Simplify the following text for a Grade 11 native English-speaking person.
Original: By ingesting this large amount of non-radioactive iodine , radioactive iodine uptake by the thyroid gland is minimized .
Simplified: The radioactive iodine easily goes into the thyroid and causes cancer . When people take iodine tablets , it fills up the thyroid with non-radioactive iodine which prevents any radioactive iodine from coming in .