Term
| What happens in the early stage of renal failure? |
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Definition
production of calcitriol in kidney is inadequate so there is inadequate calcium absorption in the intestine
--> Vit D deficiency |
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Term
| What happens in the later stage of renal failure? |
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Definition
-no production of calcitriol
-renal retention of phosphate (hyperphosphatemia - can be treated by oral antacids that bind phosphate & block uptake) --> further lowers calcium and further increases PTH --> hyperparathyroidism (severe cases require IV calcitriol administration) |
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Term
| How are synthetic tocopherols different from natural ones? |
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Definition
Synthetic tocopherols are racemic mixtures of 8 stereoisomers while natural is a single stereoisomer
-Vit E is produced by plants and does not accumulate in animals |
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Term
| What are the functions of Vitamin E? |
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Definition
-HYDROPHOBIC, CHEMICAL ANTI-OXIDANT
-scavenges free radicals and prevents oxidation of PUFA (function only once)
possible other functions:
-in mitochondrial e- transport
-in porphyrin (heme) synthesis
-maintain immune system
-may help prevent atherosclerosis, macular degeneration, and cognitive decline in the elderly |
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Term
| What are symptoms of Vit E deficiency? |
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Definition
| Neurological problems (poor nerve conduction) and anemia. Only seen in patients/infants on completely synthetic diets |
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Term
| What is 1 IU of Vitamin E equivalent to? What is RDA of Vitamin E? |
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Definition
1 IU = 2/3 mg natural a-tocopherol
(However 1 mg synthetic = 0.45mg of natural a-tocopherol)
RDA = 15 mg/day
Upper limit = 1000mg/day (one of least toxic fat-soluble vitamins, but not recommended in pregnant/nursing women) |
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Term
| Which vitamin is known as the "coagulation vitamin"? |
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Definition
Vitamin K
Chicks in Vit K deficient mothers developed hemorrhages and bled |
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Term
| Where does Vit K1 come from? |
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Definition
aka PHYLLOQUINONE or PHYTYLMENAQUINONE
-comes from green leaf vegetables |
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Term
| Where does Vit K2 come from? |
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Definition
aka MENAQUINONE
-comes from enteric bacteria |
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Term
| What is the function of Vit K? |
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Definition
| Vitamin K is an essential coenzyme in the conversion of glutamate to y-Carboxyglutamate |
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Term
| What inhibits Vit K reduction? |
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Definition
Dicoumarols:
1. 4-hydroxycoumarin (smell of cut grass)
2. Warfarin (coumadin - an anti-coagulant and rat poisoning) |
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Term
| What are the symptoms of Vit K deficiency? |
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Definition
-slower blood clotting time (rare and never due to dietary deficiency - seen with malabsorption, long term antibiotics, bulimics, and newborns)
-hemorrhaging
-low bone density |
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Term
| What is the RDA of Vit K? |
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Definition
Males: 120 ug/day
Females: 90 ug/day |
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Term
| Why do infants often have Vitamin K deficiencies? What can be done to prevent this? |
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Definition
Common in infants because
1. vitamin K does not cross the placenta very well
2. the newborn's large intestine is sterile and takes several days to become colonized with bacteria that produce Vit K
-In US, all newborns are given and injection of vit K just after birth to prevent this |
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Term
| How do anticonvulsant drugs affect nutrient demands? |
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Definition
Long term anticonvulsant therapy (diphenylhydantoin) increases the needs for Vit D, K B6, and folate
no vit D --> hypocalcemia and some bone mineral loss
no vit K --> higher risk of infant hemorrhagic disease in pregnant women
no folate --> megaloblastic anemia |
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Term
| Compared to fat soluble vitamins, water soluble vitamins: |
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Definition
-don't partition into fat or cell membranes
-don't accumulate as much in the body
-have smaller stores so deficiency symptoms appear faster
-toxicity is rare and always due to hyper supplementation
-active forms are always coenzymes
-sufficiency can be assayed via RBC enzyme activity vs. without active form of vitamin |
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Term
| What are the classes of water soluble vitamins? |
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Definition
-B vit involved in metabolic generation of energy
-B vitamins involved in blood formation
-Vit C
-carnitine and choline |
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Term
| Which B vit funtions in the mitochondrial ETS? |
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Definition
B2 - riboflavin
active forms: FMN and FAD |
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Term
| Which B Vit functions as a redox cosubstrate? |
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Definition
B3 - niacin
active forms: NAD and NADP |
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Term
| Which B Vit funtions in the TCA cycle and FA metabolism? |
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Definition
B5 - pantothenic acid
CoA and FAS |
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Term
| Which B Vit is used pharmacologically to decrease LDL and TGs and increase HDL? |
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Definition
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Term
| What are the three nutritional impairments of alcoholics? |
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Definition
1) chronically poor diet - diet consits mostly of alcohol
2) alcohol induced pathology of GI tract (impaired absorption)
3) liver damage (impairs metabolism of vitamins and other nutrients) |
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Term
| What are the most common nutritional issues with hospitalized alcoholics (>30%)? |
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Definition
1. Megaloblastic anemia (folate)
2. sideroblastic anemia (B6)
3. Peripheral neuropathy (B6)
4. Lower bone density (D) |
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Term
| Describe the relationship between Vit B6 and Oral Contraceptives |
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Definition
-Normally vit B6 can be quantified based on how much xanthourenic acid is in the urine (via a tryptophan test; high xanthourenic = B6 deficient)
-Oral contraceptive users showed very low B6 by this method
- this was an error: estrogen metabolites inhbited an enzyme in the major pathway
-however, oral contraceptive use does cause 2x increased B6 need |
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Term
| What are the effects of folate deficiency? |
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Definition
-decreased synthesis of dTMP and purines --> inhibits DNA synthesis in bone marrow --> S-phase inhibition of RBS precursor cells giving them a "megaloblastic" appearance --> these produce larger RBCs that have fragile membranes --> anemia
-folate deficiency during pregnancy increases the risk of neural tube defects |
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