vitamins Flashcards
Vitamin A functions
vision (rhodopsin), immunity, growth
Vitamin A sources
preformed = animal products, proformed = red/orange/ yellow plants (tomatoes, sweet potatoes, cantaloupe) & dark green leafy veggies (spinach)
Vitamin A deficiency
eye problems (night blindness, xerosis, xeropthalmia, Bitot's spots) #1 nutritional deficiency worldwide
Vitamin A toxicity
dry skin, bone pain, hair loss
Vitamin D(calciferol) functions
prohormone, calcium & phosphorus absorptio
Vitamin D sources
D3 (cholecalciferol) = fortified dairy, fatty fish
Hydroxylated in liver and kidneys to fully activate as calcitriol
Vitamin D Deficiency
rickets, autoimmune disease
Vitamin D toxicity
hypercalcemia
Vitamin D RDA
RDA: <1 = 400 IU/d; 1-70 years = 600 IU/d; >70 = 800 IU/d
Vitamin E (Tocopherol) functions
antioxidant in plasma membrane
Vitamin E sources
nuts & seeds, vegetable oils, olive oil, peanut butter
Vitamin E deficiency
hemolytic anemia in infants, peripheral neuropathy
Vitamin E toxicity
No known toxicity from foods; supplements may thin the blood
Vitamin K (Phylloquinone & Menaquinone) functions
Formation of carboxyglutamates in clotting (fibrinogen
pathway) and bone formation (osteocalcin)
Carboxyglutamates are calcium-binding sites
Vitamin K sources
phylloquinone = dark green leafy veggies; menaquinone =
meat, eggs, made by gut bacteria
Vitamin K Deficiency
increased blood loss due to lack of clotting
Shots of vitamin K are given to infants at birth to prevent vitamin
K-associated bleeding in the brain
Vitamin K toxicity
none
Vitamin C (Ascorbic acid) functions
antioxidant (regenerates vitamin E), required for collagen
synthesis (formation of hydroxyproline & hydroxylysine), nonheme
iron absorption
vitamin C sources
citrus fruits, peppers
Vitamin C Deficiency
scurvy
Vitamin C Toxicity
Diarrhea
Vitamin C RDA
Smokers require more than average
Thiamin (B1) Functions
coenzyme (thiamin pyrophosphate, TPP or TDP);
noncoenzyme (thiamin triphosphate; TTP) required by nervous system
Thiamin sources
enriched grains, meats, legumes
Raw fish contain thiamin-degrading enzymes
Thiamin Deficiency
fatigue, weakness, beriberi, Wernicke's encephalopathy in alcoholics Acute beriberi in infants - edema Wet beriberi in adults - edema Dry beriberi in older patients - muscle weakness, calf pain, difficulty walking
Thiamin Toxicity
none
Riboflavin (B2) functions
coenzyme (FAD & FMN) in Kreb’s & ETC, niacin
synthesis (used by dehydrogenases)
Riboflavin sources
milk, enriched grains, organ meats
Riboflavin deficiency
Ariboflavinosis = magenta tongue, glossitis, cheilosis,
angular stomatitis
Riboflavin toxicity
none
Niacin(B3) functions
coenzyme (NAD & NADPH)
NAD = used by dehydrogenases
NADPH = building pathways, lipid & cholesterol synthesis, fatty
acid elongation
Niacin sources
meat, fish, enriched grains
Synthesis from tryptophan requires riboflavin, B6 & iron
Niacin deficiency
Pellagra (4 D’s: dermatitis, diarrhea, dementia, death)
Niacin toxicity
supplements can cause flushing (hot flashes)
Pantothenic Acid (B5)
part of Coenzyme A (CoA) & acyl carrier protein (ACP)
Metabolism of carbs, lipids & proteins
Synthesis of fatty acids, cholesterol, steroid hormones,
hemoglobin, acetylcholine, melatonin
Pantothenic acid sources
widespread
Pantothenic acid deficiency
not common, Burning Feet Syndrome
Pantothenic acid toxicity
none
Biotin (B7) Functions
coenzyme for carboxylases
FA synthesis, gluconeogensis
Bitotin sources
liver, cooked eggs, soy, non-wheat cereals, meat,
tomatoes
Egg whites contain a biotin-binder called avidin
Biotin deficiency
birth defects, alopecia, fatigue
Biotin Toxicity
none
Choline Functions
cellular integrity as part of phosphatidyl choline
(lecithin), part of lipoproteins & acetylcholine
Choline sources
soy, milk, eggs, peanuts
Choline deficiency
liver & muscle damage, neural tube defects
Choline toxicty
decreased growth, fishy body odor, excessive sweating & salivation
pyridoxine (B6) functions
coenzyme (pyridoxal phosphate, PLP) for amino acid
metabolism, synthesis of: niacin, collagen, carnitine, heme, sphingomyelin
pyridoxine sources
meats, enriched grains
pyridoxine deficiency
peripheral neuropathy, microcytic hypochromic anemia
because it’s required for heme synthesis
pyridoxine toxicity
peripheral neuropathy
folate (B9) functions
methylation reactions (1 carbon metabolism) in DNA synthesis and cell replication
folate sources
dark green leafy veggies (spinach, kale), legumes (beans);
folic acid is synthetic form in supplements and fortified food
Digestion of folate requires zinc-dependent conjugase enzyme in
the SI
folate deficiency
neural tube defects, megaloblastic macrocytic anemia
folate toxicity
folic acid supplements can mask a B12 deficiency causing
permanent nerve damage
Cobalamin (B12) functions
coenzyme
Methylcobalamin = formation of S-adenosylmethionine required
for myelination
Adenosylcobalamin = amino acid metabolism
Cobalamin sources
meats
B12 requires intrinsic factor secreted from gastric parietal cells to
be absorbed
cobalamin deficiency
megaloblastic macrocytic anemia, peripheral
neuropathy
cobalamin toxicity
none