How Vitamin D Affects Thyroid Conditions
Vitamin D is well known for its importance in the control of calcium in the intestine, bones and blood and resistance to disease. However, many studies now show that vitamin D levels may be a contributing factor in many other health problems.
Researchers now believe that it plays a crucial role in how cells communicate. Clinical studies link abnormal vitamin D levels to colon, prostate, and breast cancer, as well as heart disease, weight gain, and thyroid conditions.
Vitamin D production
Vitamin D is unique compared to other vitamins in that it is nearly impossible to get what you need from food. Instead, your body naturally produces it on your skin when you’re exposed to natural or artificial UVB light.
Once your body makes vitamin D or takes it as a supplement, it is sent to the liver. The liver transforms vitamin D into 25(OH)D and sends it to various areas of the body and activates it. Once activated, it is ready to perform its functions.
autoimmune conditions
Autoimmunity occurs when the immune system treats a person’s healthy cells and tissues as a threat. When this happens, your body mounts an immune response and attacks. This response can cause damage, inflammation, and chronic pain in many parts of the body.
Vitamin D deficiencies can reduce the body’s ability to fight infection and can be linked to or cause autoimmune diseases such as Hashimoto’s thyroiditis and Grave’s disease.
Clinical studies
Several studies from 2014 presented at the annual meeting of the Thyroid Association are of special interest. Researchers from Nanjing, China, evaluated 34 patients with Hashimoto’s thyroiditis and 32 with Grave’s disease versus 52 healthy patients. The researchers measured many factors related to the thyroid, including vitamin D3.
Vitamin D is actually a group of compounds classified as vitamin D1, D2, and D3. Vitamin D3 is the natural form of the vitamin and the most biologically active.
The researchers found that patients with autoimmune thyroid disease had significantly lower levels of vitamin D3 than healthy controls. Patients with high levels of antibodies against thyroid peroxidase, which the body produces in autoimmune thyroid disease, also had lower levels of vitamin D. This suggests that insufficient vitamin D might be linked to or cause autoimmune thyroid disease.
Brazilian researchers studied 54 Hashimoto’s patients, compared with 54 healthy controls. They also found vitamin D deficiency in 63.2% of the patients. Those with low levels of vitamin D also had higher levels of thyroid-stimulating hormone and a larger thyroid.
Lack of vitamin D
Normally, the skin produces enough vitamin D when exposed to adequate UV light. However, the risks of skin cancer or melanoma now mean that many people wear sunscreen and cover their bodies. We also spend more time indoors for work and play.
With more clinical evidence showing a link between vitamin D and thyroid function, many doctors now recommend vitamin D testing as part of thyroid evaluation and care. However, functional doctors and doctors who follow the medical model may treat you differently based on their results.
Medical Model vs. Functional Model
The medical model recommends 400 International Units of vitamin D per day. It also defines a sufficient serum level of 25(OH)D above 50 nmol/L since it “covers the needs of 97.5% of the population”. The test used to measure vitamin D levels is the 25-hydroxy vitamin D blood test.
The medical model often recommends supplementation to increase low vitamin D levels. However, the functional approach to care recognizes multiple reasons that can cause low vitamin D levels. Therefore, recommending supplements before discussing general health and other potential problems can be ineffective and counterproductive.
Supplements don’t always correct low vitamin D levels because they don’t address underlying problems. The vitamin D receptor in some autoimmune patients cannot be activated due to variations in its DNA sequence. Consequently, they need higher than normal blood levels of vitamin D to avoid vitamin D insufficiency.
Vitamin D is fat-soluble, and some patients with thyroid problems such as Hashimoto’s thyroiditis have low stomach acid and poor fat absorption. Autoimmune conditions like Hashimoto’s thyroiditis and Grave’s disease also cause the immune system to work overtime, depleting the body’s stores of vitamin D. Therefore, addressing gut and digestive issues and modulating the immune system are of paramount importance before considering vitamin D supplementation.
A highly qualified functional physician will observe your intestinal and digestive health and, if satisfied, may order a 25-hydroxy vitamin D blood test to determine your vitamin D levels.
Your doctor may recommend supplementation to achieve between 60 and 80 nmol/L. This is still well below the threshold of 125 nmol/L where a patient could experience adverse effects. After several months, they will take the test again. If your serum level has risen to an acceptable level, your doctor will adjust your vitamin D intake so that serum levels remain between 50 and 60 nmol/L.
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Vitamin D insufficiency is just one factor that can contribute to thyroid problems, so self-supplementation is not recommended as it may be ineffective if underlying problems persist. Discuss your thyroid problems with a functional physician to develop an effective treatment protocol.