New information for me according the importance of vit C for the thyroid;
"The Journal of Clinical Endocrinology & Metabolism recently studied the effects of vitamin C on the absorption of a synthetic T4 hormone with 31 patients who either had autoimmune thyroiditis or idiopathic hypothyroidism. Prior to the study, all patients were not in good control when taking the synthetic T4. Serum concentrations of T3, T4, and TSH were measured at particular intervals after vitamin C therapy.
All three concentrations were improved while taking vitamin C. TSH decreased in all patients and normalized in nearly 55 percent of them. T4 was higher with 30 of the 31 patients, and T3 was increased with all patients tested. These findings are significant in the role of vitamin C and thyroid function." http://www.naturalhealth365.com/thyroid-function-adrenal-fatigue-vitamin-c-1516.html
The reason why vit C has a good effect on the thyroid, is not stated in the article, but a suggestion;
"vitamin C secretion is part of the body’s stress response. Excessive stress, along with the body’s insufficient intake of the vitamin, can create a deficiency that leads to adrenal stress.
Countless studies show chronic adrenal stress disrupts the hypothalamic-pituitary-adrenal (HPA) axis. Because thyroid hormone is directed by the hypothalamus and the pituitary glands, anything that disrupts the HPA axis will affect thyroid function.
With studies proving that vitamin C deficiency is a problem for all people who have a thyroid condition, it’s possible that adrenal fatigue could be the cause. Therefore, it’s imperative to include foods and/or supplements containing vitamin C, especially with extreme or ongoing stress."
PS I take vit C (5-6) grams daily, in addition to whatever is in my food. When I take iodine, I add some ascorbic acid to it. (This is one of the questions that come up regularly at this forum; with or without vit c :)