The recommended dietary allowance (RDA) includes the total amount of selenium you should get from foods and from any dietary supplements you take.

1. Selenium Deficiency and Dietary Supplements
The recommended dietary allowance (RDA) includes the total amount of selenium you should
get from foods and from any dietary supplements you take. Most people can get their RDA of
selenium from food. In studies supporting the use of selenium for prostate cancer prevention,
men took 200 micrograms daily. The safe upper limit for selenium is 400 micrograms a day in
adults. Anything above that is considered an overdose.
Good natural food sources of selenium include:
 Nuts, like Brazil nuts and walnuts
 Many fresh and saltwater fish, like tuna, cod, red snapper, and herring
 Beef and poultry
 Grains
Selenium intakes and serum concentrations in the United States and Canada vary somewhat by
region because of differences in the amounts of selenium in soil and in local foods consumed.
For example, concentrations are higher in residents of the Midwestern and Western United States
than in the South and Northeast. The extensive transport of food typically allows people living in
low-selenium areas to obtain sufficient amounts of selenium.
Selenium Deficiency and Dietary Supplements
Selenium deficiency produces biochemical changes that might predispose people who experience
additional stresses to develop certain illnesses. For example, selenium deficiency in combination
with a second stress (possibly a viral infection) leads to Keshan disease, a cardiomyopathy that
occurred in parts of China prior to a government-sponsored selenium dietary supplements
program that began in the 1970s. Before the Chinese government dietary supplements program,
adults in the Keshan disease areas had average selenium intakes of no more than 11 mcg/day;
intakes of at least 20 mcg/day protect adults from Keshan disease.
Selenium deficiency is also associated with male infertility and might play a role in Kashin-Beck
disease, a type of osteoarthritis that occurs in certain low-selenium areas of China, Tibet, and
Siberia. Selenium deficiency could exacerbate iodine deficiency, potentially increasing the risk
of cretinism in infants.