Fish oil supplements on the market contain different amounts of omega-3 fatty acids, with some having as little as 31.6% and others as much as 83.4% of their oil content, and the balance between omega-6 and omega-3 fats also varies significantly between products.

Testing of 15 fish oil supplements sold in the U.S. found that some contained EPA or DHA levels that were more than 20% higher or lower than what was stated on the label, suggesting that label claims for these nutrients are often inaccurate.

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.

Commercial fish oil supplements contain varying amounts of omega-3 fatty acids, with total doses ranging from 680 mg to 4,600 mg per day, and EPA and DHA doses that are lower than the 4,000 mg per day dose used in FDA-approved prescription omega-3 products.

Laboratory testing of two fish oil supplements revealed that one contained significantly less EPA than stated on the label, while another contained more DHA than claimed.

Testing of fish oil supplements sold in Bahrain found that nearly half had less of the key omega-3 fats (EPA and DHA) than advertised, and some had more EPA but less DHA than labeled, indicating variability in product quality.