A very common complaint you see, especially in functional medicine, is concerns about thyroid function. Interestingly, women are 5-8 times more likely to develop thyroid dysfunction than men with the lifetime risk of thyroid issues in women at about 12%.1  The most common cause of thyroid issues is an autoimmune disease called Hashimoto’s Thyroiditis. Like all autoimmune diseases, this is reversible. Another common thyroid issue is inadequate conversion of hormones in the periphery. We will focus on these two forms of thyroid disease.
Before getting started, I realized in the middle of writing this that thyroid issues are too complex to get through in one blog and therefore will become a three part series as well.
First, the thyroid is a powerful organ that is responsible for regulating the metabolism of every single cell in our body. If it doesn’t work, then you gain weight and experience things like brain fog, constipation, hair issues, and chronic fatigue. Because of its importance, we want to take good care of it and this starts with a deeply nourishing diet.
In order for your thyroid to function properly there are several nutrients that you need to ensure are in your diet at the proper levels. These include iron, selenium, iodine, selenium, zinc, tyrosine, vitamin A, Vitamin Bs (B2, B3, B6), and vitamin D. I will focus the major ones.
Selenium is involved in activating the enzymes that are naturally part of our body’s antioxidant systems. This helps protect a highly active thyroid from things like oxidative stress (too much work). Think of oxidative stress as long days at work and selenium as whatever you do to decompress from the long day. You want to shoot for 120 mcg/day. Plant food is an inconsistent source of selenium and would require you to eat 20 brazil nuts per day to meet your needs. In animal foods, we can get plenty from 1/2 oz of liver, 4 egg yolks, and 16 oz of lamb. This would give me 156 mcg and easily attainable for me.2,3
Zinc is involved in the production of essentially everything in the body, including thyroid hormones. It also aids in proper conversion of hormones. In order to get enough, we again need to go to animal foods as this form is 5 times more absorbable. The best sources are in oysters and red meat, so if you focus on getting at least one of these foods in your diet daily then you are likely to get enough zinc on a daily basis. I prefer people get red meat in at least twice a day to get enough protein as well. 2,3
Iron is well known for its role in blood formation, but also plays important roles in thyroid hormone production and deficiency can lead to hypothyroidism. This is a big reason that I often check iron levels on all patients, especially females. Heme iron is the form we want and again is only found in animal foods. This form is more absorbable and therefore usable by our bodies. Meat and organs are the two foods with large amounts of this vital nutrient.2,3
Iodine is the classic thyroid nutrient and is the major nutrient in thyroid hormone, hence its importance. However, it is also considered a “goldilocks” nutrient as too much can be as harmful as too little. Plant foods are again not a consistent source as foods grown in one area vs another can have 100 fold different levels of iodine because of variation in soil quality.  Focusing on milk, cheese, and fish/shellfish are the first places I have people focus on and then go from there. If you are very deficient, short term use of kelp can be beneficial, but work with someone that knows what they are doing if you are worried. Additionally, iodine deficiency is associated with fibrocystic breasts, so focusing on this nutrient can help with this as well.2,3
Vitamin A is another big player with thyroid health as it aids in both production and conversion at a nuclear level. This is again another food where focusing on animal foods is ideal. Retinol is the animal form and what is used by all the cells of our body. Beta-carotene is the plant version and requires an enzyme called BCMO1. If you have a dysfunctional variant (up to 65% of people have some level of dysfunction) then you will have a 60% reduction in retinol production from beta-carotene, making it a suboptimal nutrient form of vitamin A for most people. Again, this means focus on eggs and liver for your vitamin A.2,3
Lastly, vitamin D plays big roles in thyroid health through immune system function. Having optimal vitamin D means you are more likely to have optimal immune function, which means less likely to have autoimmune thyroid disease. During the summer, I recommend getting this from the sun (no, I don’t recommend sunscreen, but that sounds like another good blog post topic!), but during the winter I rely on high vitamin cod liver oil. Depending on the brand, you will need up to 3 tsp to get adequate vitamin D, but this is the best way I can come up with to get vitamin D from diet during less sunny months.2,3
I hope you noticed a trend when discussing nutrients for thyroid: focus on animal foods. This is where the bulk of everyone’s nutrition should come from if they want to function optimally. I always go back to ancestral wisdom when I have burning questions about nutrition and this tells me that meat and organs were the center of the diet. This means we evolved this way and because of that  we typically thrive with more animal foods in our diet.