Serum Linoleic Acid Status as a Clinical Indicator of Essential Fatty Acid Status in Children With Cystic Fibrosis

Abstract

Children with cystic fibrosis (CF) and pancreatic insufficiency (PI) are at increased risk for essential fatty acid (EFA) deficiency. To investigate serum markers of EFA status in children with CF and PI and their association with growth, body composition, and lung function. Serum phospholipid fatty acid, growth, and forced expiratory volume at 1 second (FEV1, percentage predicted) status were assessed at baseline and 12 months in 77 children with CF and PI, 7 to 10 years old. Longitudinal mixed-effects models were used to compare associations of the triene:tetraene ratio (ratio of eicosatrienoic acid to arachidonic acid) and serum linoleic acid (as a molar percentage of total serum phospholipid fatty acids, or mol%) with the clinical outcomes. Controls for serum fatty acid were 23 healthy white age- and sex-matched children. Children with CF and PI had higher median triene:tetraene ratio and lower linoleic acid than healthy controls. Depending on the triene:tetraene ratio cutoff point used (0.04 or 0.02), either 17% or 52% of the children with CF had EFA deficiency, respectively. Only linoleic acid was significantly and positively associated with z scores for weight, height, body mass index, upper arm muscle area, and FEV1 at baseline. Children with linoleic acid at 21 mol% or higher had significantly better growth and pulmonary status than those with lower concentrations. Serum phospholipid linoleic acid at 21 mol% or higher was associated with better growth, body composition, and FEV1. No clinical outcome associations were found with the triene:tetraene ratio. These findings suggest that linoleic acid concentration was a more clinically relevant biomarker of EFA status than the triene:tetraene ratio in children with CF and PI. Further research is warranted to validate this specific percentage of linoleic acid cutoff point as a new recommendation for clinical use.