• White Twitter Icon
  • White Instagram Icon

6. The Thyroid Connection by Amy Myers

The Thyroid Connection makes a really convincing case for getting your thyroid hormones looked at if you've ever suffered from chronic ailments or eaten the Standard American Diet.

 In this episode, we discuss:

Show notes:

  • Ben Greenfield suggests this product for heavy-metal detox: Metal Free

  • Toxoplasmosis is a disease from the toxoplasma gondii parasite that typically inhabits the guts of cats and can be transmitted to humans from cat poop, which is why pregnant women are told to stay away from litter boxes during pregnancy

  • Genetically modified organisms are typically these types: (1) the plant produces more of its natural pesticides; (2) the plant is resistant to glyphosate; or (3) certain growing properties are increased so the plant fares better in different climates

What is the thyroid?


The thyroid is the small, butterfly-shaped gland that sits at the base of the throat. In concert with other biological systems, it facilitates metabolism by producing thyroid hormones, which are utilized by every cell in the body. The process begins in the brain where the hypothalamus releases thyrotropin-releasing hormone (TRH), which encourages the pituitary gland to release thyroid stimulating hormone (TSH). Then the thyroid produces T4, the inactive form of thyroid hormone, and converts some of it into T3, the active form. Currently, the functions of T1 and T2 are unknown, but due to their production and presence in the body, it is assumed that they are important for optimal health.

What's the deal with iodine?

The thyroid needs iodine to produce thyroid hormones T1, T2, T3, and T4. An iodine deficiency results in an enlarged thyroid because the latter has to recycle iodine from the blood several times per day and work harder than usual. One can deduce iodine deficiency in the presence of goiter and swollen tongue. Because the soil in the Midwest has one of the lowest iodine concentrations in the world, goiters near the Great Lakes were very common in the early 20th century. Iodine was the first nutrient identified as important for human health and was added to the food supply in supplementary form.


Most of the world's iodine is found in the oceans, which means fish and sea vegetables are the best sources of dietary iodine. However, iodized salt and silos for conventional dairy are the most common sources of dietary iodine in the Standard American Diet. When people switch from the SAD to a paleo or ancestral dieting lifestyle, they often forego iodized salt in favor of sea salt or celtic salts, which have lower iodine concentrations than their industrialized counterparts. It is important for people who eat these diets and live in iodine-low regions to add iodine back into their diets with either a high-quality supplement or foods like organic seaweed or kelp—(make sure the product doesn't have any hidden vegetable oil!).

Halogens and perchlorates are bad news

In the body, iodine competes with its fellow halogens, fluorine, chlorine, and bromine. When chlorine is added to the water supply, its goal is to kill bacteria. Ingesting water with large amounts of chlorine can have adverse affects on the microbiome. Fluorine's small size, coupled with its missing valence electron, make it the most electronegative element in the Periodic Table—and the most reactive. While it is present naturally in the earth, and therefore our ancestors would have consumed it in tiny quantities, exogenous fluorine is poisonous. Fluoride is used to prevent dental cavities, even though little research exists to prove it actually does this. (Meanwhile, dental caries are an internal disease caused by nutrient deficiency and environmental toxins, as shown by Nutrition and Physical Degeneration by Weston A. Price.) Finally, bromine is used in cars for the "new car smell" and in flame retardants in fabrics. It, too, is highly toxic when consumed in manmade products.

Iodine also competes with perchlorates, which are compounds in which chlorine atoms are surrounded by four oxygen atoms. Perchlorates are used in chemical production of rockets, fireworks, missiles, bleach, air bags, etc. Ground water contaminated by these processes infects vegetation, and perchlorates end up in produce and the meat of ruminent animals.

Speaking of supplements, Julia and Sasha like the philosophy of Dave Asprey: while we prefer to get our nutrients from eating a balanced, whole-foods diet focusing heavily on organ meats from pastured animals, it is impossible to eat as cleanly as our ancestors did 10,000 years ago. The world is different, and we have way more toxins in the environment than before. Soils are depleted of nutrients; produce loses nutrient quality when in transit for a long time; most organs are thrown out at USDA processing facilities; and we are bombarded with artificial chemicals on a daily basis. In short, Dave's mantra is: if you want to get all your nutrients from food, then you should get all your toxins from food, too. Since you are not likely to get all your toxins from your food, then you can't expect to get all your nutrients from your food, either. That is why Sasha and Julia add in high-quality supplements of iodine, magnesium, and Celtic salt.

What are common thyroid conditions?

Hypothyroidism, or under-performing thyroid is usually characterized by fatigue, weight gain, depression, inactivity, constipation, etc. Hashimoto's is hypothyroidism with an autoimmune component. Hyperthyroidism, or overactive thyroid, is usually characterized by a wired feeling, anxiety, rapid weight loss, diarrhea, etc. Grave's Disease is hyperthyroidism with an autoimmune component. However, all conditions can have any of these symptoms as well as many other symptoms. Because the thyroid is essential for every biological process, a variety of symptoms can emerge when it is not performing correctly.

Estrogen affects thyroid function because excess estrogen increases production of thyroid binding globulin, which disallows conversion of T4 into T3. Xenoestrogens, present in the industrialized food supply and plastics, contribute to this process, which is why men experience thyroid issues as much as women. It's also why it is important to ensure that a test for optimal thyroid function focuses on all the markers for thyroid performance and health. Simply testing for T4, for example, will not give an accurate picture of the amount of bioavailable thyroid hormone (T3) in circulation. 

What should you test?

Amy Myers recommends testing for all of the following when testing for optimal thyroid function: 

  • TSH

  • Free T4

  • Free T3

  • Reverse T3

  • Thyroid Peroxidase Antibodies (TPOAb)

  • Thyroglobulin Antibodies (TgAb)



The Thyroid Connection, by Amy Myers, is a great introduction into the importance of diet and lifestyle changes for an optimally functioning thyroid. Amy shares her own story of an overactive thyroid and the frustration she felt as doctors refused to test her thyroid function. After treating her thyroid with radioactive iodine, something she now regrets, she has to supplement with exogenous thyroid hormone for the rest of her life. After her experience, she became committed to understanding the causes of incorrectly functioning thyroids and treating a wide variety of people. She offers hope and advice for the millions of people dealing with these debilitating conditions.

Our major critique of this book is that Amy tends to repeat a lot of the information. Whether you choose to listen to this book on Audible or Libby or read a hard copy, you can easily skip several paragraphs here and there without sacrificing content. We really like her discussion of the different hormones and signaling molecules involved in the thyroid hormone cascade, and we think her list of what to test when testing for optimal thyroid function is fantastic.