Whole blood long-chain n-3 fatty acids as a measure of fish oil compliance in children with acute lymphoblastic leukemia: a pilot study

•Fish oil supplementation is feasible in children with acute lymphoblastic leukemia.•Reported intake of n-3 LCPUFA reflects the relative content in whole blood.•Intake-biomarker correlations were disrupted when expressed in absolute concentrations and intake per kg bodyweight.•Whole blood n-3 LCPUFA response did not appear to be affected by blood transfusions and differences in bodyweight.