Consuming 55 µg of selenium daily for two weeks via Brazil nut butter or a selenium supplement increases serum selenium concentrations by approximately 18–19 µg/L in vegans and by 15–17 µg/L in omnivores, with no significant difference between the two sources, and both effectively improve selenium status in adults with suboptimal baseline levels.

When selenium is eaten, it is absorbed in the gut and turned into a basic form that the body uses to build special proteins that carry selenium in the blood. These proteins, especially one called SELENOP, are made in the liver and released into the bloodstream, raising the amount of selenium found in the blood. The body makes more of these proteins when selenium levels are low, and the type of selenium eaten affects how quickly it becomes available for this process.