Managing your thyroid disease

There are a number of lifestyle interventions that are suggested and much-discussed online as being potentially helpful within the management of thyroid disease.

Eliminating gluten

Some practitioners suggest eliminating gluten from the diet as a way of treating autoimmune thyroid disease.

This is because gluten is thought to play an important part in the leaky gut syndrome and also molecular mimicry theory implicated in autoimmune thyroid disease.

These suggestions have generally been derived from weakly powered studies and anecdotal evidence. There is a lack of large scale conclusive evidence to support the elimination of gluten from the diet, however that should not be taken to mean that it will definitely not help.

If you believe that your autoimmune thyroid condition is related to gluten, a carefully monitored ‘gluten challenge’ could be considered under the supervision of a health professional.

Whilst you are still consuming gluten, it is important to first have a blood test to rule out coeliac disease.

Gluten should then be eliminated from the diet for 4 weeks, and then reintroduced. It is important to record your symptoms before, during and after the elimination, to assess how it affects your health.

Eliminating gluten from your diet should be done with caution, as many ‘gluten-free’ products are unhealthy, and as with any elimination diet, there are risks of nutritional deficiencies.

Selenium and the thyroid

Selenium is a chemical (specifically a metal atom) that is required for correct functioning of some of the enzymes involved in the synthesis of thyroid hormones.

These enzymes are known as ‘selenoproteins’ because of their reliance on selenium. This includes the ‘deiodinase’ enzymes that are responsible for converting T4 to the active T3 that we require.

Some practitioners believe that selenium supplementation is necessary or advisable to optimise the function of the thyroid.

There have been 4 primary systematic reviews/meta-analyses of the evidence for and against selenium supplementation. The findings from these have been contradictory.

Two concluded that supplementation can lower levels of TPOAb and therefore was of benefit, you can find them here and here.

A third study found that the ‘…evidence to support or refute the efficacy of selenium supplementation in people with Hashimoto’s thyroiditis is incomplete…’ and stated that the ‘current level of evidence…does not at present allow confident decision making about the use of selenium supplementation for Hashimoto’s thyroiditis.’

The last, and most recent, also concluded that there is no evidence of benefit in terms of TSH levels, health-related quality of life or appearance of the thyroid on ultrasound scanning.

The latter two studies also conclude that more, well-designed trials are needed in order to firmly resolve the debate around selenium.

We can only say with certainty that selenium supplementation would be beneficial in those who are deficient in Selenium, and have adequate iodine intake. It is generally understood that we should not be selenium deficient unless there are extreme abnormalities of intake due to ill-health or malnutrition i.e. dietary intake should be sufficient rather than purchase of supplements.

Furthermore, studies exist that have linked selenium supplementation to high-grade prostate cancer, skin cancer and type 2 diabetes.

Given that the studies mentioned have contradictory conclusions, that supplementation has been associated with other serious diseases long-term and that dietary intake should be adequate in the absence of other disease, we would not recommend selenium supplementation using vitamins purchased over-the-counter.

We think it is reasonable and not harmful to suggest increasing dietary intake of selenium-rich foods to see if this has any effect on symptoms. Selenium-rich foods include:

  • Brazil nuts (in particular)
  • Fish
  • Meat
  • Eggs

RDAs are 0.075mg/day for men (19-64) and 0.06mg/day for women (19-64).

Iodine and the thyroid

Iodine is required for the synthesis of thyroid hormones. The most common cause of hypothyroidism worldwide is dietary insufficiency of iodine, although it is uncommon in the UK.

Some countries have chosen to ‘iodise’ or ‘add iodine to’ their salt as a public health measure. However you should be able to get sufficient levels of iodine from a normal diet alone. Foods that are particularly rich in iodine include:

  • Seafood
  • Dairy products
  • Eggs
  • Bread

The RDA for iodine for adults is 0.14mg per day.

There are certain groups of people who may be at risk of iodine deficiency including pregnant women and vegans (as a result of avoiding animal-derived products).

There is a ‘U-shaped’ association between iodine levels and thyroid dysfunction in the general population i.e. both low and high levels of iodine can be problematic and in different ways.

A large-scale study performed in Denmark found that increased iodine intake caused fewer cases of hyperthyroidism but more cases of autoimmune hypothyroidism.

Given the potential risks of over and under-correction of iodine – it has been likened to a ‘double-edged sword’ – we advise against iodine supplementation. A varied and balanced diet should provide the required amount of iodine.

More information can be found on the NHS choices website.

Iron and the thyroid

Iron, iodine and selenium deficiencies are all interlinked and all are required for correct functioning of the thyroid.

A deficiency in iron, may cause anaemia which can resemble the symptoms of an underactive thyroid. A varied and balanced diet should give sufficient amounts of iron.

There is no conclusive evidence to suggest that iron supplementation is necessary or beneficial in thyroid disease. You could consider iron supplementation if your iron levels are proven to be low but it would be important to exclude other, potentially more serious, causes of iron deficiency first.

Vitamin B12 and the thyroid

Pernicious anaemia is the most common cause of Vitamin B12 deficiency in the UK. It is an autoimmune condition that is more commonly found in people with autoimmune thyroid disease. Vitamin B12 deficiency can resemble the symptoms of an underactive thyroid gland.

Vitamin B12 is required for a number of bodily functions, particularly for the correct functioning of our nervous system. Eating a varied and balanced diet is the best way to protect against B12 deficiency.

Vegans are particularly at risk of B12 deficiency as it is mostly contained within animal-derived products.

If you are proven to be deficient in B12 you may benefit from supplementation but there is no conclusive evidence that B12 supplementation improves thyroid disease or symptoms. It would also be important to exclude other, potentially more serious, causes of B12 deficiency first.


Goitrogens are foods that contribute to the formation of a ‘goitre’. This is the, sometimes visible, swelling of the thyroid gland.

Goitrogens do this by interfering with iodine uptake by the thyroid gland so that it cannot produce thyroid hormones correctly.

Examples of goitrogenic foods include broccoli, cauliflower and kale, the ‘brassica’ or cabbage family of vegetables. Note that cooking these foods reduces their goitrogenic effects so it is unlikely that eating them would cause any real problems.


Soya can interfere with the absorption of thyroxine. There have been concerns that this may result in abnormal thyroid function and/or increase the dose of levothyroxine required by hypothyroid patients to achieve normal thyroid function.

However, a large scale review concluded that the effects of this are likely to be very minor and therefore are not of clinical importance. In practice this means that there is no need to avoid soy-containing foods.

Vitamin D supplementation

Vitamin D deficiency is increasingly implicated as a risk factor for autoimmune disease, in particular multiple sclerosis. There is evidence to suggest that Vitamin D is required for normal functioning of the immune system.

Studies exist that suggest that Vitamin D insufficiency is more commonly found in those with Hashimoto’s when compared with healthy controls. It is unclear whether this relationship is causal i.e. whether low vitamin D contributes to the development of Hashimoto’s in the first place or whether it is the result of already-established thyroid disease.

Furthermore, there is evidence to suggest that ‘Vitamin D supplementation may offer a safe and economical approach to improve thyroid function and may provide protection from developing thyroid disease.’

You could consider Vitamin D supplementation if your levels are shown to be insufficient or deficient.


Zinc is required for the synthesis of thyroid hormones. Conversely, hyper- and hypothyroidism can result in zinc deficiency.

There is no conclusive evidence to suggest that zinc supplementation is necessary or beneficial in thyroid disease.

If you eat a varied and balanced diet your zinc levels should be normal. The RDA for zinc is 9.5mg per day for men and 7mg per day for women.

Good dietary sources of zinc include

  • Meat
  • Shellfish
  • Dairy foods

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Claire is the Inbound and Content Manager here at Thriva. Her mission is break through all the clutter of information that is out there relating to health and bring you informative, easy to digest, actionable insights.