I think that natural fish oil has also other fats. In natural fish oil you have 37 percent roughly Omega3, but you also have a lot of other fat.
It seems that, to be properly absorbed and used, you need all types of fats,
because the function of the Omega3 in the cell membrane, is to make the cell membrane permeable for substances that need to come in to the cell.
The saturated fat is impermeable. You need these other types of fat to build billions of new cell membranes every day.
The ordinary fat is what is the main building material for the cell membranes.
So, to concentrate up something that is needed in a small amount to 80 percent as some do, is unnatural.
It is safer until we got more knowledge to take it in the natural form as you also get the other fatty acids. We need all the fatty acids, not only Omega3.