When should selenium be taken, in the morning or in the evening?

Selenium is an element whose requirement is expressed in such small amounts that its importance is easily overlooked. Its presence in food begins in the soil, because it is the soil's composition that determines how much selenium will first reach plants and then the animals that eat those plants. In some parts of the world, food products are significantly richer in selenium, while in others they are poorer, which can affect the health of entire populations. When you notice the first symptoms of selenium deficiency, it is important to know when and how to use it.

1. The effect of selenium on the immune system
2. Selenium supplementation and immunity
3. The role of selenium in the thyroid gland
4. Selenium supplementation and the thyroid gland
5. When to use selenium

The effect of selenium on the immune system

The most important area of selenium's action is supporting the protection of cells against oxidative stress, i.e. a condition in which too many molecules that can disrupt tissue function (free radicals) accumulate in the body. Under normal conditions, they are quickly neutralised by the natural antioxidant system, but when its action is weakened or the rate of formation of such molecules increases, the balance is disturbed.

Selenium participates in the creation of important enzymes, including glutathione peroxidase, which help restore balance and protect cells from adverse changes. The stable functioning of this system is necessary both in everyday life and in situations of increased stress on the body.

Selenium supplementation and immunity

In people with selenium deficiency, supplementation has been shown to improve the function of lymphocytes (white blood cells) and NK cells (natural killer cells, which are responsible for the rapid destruction of infected or damaged cells).

Reviews of human studies have reported an increase in the activity of enzymes that protect cells from oxidative stress, such as GPx (glutathione peroxidase), and a decrease in markers of damage caused by free radicals. This effect is important, among others, in people suffering from chronic stress, diseases or poor diet.

The role of selenium in the thyroid gland

The second key area in which selenium plays an important role is the functioning of the thyroid gland. This gland is responsible for the production of hormones that regulate metabolic rate, energy levels, body temperature and many processes related to the nervous system.

Selenium is involved in converting thyroid hormones into their active form and helps protect the thyroid gland from oxidative stress. This allows for more stable hormone levels and more efficient thyroid function. This is particularly important for people with autoimmune thyroid diseases, as selenium can affect how the immune system responds to this organ.

Selenium supplementation and the thyroid gland

Clinical trial results increasingly show that selenium supplementation can be truly beneficial for people with low selenium levels. In autoimmune thyroid diseases, it has been reported that selenium supplementation can support balanced immune system function, which in many studies has been associated with a decrease in anti-TPO (anti-thyroid peroxidase) antibodies and improved patient well-being.

More recent analyses also suggest an improvement in TSH (thyroid-stimulating hormone) levels if the thyroid gland has not yet been stabilised by treatment. Such changes often indicate that selenium supplementation can help the thyroid gland function in a more stable and predictable manner.

Estimated selenium content in selected foods

(the wide ranges are due to the varying selenium content in different regions of the world)

When to use selenium

The most convenient and best-studied method of selenium supplementation is to use it in the form of selenomethionine, as it is most easily absorbed by the body and maintains its levels more stably than other forms. Most clinical studies have used doses in the range of 100-200 µg per day, which is usually sufficient to compensate for deficiencies and remains safe for long-term use. Selenium can be taken at any time of day, but many people choose to take it in the morning. The most important thing is to take it with a meal, which improves absorption. There are no contraindications for use in the evening.

Sources:

• Huwiler, V. V., Maissen-Abgottspon, S., Stanga, Z., Mühlebach, S., Trepp, R., Bally, L., & Bano, A. (2024). Selenium Supplementation in Patients with Hashimoto Thyroiditis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Thyroid : official journal of the American Thyroid Association, 34(3), 295–313. https://doi.org/10.1089/thy.2023.0556
• Kiremidjian-Schumacher, L., Roy, M., Wishe, H. I., Cohen, M. W., & Stotzky, G. (1994). Supplementation with selenium and human immune cell functions. II. Effect on cytotoxic lymphocytes and natural killer cells. Biological trace element research, 41(1-2), 115–127. https://doi.org/10.1007/BF02917222
• Huang, Z., Rose, A. H., & Hoffmann, P. R. (2012). The role of selenium in inflammation and immunity: from molecular mechanisms to therapeutic opportunities. Antioxidants & redox signaling, 16(7), 705–743. https://doi.org/10.1089/ars.2011.4145