Selenium is a trace element vital for human health, which we can only obtain through food or supplements. It plays an important role in immune function and thyroid health, and it also contributes to the body’s antioxidant defense against free radicals. Selenium is particularly important for male fertility, as it is a key component of sperm. The amount of selenium in plant foods varies widely depending on soil levels, which are generally low in Europe. For this reason, animal-based foods such as meat, eggs, and fish are more dependable sources. Interestingly, the thyroid gland contains the highest concentration of selenium in the body.