Food As Medicine: Carbohydrates and Thyroid Hormone Conversion
After yesterday’s post, I had a number of questions regarding which carbohydrates are good for thyroid hormone conversion. So, today, I’m exploring this topic.
In Chinese medicine there is a condition called “qi deficiency”. This is metabolic weakness which has a ton of symptoms that are the same as hypothyroidism.
And with Chinese dietary therapy, qi deficiency is treated with more carbohydrates. Thus, carbohydrates are the engine of Spleen qi. For the earth phase carbohydrates are the fuel for the reactor.
As it turns out, this is also supported by Western physiology. Thyroid hormone, T4, is converted by an enzyme called deodinase. There are a number of different types of deodinase (Types 1, 2 and 3) but Type 2 deiodinase (D2) is present in the thyroid, central nervous system, and pituitary.
What that tells us is that its activity is important for negative feedback on thyroid-stimulating hormone, in other words, it has a huge influence on thyroid hormone activity.
Type 2 deiodinase is approximately 1000 times more active than other types of deodinase (D1& D3). In addition, when the D2 enzyme catalyzes T3 production, it increases thyroid hormone signaling. And researches have found that blocking D2 causes localized hypothyroidism in various tissues.
Also (and this is important), its activity is upregulated by insulin and is decreased during fasting. It is well known that insulin (in the absence of insulin resistance) can stimulate the conversion of T4 to T3 via its effect on D2 activity.
So insulin has an important influence on D2. And this is the connection to Spleen qi and carbohydrates. When insulin is functioning properly, carbohydrates are essential for thyroid hormone conversion.
And this may be why some people with Hashimoto’s and hypothyroidism do so poorly on a ketogenic diet or other low carb diets. They aren’t getting enough carbs and to add insult to injury they may have some degree of hypoglycemia and/or insulin resistance which can hamper insulin’s role in this process.
Continued in comments...