Research: BROWNING and COLLEAGUES,

Listed in Issue 221

Abstract

BROWNING and COLLEAGUES, Medical Research Council Human Nutrition Research, Cambridge, United Kingdom explored whether there are differences in the short-, medium-, and long-term incorporation of EPA and DHA into blood plasma and cells.

Background

Consumption of oily fish is sporadic, whereas controlled intervention studies of n-3 (ω-3) fatty acids usually provide capsules containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as a daily dose. This methodologic study explored whether there are differences in the short-, medium-, and long-term incorporation of EPA and DHA into blood plasma and cells with the provision of identical amounts of EPA and DHA, equivalent to 2 oily fish servings per week (or 6.54 g/wk EPA and DHA), either intermittently (i.e., 1 portion twice per week) or continuously (i.e., divided into daily amounts).

Methodology

The study was part of a randomized, double-blind controlled intervention lasting 12 mo, with participants stratified by age and sex. There were 5 intervention groups, 2 of which are reported here: the 2 intermittent portions (2I) and 2 continuous portions (2C) groups. EPA and DHA were measured in plasma phosphatidylcholine, platelets, and blood mononuclear cells (MNCs) at 9 time points. Sixty-five participants completed the study (2I group, n = 30, mean age of 49.2 y; 2C group, n = 35, mean age of 50.6 y).

Results

The incorporation pattern over the 12-mo intervention was different between the 2 groups in all samples (P < 0.0001, time × treatment interaction). At the end of the 12-mo intervention, the 2C group had higher EPA, DHA, and EPA + DHA in platelets (all P < 0.01) and higher EPA and EPA + DHA in MNCs (both P < 0.05) compared with the 2I group. No significant differences were shown for plasma phosphatidylcholine EPA (P = 0.1), DHA (P = 0.15), EPA + DHA (P = 0.07), or MNC DHA (P = 0.06).

Conclusion

In conclusion, the pattern of consumption does affect the incorporation of EPA and DHA into cells used as biomarkers of intake. The differences identified here need to be considered in the design of studies and when extrapolating results from continuous capsule-based intervention studies to dietary guidelines for oily fish consumption. This trial was registered at www.controlled-trials.com as ISRCTN48398526.

References

Browning LM, Walker CG, Mander AP, West AL, Gambell J, Madden J, Calder PC, Jebb SA. Compared with daily, weekly n-3 PUFA intake affects the incorporation of eicosapentaenoic acid and docosahexaenoic acid into platelets and mononuclear cells in humans. J Nutr. 2014 May;144(5):667-72. doi: 10.3945/jn.113.186346. Epub. Mar 19 2014.

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