biomarker causality cell signaling chromatography dna microarray dietary mineral epidemiology exon folic acid functional food gas-liquid chromatography gel electrophoresis gene gene expression gene product genetic predisposition genetic variability genetics genome genomics genotyping health health intervention high-throughput screening homeostasis leptin magnetic resonance imaging mass spectrometry metabolome metabolomics molecular biology nutrition nutritional genomics obesity overnutrition physiology protein expression proteome proteomics public health relevance research sensory ecology single nucleotide polymorphism susceptible individual