Labs to monitor: TSH, Free T4, Free T3, Reverse T3

T3 hormone is most metabolically active, and is most relevant to a fitness journey. The medication Liothyronine is the synthetic form of T3, which is sometimes abused in the fitness industry due to it’s fat loss effects. Liothyronine is not often prescribed in conventional medicine, as it is believed to be unstable and difficult to provide a steady daily dose.

Supplementing with the right nutrients will help increase your T3 levels naturally.

Who is most at risk for hypothryoid? People who have a long history with under eating or dieting, losing a significant amount of weight, rapid weight loss (eg. Fitness competitions), ketogenic dieters, under eating carbs, family history of autoimmune hypothyroid.

Thyroid and body composition. Thyroid hormone status has a significant impact on your body composition. Not only does the thyroid control the rate at which you burn calories, it also governs the body’s ability to heal and repair. Therefore, it also helps with building muscle. Technically you can still lose weight, and be on a fitness journey with a hypothyroid (lots of people don’t even know they have a hypothyroid) but you feel a whole lot better and you’ll make better progress when your thyroid is functioning optimally. To put things in perspective, having adequate thyroid hormones can mean the difference between doing an hour of cardio daily, vs only 30 minutes when in an optimal state.

Nutrients that effect thyroid.

Iodine

Iodine is an essential trace mineral for the production of thyroid hormones. The RDA for iodine is only 140 ug (micrograms). However, if you are in a state of low thyroid hormones, you will likely need to be supplementing with much more than this. Some people need as much as 12.5 mg (yes you read that right, 12.5 milligrams), but a standard maintenance dose of iodine will be a little lower at around 200 mg per day. Thyroid hormones T4 (thyroxine) is composed of 4 iodine atoms. T3 (Triiodothyronine) is composed of 3 iodine atoms. You can see that these hormones are made up of mostly iodine! Not having enough iodine on board will inhibit the production thyroid hormones, thus leading to a hypothyroid state. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4049553/

Also of note, for people who do not have a thyroid, getting iodine and other nutrients is still essential! Peripheral organs and tissue convert T4 into T3. This metabolic process uses nutrients to make this conversion happen. Therefore, if you are not intaking the proper nutrients, you can still have low T3 levels even while taking the medication levothyroxine (T4).

Vitamin A – Regulates thyroid hormone production by reducing TSH and increasing T3 production. (Lower TSH is typically indicative of adequate T4 and T3, and high TSH may indicate that something is not right). Vitamin A may help prevent subclinical hypothyroidism. https://pubmed.ncbi.nlm.nih.gov/23378454/#:~:text=Vitamin%20A%20has%20been%20shown,subclinical%20hypothyroidism%20is%20still%20unclear.

Magnesium – Also plays a key role in the secretion of T3. In addition, very low levels of magnesium have been associated with more cases of hypothyroidism, and elevated thyroid antibodies for Hashimoto’s. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6028657/. Magnesium is an imperative nutrient for anyone on a fitness journey.

Zinc – Plays a key role in the metabolism of thyroid hormones. Low levels of zinc correspond to low levels of Free T4 and Free T3. Metabolic rate is also tied to these thyroid hormones, therefore, one study found that supplementing with zinc (in zinc deficient females) increased their metabolic rate. https://pubmed.ncbi.nlm.nih.gov/17541266/

Selenium – Selenium deficiency will impair the enzymes needed to convert T4 to metabolic more active T3. https://pubmed.ncbi.nlm.nih.gov/1384621/#:~:text=Selenium%20deficiency%20impairs%20thyroid%20hormone,’%2D5%20triiodothyronine%20(T3).

Also of note, is that the thyroid contains more selenium than any other tissue! Selenium also aids iodine in the production of thyroid hormones. Selenium deficiency is associated with a host of different thyroid problems including: Hypothyroid, Hashimoto’s autoimmune thyroid, sub-clinical hypothyroid, goiter, thyroid cancer, and Graves’ disease (hyperthyroid).

Tyrosine – Combined with iodine, tyrosine helps the physiological production of thyroid hormones. Tyrosine and iodine form the precursors T1 and T2, which then turn into T3 and T4. Because Tyrosine supplementing with tyrosine provides the direct substrates needed to produce thyroid hormone, it should be used with caution, and is contraindicated for conditions such as Graves’ Disease. https://www.palomahealth.com/supplements/l-tyrosine-hypothyroidism

Please note that you do not need necessarily need to supplement with these products individually. There are thyroid specific supplements that will combine most of these ingredients. Metagenics “Thyrosol” is one such product (cheapest on Full Scripts). Thyrotain, by Othomolecular is another good thyroid product (also on Full Scripts). If you are not sure what nutrients would be best for you, please reach out to me here.