The natural fish oil concentrate used in this capsule is manufactured under strict quality control standards. It is tested to be free of potentially harmful levels of contaminants (i.e., mercury, heavy metals, PCBs, dioxins, and other contaminants). Those who suffer from nausea or reflux from other fish oils should find this enteric-coated, odor-controlled softgel easier to tolerate. DHA is an important nutrient that supports cognitive health and brain function.