Biomarkers Flashcards
Biomarkers
Any biological specimen that is an indicator of nutritional status with respect to intake or metabolism of dietary components
Biochemical assessment
Uses lavatory measurements of serum protein, serum lipids, serum glucose and serum micronutrient levels to assess general nutritional status and to identify specific nutritional deficiencies
Short term markers
Respond to dietary intake within hours
Medium term markers
Respond over weeks or months
Long term markers
Large scale epidemiological studies
Eg adipose tissue toenail or hair sample
Serum and Plasma Specimens
Reflect short term intake from a few days to one month
Erythrocytes
Reflect longer term intake due to their half life of about 120 days
Adipose tissue
Reflects long term intake
More useful to assess exposure to fat soluble vitamins
Urine
Reflects short term intake
Samples collected can be 24hr overnight or spot
Suitable for recovery Biomarkers
Inconvenient
Hair and Nails
Easy to store and collect
May be affected by environment particularly hair
Faeces
Difficult to collect
Burdensome el
Assesses gut micro biome
Relevant to colon cancer
Plasma Biomarkers
Fasting blood glucose
Indicator of diabetes
Must be repeated to ensure no false positive
3.9-5.4
5.4-6.9
7.0+
Glycated Haemoglobin
An indicator of average blood sugar level for three months
Percentage of blood sugar attached to oxygen carrying protein haemoglobin
Biomarkers are influenced by
Disease status
Age
Genetics
Environmental factors
Choice of specimens
Total Iron content assessment
Useing mccance and windows on food composition tables
Estimate harm by dividing type specific iron by total iron
Beef/lamb 65%
Serum iron
Essentially transferrin bound iron with the amount in circulation being a function of iron availability and transferrin levels
Total iron binding capacity
Two iron binding sites per transferrin molecule
Indirect measure of transferrin
Usually higher when iron levels are low
Transferrin saturation
Ratio of serum to TIBC
Measures proportion of transferrin bound to iron
More useful indicator of iron status
Normal levels between 20-50%
Ferritin
Iron without cells is stored complexed in these proteins
Measure of iron stores
Carbon reactive protein
CRP
Subjects with raised values above 10mg/l show acute inflammation
Toenail iron analysis
University of Missouri
Shows a nutritional status for 12 months or more previously
Metabolomics
Measuring a large number of low weight metabolites including essential amino acids and molecules not synthesised by the human body
Epigenetics
DNA methylation reflecting intake of methyl donors and b Vito taking part in key methylation cycle
Proteomics
Potential reflection of functional markers
