Selenium: Effects, Daily Requirement & the Best Form

Some nutrients you need in grams, selenium you need in micrograms – tiny amounts, but the body insists on them. The tricky part: whether your plate delivers enough depends on one thing that almost no one has on their radar – the soil in which your grain was grown. And European soils are often low in selenium. That is exactly why selenium is worth a second look.

Short and to the point: Selenium contributes to normal thyroid function, to a normal function of the immune system, to the protection of cells from oxidative stress as well as to the maintenance of normal hair and nails. The daily requirement is around 60–70 µg. As forms, organic selenomethionine and inorganic sodium selenite have proven their worth – but with selenium, more is expressly not better.

The most important points at a glance

• Selenium contributes to normal thyroid function and to a normal function of the immune system.
• It also supports normal hair and nails as well as the protection of cells from oxidative stress.
• Daily requirement: around 60 µg (women) to 70 µg (men); upper limit according to EFSA 300 µg.
• European soils are often low in selenium – Brazil nuts are a well-known but highly variable source.

What selenium does in the body

Selenium does not act as a loose mineral, but as a firmly built-in component of certain enzymes – the so-called selenoproteins. Two examples make this vivid. The glutathione peroxidases are part of the body's own antioxidant system and help protect cells from oxidative stress – this is where the approved cell-protection claim applies. And the deiodinases are enzymes that convert the hormone T4 into its active form T3 in the thyroid – hence the claim about normal thyroid function. Without selenium, these enzymes simply cannot do their job.

Approved claims for selenium

Selenium is one of the minerals with many officially approved claims – ones you can use with confidence:

Selenium and the thyroid – why the duo with iodine matters

Hardly any organ is as selenium-dependent as the thyroid – it is one of the most selenium-rich tissues in the body. The reason lies in hormone metabolism: the thyroid first produces the storage hormone T4, which must be converted into the active form T3 in the tissue. The enzymes that carry out this conversion need selenium. At the same time, during hormone formation the thyroid produces reactive compounds against which selenium-dependent protective enzymes work. That makes two processes selenium-dependent at once. But because iodine is also central to the thyroid, only the interplay gives a complete picture – as explained in Iodine: Effects, Requirement & Thyroid. All thyroid questions belong in medical hands.

How much selenium per day – and the narrow range

As a guideline, the DGE cites around 70 µg for men and 60 µg for women per day. According to EFSA, the tolerable total amount is 300 µg per day. That sounds like a lot of leeway, but compared with other nutrients it is rather narrow – selenium is one of the trace elements with a relatively slim range between a sensible intake and too much. Rule of thumb: with selenium, "more" brings no bonus, but quickly leads into unnecessary territory. How to classify the amount in general is explained in Selenium: How much per day?.

Selenium forms: organic or inorganic?

On the label you will mainly encounter two forms that complement each other well:

Some products combine both forms to unite the advantages: the storability of the organic and the controllability of the inorganic form.

What research is investigating

Textbook-solid is the role of selenium as a building block of the selenoproteins – without selenium, no functioning glutathione peroxidases and deiodinases. That is the solid core on which the approved claims are based. Particularly intensively researched is the connection with the thyroid: because the thyroid is one of the most selenium-rich organs and the conversion of thyroid hormones runs in a selenium-dependent way. The role in the antioxidant network is also an active field. Important for an honest classification: from "selenium is important for the thyroid" it does not follow that more selenium "improves" the thyroid – the benefit lies in an adequate supply, not in an excess. Questions around the thyroid belong in medical hands anyway; more in the guides Nutrients for the thyroid and Iodine & thyroid.

In practice: timing, combinations and for whom it makes sense

Selenium can be taken easily with a meal. Frequently asked combination questions: selenium and zinc can be taken together (explained here), and the ratio of the two is put into context by Zinc and copper. Those who should keep selenium particularly in mind: people with a purely plant-based diet (fish, eggs and meat as sources fall away – see Nutrients for vegans), people with a one-sided diet and everyone with a focus on skin, hair & nails. Whether supplementation is a good fit depends on individual status – if in doubt, clarify medically, as the guide Selenium deficiency: signs sets out.

Why European soils are often low in selenium

One detail makes selenium almost unique among the minerals: how much of it is in your grain or vegetables depends directly on the selenium content of the soil in which it grew. Plants take up selenium from the soil – if there is little there, the food also contains little. Large parts of Europe are considered rather low in selenium, while, for example, North American growing regions are often significantly richer in selenium. For you, this means concretely: the same wholegrain variety can deliver more or less selenium depending on its origin, and "but I eat healthily" is no guarantee of a particular selenium intake. That is exactly why, with selenium, it makes sense to look beyond the mere choice of food – and, if a scarce supply is suspected, to have it determined medically, as Selenium deficiency: signs sets out.

Food sources & safety

Particularly rich in selenium are Brazil nuts – just a few already cover the daily requirement. But this is exactly where caution is advised: their content varies greatly and can be very high, so eat them deliberately and sparingly. Other good sources are fish, eggs and meat. With plant-based foods such as grain, the content depends heavily on the growing region – the same variety can contain more or less selenium depending on the soil. Because the range between requirement and upper limit is narrow, the rule is: do not dose arbitrarily high.

Honestly classified

Selenium is an essential trace element with several clearly approved functions – and a peculiarity worth knowing: the supply in Europe is variable because of selenium-poor soils, while at the same time there is little room upwards. Both together mean: selenium is a good candidate for a targeted, moderate supplementation – but not a nutrient to dose high "on suspicion". Status decides, not gut feeling.

Matching products from Scheunengut

You will find selenium in our category Selenium – lab-tested and made in Germany. Matching partners around the immune system and beauty are available under Zinc and Minerals. Further reading: How much selenium per day?, Selenium deficiency signs, Skin, hair & nails, Nutrients for the thyroid and Immune system: Vitamin C, D & Zinc.

Frequently asked questions (FAQ)

What is selenium important for?

Selenium contributes to normal thyroid function, to a normal function of the immune system, to the protection of cells from oxidative stress as well as to the maintenance of normal hair and nails. It acts as a building block of certain enzymes, the selenoproteins.

How much selenium should you take per day?

The DGE cites around 70 µg for men and 60 µg for women per day. The tolerable upper limit according to EFSA is 300 µg. Because the range between requirement and upper limit is narrow, selenium should not be dosed arbitrarily high – more is not better here.

Which selenium form is the best?

Organic selenomethionine (well absorbable and storable) and inorganic sodium selenite (easy to control, independent of methionine metabolism) have proven their worth. Some products combine both forms to unite their respective advantages.

Why is the selenium supply in Europe often scarce?

The selenium content of plant-based foods depends heavily on the selenium content of the soil. European soils are in part lower in selenium than, for example, North American ones, so intake through diet varies. If a scarce supply is suspected, it is best to have your status determined medically.