Why have people inadequate vitamin D status? Is it just (the lack of) sun exposure, or is it related to hormone and thyroid function?
Here in Australia there are more cases of vitamin D shortage than in England. Given the double amount of sun hours per annum here in Down Under, that's quite counter intuitive. In fact, an estimated 31% of adults in Australia have inadequate vitamin D status, increasing to more than 50% in women during winter–spring and in people residing in southern states (Nowsen et al., 2012).
It turns out that in Australia people are, rightfully, careful of sun exposure due to the thin ozone layer and the resulting high incidence of skin cancer. As a result, people here wear long-sleeves on the beach, use high-factor sunscreens, wear sun hats, use umbrellas to evade the sun etcetera. The Australian Cancer Council supports the famous "slip, slop, slap" slogan:
Slip on a shirt, slop on sunscreen and slap on a hat, Slip, Slop, Slap! You can stop skin cancer [..]!
Hence, folks here in fact often take vitamin D supplements, despite the large amounts of sun hours.
- Nowsen et al., MJA (2012); 196(11): 686-7
Vitamin D deficiency is most probably the cause of the thyroid disfunction and not the result. So the cause of vitamin D deficiency is the lack of UV exposure.
To conclude, the results of the present study suggest that moderate to severe vitamin D deficiency is a risk factor for hypothyroidism. As vitamin D deficiency is highly prevalent in north Indian population, these findings may ha ve some public health implications. Further, large scale clinical trials and prospective studies will be required to establish a cause and effect relation of vitamin D deficiency in pathogenesis of hypothyroidism. Supplementation of vitamin D in hypothyroi dism may ameliorate its symptoms and prevent further deterioration of thyroid function, so, for the ease, safety and low cost of treating this modifiable risk factor we recommend its screening in all hypothyroid patients.
In the present study, we demonstrated that serum vitamin D levels were significantly lower in female GD patients without remission than in those with remission.