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32 Cards in this Set
- Front
- Back
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Absorption of Water Soluble Vitamins vs Fat Soluble Vitamins |
directly in the blood vs. into the lymph then the blood |
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Transport of Water Sol vs Fat Sol Vitamins |
travel freely vs many require protein carriers |
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In the cells associated with fat |
Storage of Fat Sol Vitamins |
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circulate freely in water-filled parts of the body |
Storage of Water Sol Vitamins |
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kidneys detect then remove excess in urine |
excretion of water soluble vitamins |
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less readily excreted, tend to remain in fat storage sites, some fecal excretion |
excretion of fat soluble vitamins |
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possible to reach toxic levels when consumed from supplements/needed in frequent doses (1-3 days) |
toxicity of WSV/frequency requirements |
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likely to reach toxic levels when consumed from supplements/needed in periodic doses (weeks or months) |
toxicity of FSV/frequency requirements |
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retinoids |
Vit A form that come from animal products include: retinol, retinal, retinoic acid, retinyl ester |
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main form of Vit A in foods |
retinyl palmitate (retinyl ester) |
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carotenoids |
plant form of Vit A (precursor)/can be cleaved centrally to form two molecules of retinal or eccentrically to form different metabolites |
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lycopene, alpha carotene, beta carotene, lutein |
various plant carotenoids |
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retinal dehydrogenase |
enzyme responsible for converting retinal to the active form of Vit A (retinoic acid) |
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retinol dehydrogenase |
converts retinol to retinal |
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retinal reductase |
converts retinal to retinol |
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retinyl ester hydrolase |
converts retinyl ester (storage form of Vit A) to retinol |
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LRAT |
lecithin retinol acyl transferase; catalyze the formation of the storage form of Vit A (retinol -> retinyl ester) |
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Main Functions of Vitamin A |
Plays a role in the vision cycle maintenance of epithelial and mucosal cells immunity bone and tooth development cell differentiation reproduction/pattern forming in embryogenesis |
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Vitamin A and alcohol use
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EtOH competitively inhibits Vit A oxidation to retinoic acid, enhances CYP450 enzymes that catabolize Vit A, alters retinoid homeostasis by increasing Vit A mobilization from liver to extrahepatic tissues |
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Vitamin A Deficiency |
hypovitaminosis A |
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Symptoms of Vitamin A deficiency |
night blindness, total blindness, corneal drying, hardened epithelial cells on the eye, softening of the cornea, corneal degeneration and blindness |
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Vitamin A Toxicity |
hypervitaminosis A large intake of Vit A over a long period of time (eskimos); Vit A analog medications (Accutane, Retin-A) |
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Symptoms of Vitamin A Toxicity |
hair loss, bone and muscle pain, headache, visual impairment, liver damage (most significant and possible permanent); can be teratogenic (spontaneous abortion or birth defects) |
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Energy Releasing B Vitamins |
Thiamin (B1), Riboflavin (B2), Niacin (B3), pantothenic acid, biotin, pyridoxine (B6) |
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Hematopoietic B Vitamins |
Folate, cyanocobalamin (B12), pyridoxine (B6), panthothenic acid
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B vitamin stored in the liver |
cyanocobalamin (B12) |
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Vitamin B6 |
functions in protein and nitrogen metabolism (decarboxylation and transamination rxns); CHO and lipid metabolism, neurotransmitter and heme synthesis, conversion of Trp to Niacin, xtural rearrangement of aa's (racemase) usually Schiff base reactions |
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Best sources of B6 |
fortified cereals, broccoli, tomato juice, banana, watermelon |
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B6 absorption |
must be dephosphorylated to be absorbed absorption occurs via passive diffusion (unique) travels to liver where it is converted to PLP by FMN dependent oxidase (rephosphorylated) |
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B6 Assessments |
static: blood test, serum PLP indirect: measure xanthurenic acid in the urine following Trp load fxnal: measure RBC transaminase activity before and after addition of B6 |
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microcytic hypochromic anemia |
disease caused by B6 deficiency, rate limiting step in heme synthesis is B6 dependent lack of heme = inability to transport O2 |
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Deficiency and Toxicity of B6 |
elderly = at risk group, alcoholism toxicity Sx=neuropathies (UL=100mg/d) |
