Serum n-6 and n-9 Fatty Acids Correlate With Serum IGF-1 and Growth Up to 4 Months of Age in Healthy Infants

The aim of this study was to study the relationship between insulin-like growth factor-1 (IGF-1), serum phospholipid fatty acids, and growth in healthy full-term newborns during infancy.Prospective observational study of a population-based Swedish cohort comprising 126 healthy, term infants investigating cord blood and serum at 2 days and 4 months of age for IGF-1 and phospholipid fatty acid profile and breast milk for fatty acids at 2 days and 4 months, compared with anthropometric measurements (standard deviation scores).At all time-points arachidonic acid (AA) was negatively associated with IGF-1. IGF-1 had positive associations with linoleic acid (LA) at 2 days and 4 months and mead acid (MA) showed positive associations in cord blood. Multiple regression analyses adjusted for maternal factors (body mass index, weight gain, smoking, education), sex, birth weight and feeding modality confirmed a negative association for the ratio AA/LA to IGF-1. MA in cord blood correlated to birth size. Changes in the ratios of n-6/n-3 and AA/docosahexaenoic acid from day 2 to 4 months together with infants' weight and feeding modality determined 55% of the variability of delta-IGF-1. Breast-fed infants at 4 months had lower IGF-1 correlating with lower LA and higher AA concentrations, which in girls correlated with lower weight gain from birth to 4 months of age.Our data showed interaction of n-6 fatty acids with IGF-1 during the first 4 months of life, and an association between MA and birth size when adjusted for confounding factors. Further follow-up may indicate whether these correlations are associated with later body composition.