Testing of 25 fish oil supplements sold in China found that many did not contain the amount of EPA and DHA stated on their labels, which could affect their intended health benefits.

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.

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.

Many fish oil supplements sold commercially do not contain the amount of EPA and DHA claimed on their labels, show signs of degraded fats beyond safe limits, and may contain harmful contaminants like heavy metals.

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.

A study found that most fish oil supplements sold in New Zealand contained significantly less of the key omega-3 fatty acids (EPA and DHA) than stated on their labels, with only a small number meeting their advertised content.