2.6. Serum Fatty Acid Measurements and Primary/Secondary Outcomes
BLOOD
Blood was collected from the infants at 5–6 months of age, prior to the introduction of solid foods. In the ABC trial, 25-hydroxyvitamin D, total IgE, and antigen-specific IgE levels were measured. If sufficient residual serum samples were available, they were utilized to measure the composition of 24 serum fatty acids. The serum samples were stored at −80 °C and sent to Standard Reference Laboratory Inc. (Tokyo, Japan) for analysis. The concentration of each fatty acid was measured by gas chromatography-mass spectrometry using a calibration curve method and expressed as the weight percentage of total fatty acids [