Because it’s easier for the body to absorb and utilise, at least in the short term. When fish oil is concentrated and purified, its natural triglycerides are converted into a synthetic substance called ethyl ester (EE). Most supplement companies leave it in this form, but we go the extra step of converting the fish oil back into natural triglycerides, the way they occur in whole foods.
To do so is more costly, but we do this because your liver must first filter out the ethyl alcohol before it can get to work on the fatty acids, meaning it can be harder to absorb.
However it’s worth mentioning (and because we believe in transparency) that while the TG form of Omega 3 is superior in the short term, results from comparative studies, in general, suggest that absorption of Omega 3 fatty acids EPA and DHA from TG or from EE are similar over time when fish oil is routinely supplemented.