Metabolism - Lecture Twenty-Six Flashcards
Vitamins and Minerals in minor details
How do we know if we get enough vitamins and minerals from the foods we eat?
Clinical examination, anthropometry, biochemical tests and dietary assessment
Clinical examination
Look for symptoms
Anthropometry
Energy balance/growth
Dietary assessment
Measure what you eat (record or recall or questionnaire)
Convert foods into nutrients (food composition database)
Compare with Nutrient Reference Values
Individuals, Groups or National samples
Adult Nutrition Survey, the last one was done 2008/09
Vitamin characteristics
“Vital to life” or “vital amines”
Essential, individual, organic molecules
Do not provide energy when broken down
If absent or low in the diet, symptoms of deficiency appear
Required in the diet in small amounts i.e. μg or mg
Bioavailability = amount absorbed and used
Fat soluble vitamins
Vitamins A, D, E and K
Water soluble vitamins
Vitamin C and all B
B1
Thiamin
B2
Riboflavin
B3
Niacin
B5
Pantothenic acid
B6
Pyridoxine
B7
Biotin (Vitamin H)
B9
Folate (folic acid)
B12
Cobalamin
Roles of vitamins and minerals
Coenzymes, cofactors, structural, antioxidants, DNA/RNA
Coenzymes
Organic carrier molecules
Cofactors
Participate in catalysis
Venous pooling and oedema: heart failure
Beriberi
Cerebral beriberi and psychosis
Wernicke-Korsakoff
Part of co-enzyme thiamin pyrophosphate
Pyruvate ➝ Acetyl CoA
CA cycle
Role in nerve cells
Deficiency in thiamin
Glucose ≠ Energy
Increase in Pyruvate and Lactate: vasodilators
Venous pooling and oedema: heart failure ➝ Beriberi
Cerebral beriberi and psychosis ➝ Wernicke-Korsakoff
Wernicke-Korsakoff
Alcoholics, flour fortified with thiamin in Australia and NZ
Beriberi
‘Polished risk’ (germ and bran removed) provided 80% of energy in Cambodia and diversify diet
Randomised controlled trial
Highest level of evidence
Placebo (control group) vs Treatment
Randomised, Double Blind
Outcomes (biochemical, clinical, diet)
Minerals
Essential, non-organic elements
Do not provide energy
If absent or low in the diet, symptoms of deficiency may appear
Required in the diet in small amounts i.e. μg or mg
Bioavailability = amount absorbed and used
Roles of minerals
Cofactors Structural role Key constituent of Molecules Transfer of electrons Nerve impulse and muscle contraction Fluid and electrolyte balance
Transfer of electrons
Oxidation:reduction reactions
Structural role
Hydroxyapatite crystal: Ca5(PO4)3(OH)
Magnesium deficiency
Cofactor >300 enzymes involved in myraid of cellular processes
Stabilises proteins, nucleic acids, membranes
Electrolyte
Bone metabolism and remodelling
Nerve impulse and muscle contraction
Cofactor >300 enzymes involved in myraid of cellular processes
Chelates to ATP (kinases)
Enzymes requiring water, acts as carrier
CHO metabolism (glycolysis, glucose homeostasis, insulin action)
Lipid, protein and nucleic acid synthesis