Hypothyroidism and subclinical hypothyroidism are very common presentations in today's world. Essentially there are 2 forms of low thyroid function: autoimmune hypothyroidism and non-autoimmune hypothyroidism. Because thyroid hormone is essential to every cell of the body, decreases in thyroid function may result in an array of symptoms and altercations to many bodily systems and functions. In many cases low thyroid activity is a "chicken and egg" problem. The thyroid gland itself is not the actual cause of low thyroid function, but rather the result of varying levels of dysfunction. Additionally, low thyroid activity can result in many abnormalities related to: lipid dysregulation, poor iron utilization, digestive inadequacies, blood sugar-handling issues, adrenal-related issues, fluid retention, and liver issues.
In autoimmune hypothyroidism, referred to as Haschimoto's, immune antibodies attack an important thyroid enzyme known as thyroid peroxidase. In this situation, the primary issue involves the aberrant immune response targeting the body's own tissues. Non-autoimmune hypothyroidism, however, does not involve autoimmune attack, but rather exhibits functionally low thyroid activity.
Low Iron, Hemoglobin & Low Thyroid
Among the many issues that result from low thyroid activity, iron-deficiency is one of the more common. Iron and its proteins play many essential roles in the body. Iron is needed to form cytochrome, which is the basis of ATP and energy production. Iron in it's heme form is critical for the formation of catalase, a key antioxidant that protects cells from free radicals, by degrading hydrogen peroxide to water and oxygen.
Iron is referred to as the 'blood-building mineral', because its co-factor heme forms the color of blood. Important blood proteins such as hemoglobin transport iron in red blood cells. Hemoglobin is critical for iron, oxygen and carbon dioxide transport, safely delivering oxygen from the lungs to the peripheral tissues, where it is being used and then bringing carbon dioxide (Co2) back to the lungs. It doesn't get more fundamental than this.
There are a few main reasons why iron and hemoglobin tend to be decreased among those with hypothyroidism.
First, literature supports the reality that most people with hypothyroidism have digestive insufficiency, especially low gastric acid secretion. Gastric acid is essential for the uptake of minerals such as iron, calcium, magnesium and zinc. It stands to reason that low thyroid activity may alter nutrient absorption, and iron-deficiency is one of many common deficiencies likely to occur with low hypothyroid activity.
Second, here's where it gets a bit complex: Heme I, a major component of hemoglobin, is bonded to thyroid peroxidase (TPO), the enzyme that releases iodine to tyrosine needed to form both thyroid hormones, T4 and T3. Inadequate iron means inadequate hemoglobin, means low TPO bonding, means low thyroid hormone synthesis. Because thyroid hormone alters the rate of heme oxidation in the liver, low thyroid function can cause a vicious cycle involving iron-deficiency.
The Thyroid Requires Several Nutrients, Not Just Iron
Many people who are hypothyroid begin taking supplemental iron with the idea of boosting iron values. This methodology is flawed for many reasons.
First, if digestive insufficiencies are present, such as low gastric acid, the iron may not be taken up efficiently. Second, many forms of supplemental iron are poorly used by the body. Iron is a powerfully reactive pro-oxidant, so much so that the body has several mechanisms in place to prevent free iron from being released. In fact, under periods of increased oxidative stress and free radical activity, the cells cleverly are programmed to rapidly degrade heme, presumably to prevent free iron from entering circulation. Supplemental iron could very likely add to the pro-oxidant activity, especially when unbound by proteins. It stands to reason that if those with hypothyroidism have even a mild increase in oxidative stress, increasing potential pro-oxidation via iron supplements seems like a hazard.
Does the thyroid need iron to function? Absolutely, but inorganic forms of iron aren't the way to go. Far superior would be whole foods containing heme iron. Additionally, multiple nutrients are required for healthy thyroid function. Most notably: Vitamin A, zinc, selenium, Vitamin D, iodine. Deficiencies of any of these could negatively affect thyroid health.
What is essential is to support the body in a holistic manner. This means that a person's individual food and nutrient needs should be considered more fundamentally essential than "treating the thyroid". Eating in harmony with your type of metabolism, has been from my experience, the most essential starting point to address individual nutrient needs.
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