Transcript Biomarkers
University of Turku Department of Biochemistry Jukka-Pekka Suomela Biomarkers Biomarkers …a biochemical indicator of dietary intake/nutritional status (recent or long term) can be used to complement/replace methods of dietary intake measurements …or an index of nutrient metabolism …or a marker of the biological consequences of dietary intake Biomarkers Diplock et al. Scientific concepts of functional foods in Europe: Consensus document. British Journal of Nutrition 1999; 81: S1-S27. Does a biomarker correlate with nutrient intake? Nutrient itself (e.g. fat-soluble (storage) vs. water-soluble vitamins) Genetic factors Variation in life style and physiological factors Nutrient intake related factors Sample type, taking and handling of samples Analytical methods Example: vitamin A Retinol concentration in the serum does not reflect the intake because the concentration is regulated by retinol storages and carrier protein levels in the liver Beta-carotene in serum is a fair indicator of the intake of vitamin A Sample types Whole blood Plasma/serum Blood cells Lipoproteins Urine Feces Hair Nails Tissue sample, e.g. fat biopsy Collection and handling of samples Fasting/postprandial specimen Time of sample collection, possible time points Instruments for sample collection Sample handling Marking and coding of the samples Storage (temperature, timeperiod) Analytical methods Quality assurance is important Validity and relevance Need for validation of the measurement techniques Information on sensitivity, specificity, and reproducibility needed Biological relevance: biomarkers need to be clearly linked to the phenomena involved in the biological process being studied Genes and diet Jenab M. et al. Hum Genet 125: 507-525 Genes and diet Genetic variation, gene–diet/nutrient ineractions and gene– gene interactions individual differences in response to diet and in the measurable level of the biomarker nutrigenetics: study of how genetic disposition affects response to diet and its components nutrigenomics: study of how diet influences gene transcription, protein expression and metabolism Utilization of biomarkers and search for novel ones E.g. links between fruits/vegetables and cancer is not strong – true or caused by errors in measurement? Should biomarkers be utilized more? Novel biomarkers are needed Profiling of novel biomarkers ”omics” as a comprehensive approach Metabonomics: metabolic response to biological, genetic, environmental or dietary stimuli are measured linkages between genes, diet, lifestyle and health e.g. utilization of metabolic profiles to measure dietary intake, dietary changes, or the efficiency of dietary interventions certain ”metabonomic profiles” as biomarkers? Metabolomics: comprehensive analysis of all measurable metabolite concentrations under a given set of conditions also: transcriptomics, proteomics, lipidomics… Profiling of novel biomarkers Biomarkers References Diplock et al. Scientific concepts of functional foods in Europe: Consensus document. British Journal of Nutrition 1999; 81: S1-S27. Jenab M. et al. Biomarkers in nutritional epidemiology: applications, needs and new horizons. Hum Genet 2009; 125: 507-525.