Key Points Summary
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Thyroid and Metabolism: The thyroid regulates metabolism via T4 and T3 hormones, essential for energy (ATP) production.
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Underactive Thyroid Signs: Weight gain, brain fog, cold extremities, constipation, high cholesterol, muscle aches, heavy periods, or enlarged thyroid gland.
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Nutrients for Thyroid Function: Iodine, selenium, tyrosine, vitamins A, B, C, zinc, and NAC support the production and conversion of thyroid hormones, and overall thyroid health.
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Digestion and Detoxification: Disrupted gut lining, poor digestion, and toxins (like fluoride) may hinder iodine absorption and thyroid hormone production.
Thyroid disorders affect one in twenty people in the UK – could you be one of them?1
The thyroid gland is small, but mighty. It regulates how quickly our mitochondria produce adenosine triphosphate (ATP), the ‘energy currency’ of our body, and in doing so, underpins metabolism and the health of every body system.2 Its key tools are thyroid hormones that communicate with our body cells - thyroxine (T4) which can be converted to the more active triiodothyronine (T3).
What is Hypothyroidism?
If the thyroid functions too slowly, as in hypothyroidism, there is too little fuel to feed the fire and metabolism becomes sluggish.
What is Hyperthyroidism?
If the thyroid functions too efficiently, as in hyperthyroidism, there is too much fuel to feed the fire, and metabolism starts to work too fast.
As hypothyroidism is much more common, this is what we will focus on in this article.
Key symptoms of underactive thyroid
- Weight is easy to gain and hard to lose
- Brain ‘fog’ and poor concentration
- Cold extremities and temperature sensitivity
- Constipation
- Fatigue and low energy levels
- High cholesterol
- Achy muscles
- Heavy periods
- Goitre (enlarged thyroid gland)
Which nutrients support healthy thyroid function?
The starting point to natural thyroid support is provision of the nutrients it needs to function. Iodine and tyrosine make T4, supported by iron, selenium, and vitamin A, B2, B3, B6, and C. Selenium, zinc, and copper are needed to convert it to T3.3,4 Depletion of these nutrients is common, particularly iodine5 from low seafood intake, and selenium from soils becoming mineral deprived.6 N-acetyl cysteine (NAC) is also an important amino acid. It combines with selenium to form selenocysteine, a key thyroid antioxidant,7 and supports production of glutathione peroxidase.
However, you can take the best thyroid supplement and pack your diet full of these essential nutrients, but if you have compromised digestion, detoxification, and blood sugar management, autoimmunity, and chronic stress, you will probably experience frustratingly slow progress.
Digestion
Compromised digestion can be an underlying factor, especially of autoimmune thyroid disease such as Hashimoto’s Thyroiditis, due to the association with increased intestinal permeability (‘Leaky Gut’).8 This is often mediated by gluten,9 imbalanced gut bacteria,10 and stress,11 which drives autoimmunity, especially if an individual is genetically susceptible.12 If food is also poorly digested, say from eating on the go, and moves through the gut too fast due to diarrhoea, nutrient absorption becomes harder. So, even if you manage to consume sufficient thyroid-supportive nutrients, how much of that are you actually absorbing?
Immunity
Low vitamin D is a mediator of autoimmunity13 which can arise from low sunlight exposure14 and being a carrier of variants of the vitamin D receptor gene, VDR.15 Meanwhile, chronic inflammation driven by intestinal permeability and autoimmunity, and other factors like processed food16and poor sleep,17 may suppress thyroid activity.
Energy and Nervous System
Disrupted blood sugar due to a high sugar diet and high stress often accompany thyroid dysfunction. Cortisol is produced by our adrenal glands in times of stress. When produced excessively, it may suppress the release of Thyroid Stimulating Hormone from the pituitary.18 It also forces T4 to be converted to ‘reverse T3’ (rT3) which actually blocks thyroid function, even though thyroxine levels look adequate when tested.19 Blood glucose imbalance also triggers cortisol secretion, and insulin resistance may have a direct negative effect on the thyroid, too.20
Feeling Stressed?
Read our best lifestyle and diet tips to reduce feelings of stress and promote calm.
Detoxification
‘Halide’ molecules, such as fluoride from tap-water,21 are similar to iodine and can prevent uptake of iodine into the thyroid. Other toxins like heavy metals, such as mercury from dental fillings, can impair conversion of T4 to T3.22 High exposure to these toxins, coupled with impaired detoxification due to poor diet, nutrient depletion from chronic stress, and genetic factors, may give them the opportunity to disrupt thyroid function.
How to support the thyroid
The health of the body regulates the health of the thyroid. This is the ‘golden nugget’ which can help individuals with a thyroid disorder to achieve the lasting balance which they deserve. In practice, this involves provision of thyroid-supportive nutrients, especially:
- Iodine
- Tyrosine
- Selenium
- N-acetyl cysteine
- Vitamin A
- Vitamin C
- Zinc.
Also consider support for digestion (e.g. probiotics), immunity (e.g. vitamin D3,)23 a balanced nervous system (e.g. magnesium),24 blood sugar management (e.g. chromium)25, and detoxification (e.g. glutathione),26 as well as mitochondrial function (e.g. D-ribose). 27
Looking after yourself and focusing on some key nutrients really can help you to keep both body and thyroid in good health.
References
1. What we do. Accessed March 10, 2025. https://www.btf-thyroid.org/whatwedo
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8. Fasano A. Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer. Physiol Rev. 2011;91(1):151-175. doi:10.1152/PHYSREV.00003.2008
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13. Décard BF, Von Ahsen N, Grunwald T, et al. Low vitamin D and elevated immunoreactivity against Epstein-Barr virus before first clinical manifestation of multiple sclerosis. J Neurol Neurosurg Psychiatry. 2012;83(12):1170-1173. doi:10.1136/JNNP-2012-303068
14. Simpson S, Blizzard L, Otahal P, Van Der Mei I, Taylor B. Latitude is significantly associated with the prevalence of multiple sclerosis: a meta-analysis. J Neurol Neurosurg Psychiatry. 2011;82(10):1132-1141. doi:10.1136/JNNP.2011.240432
15. Agliardi C, Guerini FR, Saresella M, et al. Vitamin D receptor (VDR) gene SNPs influence VDR expression and modulate protection from multiple sclerosis in HLA-DRB1*15-positive individuals. Brain Behav Immun. 2011;25(7):1460-1467. doi:10.1016/J.BBI.2011.05.015
16. Shi H, Kokoeva M V., Inouye K, Tzameli I, Yin H, Flier JS. TLR4 links innate immunity and fatty acid-induced insulin resistance. J Clin Invest. 2006;116(11):3015-3025. doi:10.1172/JCI28898
17. Carnethon MR, De Chavez PJD, Lauderdale DS, Carson AP, Liu K, Knutson KL. Abstract MP90: Association of Sleep Duration and Quality with Incident Diabetes: Coronary Artery Risk Development in Young Adults Sleep Study. Circulation. 2013;127(suppl_12). doi:10.1161/CIRC.127.SUPPL_12.AMP90
18. Benker G, Raida M, Olbricht T, Wagner R, Reinhardt W, Reinwein D. TSH secretion in Cushing’s syndrome: relation to glucocorticoid excess, diabetes, goitre, and the “sick euthyroid syndrome.” Clin Endocrinol (Oxf). 1990;33(6):777-786. doi:10.1111/J.1365-2265.1990.TB03915.X
19. Mancini A, Di Segni C, Raimondo S, et al. Thyroid Hormones, Oxidative Stress, and Inflammation. Mediators Inflamm. 2016;2016. doi:10.1155/2016/6757154
20. Tang Y, Yan T, Wang G, et al. Correlation between Insulin Resistance and Thyroid Nodule in Type 2 Diabetes Mellitus. Int J Endocrinol. 2017;2017. doi:10.1155/2017/1617458
21. Peckham S, Lowery D, Spencer S. Are fluoride levels in drinking water associated with hypothyroidism prevalence in England? A large observational study of GP practice data and fluoride levels in drinking water. J Epidemiol Community Health (1978). 2015;69(7):619-624. doi:10.1136/JECH-2014-204971
22. Chen A, Kim SS, Chung E, Dietrich KN. Thyroid hormones in relation to lead, mercury, and cadmium exposure in the National Health and Nutrition Examination Survey, 2007-2008. Environ Health Perspect. 2013;121(2):181-186. doi:10.1289/EHP.1205239
23. Antico A, Tampoia M, Tozzoli R, Bizzaro N. Can supplementation with vitamin D reduce the risk or modify the course of autoimmune diseases? A systematic review of the literature. Autoimmun Rev. 2012;12(2):127-136. doi:10.1016/J.AUTREV.2012.07.007
24. Abbasi B, Kimiagar M, Sadeghniiat K, Shirazi MM, Hedayati M, Rashidkhani B. The effect of magnesium supplementation on primary insomnia in elderly: A double-blind placebo-controlled clinical trial. J Res Med Sci. 2012;17(12):1161. Accessed March 13, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC3703169/
25. Martin J, Wang ZQ, Zhang XH, et al. Chromium picolinate supplementation attenuates body weight gain and increases insulin sensitivity in subjects with type 2 diabetes. Diabetes Care. 2006;29(8):1826-1832. doi:10.2337/DC06-0254
26. Atkuri KR, Mantovani JJ, Herzenberg LA, Herzenberg LA. N-Acetylcysteine--a safe antidote for cysteine/glutathione deficiency. Curr Opin Pharmacol. 2007;7(4):355-359. doi:10.1016/J.COPH.2007.04.005
27. Teitelbaum JE, Johnson C, St. Cyr J. The use of D-ribose in chronic fatigue syndrome and fibromyalgia: a pilot study. J Altern Complement Med. 2006;12(9):857-862. doi:10.1089/ACM.2006.12.857