Improving thyroid health with a plant-based diet

The thyroid gland is a butterfly shaped organ in the neck which plays a major role in many processes of the body, especially helping to maintain body temperature and balancing metabolism. Dysfunction of the main thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine), can affect overall health.

According to NICE (National Institute for Health and Care Excellence), low functioning thyroid (hypothyroidism) and over active thyroid (hyperthyroidism) affects 1-2 per cent of the UK population, with women being 10 times more prone as compared to men¹.

Hashimoto’s thyroiditis remains the commonest type of hypothyroidism. This is an autoimmune condition where the body’s own defence system reduces the production of T3 and T4.

Hyperthyroidism on the other side, is also an autoimmune condition where the autoantibodies (antibodies made against substances formed by a person’s own body) cause over production of the thyroid hormones.

There are no studies specifically related to thyroid disorders and a whole food plant-based diet, yet research ² does show that it can be beneficial for reducing the risk for autoimmune diseases, which, as discussed above, the majority of the thyroid disorders are.

This is not surprising considering that a whole food, plant-based diet is anti-inflammatory³, high in antioxidants, rich in fibre and low in toxins.

The thyroid and the gut

A small study ⁴ has shown there may be a positive effect on thyroid homeostasis when the gut microbiome is supported with the use of prebiotics and probiotics. Prebiotics are a form of fibre that feed the healthy bacteria in the gut.

Some healthy prebiotics foods include chicory, artichokes, leeks, onions, garlic, asparagus, bananas and barley.

Probiotics on the other hand, are live bacteria and yeast found in certain foods, which support the friendly gut bacteria. These could be added to the meal plan in the form of fermented foods like kimchi, sauerkraut and sourdough bread.

While larger studies would be needed to confirm this, I feel adding a variety of colourful wholefood plants, including fruits, vegetables, herbs and spices will certainly be beneficial for thyroid health.

Iodine deficiency and thyroid disorders

The most common cause for thyroid disorders globally is iodine deficiency⁵. Hence it is important to have enough iodine in the diet to maintain healthy levels. However, taking too much iodine can be harmful too, which is why one needs to be specifically mindful about this micronutrient.

Plant-based dietary sources of iodine include fortified plant-based milks, iodised salt or seaweed. I normally advise having nori sheets, which are easily available and each sheet roughly contains 35-40mcg of iodine.

If this is not possible, 150mcg of iodine as a supplement would be sufficient. Women who are pregnant or breastfeeding would need a higher dose.

People often worry about adding cruciferous vegetables or soya to their diet when they have thyroid disorders. Nonetheless, research shows that as long as dietary iodine levels are maintained there is no harm in adding these extremely nutrient dense food items to regular meals.

How toxins impact thyroid health

Toxins also seem to be the leading cause of poor thyroid health⁶. They can be found in processed food, water, food packaging, personal care products as well as plastic ware.

These toxins behave as endocrine disrupting chemicals that affect the proper functioning of the thyroid hormones, by interfering with various pathways of its production and transport.

It would be very hard to eliminate or avoid all these toxins all the time, however reducing processed food and aiming to have organic produce where possible can reduce the overall toxic load on the body.

Supporting the body to eliminate the toxins becomes vital for thyroid health. This is again an area where a wholefood plant-based diet rich in wholegrains, fruits, vegetables, legumes and beans can be extremely beneficial.

Being so rich in fibre, it makes removal of toxins easier by supporting the detoxification process in the liver. Other ways to support removal of toxins from the body include drinking plenty of water every day and incorporating regular aerobic exercise.

Lifestyle factors that impact our thyroid health

Reducing your alcohol intake is important, as it has been associated with disruption of thyroid hormone pathways⁷, while smoking increases the exposure of cadmium, which too acts as a thyroid hormone disruptor.

The role of stress and sleep in autoimmune conditions ⁸ is becoming more evident. This is important when it comes to thyroid health too. In fact, in a small randomised control trial ⁹ it was seen that an eight-week program of stress management led to a reduction in the autoantibodies in women with Hashimoto’s thyroiditis.

It is very difficult to discuss this complex topic in one small article, however my aim has been to share how a whole food, plant-based diet and lifestyle changes can support thyroid health, whether it is low functioning or overactive thyroid.

Essential nutrients for thyroid health

As well as iodine and prebiotic and probiotic foods, make sure your diet includes plenty of these nutrients

Iron

Iron is vital for production of thyroid hormone. I commonly see women of reproductive age who are iron deficient. Hence this is one of the nutrients I focus on regularly when discussing a plant-based diet and thyroid disorders.

Plant-based sources of iron include seeds, nuts, legumes, beans, wholegrains and dried fruit like figs and dates. Green vegetables and dark chocolate can be good sources too. Pairing these with vitamin C rich fruits and vegetables will enhance the absorption of iron further.

Omega-3

Omega-3 inhibits pro-inflammatory chemicals called cytokines. These fatty acids have anti-inflammatory properties that may help reduce inflammation in thyroid gland disorders. Omega-3 is especially important during pregnancy, post-delivery and for women with recurrent miscarriages (increased risk with hypothyroidism).

Good plant-based sources that I tend to use are linseeds (flaxseed), chia seeds and walnuts.

Selenium

Selenium is vital for normal functioning of the thyroid gland. Maintaining physiological levels with a balanced diet is required not only for preventing thyroid related diseases, but for overall wellbeing. Good dietary sources would include Brazil nuts, green and brown lentils, mushrooms, brown rice and cashew nuts.

Zinc

Zinc is a micronutrient that is also important for production of the thyroid hormone. Sprouted and fermented lentils, legumes as well as beans are rich sources of zinc. Adding garlic to zinc rich food can improve its absorption and enhance the flavour too.

It’s the plant milk taking the world by storm, but is oat milk good for you? 

Featured image credit: mixetto via Getty Images

References

1. NICE (2019) Thyroid disease: assessment and management [online] Available at: www.nice.org.uk/guidance/ng145/chapter/Context [accessed 1 March 2023]
2. Tonstad S, Nathan E, Oda K, Fraser G. (2013) Vegan diets and hypothyroidism. Nutrients. Nov 20;5(11):4642-52.
3. Barbaresko J, Koch M, Schulze MB, Nothlings U. (2013) Dietary pattern analysis and biomarkers of low-grade inflammation: a systematic literature review. Nutr. Rev. 2013;71:511–527.
4. Knezevic J, Starchl C, Tmava Berisha A, Amrein K. (2020) Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function? Nutrients. Jun 12;12(6):1769.
5. Zimmermann MB, Boelaert K. (2015) Iodine deficiency and thyroid disorders. Lancet Diabetes Endocrinol. Apr;3(4):286-95. doi: 10.1016/S2213-8587(14)70225-6. Epub 2015 Jan 13.
6. Rezaei M, Javadmoosavi SY, Mansouri B, Azadi NA, Mehrpour O, Nakhaee S. (2019) Thyroid dysfunction: how concentration of toxic and essential elements contribute to risk of hypothyroidism, hyperthyroidism, and thyroid cancer. Environ Sci Pollut Res Int. Dec;26(35):35787-35796.
7. Hernandez A. (2019) Thyroid Hormone and Alcoholic Fatty Liver: The Developmental Input. Alcohol Clin Exp Res. Sep;43(9):1834-1837.
8. Stojanovich L, Marisavljevich D. (2008) Stress as a trigger of autoimmune disease. Autoimmun Rev. Jan;7(3):209-13.
9. Markomanolaki ZS, Tigani X, Siamatras T, Bacopoulou F, Tsartsalis A, Artemiadis A, Megalooikonomou V, Vlachakis D, Chrousos GP, Darviri C. (2019) Stress Management in Women with Hashimoto’s thyroiditis: A Randomized Controlled Trial. J Mol Biochem. 2019;8(1):3-12.