Are you a vegan with a thyroid condition? Read below to find out how the food you eat impacts your autoimmune condition, and what you can do to keep symptoms at bay.
The thyroid gland is a butterfly-shaped endocrine gland found in the neck, below the Adam’s apple. Its main function is to create thyroid hormones, T4 and T3. these hormones are released into the blood and transported through the body, controlling metabolism, converting calories to energy. Each cell in the human body has receptors for thyroid hormones.
The thyroid gland is part of a network called the hypothalamic-pituitary-thyroid axis (HPT axis), including the hypothalamus and the pituitary gland. The pituitary gland reads and responds to the amounts of T4 circulating in the blood, but also responds to the hypothalamus, a section of the brain that releases the hormone thyrotropin-releasing hormone. TRH stimulates thyroid-stimulating hormone release in the pituitary gland that releases thyroid hormone production.
Hyperthyroidism is when the thyroid gland produces too much thyroid hormone; symptoms include weight loss, tiredness and weakness, sensitivity to heat and mood swings. Whereas, hypothyroidism is when the thyroid gland fails to produce enough hormones. Symptoms of hypothyroidism are sensitivity to the cold, weight gain, constipation, muscle cramps and aches and slow movements (NHS, 2017).
There is increasing awareness that a plant-based diet decreases morbidity and mortality within a range of chronic diseases. Veganism does not include consumption of animal meat or dairy products.
Some issues vegan and vegetarian diets may cause for those who have thyroid include exacerbated blood sugars, mainly because of the carbohydrate-heavy diets, nutrient-deficient in vitamin A, vitamin B3, vitamin B9, vitamin B12, vitamin D, calcium, chromium, copper, iodine, iron, magnesium, carnitine, manganese, zinc and omega-3’s. The rich food source of iodine is animal products; non-meat protein sources such as legumes, dairy, grains, soy and nuts may prevent the gut from healing, especially leaky gut, as these foods are found to be reactive and can perpetuate the intestinal permeability.
Many studies indicate those who follow a vegan diet are more likely to develop hypothyroidism, as well as nutritional deficiencies iron the main one. Iron is essential for thyroid hormone production as it converts T4 to T3. Beef, chicken liver and shellfish are all excellent sources of heme iron, a form of iron that is easily absorbed by the body. On the other hand, iron-rich plant foods, e.g.spinach, contain the non-heme form of iron, which is less readily absorbed and utilized by the body. Many vegans find it hard to absorb the required amount of iron from plant foods, putting them at greater risk for thyroid disease. A study looked at the effect of low iron in young women and found participants with lower iron levels had higher amounts of T3/T4 suggesting an impairment in thyroid metabolism.
Cruciferous vegetables like kale, broccoli, cauliflower and bok choy may affect thyroid of getting enough iodine. The presence of thiocyanates in this food group can affect iodine consumption. Eating too much of these vegetables could be a problem for people who don’t get enough dietary iodine and too little selenium since a lack of both of these minerals can increase the risk of hypothyroidism.
If you have hypothyroidism or family history, you can minimise the risk of developing this condition by mixing up your choice of vegetables so you aren’t eating a lot of the same vegetables every day, cooking your vegetables and chewing them thoroughly which helps to break down some of the active substances. Additionally, cooking methods can also impact the nutritional intake; lightly steaming these vegetables can deactivate the thiocyanates. The amount of broccoli, cabbage and kale in our usual diets is considered of minimal risk, a study concluded there was no adverse effect on thyroid function from consuming cooked Brussel sprouts every day for four weeks.
Some experts claim eating these cruciferous vegetables could be beneficial if you have an autoimmune hypothyroidism as the thiocyanates may slow the absorption of iodine for those getting too much, possible if you are eating a typical Western diet of fast foods, and other processed products, that contain iodised salt, or you are heavy-handed with the salt shaker.
The isoflavones in soy-based products (e.g.tofu, soy protein, tempeh and edamame) inhibit thyroid peroxidase (TPO), an enzyme involved in the production of thyroid hormones.TPO is often tested when an autoimmune condition such as Hashimoto’s. Consuming too many soy-based products may lead to a depleted thyroid hormone level.
Eliminating whole food groups or specific food groups (soy, gluten or cruciferous vegetables) is not the answer to thyroid health. Due to the lack of strong scientific data supporting ‘fad diets’ being beneficial for thyroid, those with the condition should try and eat a well-rounded, balanced diet and avoid any unnecessary dietary restrictions. Having said that, it is crucial that you are not having too much iodine as well as not being deficient; 150 mcg of iodine is recommended for those with dietary restrictions, such as vegans.
In effect, there is no specific diet or single vitamin/mineral supplement that has been proven to eliminate or ‘cure’ thyroid.
If you would like more guidance of the right diet to meet your individual needs, consider working with a registered Nutritionist or Functional Medicine Practitioner who can guide you with the right foods to maintain your condition and keep symptoms at minimal.
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Tonstad S, Nathan E, Oda K, Fraser G. Vegan diets and hypothyroidism. Nutrients. 2013;5:4642-4652.