Iodine
Iodine from a measured kelp dose — never a pinch.
Seaweed is the clean food source of iodine, but commercial seaweeds span a ~200-fold range (16 to 2,984 mcg per gram), and the adult upper limit is 1,100 mcg/day — above which thyroid function can suffer. That variability is why kelp is dosed by the jar’s measured 90 mg scoop and never as a casual pinch.
Sources: 21