Formula C20H30O2 Melting point -54 °C | Molar mass 302.451 g/mol | |
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IUPAC ID (5Z,8Z,11Z,14Z,17Z)-eicosa- 5,8,11,14,17-pentenoic acid Classification Eicosanoid Precursor, Omega-3 fatty acid | ||
Eicosapentaenoic acid (EPA; also icosapentaenoic acid) is an omega-3 fatty acid. In physiological literature, it is given the name 20:5(n-3). It also has the trivial name timnodonic acid. In chemical structure, EPA is a carboxylic acid with a 20-carbon chain and five cis double bonds; the first double bond is located at the third carbon from the omega end.
EPA is a polyunsaturated fatty acid (PUFA) that acts as a precursor for prostaglandin-3 (which inhibits platelet aggregation), thromboxane-3, and leukotriene-5 eicosanoids. Studies of fish oil supplements, which contain EPA, have failed to support claims of preventing heart attacks or strokes.
Clinical significance
The US National Institute of Health's MedlinePlus lists medical conditions for which EPA (alone or in concert with other ω-3 sources) is known or thought to be an effective treatment. Most of these involve its ability to lower inflammation.
Intake of large doses (2.0 to 4.0 g/day) of long-chain omega-3 fatty acids as prescription drugs or dietary supplements are generally required to achieve significant (> 15%) lowering of triglycerides, and at those doses the effects can be significant (from 20% to 35% and even up to 45% in individuals with levels greater that 500 mg/dL).
It appears that both EPA and DHA lower triglycerides, however DHA appears to raise low-density lipoprotein (the variant which drives atherosclerosis; sometimes very inaccurately called: "bad cholesterol") and LDL-C values (always only a calculated estimate; not measured by labs from person's blood sample for technical and cost reasons), while EPA does not.
The big difference in effect between dietary supplement and prescription forms of omega-3 fatty acids is that the prescription variants are concentrated to markedly increase the amount of these key fatty acids per capsule over the many other fats present in "fish oil" and the mercury, also present in "fish oil", has been removed.
EPA and DHA ethyl esters (all forms) may be absorbed less well, thus work less well, when taken on an empty stomach or with a low-fat meal.