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:

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  linkages between genes, diet, lifestyle and health  Metabonomics: metabolic response to biological, genetic, environmental or dietary stimuli are measured  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: