Vitamin D Deficiency and Thyroid

Vitamin D, or the sunshine vitamin, is concerned with the regulation of calcium and phosphorus levels in the body, and bone metabolism. It has also been linked to heart disease, cancer, Graves’ disease, Hashimoto’s disease and autoimmune disorders.

One of the major sources of this vitamin is the ultraviolet rays of the sun, which enables the body to make vitamin D after exposure. Food sources include fatty fish such as tuna, salmon, trout, and sardines, cod liver oil, dairy products such as milk and yoghurt, hard boiled eggs, fortified cereals, and so on.

If the level of vitamin D is less than 30 nmol/L, it is considered as a deficiency. Any reading between 30 and

49 nmol/L indicates a risk for vitamin D deficiency.

Vitamin D levels have been linked to autoimmune thyroid disease. Those who have this disease are advised to maintain vitamin D levels between 50 and 75 nmol/L, preferably towards the upper limit. Other direct consequences of vitamin D deficiency include rickets and osteomalacia, as well as improper absorption of calcium and phosphorus (and the consequent disorders).

Autoimmune thyroid diseases (AITD) include Hashimoto’s thyroiditis and Graves’ disease. Studies have shown that vitamin D deficiency often accompanies autoimmune thyroid disease, the levels being much lower in these cases. It may also be a trigger for anti-thyroid antibodies which cause AITD. These diseases cause the body to turn against its own thyroid gland, causing it to decrease hormone production. This would lead to hypothyroidism.

Taking vitamin D supplements has been found to reduce antibodies in AITD. It is also true that screening for vitamin D deficiency and serum calcium levels is recommended for all thyroid patients. However, no direct link between the two has been observed. The conclusion is that vitamin D may play a role in thyroid health, but whether the two are directly correlated remains to be tested.