DHA increases Omega 3 Index more than EPA

DHA contributes more than EPA to the increase in Omega-3 Index, a parameter, useful in cardiac risk assessment, that indicates the percentage of EPA and DHA in red blood cell membranes. Specifically, the increase in Omega-3 Index, is significantly greater after supplementation with 2.7 grams per day of DHA, compared to the same amount of EPA.

This is what researchers at the University of Quebec (Canada) discovered and reported in the pages of the journal Prostaglandins, Leukotrienes and Essential Fatty Acids.

Omega-3 index and cardiovascular risk

Several researches in recent years have been conducted to determine the association between consumption of polyunsaturated fatty acids and cardiovascular risk. Indeed, omega-3 EPA and DHA are able to modulate a variety of risk factors such as blood lipid concentration and type, blood pressure, inflammation, and platelet aggregation, and possess significant antiarrhythmic action. Fatty fish from the cold seas and dietary supplements of marine origin are the main sources of EPA and DHA. Although recent experimental evidence suggests that EPA and DHA may exert different effects on blood lipids and inflammation signaling molecules, such evidence is scant, and most studies to date have evaluated these effects using a mixture of EPA and DHA in different forms and proportions. Little is known about the specific effects of EPA and DHA on biological processes affecting cardiometabolic health, that is, affecting both heart disease and metabolic diseases such as diabetes. The fatty acid composition of cell membranes influences their physicochemical properties and organ functions. The Omega-3Index, or Omega-3 Index, is the sum of EPA and DHA in the membranes of red blood cells and is expressed as the percentage of these two fatty acids out of the total fatty acids in the membranes, but it reflects the composition of tissues, including cardiac tissues. Based on epidemiological research conducted on the link between the risk of sudden cardiac death, that is, an unexpected death from cardiac causes, and the percentage of omega-3 in red blood cells, scientists concluded that:

• Se l’Indice Omega-3 è < del 4% c’è una forte probabilità per un individuo di essere colpito da morte cardiaca improvvisa
• If the Omega-3 Index is between 4 and 8 percent, the risk is moderate
• If the Omega-3 Index is > 8% , the situation is low risk

A very high Omega-3 Index, that is, between 8-12% has been associated with a lower risk of coronary heart disease and mortality in epidemiological studies.

Omega-3 index: greater increase with DHA

The objective of this study was to compare the effects of high doses of EPA and DHA on the Omega-3 Index, a parameter that can be modified by diet and supplementation. Indeed, while there is scientific evidence to suggest that DHA may be more potent than EPA in modifying cardiometabolic risk, their respective impacts on the Omega-3 Index had never been thoroughly examined. In fact, according to the scientists' statement, this is the first study of its kind to show that the increase in Omega-3 Index is significantly greater after supplementation with DHA at a dose of 2.7 grams per day compared with a comparable dose of EPA.

The details of the research

To arrive at these conclusions, the scientists analyzed data from 154 men and women with abdominal obesity and inflammation who were assigned a treatment that included one of three supplements: 2.7 grams per day of EPA; 2.7 grams per day of DHA; or 3 grams per day of corn oil (free of EPA and DHA) for 10 weeks. Red blood cell membrane fatty acid composition and Omega-3 Index were assessed at the beginning and end of each treatment. The results of the analyses indicated that the Omega-3 Index of participants who had received DHA had increased, on average, by 5.6 percent, compared with a 3.3 percent increase in those who had consumed EPA. Based on previous studies on fatty acid metabolism in men and women, the scientists also investigated potential gender differences in the increase in Omega-3 Index, observing a greater increase in the percentage of EPA and DHA in men, compared with women.

A preliminary study paving the way for new investigations

EPA and DHA supplements are recommended for secondary prevention of cardiovascular disease or management of plasma triglycerides. Although a high Omega-3 Index has been associated with a lower risk of cardiovascular disease and mortality, more research will be needed to compare the effects of different omega-3s on this clinical tool, which is useful for cardiovascular risk management. "The increase in the Omega-3 Index is greater with the addition of high-dose DHA than with EPA, and this is consistent with the greater ability of DHA to modulate cardiometabolic risk factors," said the research authors. "However, the extent to which differences between EPA and DHA may influence long-term cardiovascular risk needs to be investigated with further studies in the future," they concluded. Of the same opinion is Harry Rice, vice president of the Organization for EPA and DHA (Goed), who, commenting on the study's findings, said that the well-designed and conducted Canadian research provides a solid basis on which further studies can be designed, but it is still not enough to push people to choose different supplements. Until it is determined whether the differences in the Omega-3 Index relate to the risk of cardiovascular outcomes, such a change would be premature.

Source: J. Allaire et al. Supplementation with high-dose docosahexaenoic acid increases the Omega-3 Index more than high-dose eicosapentaenoic acid." Prostaglandins, Leukotrienes and Essential Fatty Acids (PLEFA)."