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Updated: Feb 4, 2026

Dietary Supplementation of Polyunsaturated Fatty Acids in Caenorhabditis elegans
Published on: November 29, 2013
Presence of Fatty-Acid Ethyl Esters in Krill Oil Dietary Supplements
Cynthia T Srigley1, Isa C Orr-Tokle1
1Center for Food Safety and Applied Nutrition (CFSAN), United States Food and Drug Administration (FDA), 5001 Campus Drive, College Park, MD, 20740, USA.
Abstract:
Krill oil dietary supplements are increasingly used for their high concentrations of phospholipids (PL), which offer reportedly greater bioavailability of n-3 polyunsaturated fatty acids (PUFA) than those of triacylglycerols or fatty-acid ethyl esters (FAEE) commonly found in fish oils and fish-oil concentrates. This work evaluated the lipid composition of 22 commercial krill oil (CKO) supplements available in the US market, and found ten products (i.e. 45%) contained significant amounts of FAEE, varying from 41% to 75%, by weight. These concentrations of FAEE differed from the minor abundances of FAEE (<3%, by weight) found in manufacturer-supplied krill oil. The potential clinical and regulatory implications for these findings warrant further investigation.
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