What are the root causes? Functional Medicine sheds light as to why: So many Thyroid Patients continue to experience: weight gain, low energy, brain fog, hair loss, insomnia, depression, brittle nails, and anxiety. Others could include difficulty regulating body temperature, dry skin, and mood swings. Regardless of being on Medication and Being told their labs are normal.
The thyroid is a gland that sits just under the skin in the front part of the neck.1 It is small (only about 2½ inches wide, 2 inches high, and ½ inch think), and shaped like a butterfly. Each “wing” of the butterfly sits on one side of the trachea (the windpipe), and the two wings are joined by a narrow piece of gland (the “isthmus”).
As a gland, the thyroid is part of the endocrine system, which is the body system that produces hormones. It is primarily involved in regulating metabolism and body development, and produces three hormones: T3 (triiodothyronine), T4 (thyroxine), and calcitonin.2
Disorders of the thyroid can result in one of two effects:3,4,5
- Hypothyroidism – an underactive thyroid, with inadequate hormone production, and
- Hyperthyroidism – an overactive thyroid, with excess hormone production.
The prevalence of thyroid disease varies widely by geographic region, but many areas have experienced apparent increases.6 The reasons for this are uncertain, but are likely due to variations in the causes of thyroid dysfunction, such as:
- Inadequate dietary iodine – iodine is required for the thyroid to work properly, and iodine deficiency is one of the leading causes of thyroid disease worldwide.4 In many countries – including the U.S. – this has been overcome, mostly by adding iodine to table salt (“iodized salt”). However, the salt in processed food and salt from “natural” sources do not contain iodine, so people who get their salt from these sources may become deficient,
- Too much iodine – getting too much iodine is also toxic to the thyroid, so people who take supplemental iodine may unknowingly be harming their thyroid,4
- Vitamin D – deficiency in vitamin D has been associated with hypothyroidism, although the mechanism is unclear. Vitamin D deficiency is very common in the U.S., particularly in people who live at higher latitudes and do not get adequate sunlight,4
- Goitrogens – these are vegetables that produce goitrin, which is a natural thyroid toxin that reduces hormone production. Soy, broccoli, cabbage, and cauliflower are examples of goitrogens,4
- Smoking – smoking has been shown to have a significant detrimental effect on thyroid function,7
- Environmental toxins – it appears that environmental toxins are playing a role in increasing thyroid disease in certain areas.8 These include heavy metals, PCBs (polychlorinated biphenyls), brominated flame retardants, perfluorinates, and a long list of other chemicals that have found their way into the environment,8
- Gender – thyroid disease is more prevalent in women,9
- Pregnancy – associated with increased risk of hypothyroidism,8
- Medications – many medications are toxic to the thyroid; lithium and amiodarone are two examples,8
- Gut bacteria – changes in the balance of bacteria in the digestive system can induce thyroid disease,8
- Radiation – external radiation exposure, and medical radiation can be highly toxic to the thyroid,8
- Genetics – genetic susceptibility can play a significant role in the development of thyroid disease for certain individuals. A significant family history may be a red flag,8
- Stress – stress can be a factor in the development of thyroid disease, mostly through the effects of cortisol, the “stress hormone,”10
- Age – thyroid disorders increase with increasing age. In populations with increases in average age, there may be an increase in thyroid disorders,9 and
- Increased testing – apparent increases in thyroid disorders may simply be due to increases in testing, given that many individuals with thyroid disorders do not display any overt symptoms.11,12
Although the increase in incidence in thyroid disorders in some populations is not well understood, and probably varies significantly in different areas, one or more of these factors are likely behind local increases.
- Harvard Medical School. (2021). Thyroid diseases. Harvard Health Publishing.
- Boelaert, K., & Franklyn, J.A. (2005). Thyroid hormone in health and disease. Journal of Endocrinology, 187(1), 1-15.
- Doubleday, A. R., & Sippel, R. S. (2020). Hyperthyroidism. Gland Surgery, 9(1), 124-135.
- Harris, C. (2012). Thyroid disease and diet – nutrition plays a part in maintaining thyroid health. Today’s Dietician, 14(7), 40.
- National Institutes of Health (NIH). (2015). Thinking about your thyroid.
- Flynn, R. W., MacDonald, T. M., Morris, A. D., Jung, R. T., & Leese, G. P. (2004). The thyroid epidemiology, audit, and research study: Thyroid dysfunction in the general population. The Journal of Clinical Endocrinology and Metabolism, 89(8), 3879-3884.
- Kim, S., Kim, M.J., Yoon, S.G., Myong, J., Yu, H., Chai, Y., et al. (2019). Impact of smoking on thyroid gland: Dose-related effect of urinary cotinine levels on thyroid function and thyroid autoimmunity. Scientific Reports, 9, 4213.
- Ferrari, S. M., Fallahi, P., Antonelli, A., & Benvenga, S. (2017). Environmental issues in thyroid diseases. Frontiers in Endocrinology, 8, 50.
- Chaker, L., Bianco, A. C., Jonklaas, J., & Peeters, R. P. (2017). Hypothyroidism. Lancet, 390(10101), 1550-1562.
- Walter, K. N., Corwin, E. J., Ulbrecht, J., Demers, L. M., Bennett, J. M., Whetzel, C. A., et al. (2012). Elevated thyroid stimulating hormone is associated with elevated cortisol in healthy young men and women. Thyroid Research, 5(1), 13.
- Chiovato, L., Magri, F., & Carlé, A. (2019). Hypothyroidism in context: Where we’ve been and where we’re going. Advances in Therapy, 36(Suppl 2), 47-58.
- Vanderpump, M.P.J. (2019) Epidemiology of thyroid disorders. In: M. Luster, L. Duntas, & L. Wartofsky (Eds.) The thyroid and its diseases. Springer. (obtained from library resources)