The other day I made a trip down to GNC to pick up some fish oil. I don’t know what it is about the employees at GNC but I must look like I don’t know squat about supplements or foods. Every time I go in all the GNC employees try to give me a lecture on whatever supplement it is that I’m looking for – this time it was about fish oil and the differences between EPA and DHA when it comes to Omega-3. Here are some things you should know about the differences between EPA and DHA so you know better the next time a GNC employee counters you in the corner.

The Difference Between EPA and DHA Fish Oil

I’ve covered fish oil in the past here, especially the differences between omega-3 and omega-6 oils. Generally speaking, omega-3 offsets the inflammatory effects that omega-6 has – which is a good thing because in the average diet, we get way too many omega-6 fatty acids compared to what we get in omega-3 fatty acids. Some studies put an omega-6 to omega-3 ratio as high as 20:1. There are a few different types of omega-3 fatty acids but two of the most studied are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – these are the two most prevalent types of omega-3 fatty acids found in almost every fish oil and omega-3 supplement in stores. Here’s to helping you understand the difference between EPA and DHA.

EPA and the difference between DHA Fish Oil

EPA is an omega-3 fatty acid that is found in large amounts in fish oils and one of two most studied omega-3 oils. Inside the body EPA goes on to form a group of compounds known as eicosanoides. Eicosanoids are hormone like compounds which go on to make other compounds that help to regulate the body’s anti-inflammatory response and actually help to reduce inflammation. In addition to helping to regulate the body’s inflammatory response, EPA also competes with arachidonic acid (omega-6 fatty acids) for absorption. It’s widely known that omega-6 fatty acids are inflammatory and in Western diets – particularly the American diet, high ratios of omega-6 to omega-3 occur in our diets. It’s possible that by decreasing consumption of omega-6 fatty acids and increasing EPA could help to contribute even more to reduced inflammation within the body.

EPA also helps to produce prostacyclins – prostacyclins are produced in the blood vessel walls and help to reduce blood clotting. EPA also decreases blood viscosity and decreases platelet aggregation in the same way that aspirin works. Overall, EPA appears to have more of an effect on inflammation and decreased platelet aggregation than DHA.

DHA and The Difference Between EPA Fish Oil

DHA is the other significant omega-3 and within the body it’s highest concentrations are in the eyes, brain, and spermatazoa. DHA is highly important for brain development as well as brain function (1,2). In fact, research shows that premature babies who are fed formulas low in DHA show alterations in visual development compared with premature babies who are not. DHA also plays an important role in building cell membranes and helps to maintain the structure and function of your body’s cells.

Within the eye, a decrease of DHA has been linked to alterations in retina function – the retina is responsible for capturing what you see with the eyes and transmitting it to the brain where the magic works and you come up with what you see. It’s theorized that the high concentrations of DHA within the retina help to maintain tissue permeability, tissue thickness, and help to enhance nerve transmission, and overall retinal function.

Other studied effects of DHA show that this fish oil can have a direct effect on inhibiting cyclooxygenase which inside the body is responsible for triggering inflammation and pain – non-steroidal anti-inflammatory medications such as aspirin and ibuprofen work to reduce pain and inflammation in the same way.

As for the effects on the heart – unlike EPA, with epidemiological research DHA levels have not protected against heart attacks. However, it’s possible that DHA might lower the blood pressure by making it easier for your blood vessels to be more relaxed (vasodilated). There are also some indications that DHA might help to have an effect that increases your blood clotting time – reducing the risk for clots (which can lead to stroke or heart attacks), however, more research is needed and so far it still appears that EPA fish oil is better at reducing platelet aggregation than DHA. The good news is that DHA has been shown to reduce triglyceride levels and increase HDL cholesterol levels. In fact, one study had showed that high-DHA fish oil helped to reduce triglyceride and cholesterol levels over the use of the popular medication class called statins.

On an important note: EPA can be used by the body to make DHA (from a type of omega-3 acid called alpha-linolenic acid); however, DHA does not go on to produce the same type of benefits that EPA does, which is why it’s important to get both types of omega-3 out of in your supplement.

Hopefully this helps to sum up the differences between EPA and DHA omega-3 fatty acids so the next time a GNC employee corners you in the back you don’t have to rely on their information.


1. Your Living Body – Omega-3 vs. Omega-6 Fatty Acids
2. Hampl, Jeffry S. Wardlaw, Gordon, M. Perspectives in Nutrition. 7th ed. New York: McGraw-Hill Companies Inc., 2007. 197-198. Print.
3. E. Chew., SanGiovanni, J. “The Role Of Omega-3 Long-Chain Polyunsaturated Fatty Acids In Health and Disease Of The Retina.” Progress In Retinal and Eye Research. 24 January 2005. Web. 27 January 2015.
4. N.a. “DHA (Docohexaenoic Acid). Natural Standard – The Authority On Integrative Medicine. 2013. Web. 27 January 2015.
5. N.a. “EPA (Eicosapentaenoic Acid). Natural Standard – The Authority On Integrative Medicine. 2013. Web. 27 January 2015.
6. Block, R. Mousa., A., Swanson, D. “Omega-3 Fatty Acids EPA and DHA: Health Benefits Through Life.” Advances In Nutrition – An International Review Journal. January 2012. Web. 27 January 2015.