It is screened for the absence of potentially harmful levels of contaminants (i.e. mercury, heavy metals, PCB's, dioxins, and other contaminants).Those who experience nausea or reflux from other fish oils should find this enteric coated, odor controlled softgel easier to digest.The Fish Oil Concentrate is primarily derived from sardines, anchovies and mackerel.Serving Size: 1 SoftgelSuggested Use: