Selenium: Benefits, Sources, and Risks

Selenium, an essential trace element, plays a crucial role in various bodily functions, including antioxidant defense and thyroid hormone metabolism. Plant foods serve as the primary dietary sources of selenium worldwide, with their selenium content determined by the soil in which they are grown. This soil selenium content varies significantly by region, influencing local dietary intake levels.

In the United States, the high plains of northern Nebraska and the Dakotas are notable for their selenium-rich soils. Consequently, residents of these areas have the highest selenium intakes in the country. In stark contrast, regions in China and Russia have soils with very low selenium levels, leading to frequent dietary deficiencies. These deficiencies are linked to various health issues, including Keshan disease, a potentially fatal condition affecting the heart.

Beyond plant foods, selenium is also present in certain meats and seafood. Animals consuming grains or plants grown in selenium-rich soils tend to have higher selenium levels in their muscles. In the United States, meats and bread are significant sources of selenium, reflecting the country’s agricultural practices. Nuts, particularly Brazil nuts and walnuts, are exceptional sources of selenium, often providing more than the daily recommended intake in just a few servings. Recent studies have highlighted the importance of these nuts in preventing selenium deficiency and supporting overall health.

While adequate selenium intake is beneficial, excessive selenium can pose health risks. Chronic high intake can lead to selenosis, characterized by symptoms such as gastrointestinal distress, hair loss, white blotchy nails, and mild nerve damage. In severe cases, it can cause more serious issues like respiratory distress, kidney failure, and even death. Thus, a balanced diet, avoiding excessive supplementation, is crucial for maintaining optimal health and preventing selenium toxicity.
Selenium: Benefits, Sources, and Risks