Chapter 13: Water-Soluble Vitamins

Question 1

What vitamins are water soluble?

Answer 1

B & C

Question 2

How does cooking affect water-soluble vitamins?

Answer 2

cooking destroys vitamins

Question 3

Understand beriberi and thiamin, pellagra and niacin, folate and B12 in anemia, folate and neural
tube defects, and vitamin C and scurvy

Answer 3

beriberi = thiamin deficiency
pellagra = niacin deficiency
anemia = B-12 deficiency
neural tube defects = folate deficiency
scurvy = vitamin C deficiency

Question 4

Thiamin

Answer 4

Sources:
pork product, sunflower seeds, legumes, whole & enriched grains, cereals

formation & absorption:
2 phosphate groups added to form thiamin’s coenzyme thiamin triphosphate (TPP), bond easily destroyed by heat

functions:
coenzyme = thiamin triphosphate (TPP)
required for the metabolism of CHO & BCAA
and normal function of the nervous system

deficiency:
beriberi = peripheral & neuropathy weakness
dry beriberi = symptoms related to the nervous & muscular system
wet beriberi = nervous system & CV system affected
infantile beriberi = breast milk contains insufficent thiamin
wernicke-korsakoff syndrome = found mainly with alc abuse, causes damage to the brain, REM, confusion

Question 5

Riboflavin

Answer 5

sources:
milk, enriched grains, eggs, meat

formation & absorption:
3 linked 6-membered rings w/sugar alcohol attached, exposure to sunlight causes breakdown so food is packaged in paper or plastic, the “yellow enzyme”

function:
forms 2 coenzymes of energy metabolism, involved in the citric acid cycle, beta-oxidation, & electron transport chain

deficiency:
effects mouth, skin, & RBCs
caused by poor diet

NO UPPER LIMIT

Question 6

Niacin

Answer 6

sources:
poultry, meat, fish, enriched grains, mushrooms, peanuts, can be synthesized from tryptophan

functions:
coenzymes participate in oxidation/reduction reactions, required for the metabolism of carbs, fats, protein, & alc

bioavailability = low

deficiency:
pellagra = 4 D’s (dermatitis, diarrhea, dementia, death)

Question 7

Folate

Answer 7

sources:
largest amount and bioavailability in liver, leafy greens, legumes

formation & absorption:
glutamates are hydrolyzed by folate conjugases, distributed through blood, & converted to polyglutamate which “traps” folate in the cell, excreted by the urine, feces, bile

functions:
DNA synthesis, amino acid metabolism, neurotransmitter synthesis, may help maintain blood pressure & reduce the risk of some cancers

deficiency:
megaloblastic (macrocytic) anemia = common before fortification, cells have short lifespan & rapid turnover, DNA cannot divide normally, cells remain large & immature
spina bifida = paralysis, hydrocephalus, learning disabilities
anencephaly = born with no/little brain, die shortly after birth

Question 8

B-12

Answer 8

sources:
bound to protein in food

formation & absorption:
binds to protein in the stomach to aid absorption, stored up to years in the liver or secreted

functions:
formation of methionine from homocysteine, metabolism of some fatty acids

deficiency:
pernicious anemia, macrocytic anemia, neurological changes, elderly, and those with malabsorption at risk

Question 9

Vitamin C

Answer 9

sources:
citrus fruit, peppers, green veg

functions:
electron donor, least stable vitamin, easily lost in storage, process, & cooking, synthesis of collagen, iron absorption, immune function

absorption & formation:
absorbed by active transport & facilitated diffusion in SI,
high concentrations stored in pituitary & adrenal gland, white RBCs, eyes & brain

deficiency:
scurvy = prevents the normal synthesis of vit D, fatigue, pinpoint hemmoraghes, bleeding gums & joints, impaired wound healing