In Brazil, people with lower income and non-white skin color tend to consume less selenium in their diet than those with higher income and white skin color, which may increase their risk of not getting enough of this essential nutrient.

In Brazilian adults, people who consume more selenium tend to be women, older than 60, have higher income or education, drink alcohol, or engage in regular physical activity. People who consume less selenium tend to have non-white skin color or smoke.

In Brazil, people who currently smoke consume about 7.77 micrograms less selenium per day than those who have never smoked or have quit, suggesting their diet tends to include less selenium-rich foods.

In healthy adults from Galicia, Spain, people who consume more dietary oil tend to have lower levels of selenium in their blood, which may be related to how fat in the diet affects selenium absorption or reflects broader dietary habits.

In healthy adults from Galicia, Spain, the amount of selenium in the blood changes more noticeably with dietary intake than the levels of zinc, copper, or iron, which stay relatively constant due to biological regulation. This makes selenium a more reliable indicator of whether dietary intake is sufficient.