Human milk fatty acids from lactating mothers of preterm infants: A study revealing wide intra- and inter-individual variation

Docosahexaenoic acid (DHA) and arachidonic acid (AA) are important nutrients in the preterm diet and fixed ratios have been proposed for formula. We evaluated the intra- and inter-individual variation in milk fatty acids from mothers of preterm infants involved in a randomised trial of tuna oil or placebo supplementation. Milk samples were collected every 2 weeks while infants were hospitalised and fatty acids analysed by capillary gas chromatography. DHA was higher in milk of supplemented mothers than control (% total fatty acids, mean±SD, treatment 0.9±0.4, control 0.3±0.1, p<0.0005) and ranged between 0.3-2.5% and 0.1-1.1%, respectively. AA did not differ between groups and ranged between 0.2-0.9% and 0.3-0.9%, respectively. Control mothers milk had wider AA:DHA ratio than treatment mothers (0.4-3.2 versus 0.2-2.1). Due to the wide variation in milk AA and DHA, statements recommending infant formula based on a fixed AA:DHA ratio should be re-examined.