Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults

Abstract

Studies reporting blood levels of the omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were systematically identified in order to create a global map identifying countries and regions with different blood levels. Included studies were those of healthy adults, published in 1980 or later. A total of 298 studies met all inclusion criteria. Studies reported fatty acids in various blood fractions including plasma total lipids (33%), plasma phospholipid (32%), erythrocytes (32%) and whole blood (3.0%). Fatty acid data from each blood fraction were converted to relative weight percentages (wt.%) and then assigned to one of four discrete ranges (high, moderate, low, very low) corresponding to wt.% EPA+DHA in erythrocyte equivalents. Regions with high EPA+DHA blood levels (>8%) included the Sea of Japan, Scandinavia, and areas with indigenous populations or populations not fully adapted to Westernized food habits. Very low blood levels (≤4%) were observed in North America, Central and South America, Europe, the Middle East, Southeast Asia, and Africa. The present review reveals considerable variability in blood levels of EPA+DHA and the very low to low range of blood EPA+DHA for most of the world may increase global risk for chronic disease.

n-3 Polyunsaturated Fatty Acids and Cardiovascular Disease: Principles, Practices, Pitfalls, and Promises - A Contemporary Review

“…They too endorsed use of n-3 PUFA levels or the omega-3 index, a convenient and increasingly available tool [16,23,86]. Users should become familiar with reports in the various fatty acid profiles, with particular care in interpreting effects of the composition and properties of the n-3 PUFA administered, especially plant ALA, and the individual fatty acid levels reported.…”

“…As mentioned above, in the AHA Advisory, studies using n-3 PUFA levels were deliberately excluded [99]. Yet the variation of levels within populations is striking [23]. In many instances, administering a fixed physiological dose of n-3 PUFA to a cohort in which background levels randomly vary may result in overlap between baseline levels and postintervention levels.…”

“…The inclusion of studies that rely upon self-recall of n-3 product use, while rejecting those that rely upon n-3 PUFA levels, is particularly concerning. In the future, perhaps knowledge of n-3 PUFA levels will be considered as an advantage, not as a confounder to be ignored [14,23,[81][82][83][84][86][87][88]. Second, as discussed above, as the dual epidemics of obesity and T2D progress, glucose intolerance and atherogenic dyslipidemia follow, with increases in levels of TG, TRL, and cholesterol remnants.…”

“…A recent review of 298 studies provided levels of fatty acids as plasma total lipids, plasma phospholipid, in erythrocytes and in whole blood [23]. For comparison, these data were converted to "relative weight percentages."…”

Effects of a low and a high dietary LA/ALA ratio on long-chain PUFA concentrations in red blood cells

“…Accordingly, blood levels of EPA and DHA are low. 9 The essential n3 precursor fatty acid alpha-linolenic acid (ALA, C18:3n3) is present in high amounts in some plant oils, particularly linseed-, chia-, perilla-and walnut oil and can be converted into EPA and DHA in a multistep elongation and desaturation reaction. 10 However, the efficiency of this process is generally low in adult humans.…”