Your body absorbs omega-3s from fish oil better depending on the form they're in — free fatty acids are easiest to absorb, triglycerides are okay, and ethyl esters are the hardest.

How fish oil is made and packaged can change how well your body absorbs it, whether you like taking it, and how much it might help your health.

Fish oil supplements sold in stores contain different amounts of omega-3 fatty acids, with some having as little as 33% and others as much as 79% of their total fatty acids, showing that the composition of these products is not consistent.

Fish oil supplements contain more than 30 different fatty acids, including 10 to 14 types of saturated fatty acids, which are not commonly found in products marketed as pure omega-3.

Fish oil supplements sold over the counter have more oxidized fats than prescription omega-3 products that meet international quality standards.

Fish oil supplements with over 95% re-esterified triglycerides (a type of fat form) seem to get more omega-3s into your blood cells after 16 weeks than those with less than 70%, so this might be a good sign of a better-quality supplement.