NUTR100 Lecture Notes - Lecture 12: Neural Tube Defect, Megaloblastic Anemia, Folate Deficiency
13 Jun 2018
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Chapter 8 Part 2
- Folate or Folic Acid
o Facilitates transfers a methyl group between different compounds
o When it facilitates transport of single carbons, ensures replication of DNA is
possible
o Needed for synthesis of some amino acids
o Important for growth of new cells
o Deficiency:
▪ Anemia(macrocyctic anemia)also megaloblastic anemia: large immature
red blood cells because hemoglobin synthesis is not impaired, impaired
division of cells, prevents proper formation of red blood cells
• Red cell precursors unable to divide
▪ Low folate intake in early pregnancy is associated with an increased risk
of neural tube defects
• Spino bifida may occur more frequently
• Low folate may prohibited which genes are switched on and off in
a cell
• DNA methylation forms spino bifida
▪ Low folate intake has been associated with an increased risk of heart
disease and cancer
o 1998 folic acid added to white flour, pasta and cornmeal
▪ has decreased neural tube defects
▪ may have led to increased cancer risk
o Sources: leafy green veggies, oranges, legumes, seeds, organ meats, eggs,
enriched flour
o At least 400mg of folate a day for pregnant women
- Vitamin B12(cobalamin) cobalt forms
o Necessary for proper absorption of iron in the body
▪ Nerve functioning
▪ Synthesis of hemoglobin and DNA(single carbon metabolism)
▪ Breaks down fatty acids with odd number of carbons(rare)
▪ High intake of supplemental folic acid can mask B12 deficiencies
▪ Complex absorption
o Absorption
▪ Requires healthy stomach, pancreas, small intestine
▪ B12 is bound to proteins in food
▪ Released in stomach by acid
▪ In small intestine, B12 will bind to intrinsic factor(protein secreted by
stomach)
▪ Absorbed by small intestine, only small amount can be absorbed if no
intrinsic factor
▪ B12 is secreted in bile, but is reabsorbed again
o Deficiency:
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