BIBC 120 Water Soluble Vitamins
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Where are water-soluble vitamins absorbed?
What do water-soluble vitamins function as?
Which has more potential for toxicity from over consumption: water-soluble or fat-soluble vitamins?
What kind of nutrients are vitamins?
What is the key for vitamin intake?
variety in diet
What must happen to vitamins before they are absorbed?
the proteins that they are bound to must be digested away
What can affect the bioavailability of vitamins?
What is the most important metabolic organ?
What kind of coenzyme is vitamin C?
electron donor coenzyme
What are choline and carnitine?
conditionally essential nutrients
How are vitamins removed from foods?
Vitamins are often removed by processing (ie. milling of grains)
What is the difference between fortified and enriched foods?
- fortified: any addition of nutrients
- enriched: more stringent; must contain FDA specified levels of vitamins; only for grain based foods
For whom can vitamin supplements be beneficial?
pregnant women or when diet omits a large amount of food variety (vegan diet)
Name two water-soluble vitamins
What is Vitamin B12 also known as?
What does vitamin B12 contain?
Where can vitamin B12 only be synthesized?
Vitamin B12 can only be synthesized by bacterial sources - gut microbiota
What is the only source of vitamin B12?
animal dietary sources
What are two good sources of vitamin B12?
liver and clams
What two things does vitamin B12 bind to?
- Intrinsic Factor (IF)
- R protein
Where is Intrinsic Factor secreted from?
parietal cells in gastric pits
IF/B12 complex binds to what?
receptors on brush-border epithelium for transport
What does the R protein do?
protects B12 in stomach
What are the only two reactions involving the coenzyme vitamin B12?
- Methionine metabolism
- Propionate metabolism
What is folate?
Another Vitamin B (B9)
What does tetrahydrafolate (THF) do?
accepts/donates single carbon units in amino acid and nucleotide metabolism
Which step of the creation of methyl-THF is irreversible?
the final step from N5, N10-methylene-THF to N5-methyl-THF
What is the only metabolic chemical reaction that uses methyl-THF?
What are some consequences of Vitamin B12 deficiency?
- pernicious anemia - lack of red blood cells
- no THF available for nucleotide synthesis
- increase in serum levels of homocysteine increases risk for heart disease
What are the consequences of vitamin B12 deficiency in propionate metabolism?
odd chain fatty acid accumulation in phospholipids of neuronal membranes cause neurodegenerative symptoms
What do elderly individuals have a hard time producing?
Which two deficiencies are hard to distinguish and are often treated by supplements of both vitamins?
folate and B12
What does Vitamin C do?
- donor/acceptor of single electrons
- acts as a coenzyme for specific biosynthetic reactions
- donates electron to reduce metal ion cofactors that have donated an electron in the reaction
How is vitamin C "recharged" (reduced)?
dehydroascorbate reductase using glutathione as electron source
Where is vitamin C synthesized?
from glucose in plants
Which two animals can synthesize vitamin C?
rats and chicken
What are two good sources of vitamin C?
sweet red peppers (raw) and orange juice (fresh)
Does vitamin C help to prevent rando oxidative damage in the body from free radicals and peroxides?
efficient at reducing superoxide radicals and hydrogen peroxide in vitro
no evidence yet that vitamin C acts to reduce random oxidative damage in vivo
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