Minerals Flashcards
B9 Functions
- Folate
- Precursor of tetrahydrofolate, coenzyme involved in generating precursors for DNA and protein synthesis
B9 Deficiency
- Folate
- Neural tube defects
- Macrocytic anemia
- Hyperhomocysteinemia
- Decreases availability of purines and dTMP inhibiting DNA synthesis
B12 Function
- Cobalamin
- Coenzyme in methionine synthesis and in conversion of methylmalonyl CoA to succinyl CoA
- Folate metabolism
B12 Deficiency
- Cobalamin
- Pernicious anemia (megaloblastic anemia with demyelination
- Can arise from deficiency in intrinsic factor
- Can be stored efficiently in liver
Absorption of B12
- Released from protein by acid hydrolysis in stomach
- Then binds to intrinsic factor to be absorbed by ileum
B9/B12 connection
-In the absence of vitamin B12, B9 becomes trapped in a form that cannot be used for purine and dTMP synthesis
Cause of macrocytic anemias
- Deficiency in nucleotides leads to decreased DNA and RNA synthesis
- Cells increase in size without dividing
- Do not carry sufficient oxygen
Pernicious anemia
-Lack of intrinsic factor
Macrominerals important for fluid homeostasis
-Potassium, sodium, chloride
Calcium function
-Bone, signaling, coagulation, muscle contraction, neurotransmission
Calcium deficiency
-Muscle cramps, osteoporosis, rickets
Calcium distribution in the body
- 98% is in bone and teeth in the form of hydroxyapatite
- Bone is the body’s calcium reservoir
- 2% is in the rest of the body
Magnesium functions
- Essential for enzymes that use MgATP as substrate
- Present at high levels in bone, required for formation
Magnesium deficiency
- Weakness, tremors, cardiac arrhythmia
- Required for many transporters that requires MgATP or MgADP as substrate.
Phosphorus functions
- Mostly present in phosphates
- Major component of bone (hydroxyapatite)
- Part of nucleic acids, membrane lipids
- Required in all energy-producing reactions
Phosphorus deficiency
- Rare
- Rickets, muscle weakness, muscle breakdown, seizure
Iron functions
- O2/CO2 transport in hemoglobin
- Oxidative phosphorylation
- Cofactor in several nonheme iron proteins and cytochromes
Iron deficiency
- Microcytic anemia
- Decreased immunity
Reduction of iron
- Fe3 reduced to Fe2 by vitamin C
- Low pH released Fe3 from ligands
- Usually bound to carriers
Two major barriers of iron absorption
- Release of Fe3 from food
- Availability of reducing agent to convert Fe3 to Fe2
Transferrin
-Iron transport
Ferritin
-Iron storage
Hepcidin
- Signals iron sufficiency
- Prevents export of Fe2 from the duodenal mucosal cell by downregulating the exporter
Iron toxicity
- Long term: hemochromatosis- iron overload leads to iron deposits in tissues and lactic acidosis due to compromised mitochondrial function
- Acute: iron overdose in children
- Can replace other metals in reactions
Copper functions
- Assists iron absorption through ceruloplasmin
- Cofactor for enzymes required in collagen synthesis, FA metabolism, and elimination of ROS
- Helps iron bind transferrin for distribution
Copper deficiency
- Rare
- Anemia, hypercholesterolemia, fragility of large arteries, bone demineralization, demyelination
- Menkes’ syndrome or consuming zinc makes patients more susceptible
Menkes disease
- Mutations in Cu transporter ATP7A
- Presents as a copper-deficiency disorder
- Many enzymes secreted without copper
Wilson’s disease
- Mutations in ATP7B
- Results in copper overload
- Liver failure and liver cancer
Zinc function
- Cofactor for over 300 metalloenzymes
- Structural role in many proteins (zinc fingers)
Zinc deficiency
-Poor wound healing, dermatitis, reduced taste acuity, poor growth, impaired sexual development in children
Chromium function
-Component of chromodulin: facilitates insulin binding to its receptor
Chromium deficiency
-Impaired glucose tolerance
Iodine function
- Incorporated into T3 and T4
- Regulates basal metabolic rate
Iodine deficiency
- Goiter
- Hyperthyroidism or hypothyroidism
Selenium function
- Component of antioxidant enzymes (glutathione peroxidase)
- Component of deiodinase enzymes involved in T3 and T4 metabolism
Selenium deficiency
-Keshan disease: in areas with little selenium in soil
