Vitamin D and Thyroid Health

Vitamin D and Thyroid Health

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Vitamin D supplementation has been widely promoted for its potential benefits on bone and immune system health, as well as its role in managing conditions like depression and diabetes. This has led to the rapid growth of the supplement market. According to the CDC data from 2017 to 2018, among U.S. adults aged 20 and over, 57.6% used any dietary supplement in the past 30 days, with the usage being higher among women (63.8%) than men (50.8%)​​. Specifically, vitamin D was one of the most common types of dietary supplements used across all age groups​. In this article, we will discuss the relationship between vitamin D levels and various thyroid conditions, including autoimmune thyroid disorders, hypothyroidism, hyperthyroidism, and thyroid cancer. We will also look at some recommendations for vitamin D intake and some practical tips for maintaining adequate vitamin D levels.

The Role of Vitamin D in Thyroid Health

Vitamin D, also known as calciferol, is a fat-soluble vitamin that plays an important role in maintaining various bodily functions, including the regulation of calcium and phosphate levels in the body. This helps promote healthy bones and teeth. 

Vitamin D comes in two main forms: D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D3 is produced in the skin in response to sunlight and is found in animal-based foods, while D2 is found in plant-based foods and fortified products. Both forms are important for maintaining healthy vitamin D levels in the body.

Beyond its benefits for bone health, vitamin D is also essential in immune system regulation and has been linked to thyroid health according to research.

Autoimmune Thyroid Diseases

Autoimmune thyroid disorders occur when the immune system mistakenly attacks the thyroid gland. The two main autoimmune thyroid conditions are Hashimoto’s thyroiditis and Graves’ disease.

1. Hashimoto’s Thyroiditis

Hashimoto’s thyroiditis, a major cause of hypothyroidism, is characterized by chronic inflammation of the thyroid gland. Research has shown  a significant correlation between low vitamin D levels and Hashimoto’s thyroiditis. Some studies further suggest that vitamin D deficiency may worsen the autoimmune response, potentially increasing the severity of the disease. Ensuring adequate vitamin D levels through supplementation might help modulate the immune system and reduce the risk or severity of Hashimoto’s thyroiditis.

2. Graves’ Disease

Graves’ disease, the primary cause of hyperthyroidism, is another autoimmune disorder affecting the thyroid. Although the connection between vitamin D and Graves’ disease is less clear than with Hashimoto’s, some studies have found lower vitamin D levels in patients with Graves’ disease. Vitamin D’s role in immune regulation suggests it may influence the disease’s progression, though more research is needed to establish a definitive link.

Thyroid Cancer

Thyroid cancer is one of the more common endocrine cancers, and researchers have examined its relationship with vitamin D levels. Both lab and animal studies have shown that vitamin D can slow tumor growth, help cells mature, promote cell death, and reduce inflammation. However, according to the British Thyroid Foundation, it remains unclear whether low vitamin D levels cause thyroid cancer, result from it, or are unrelated. Just as for other thyroid conditions like hypothyroidism and hyperthyroidism, ensuring adequate vitamin D levels may support the immune system and help manage the disease, but more research is needed to understand its full impact.

Recommendations for Vitamin D Intake

Despite ongoing research, the National Institutes of Health recommends that all adults (19–70 years) obtain about 15 mcg (600 IU) of vitamin D daily. This should come from a combination of supplements, outdoor activities, and dietary sources such as fatty fish, liver, egg yolks, and fortified products. While vitamin D supplements are available in various concentrations, the British National Health Service (NHS UK) recommends against taking more than 100 mcg (4,000 IU) of vitamin D per day without a doctor’s prescription. Symptoms of vitamin D overdose include nausea, vomiting, weakness, stomach pain, constipation, and frequent urination. Severe toxicity can lead to bone pain and kidney problems, such as the formation of calcium stones and renal failure. It is important to note that excessive sun exposure does not cause vitamin D toxicity because the body regulates the amount of vitamin D it produces from sunlight.

Practical Tips for Maintaining Adequate Vitamin D Levels

1. Sun Exposure

Spend time outdoors in sunlight, especially during midday when the sun’s ultraviolet B (UVB) rays are most intense. Aim for about 10-30 minutes of sun exposure several times a week, depending on your skin type and local climate.


2. Dietary Sources

Include vitamin D-rich foods in your diet. These include fatty fish (like salmon, mackerel, and sardines), beef liver, cheese, egg yolks, and fortified foods such as milk, orange juice, and cereals.


3. Supplementation

 If dietary intake and sun exposure are insufficient, you may consider taking a vitamin D supplement. Consult with your healthcare provider to determine the appropriate dosage based on your individual needs.


4. Regular Monitoring

 Regularly check your vitamin D levels through blood tests, especially if you have a thyroid condition or are at risk of deficiency. This can help ensure you are maintaining optimal levels for overall health.


5. Holistic Health Approach

Maintain a balanced diet, engage in regular physical activity, and manage stress to support overall thyroid and immune health.

Key Takeaways

  • Low vitamin D levels are linked to autoimmune thyroid conditions like Hashimoto’s thyroiditis and Graves’ disease, potentially affecting disease severity and progression.
  • Vitamin D exhibits anti-tumor properties in thyroid cancer, but its exact role remains unclear, necessitating further study.
  • While research continues to evolve, it is clear that maintaining adequate vitamin D levels plays a significant role in supporting overall health. 
  • It is recommended that adults get an average of 15 mcg (600 IU) of vitamin D daily.
  • By incorporating a combination of sun exposure, dietary sources, and supplements when necessary, you can help ensure your vitamin D levels are within the optimal range.

You can track your vitamin D levels using the ThyForLife app, along with hundreds of other blood parameters. Setting up reminders for your daily supplement intake or annual check-ups can also help you stay on top of your health.


At ThyForLife, we do our utmost to provide accurate information. For detailed medical information regarding diagnosis, treatment, and general practices please consult your healthcare professional. Always listen to the advice of your healthcare provider.
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