Selenium

Studies in people

• Open question

  Pregnancy outcomes²

  Scientists do not yet know whether taking selenium during pregnancy lowers the chance of premature birth.

• Open question

  Cancer risk⁴

  People with less selenium in their blood seem more likely to get cancer than those with more.

• Benefit

  Liver infection risk⁷

  In people, selenium added to table salt was linked to fewer hepatitis infections in one Chinese county.

How it’s made and used

• Blood levels from supplements³

  Selenium supplements raised selenium levels in the blood of healthy Belgian adults who did not get enough from food.

• Trace elements in milk⁵

  Selenium levels in breast milk change over time, and babies fed cow's milk may get different amounts.

• Nutrient levels over time⁶

  Selenium in breast milk drops as babies get older, settling at a steady level after about 20 days.

• Viral infection severity⁸

  Selenium deficiency is still common in some regions, and low levels may make viral infections worse.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least one finding in people. When most findings in people point one way, the page leans that way (“Mostly”), and every finding is still shown. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.