Selenium is one of those minerals that goes unnoticed until it starts to run low. It is needed in very small amounts, but its role is enormous: it is involved in thyroid function, acts as an antioxidant, and helps the immune system respond as it should. In this article, we explain exactly what selenium does in the body, how much you need daily, what foods to find it in, and when it makes sense to resort to a supplement.

What is selenium and why does your body need it?

Selenium is an essential trace element, meaning the body cannot produce it on its own and must obtain it through diet. It is incorporated into a group of proteins called selenoproteins, among which glutathione peroxidase stands out, one of the body's main antioxidant defenses. It also participates in the synthesis of thyroid hormones and the regulation of the immune system, making it a key mineral even though the amounts we need are minimal.

Health benefits of selenium

Selenium and thyroid

The thyroid is the organ with the highest concentration of selenium per gram of tissue in the entire body. The mineral is essential for converting the T4 hormone into its active form, T3, and for protecting the gland from the oxidative stress generated by hormone production itself. Therefore, an insufficient intake of selenium can affect thyroid function over time, especially in people predisposed to autoimmune thyroid disorders. Some studies have observed that selenium supplementation, in controlled doses and for several months, can help reduce certain antithyroid antibodies in people with autoimmune thyroiditis, although this should never replace treatment or regular medical follow-up.

Selenium as an antioxidant

Through glutathione peroxidase, selenium helps neutralize free radicals and protect cells from oxidative damage. This antioxidant effect complements other nutrients in this family well, such as vitamin C or vitamin E, with which it often works as a team within the body.

Selenium and the immune system

Selenium contributes to the normal functioning of defenses, promoting both innate and adaptive immune responses. Adequate levels are associated with a better capacity of the body to respond to infections, which makes this mineral another ally to consider during times of low defenses.

Other benefits: skin, hair, and nails

Selenium also contributes to the maintenance of normal hair and nails, thanks in part to its structural and antioxidant role in these tissues.

How much selenium do you need daily?

According to the European Food Safety Authority (EFSA), the reference intake for adults is around 55 micrograms (mcg) per day. During pregnancy, this amount rises slightly to 60 mcg, and during lactation, up to 70 mcg daily. It is important not to exceed it: the safe upper limit is set at 300 mcg per day, and doses above 400 mcg can be toxic in the long term, causing symptoms such as garlic-smelling breath, hair loss, or changes in nails.

For this reason, it is best to adjust supplementation to your real needs and, if you have doubts or a diagnosed thyroid condition, consult a healthcare professional before starting.

Foods rich in selenium

Before thinking about a supplement, it is worth reviewing your diet. Some of the best natural sources of selenium are:

• Brazil nuts, by far the richest food in selenium (one or two can cover the daily intake).
• Fish and seafood, especially tuna, sardines, and shrimp.
• Eggs and lean meats.
• Legumes and whole grains, although their content depends on the soil where they are grown.

In Spain, some soils are relatively poor in selenium, which can result in a somewhat lower intake than recommended for part of the population. Therefore, it is advisable to consider not only the quantity of selenium-rich foods consumed but also the general variety of the diet throughout the week.

When does it make sense to take a selenium supplement?

A selenium supplement can be useful in situations such as a monotonous diet, intestinal absorption problems, or as a supplement under medical supervision in people with autoimmune thyroid disorders. It is also frequently used in multivitamin formulas along with other antioxidants such as vitamin C, vitamin E, or zinc, as these nutrients work synergistically to protect cells. If you are looking to boost your defenses for the change of season, you can also find selenium combined with other nutrients in our defenses and immunity collection.

During pregnancy and lactation, when selenium needs increase slightly, special attention should be paid to the intake of this mineral; in our women's health collection, you will find formulations designed for these stages.

In summary

Selenium is a mineral that we need in very small doses, but its absence can be noticed in the thyroid, in defenses, and in the general state of cells. Maintaining a varied diet, with the presence of fish, eggs, and some nuts like Brazil nuts, is usually enough to cover daily needs. When the diet is insufficient or there is a specific need, a well-dosed selenium supplement can make a difference, always within the recommended safe limits.

On andavida.es you will find a selection of selenium and other antioxidant supplements from brands like Solgar, Solaray, and Nutralie, designed to support you in your daily health care. Explore our catalog and find the option that best suits your needs.