A: Many store-bought omega-3s are in a synthetic (ester) or unpurified form, which is difficult to absorb and leaves a fishy odor/aftertaste. PRN Omega-3s are in an ultra-purified triglyceride (rTG) form, which is a similar form to a piece of fish, but without the impurities. This form is easier for your body to absorb and micro-distilled to remove contaminants like PCBs, lead, mercury and more. PRN omega-3s are manufactured in a NSF® and cGMP facility.