Even today, respect for the toxicity of selenium is often greater than attention to its important functions in our metabolism. Selenium is important for the functions of the immune system and thyroid hormone metabolism.

The functions of the trace element in the body

Antioxidant effect
Selenium is an integral component of many seleneproteins, most of which are involved in remedying the consequences of oxidative stress.
The best-known seleneprotein is certainly glutathione peroxidase. This enzyme serves as a cell protection factor against aggressive activated oxygen forms, which are formed by external influences (such as environmental toxins, radiation, smoking), but also normally in the metabolism itself. 
It should be noted that statins also inhibit the formation of seleneproteins, among other things.

Immune system
Selenium seems to stimulate antibody production, especially immunoglobulin G. In addition, selenium also stimulates the activity of natural killer cells, which are of great importance for our defense system. However, in excessive doses, this effect can also be reversed.

Thyroid hormone metabolism 
The function of the enzyme type I iodothyronine-5-deiodase is dependent on selenium. This enzyme plays an important role in the conversion and activation of thyroid hormones. A selenium deficiency can therefore lead to hypothyroidism.

The functions of the trace element in the body

  • The daily requirement of selenium is 60-70 µg (except pregnant and breastfeeding women)
  • Soils in Switzerland tend to be low in selenium, which is why the selenium concentration in foods grown here is no high
  • Central European countries, Scandinavia, China and New Zealand are considered "selenium deficient" countries

Can selenium be overdosed?

Yes, definitely. Studies showed that long-term doses of more than 750 µg per day result in a prolongation of the blood clotting time as well as an increased formation of white blood cells. Symptoms of chronic selenium overload can include disturbances in hair and nail structure, skin redness and swelling, vomiting, diarrhea, weight loss and garlicky breath.

Long-term doses of up to 300 µg per day as well as single doses of max. 3.5 mg selenium are considered safe and free of side effects.

What are the consequences of a selenium deficiency?

  • Increased susceptibility to infections
  • Heart enlargement and heart failure
  • weakening of the immune system
  • fertility disorders in men
  • fertility disorders in women (impaired formation and secretion of luteinizing hormone and follicle-stimulating hormone)
  • pre-eclampsia, gestational diabetes
  • eye diseases
  • muscle weakness
  • changes in hair structure
  • lightening of skin and hair

Selenium in food (per 100 g)

herring   140 µg           sardine   85 µg
wholemeal wheat bread      55 µg   beef   35 µg
pork    31 µg   cod, salmon     25 µg

The following products contain selenium...