Nutrients for the Thyroid: Iodine & Selenium

Weighing just 20 grams and shaped like a butterfly at the front of the neck, it nonetheless sets the pace for countless metabolic processes throughout the body: the thyroid gland. When it comes to its nutrients, almost every question revolves around two trace elements: iodine and selenium. An important note upfront: with thyroid topics and any suspicion of an overactive or underactive thyroid, the rule is always the same – have it checked by a doctor. Iodine cures taken on your own initiative are expressly not advisable.

The direct answer: Iodine contributes to a normal production of thyroid hormones and to normal thyroid function. Selenium contributes to normal thyroid function. The thyroid needs both to do its work – but in an amount that matches its needs, not in the highest possible dose.

What the thyroid does

The thyroid produces the hormones thyroxine (T4) and triiodothyronine (T3). Among other things, these help regulate energy metabolism, body temperature and many further processes. The decisive point: to produce these hormones, the thyroid absolutely needs iodine – the numbers in T3 and T4 even indicate how many iodine atoms each hormone contains. No iodine, no thyroid hormone – the connection really is that simple.

Selenium, in turn, is a component of certain enzymes that play a role in thyroid metabolism – among other things in hormone conversion and in cell protection. You can picture the thyroid as a small control centre that, through its hormones, helps set the pace of many processes. The control itself runs via the pituitary gland, which uses the hormone TSH to signal whether to produce more or fewer thyroid hormones. Iodine and selenium provide the basis that allows the thyroid to work at all – but they do not intervene in this regulation. That is precisely why they should be understood as supportive, not as a substitute for medical treatment.

Iodine and selenium – the approved statements

For both trace elements there are officially approved statements that reach beyond the thyroid:

You will find more in-depth information in the guides Iodine: Effects, Requirements & Thyroid and Selenium: Effects, Daily Requirement & Form. In short: iodine supplies the immediate building material for the hormones, while selenium, as an enzyme component, is involved in thyroid metabolism. Beyond that, both have further tasks in the body – a good example of how trace elements rarely fulfil just a single function. For an overall overview, see Minerals & Trace Elements at a Glance.

Iodine supply in Germany

Germany is one of the regions with naturally low iodine content in soils and foods – historically our country is a classic iodine-deficiency area. Important iodine sources are iodised table salt, sea fish, seafood and dairy products. People who eat a vegan diet or little fish more often have a tighter intake. At the same time, the rule is: too much iodine is undesirable as well – high-dose iodine supplements without medical advice are therefore not recommended. Signs of an inadequate supply are described in Iodine Deficiency: Signs.

Good sources of iodine and selenium

A note on algae products: some sea algae contain a great deal of iodine, sometimes in strongly fluctuating amounts. Caution is advised here, so as not to take in too much unintentionally. If you live vegan, you will find further guidance in Nutrients for Vegans. With selenium, Brazil nuts deserve a special mention: they are among the most selenium-rich foods of all – just a few a day can contribute a great deal, and usually no more is needed. How much makes sense is put into context in Selenium: how much per day?, and signs of a tight supply are described in Selenium Deficiency: Signs. For both, the rule applies: matching your needs is the goal, not as high as possible.

What research is investigating

Well-established textbook knowledge is the indispensable role of iodine as a building block of thyroid hormones and the function of selenium-dependent enzymes in thyroid metabolism. It is equally well established that both too little and too much iodine can disturb the fine balance.

Research is continuing to examine the interplay between iodine and selenium supply, its significance for different stages of life and individual differences in requirements. Much of this depends heavily on the individual case. Honestly and importantly: with existing thyroid conditions, medical care is indispensable – nutrients replace neither diagnosis nor therapy.

Selenium – small requirement, big task

Selenium is a good example of how a nutrient can be important even in tiny amounts. As a component of what are known as selenoproteins, it is involved in enzymes that take part in thyroid metabolism and in protecting cells from oxidative stress. The daily requirement is in the microgram range – just a few Brazil nuts can contribute a great deal. At the same time, the gap between an intake that matches your needs and an undesirably high amount is comparatively small with selenium, which is why here too the rule is: match your needs rather than take as much as possible. How much makes sense in everyday life is put into context in Selenium: how much per day?.

Who should be particularly attentive?

Some groups tend to have a tighter iodine supply or an increased requirement:

• People on a vegan or low-salt diet who do not use iodised table salt.
• People who rarely eat fish or dairy products.
• Pregnant and breastfeeding women have an increased iodine requirement – please always have this checked by a doctor.

For everyone the rule is: rather than dosing high on your own initiative, a balanced diet is the first choice. If an inadequate supply is suspected, a medical check-up will help.

Caution with illnesses and medications

Thyroid disorders – such as an overactive or underactive thyroid or autoimmune thyroiditis – need to be clarified and treated by a doctor. Nutrients do not replace a medical diagnosis or therapy. Anyone already taking thyroid medication such as levothyroxine should discuss taking supplements beforehand, as interactions with absorption can occur. Guidance on this is given in Supplements and Thyroid Medication. With thyroid topics, the general rule is: have it checked by a doctor.

Why a sense of proportion with iodine is so important

Unlike with many other nutrients, with iodine both too little and too much can disturb the fine balance of the thyroid. This makes iodine a trace element for which “more helps more” is expressly not true. That is why high-dose iodine supplements – such as strongly iodine-containing algae products of fluctuating concentration – should be treated with caution without medical advice. For everyday basic supply, iodised table salt together with the regular consumption of sea fish or dairy products is usually quite sufficient. If you are unsure whether your own intake is right, it is best to have it assessed by a doctor rather than dosing high yourself.

Honestly put: requirement and sensible supplementation

The daily iodine requirement is in the range of a few hundred micrograms and can often be met well with iodised table salt and regular sea fish or dairy products. With selenium, even small amounts suffice, for example from a few Brazil nuts. Targeted supplementation can make sense if the diet contains hardly any of these sources – for instance with a vegan or low-salt diet. However, because with iodine both a deficiency and an excess can be problematic, particular restraint is called for: always have a high-dose intake checked by a doctor. Anyone taking thyroid medication should, as a rule, not start supplements without medical advice.

Suitable products from Scheunengut

In the categories Iodine and Selenium you will find suitable single-nutrient products in organic quality, such as iodine from kelp algae and selenium as sodium selenite or from selenium yeast. For the organ itself, it is worth taking a look at Thyroid, and for the overall overview Trace Elements. All products are lab-tested and made in Germany. Please observe the recommended daily amount and, with thyroid topics, clarify use with a doctor.

Frequently Asked Questions (FAQ)

Which nutrients does the thyroid need?

Above all iodine and selenium. Iodine contributes to a normal production of thyroid hormones and to normal thyroid function, and selenium to normal thyroid function. The thyroid needs both in an amount that matches its needs – not in the highest possible dose.

Should you supplement iodine for thyroid problems?

Not on your own initiative. With thyroid topics – such as a suspected overactive or underactive thyroid, nodules or autoimmune conditions – the rule is always: have it checked by a doctor. Both too little and too much iodine can be problematic, which is why high-dose supplements without medical advice are not recommended.

Why is Germany an iodine-deficiency area?

The soils, and therefore the foods, naturally contain little iodine in this country. Important sources are iodised table salt, sea fish, seafood and dairy products. People who eat low-salt, without iodised salt or vegan more often have a tighter iodine intake.

Are Brazil nuts a good source of selenium?

Yes, Brazil nuts are among the most selenium-rich foods of all, though the content varies depending on the growing region. Just a few a day can contribute a great deal to your supply – usually no more is needed. With selenium, an intake that matches your needs is the goal, not the highest possible dose.