Constant tiredness, feeling cold when everyone else is comfortable, hair falling out, constipation and an unexplained rise on the scales… Many people who go to the doctor with these complaints learn that their thyroid gland is underactive. After the diagnosis, the first questions are almost always the same: “What should I eat, what should I cut out, do I have to give up gluten, can I use iodised salt?”
A good deal of what circulates online about nutrition in thyroid conditions is either exaggerated or wrong. On this page you will find what nutrition can really change in hypothyroidism, Hashimoto’s thyroiditis and hyperthyroidism, which nutrients matter, what affects the absorption of thyroid medication and how weight management should be approached.
What does the thyroid gland do?
The thyroid is a small butterfly-shaped gland at the front of the neck. The hormones it secretes set the body’s working pace: energy expenditure, body temperature, heart rhythm, bowel movement and the renewal of skin and hair all depend on them. When the thyroid is underactive everything slows down; when it is overactive everything speeds up. This is why the symptoms of thyroid conditions are felt throughout the body.
The difference between hypothyroidism, Hashimoto’s and hyperthyroidism
Hypothyroidism (underactive thyroid)
Too little thyroid hormone is produced. Tiredness, feeling cold, constipation, dry skin, hair loss, irregular periods, forgetfulness and mild weight gain are the most common symptoms. Treatment consists of replacing the missing hormone with medication.
Hashimoto’s thyroiditis
This is an autoimmune disease in which the immune system targets the thyroid gland, and it is one of the most common causes of hypothyroidism. It is recognised by raised thyroid antibodies in the blood. The disease progresses slowly over years; in some people thyroid hormones stay normal for a long time.
Hyperthyroidism (overactive thyroid)
More thyroid hormone is produced than needed. Palpitations, sweating, trembling hands, irritability, sleeplessness, frequent bowel movements and weight loss despite increased appetite are seen. One of its most common causes is Graves’ disease, which is also autoimmune.
In all of these conditions, the diagnosis, medication and dose adjustment are the responsibility of an endocrinologist or internal medicine specialist.
Does nutrition treat thyroid disease?
It is necessary to be frank: no diet, food or herbal mixture takes the place of thyroid medication or makes Hashimoto’s disappear. Promises of a “diet that heals the thyroid” do not reflect reality and can have serious consequences when they lead people to stop their medicine.
Nutrition does, however, make a real difference in these areas: proper absorption of your medication, adequate intake of the nutrients the thyroid needs, preserving weight and muscle mass, easing complaints such as constipation and tiredness, and managing conditions that often accompany thyroid disease, such as insulin resistance, high cholesterol and anaemia.
Important nutrients for thyroid health
Iodine
Iodine is a building block of thyroid hormone; a lack of it leads to goitre and hypothyroidism. But too much is also harmful and can make things worse, particularly in people with Hashimoto’s. Moderate use of iodised salt in everyday cooking is enough for most people. Seaweed tablets and high-iodine supplements sold as “thyroid support” should not be used unless a doctor recommends them. Decide whether or not to stop using iodised salt with your doctor, not on your own.
Selenium
Selenium is part of the enzymes that convert thyroid hormone into its active form. Fish and seafood, eggs, meat and nuts are good sources. Because Brazil nuts are a very concentrated source of selenium, they should not be eaten by the handful. Not everyone needs a selenium supplement; too much can cause problems such as hair loss and damaged nails.
Iron, zinc, vitamin D and B12
Iron and zinc deficiency can impair the production and use of thyroid hormones; they also increase tiredness and hair loss. B12 and vitamin D deficiency are more common in people with Hashimoto’s. When tiredness continues although thyroid values have improved, one of these deficiencies is often behind it. Your doctor decides which values to check; if a deficiency is found, diet and, where needed, supplementation are planned.
Protein
Adequate protein is needed both to carry thyroid hormones in the blood and to preserve muscle mass. Because metabolism slows in hypothyroidism, preventing muscle loss is especially important.
Thyroid medication and nutrition: what affects absorption?
Thyroid hormone medication is easily affected by food and drink. In people whose values will not settle, the problem is often not the dose but the way the medicine is taken. The general points to watch are:
- On an empty stomach, with water: The medicine is usually taken in the morning on an empty stomach with water only, and you wait before breakfast for as long as your doctor advises.
- Coffee and tea: Coffee drunk straight after the medicine can reduce absorption. Morning coffee should be left until the end of the waiting period.
- Calcium, iron and magnesium: Supplements and stomach medicines containing these minerals bind thyroid medication. Several hours should be left between them.
- Soya and very high-fibre meals: When eaten close to the time of the medicine they can lower absorption.
- Routine: Taking the medicine in the same way every day is at least as important as these rules themselves.
What applies to when and how you take your medicine is the instruction your doctor has given you. Be sure to tell your doctor and dietitian about any supplements you use.
Are cabbage, broccoli and soya bad for the thyroid?
Vegetables such as cabbage, broccoli, cauliflower, Brussels sprouts, radish and rocket contain compounds called goitrogens. Taken raw in very large amounts, and when iodine is also lacking, these compounds can make it harder for the thyroid to use iodine. However, vegetables eaten in normal portions, and especially when cooked, are not a problem for people with thyroid conditions. Removing them from the table means giving up, for no good reason, a food group rich in fibre and antioxidants. What needs care is large daily amounts of vegetable juice containing raw cabbage or kale.
Soya products are also not a problem in moderation; they simply should not be taken at the same time as the medicine.
Do you need to cut out gluten with Hashimoto’s?
This is one of the most frequently asked questions. What is known is this: coeliac disease is more common in people with Hashimoto’s than in the general population. For this reason, if there are complaints such as bloating, diarrhoea, iron deficiency or unexplained weight loss, the doctor may request coeliac screening. If coeliac disease is found, a gluten-free diet is essential.
In people with Hashimoto’s who do not have coeliac disease, there is not enough evidence to justify recommending a gluten-free diet to everyone. Some people do feel better when they give up gluten; this usually has to do with eating fewer pastries and packaged products. If you want to try it, have your coeliac tests done first, and then run the process in the spirit of an elimination diet, for a limited time and under supervision.
Weight management in hypothyroidism
When the thyroid is underactive, metabolism slows and the body retains water; but the weight gain due to hypothyroidism is usually not as large as people think, and part of it comes from fluid. Once hormones return to normal with medication, losing weight is as possible as it is for someone without thyroid disease.
If weight is not coming off although thyroid values are normal, the cause needs to be sought elsewhere: sleep, movement, meal pattern, insulin resistance or the muscle loss created by years of restrictive dieting. Very low calorie diets can lower the active form of thyroid hormones and slow metabolism even further; this is why the “eat less, lose fast” approach backfires especially in hypothyroidism. For details, see the weight management page.
Nutrition in hyperthyroidism
While the thyroid is overactive, energy expenditure increases; if not enough is eaten, both fat and muscle are lost. During treatment it is important that energy and protein intake are adequate and that sources of calcium and vitamin D are included for bone health. Coffee, strong tea and energy drinks are limited because they can increase palpitations and tremor. The doctor’s advice is followed regarding supplements and foods high in iodine; a short period of low-iodine eating may be requested before some treatments.
Common nutrition mistakes made by people with thyroid conditions
- Taking the medicine with breakfast or with coffee: This lowers absorption and causes values to fluctuate.
- Using seaweed, kelp or high-iodine supplements: Far from supporting the thyroid, they can disturb its function.
- Giving up vegetables for fear of goitrogens: Cooked vegetables in normal portions are not a problem.
- Cutting out gluten without being tested: This makes a possible coeliac diagnosis harder.
- Going on a very low calorie diet: This increases tiredness, hair loss and muscle loss.
- Stopping the medicine or changing the dose when you feel well: Decisions about medication belong to the doctor alone.
When should you see a doctor?
See a doctor if you have swelling or a lump in the neck, difficulty swallowing, hoarseness, an unexplained change in weight, palpitations, marked tiredness and feeling cold, or, on the contrary, excessive sweating and tremor. Women taking thyroid medication should inform their doctor without delay when they plan a pregnancy or learn that they are pregnant; the need for medication changes in pregnancy.
Frequently asked questions
Should people with thyroid conditions use iodised salt?
For most people, a moderate amount of iodised salt is appropriate. Unless your doctor has recommended a specific restriction, you do not need to stop using it. What really should be avoided are supplements containing high doses of iodine.
How long after my thyroid medicine can I drink coffee?
Because coffee can reduce absorption of the medicine, it should not be drunk before the waiting period is over. Your doctor decides how long that period should be; having your coffee with breakfast is a practical solution.
Does Hashimoto’s go away with diet?
No. Hashimoto’s is an autoimmune disease and does not disappear with diet. Balanced nutrition helps to ease complaints, correct deficiencies and protect general health.
My thyroid values are normal but I cannot lose weight. Why?
If the values are normal, the reason for not losing weight is most probably not the thyroid. Meal pattern, sleep, movement, insulin resistance and past restrictive diets should be assessed together.
Should I take a selenium supplement?
Selenium needs are usually met through diet. A supplement should be used only when your doctor considers it necessary and for the period recommended; too much is harmful.
