Although there is no specific diet for an underactive thyroid, the condition may be made more manageable by implementing the correct diet. Claims have been made that eating specific foods can improve the function of the thyroid in individuals with an underactive thyroid, but there is, as yet, no scientific evidence to prove this.

However, by ensuring you are eating the right amounts of specific nutrients and eating a healthy, balanced diet can make the symptoms of hypothyroidism controllable.

Can diet changes improve an underactive thyroid?

Diet, and indeed lifestyle, is implicated in nearly all aspects of our health, in one way or another. Hypothyroidism, or an underactive thyroid, is the most common thyroid condition. Even though it can be caused by an autoimmune condition known as Hashimoto’s disease, it can result from an iodine deficiency. Iodine status can be a key determinant in the development of thyroid disorders, particularly hypothyroidism.

When caused by an autoimmune condition, the body, by mistake, identifies its own tissues as an invader just like it does bacteria and viruses. Therefore, the body’s immune system attacks its own tissues. In the case of the thyroid, the chronic attack by the body on itself prevents it from releasing the required levels of hormones T3 and T4. Without adequate levels of these hormones, the body is unable to function appropriately, leading to symptoms such as weight gain, difficulty concentrating, dry skin and hair, as well as fatigue.

Diet changes are responsible for affecting the thyroid gland. However, it’s not just a deficiency which can cause problems. Both deficiency and excess of certain nutrients can trigger symptoms or make them worse.

What to eat for an underactive thyroid?

Knowing what to eat if you have an underactive thyroid can be a challenge, especially as there is so much conflicting evidence available.

Foods to avoid

Goitrogenic foods

Goitrogenic foods are foods which can disrupt the function of the thyroid, altering the production of thyroid hormones through the interference of iodine uptake in the thyroid gland. Goitrogenic foods stop the thyroid from using available iodine. Goitrogenic foods include:

  • Brussels sprouts
  • Turnips
  • Cauliflower
  • Cabbage
  • Kale
  • Almonds
  • Peanuts
  • Walnuts
  • Soya
  • Sweetcorn


If you have been diagnosed with hypothyroidism and are receiving treatment for it, you should avoid eating foods which are high in iodine. If you have an underactive thyroid and you eat a diet high in iodine then you risk making the condition worse.

Adults need 150 micrograms of iodine per day, but this should be able to be achieved by eating a healthy, balanced diet. If you are taking a thyroid hormone supplement such as levothyroxine then there is no requirement for supplementing your iodine intake as it will do your body no good.


Calcium is required for strong, healthy bones amongst other functions within the human body. However, calcium and its supplements can interfere with the absorption of levothyroxine. Therefore, you should have a gap of at least 4 hours before or after taking your medication and consuming calcium to avoid impacting your thyroxine levels.

You may also wish to consider weight gain here, too. Most of our calcium intake comes from dairy products and if you are trying to lose weight, you should choose lower fat options. However, these will still contain high amounts of calcium and you should bear this in mind when taking your medication.

The best diet for hypothyroidism

Eating a healthy, balanced diet is key if you have an underactive thyroid. Many people experience weight gain because of hypothyroidism, which is associated with its own risks including cardiovascular disease and diabetes.

Emphasis should be placed on eating:

  • Lean meat and proteins
  • Fruit
  • Vegetables
  • Omega 3 fatty acids

Increasing your fibre intake is paramount for preventing constipation and aiding the function of your digestive system. You should also make sure you are eating appropriate portion sizes, particularly if you want to avoid more weight gain or even induce weight loss.

If you are taking thyroid medication, it is best to avoid coffee or fibre supplements for at least an hour before and after taking your medication. This is because these foods can reduce the absorption of thyroid medication.

In the past, there has been speculation about whether a vegan or vegetarian may increase the risk of hypothyroidism. Mainly due to a vegan diet lacking iodine because no animal products are consumed. However, research has shown that neither vegan nor vegetarian diets increase the risk of developing an underactive thyroid.

There is no specific diet you should follow if you have an underactive thyroid, but there are some foods you should avoid or at least take into consideration when administering your medication to avoid any unwanted side effects. Eating a normal, healthy and balanced diet should be enough to help control your symptoms and help you to lead a normal, healthy life.




Benvenga S et al. (2008). Altered Intestinal Absorption of L-Thyroxine Caused By Coffee. Thyroid:18(3), 293-301.

Tonstad, S et al. (2013). Vegan Diets and Hypothyroidism. Nutrients: 5(11), pp 4642-4652.

Vanderpump, M, P, J. (2011). The Epidemiology of Thyroid Disease. British Medical Bulletin: 99(1), pp 39-51.

Zimmerman, M, B and Boelaert, K. (2015). Iodine Deficiency and Thyroid Disorders. The Lancet Diabetes and Endocrinology: 3(4), pp 286-295.