Selenium content depends on the soil. It's different all over the world.. Basically, in the US, the way they determine selenium content is: The government tests the selenium content of produce from all over the country, and then the "average" is what is posted in all food databases and such.
Example: tomatoes from Louisiana may have more selenium than tomatoes from Minnesota, but a food database is going to say that they have the same amount of selenium: the average of all samples taken of tomatoes across the country.
This only applies to produce though. I'm sure processed foods aren't as affected by soil quality.
So basically: food databases are not going to be completely accurate concerning selenium, especially if you eat a lot of produce.
|