Posted by raybakes on October 1, 2004, at 7:20:25
In reply to Re: Supplements for brain fog? » raybakes, posted by karaS on September 30, 2004, at 20:27:31
Hi Kara, came across this info about the relationship between selenium and iodine in thyroid health. Thyroxine production is quite a dangerous process as thyroid peroxidase produces the powerful free radical hyrogen peroxide, to oxidise iodine before adding it to thyroxine. N acetyl cysteine has been mentioned on this thread recently and both selenium and NAC are needed for glutathione peroxidase synthesis, to protect the thyroid from being damaged by it's own hydrogen peroxide - defficiency in glutathione/selenium has been suggested as one of the factors leading to hashimoto's. To take iodine when there is a glutathione/selenium deficiency, could cause the thyroid to produce more hydrogen peroxide than it can manage, and exacerbate the thyroid problems - the article also says too much selenium causes problems because it acclerates the T4-T3 conversion, exhausting supplies of T4.
Hope it's interesting!
a selenium deficiency causes an iodine deficiency to get worse. This may be a protective adaptation by the body to limit the damage caused to the thyroid when selenium is deficient and iodine is adequate. Let's examine this part of the interaction.We've all heard that many doctors tell hypo patients, especially those with Hashimoto's thyroiditis, not to take iodine because it can aggravate their condition. The reason seems to be that selenium protects the thyroid gland from oxidative damage and this damage can increase significantly if iodine is supplemented. Taking iodine will increase thyroid hormone production and the production of H2O2 which damages the thyroidal cells. The lack of selenium prevents GPX from being able to protect the cells from this oxidative damage. While I doubt if most doctors realize why iodine should be restricted (it certainly seemed counter-intuitive to me at first), they have learned through experience that iodine can increase the thyroid damage in Hashimoto's. The information that selenium should be supplemented along with iodine is so new that most of them are unaware of it.
Here's what we have: Studies have shown that if iodine is low, selenium must also be kept low to prevent the hypothyroidism from becoming worse (from increased DI-I and T4 depletion, as explained above.) So if both minerals are low, then the person is hypo and gets a goiter, but the damage to the thyroid is kept to a minimum. More severe problems happen when either selenium or iodine is high and the other is low. If selenium is high and iodine low, then T4 to T3 to T2 conversion is accelerated without T4 being replenished, leading to a worsening of the hypoT. If iodine is high and selenium is low, then H2O2 is not degraded by GPX. Since H2O2 drives the thyroid hormone production, then the thyroid over-produces thyroid hormone (Grave's hyperthyroidism), the thyroid is damaged from the oxidation by the H2O2, and the end result is that the damaged thyroid ultimately decreases activity and hypothyroidism results (Hashimoto's thyroiditis). This could explain the observed progression of Grave's to Hashimoto's.
poster:raybakes
thread:359642
URL: http://www.dr-bob.org/babble/alter/20040928/msgs/397786.html