It took us more than 2 years to develop this essential fatty acid complex that meets our specifications for heavy metals, especially mercury, microbials, pesticides, chemicals and purity. Marine lipids from fish oil are arguably the most effective form of omega-3 essential fatty acids which makes them more challenging to find in pure form, and another reason why we test them exhaustively before incorporating them in this product. Essential fatty acids are nutrients that we must take in our diets because our bodies cannot manufacture them. They are critically important for immune system function, skin, cardiovascular health, vision and many other important human functions.