Download Biomarkers

University of Turku
Department of Biochemistry
Jukka-Pekka Suomela
Biomarkers
Biomarkers
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…a biochemical indicator of dietary intake/nutritional status
(recent or long term)
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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?
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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
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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
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Whole blood
Plasma/serum
Blood cells
Lipoproteins
Urine
Feces
Hair
Nails
Tissue sample, e.g. fat biopsy
Collection and handling of samples
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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
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Quality assurance is important
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Validity and relevance
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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
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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
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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
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”omics” as a comprehensive approach
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Metabonomics: metabolic response to biological, genetic,
environmental or dietary stimuli are measured
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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
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References
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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.