by Travis DeGraff

FISH OIL – It’s one of the most commonly used supplements in the United States today.  That is why the FDA set out to recently see how accurate the labeling claims on fish oil really are.  Their findings were just published in the Journal of Agricultural and Food Chemistry [Ref 1].

The study had a few goals, but the first was to use a method called  gas chromatography with flame ionization detection.  The purpose of this method was to detect trans-isomers of EPA and DHA (the two fatty acids that provide many of the health benefits of fish oil).  A more traditional method of testing fish oils can often confused trans-isomers of EPA and DHA for actual EPA and DHA contest (resulting in an over estimation of the good stuff).  The second reason was to determine how closely fish oil supplements met label claims for EPA and DHA.

Trans-Isomers in Fish Oil

The trans-isomers in fish oil are created from high heat processing during the manufacturing of these supplements.  Trans-isomers are a hotly debated topic, but in general, believed to be very poor for your overall health [Ref 2].  Potential health problems from trans fatty acids include:

  • Increases low density lipoprotein (LDL)
  • Reduces high density lipoproteins (HDL)
  • Atherogenic 

What they found after analyzing 46 different fish oil products, is that those with higher EPA/DHA contents, or “concentrates”, tended to have the most trans-isomer EPA/DHA.  And overall…

“In the present study, the concentration of the trans isomers of EPA and DHA in the supplements varied from 0.1% to 1.5% of total fat, corresponding to a mean content of 8 ± 10 mg/serving (Table 3) and a mean estimated intake of 10 ± 11 mg/d (Supporting Information, Table 1).”

Are Fish Oil Label Claims Accurate?

What would be extremely useful to us, would be the name of each product tested in this study and how close or accurate the label was to the actual contents of the product.  Unfortunately they do not provide this data.  However in general we can see that of the 46 products tested, most of them have labels accurate within +-20% of actual EPA and DHA content.  In fact, several were overdosed.  Here’s a look at content (based on %) of all 46 fish oil supplements.

fish oil label claims


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