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.

Results indicate that EPA+DHA may be associated with reducing CHD risk, with a greater benefit observed among higher-risk populations in RCTs.

IntroductionSubjective memory complaints are common with aging. Docosahexaenoic acid (DHA; 22:6 n-3) is a long-chain polyunsaturated fatty acid (LCPUFA) and an integral part of neural membrane phospholipids that impacts brain structure and function. Past research demonstrates a positive association between DHA plasma status/dietary intake and cognitive function.ObjectivesThe current meta-analysis was designed to determine the effect of DHA intake, alone or combined with eicosapentaenoic acid (EPA; 20:5 n-3), on specific memory domains: episodic, working, and semantic in healthy adults aged 18 years and older. A secondary objective was to systematically review/summarize the related observational epidemiologic literature.MethodsA systematic literature search of clinical trials and observational studies that examined the relationship between n-3 LCPUFA on memory outcomes in healthy adults was conducted in Ovid MEDLINE and EMBASE databases. Studies of subjects free of neurologic disease at baseline, with or without mild memory complaints (MMC), were included. Random effects meta-analyses were conducted to generate weighted group mean differences, standardized weighted group mean differences (Hedge’s g), z-scores, and p-values for heterogeneity comparing DHA/EPA to a placebo. A priori sub-group analyses were conducted to evaluate the effect of age at enrollment, dose level, and memory type tested.ResultsEpisodic memory outcomes of adults with MMC were significantly (P<.004) improved with DHA/EPA supplementation. Regardless of cognitive status at baseline, > 1 g/day DHA/EPA improved episodic memory (P<.04). Semantic and working memory changes from baseline were significant with DHA but no between group differences were detected. Observational studies support a beneficial association between intake/blood levels of DHA/EPA and memory function in older adults.ConclusionDHA, alone or combined with EPA, contributes to improved memory function in older adults with mild memory complaints.

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Due to the numerous proposed cardiovascular benefits associated with consumption of omega-3 fatty acids, marketing of an egg enriched by omega-3 fatty acid may benefit the egg producer. Effects on yolk composition of a standard laying hen diet enriched with 3% menhaden oil (test diet), versus an isocaloric (control) diet containing no added fat, were evaluated for 18 wk. Dietary menhaden oil did not alter egg production, egg weight, total yolk fat, or yolk cholesterol. However, yolk contents of omega-6 and omega-3 fatty acids were influenced by diet. Arachidonic acid decreased and eicosapentaenoic acid increased in eggs from hens fed the test diet following 1 wk of dietary treatment. Docosahexaenoic acid and linolenate increased in eggs from hens fed the test diet at 2 and 3 wk of the trial, respectively. These alterations in yolk composition resulted in a decrease in the ratio of omega-6 to omega-3 fatty acids from 18 for eggs from hens fed the control diet to 3 for eggs from hens fed the test diet. At Weeks 14 and 18, hens (n = 10 per diet) were killed and necropsied. No change in gross scoring of hepatic lipidosis was observed. Histologically, significantly greater scores for hepatocellular lipid infiltration were recorded for liver sections from hens fed menhaden oil than for control hens. Increased microscopic hepatic lipid infiltration observed with dietary omega-3 administration may have significance for flocks predisposed to fatty liver syndrome and may also provide a unique system in which to study the effects of dietary omega-3 fatty acids on liver lipid metabolism.