

Addressing Deficiencies

Whether it is due to a direct link to thyroid function or the result of secondary problems that occur in chronic disease processes, it is clear that vitamins and minerals play a key role in thyroid disease and should be addressed in the context of an integrative approach to treatment.

It can be overwhelming to know where to start in addressing these possible nutrient deficiencies. Talking to your thyroid doctor about testing your levels of these key nutrients, as well as maintaining a nutrient-dense diet, are both good first steps toward improving your thyroid and overall health.

Looking for high-quality supplements to address your nutrient deficiencies?!

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