“A high O3I, which reflects a relatively high content of EPA and DHA in the membranes of [red blood cells], has been associated with a lower risk of CHD [coronary heart disease] and mortality in observational studies,” explained the study authors in Prostaglandins, Leukotrienes and Essential Fatty Acids . “While there is emerging evidence suggesting that DHA may be more potent than EPA in modifying cardiometabolic risk their respective impacts on the O3I have not been thoroughly examined.
“To the best of our knowledge, this is the first randomized double-blind controlled crossover trial to show that the increase in O3I is significantly greater after supplementation with high dose DHA (2.7 g/d) than with a comparable dose of EPA.”
Scientists from the Université Laval in Québec, The University of South Dakota, and OmegaQuant Analytics, LLC, analyzed data from 154 men and women randomly assigned to receive 2.7 grams per day of EPA or DHA or 3 grams per day of corn oil for 10 weeks.
Results of the double-blind controlled crossover study indicated that the Omega-3 Index of participants in the DHA group increased by an average of 5.6%, compared with a 3.3% increase in the EPA group.
In addition, the researchers observed potential gender differences, with a greater O3I increase in men than in women.
“The increase in the O3I is greater with high dose DHA supplementation than with high dose EPA, which is consistent with the greater potency of DHA to modulate cardiometabolic risk factors,” they wrote. “The extent to which such differences between EPA and DHA in increasing the O3I relates to long-term cardiovascular risk needs to be investigated in the future.”
Commenting on the study’s findings, Harry Rice, PhD, VP of scientific and regulatory affairs for Global Organization for EPA and DHA Omega-3s (GOED), told us: “Given the debate about which is better, EPA or DHA, this study is long overdue. While it's a well designed and conducted study, with an outcome that serves as a solid basis upon which further research can be designed, don't switch your supplement just yet. Until it is determined if the differences in the Omega-3 Index relate to the risk of cardiovascular outcomes, such change would be premature. This is definitely a topic worth following and one that is unlikely to be resolved in the near future.”