Translating n-3 polyunsaturated fatty acid status from whole blood to plasma and red blood cells during pregnancy: Translating n-3 status across blood fractions in pregnancy

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Women with low n-3 (omega-3) status in pregnancy can reduce their risk of early preterm birth (<34 weeks’ gestation) through n-3 long chain polyunsaturated fatty acid (LCPUFA) supplementation. As investigators measure fatty acid status in different blood fractions, equations are needed to compare results across studies. Similarly, derived cut-points for defining low and replete n-3 status are needed to assist clinical interpretation during early pregnancy. Our aims were to develop equations to convert the percentage of total n-3 fatty acids, EPA+DHA and DHA between whole blood, plasma and red blood cells (RBC), and to derive cut-points for defining low and replete total n-3 fatty acid status in plasma and RBC from those already established in whole blood. Using blood samples from 457 pregnant women in a multicentre randomised controlled trial, equations for these interconversions were developed using simple linear regression models. Measures of n-3 fatty acid status in whole blood and plasma were strongly related (R2 > 0.85), while more moderate relationships were observed between measures in whole blood and RBC (R2 0.55 – 0.71), or plasma and RBC (R2 0.55 – 0.63). Using the conversion equations, established cut-points for low and replete n-3 status in whole blood (<4.2% and >4.9% of total fatty acids) converted to <3.7% and >4.3% of plasma total fatty acids, and to <7.3% and >8.1% of RBC total fatty acids. Agreement to define low and replete n-3 status was better between whole blood and plasma, rather than between whole blood and RBC. Our data also show that total n-3 fatty acids in plasma and serum are interchangeable. We conclude that either whole blood or plasma total n-3 fatty acids can be used to define low status in pregnancy and identify women who will most benefit from n-3 LCPUFA supplementation to reduce their risk of early birth. Further research is needed to determine the clinical utility of other fatty acid measures in various blood lipid fractions.

Original languageEnglish
Article number102367
JournalProstaglandins Leukotrienes and Essential Fatty Acids
Publication statusPublished or Issued - Jan 2022


  • Blood fraction conversions
  • Docosahexaenoic acid
  • Early preterm birth
  • Pregnancy
  • Total n-3 fatty acids

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology

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