The thyroid is a butterfly-shaped endocrine (hormone-producing) gland located at the base of the neck, just above your collarbone, and is often referred to as the “master regulator”. The hormones produced by this little gland are responsible for regulating digestive action, metabolism, body temperature, heart rate, sweating, and mood, among others.(1)
The role of the thyroid is to take iodine and convert it into thyroxine, (T4). T4 is then converted to an active hormone, triiodothyronine (T3), by the removal of an iodine atom. Every cell in the body depends on these thyroid hormones for regulation of their metabolism. Clearly thyroid function is just a little important.
Production of thyroid hormones is controlled by the pituitary gland. The pituitary gland produces and secretes thyroid stimulating hormone (TSH) depending on the amount of T4 in the bloodstream. If T4 levels are low, production of TSH goes up. Once T4 levels are adequate, production shuts down.
There are two types of thyroid disorders, hyperthyroidism and hypothyroidism. Hyperthyroid is an overactive thyroid and typically causes symptoms of nervousness, irritability, sleeplessness, rapid pulse, increased appetite, weight loss, and muscle fatigue.(1) Hyperthyroid can be caused from a viral infection, growth or tumor, or most commonly, from Graves’ disease (an autoimmune disorder).
Hypothyroidism is much more common and can cause symptoms such as weight gain, fatigue, changes in mood, cold intolerance, severe constipation, joint and muscle aches, hair loss, dry skin, and heavy periods. Women are ten times more likely to suffer from hypothyroid disease than men.(2) This makes it difficult to ignore the link between estrogen and hypothyroid.
Hormone Balance & Your Thyroid
While there are several causes of hypothyroidism, it appears many cases of hypothyroid may actually be the result of estrogen dominance. Estrogen dominance refers to a lack of balance between estrogen and progesterone; there is too much estrogen in comparison to progesterone. This does not always mean your estrogen level is too high. You can have estrogen dominance even if your estrogen is low, if your progesterone is also low.
Everything is about balance and equilibrium. Your thyroid is no different. In order for your thyroid to function properly, your hormones must be balanced. This is especially true with estrogen and progesterone. The balance of estrogen and progesterone is absolutely crucial for a healthy thyroid.
Production of thyroid-binding globulin, a protein which binds with thyroid hormones and makes them inactive, is stimulated by increases in estrogen. Conversely, progesterone decreases thyroid-binding globulin, which increases the activity of thyroid hormones.(3) Since we rely on the activity of thyroid hormones to maintain our metabolism keeping our estrogen/progesterone ratio in check (so thyroid-binding globulin is not over or under produced) is crucial.
Estrogen is also connected to hypothyroidism in several other ways. Excessively high estrogen levels actually prevent the liver from converting T4 (thyroxine) into T3 (triiodothyronine). As we mentioned earlier, the body must convert T4 to the active hormone T3 before it can be used.
High estrogen can also prevent proteolytic enzymes (enzymes that break down protein) from functioning. Protein metabolism is critical for thyroid function since T4 is converted to T3 in your muscles and your thyroid hormones rely on a carrier protein as their ride to your cells.
For many women, hypothyroid manifests as the autoimmune disease Hashimoto’s thyroiditis. In fact, Hashimoto’s disease is the most common cause of hypothyroidism in the United States.(4) Hasimoto’s typically results from a combination of three factors:
- A genetic predisposition, having someone in your family with Hashimoto’s or another autoimmune disorder, increases your risk of developing this condition.(5)
- Intestinal hyperpermeability, also known as leaky gut syndrome, is when the intestinal lining becomes damaged and no longer keeps unhealthy substances (such as toxins, bacteria, undigested foods, etc.) from passing into the bloodstream. This creates an immune response and inflammation, which can trigger autoimmune diseases like Hashimoto’s thyroiditis.
- A trigger, which is often the change in reproductive hormones during transitory times like menopause, is associated with the greatest risk of onset.
Why is Hypothyroid Becoming So Common?
The incidence of thyroid disease is steadily increasing, with an estimated 200 million people currently dealing with some form of thyroid issue. The U.S. is close to epidemic rates and the truly scary part is that many of these cases go undiagnosed or misdiagnosed.
So what is contributing to these high rates of thyroid disease? Well, we have already demonstrated estrogens importance in thyroid health and that estrogen dominance not only has very similar symptoms, but can also be a catalyst to hypothyroidism. So it only makes sense that at a time when estrogen dominance is at an all time high that we would start seeing higher rates of thyroid disease.
Here are a few contributing factors to estrogen dominance:
- Poor digestive health
- Sluggish liver and/or gall bladder
- High animal protein intake (lots of meat and dairy)
- Low fiber diets
- Hormone replacement therapy
- Oral contraceptives
- Xenoestrogens – endocrine-disrupting chemicals that mimmick estrogen and bind to estrogen receptors. These chemicals are found in foods, plastics, cosmetics and personal care items, pesticides, etc.
What Can You Do?
One of the most important steps you can take is to support healthy digestion and your liver. This will help your body better metabolize and remove estrogen. Eating a diet high in fiber, fresh fruits, and vegetables along with drinking plenty of water is a good place to start. If you think you may have digestive issues or leaky gut syndrome then we urge you to address these issues right away. You can learn more about gut health here.
Avoiding exposure to xenoestrogens whenever possible is another way to balance your estrogen level. While it may not be possible to avoid all xenoestrogens, there are a number of sources you can eliminate. Purchase organic foods as much as possible, especially meats, dairy, and fruits and vegetables from the dirty dozen list. Avoid storing (and especially heating) foods in plastic containers. Purchase cosmetic products that do not contain known xenoestrogen chemicals (we recommend Beautycounter products for safer alternatives to your cosmetic and personal care items).
1. Hoffmann, D. Medical Herbalism. Rochester, VA: Healing Arts Press; 2003.
2. Estrogen dominance and hypothyroidism: Is it hypothyroidism or hormone imbalance? The National Academy of Hypothyroidism. https://www.nahypothyroidism.org/estrogen-dominance-and-hypothyroidism-is-it-hypothyroidism-or-hormone-imbalance/.
3. Walsh, B. 7 thyroid issues your doc likely missed. Precision Nutrition. https://www.precisionnutrition.com/thyroid-and-testing.
4. Hashimoto’s disease. MayoClinic.com. https://www.mayoclinic.org/diseases-conditions/hashimotos-disease/symptoms-causes/syc-20351855.
5. Hashimoto thyroiditis. U.S. National Library of Medicine. February 2018. https://ghr.nlm.nih.gov/condition/hashimoto-thyroiditis#inheritan