Self-supplementation is not recommended.
The current findings on vitamin D and the risk of thyroid cancer are inconsistent. Studies have found that insufficient vitamin D in the body may increase the risk of thyroid cancer. However, it has also been reported that there is no significant relationship between the progression and recurrence of thyroid cancer and the presence or absence of vitamin D deficiency in the body. There is not enough evidence on the safety and efficacy of vitamin D preparations for patients with thyroid cancer, so it is not recommended that thyroid cancer patients take vitamin D supplements on their own. For patients with vitamin D deficiency, vitamin D preparations can be taken under medical supervision.