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.
Level 3 - non-randomized controlled study
Cross-sectional biomarker validation/calibration analysis nested within a randomized controlled trial
PubMed 34864617 · doi:10.1016/j.plefa.2021.102367
What was done
Blood samples from 457 pregnant women participating in a multicenter randomized controlled trial were analyzed using simple linear regression models. The authors developed equations to interconvert the percentages of total n-3 fatty acids, EPA+DHA, and DHA across whole blood, plasma, and red blood cells (RBC), and derived plasma and RBC cut-points corresponding to established whole blood thresholds for low and replete n-3 status.
What was found
Measures of n-3 fatty acid status in whole blood and plasma were strongly related (R^2 > 0.85), whereas correlations were moderate between whole blood and RBC (R^2 = 0.55 to 0.71) and between plasma and RBC (R^2 = 0.55 to 0.63). Established whole blood cut-points for low (<4.2%) and replete (>4.9%) n-3 status converted to <3.7% and >4.3% of total fatty acids in plasma, and <7.3% and >8.1% in RBCs. Agreement was superior between whole blood and plasma compared to RBCs, and total n-3 fatty acids were interchangeable between plasma and serum.
Why it matters
These conversion equations facilitate harmonization across clinical studies utilizing different blood fractions to identify pregnant women with low omega-3 status who may benefit from supplementation to reduce early preterm birth risk.
Limits
The analysis is cross-sectional without reported external validation in an independent cohort. Abstract lacks demographic details and exact gestational timing of sampling. Red blood cell status showed only moderate correlation with whole blood and plasma fractions.
Cited by
- context A red blood cell DHA level of 3% or lower is associated with high risk for preterm birth, whereas levels above 5% are not high risk.