OBJECTIVES: We conducted a pilot study to estimate the biological variability and effects of a prior meal on the omega-3 fatty acid (FA) content of 3 blood FA pools.

DESIGN AND METHODS: We measured FA levels in red blood cells (RBCs), plasma and plasma phospholipids (PL) obtained from 20 healthy volunteers tested weekly over 6 weeks.

RESULTS: The within-subject coefficients of variation were 4.1%+/-1.9%, 15.9%+/-6.4%, and 14.5%+/-8.4%, respectively (RBC vs. others, p<0.001). RBC omega-3 FA content had the lowest biological variability and was not altered in the fed state.

CONCLUSIONS: From the perspective of variability and of the sample types tested, RBCs may be the preferred sample type for assessing omega-3 FA status.