DNA extraction
DNA was extracted from a single buffy coat extract per seAFOod trial participant using an in-house phenol-chloroform method, followed by washing with absolute ethanol and storage at 4°C in DNase/RNase-free water, prior to spectrophotometric assessment of the DNA quantity and quality. If any sample had a DNA yield <20 ng/μL, a second sample for that individual was obtained from the Biobank for DNA extraction.