Biochemistry First Aid- Nutrition (91-97) Flashcards by Tsion Aberra

which vitamins are fat soluble

A, D, E, K

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why do fat soluble vitamins have a higher risk of toxicity than water soluble

they accumulate in fat in the body tissues

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what kinds of conditions can lead to deficiencies of fat soluble vitamins

malabsorption due to steatorrhea (e.g. caused by CF or sprue), mineral oil intake

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list the water soluble vitamins (and their names)

B1=thiamine, B2=riboflavin, B3=niacin, B5=pantothenic acid, B6=pyridoxine, B7=biotin, B9= folate, B12= cobalamin
C= ascorbic acid

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which water soluble vitamins don’t easily wash out of the body

cobalamin (B12) and folate (B9), which are stored in the liver

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what illnesses commonly result from B complex (multiple B vitamin) deficiencies

dermatitis, glossitis, diarrhea

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what is vitamin A called and what does it do

retinol:

antioxidant, visual pigments (retinal), important for specialization of epithelial cells, prevents squamous metaplasia

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vitamin A is used to treat what conditions

measles and AML subtype M3

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what does vitamin A deficiency cause

night blindness (nyctalopia), dry scaly skin (xerosis cutis), alopecia, corneal degeneration (keratomalacia), immune suppression

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what is caused by excess vitamin A

arthralgias, skin changes (scaliness), alopecia, cerebral edema, pseudotumor cerebri (idiopathic intracranial hypertension), osteoporosis, hepatic abnormalities, teratogenic (cleft palate, cardiac abnormalities)

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what must you do before prescribing a female isotretinoin for severe acne

pregnancy test must be negative

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what are natural sources of vitamin A

liver and leafy veggies

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thiamine pyrophosphate (TPP) is a cofactor for what enzymes

pyruvate dehydrogenase, alpha ketoglutarate dehydrogenase, transketolase, branched-chain ketoacid dehydrogenase

mnemonic for the first 3: ATP (alpha ketoglutarate dehydrogenase, transketolase, pyruvate dehydrogenase)

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what major process is impaired in vitamin B1 deficiency

glucose breakdown

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which tissues are affected first in vitamin B1 deficiency

highly aerobic tissues first: brain and heart

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what two conditions are caused by thiamine deficiency

Wernicke-Korsakoff and beriberi

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how is thiamine deficiency diagnosed

increased RBC transketolase activity after vitamin B1 administration

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what parts of the brain are damaged in Wernicke-Korsakoff syndrome

medial dorsal nucleus of thalamus and mammillary bodies

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what are the symptoms of dry beriberi vs. wet beriberi

dry: polyneuritis, symmetrical muscle wasting
wet: dilated cardiomyopathy, edema

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what is the function of vitamin B2 (riboflavin)

vit B2 serves as a component of FAD and FMN (cofactors for redox reactions

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what results from riboflavin deficiency

cheilosis (inflammation of lips and scaling at corners of mouth), corneal vascularization

what is the function of vitamin B3 (niacin)

component of NAD+ and NADP+, which are used in redox reactions

what amino acid is niacin derived from

tryptophan

niacin synthesis requires what other 2 vitamins

riboflavin (B2) and pyridoxine (B6)

what is niacin used to treat

dyslipidemia (lowers VLDL and raises HDL)

what does niacin deficiency cause

glossitis and pellagra

what are the ways in which pellagra can be caused

Hartnup disease (decreased tryptophan absorption), malignant carcinoid syndrome (GI tumors cause tryptophan metabolism to favor serotonin over niacin), isoniazid (decreased B6)

what are the symptoms of pellagra

diarrhea, dementia (and hallucinations), dermatitis (hyperpigmentation of sun-exposed areas), death (within 4-5 years)

what results from excess niacin

facial flushing (induced by prostaglandin, not histamine), hyperglycemia, hyperuricemia

what is the function of vitamin B5 (pantothenate)

essential component of coenzyme A (CoA) and fatty acid synthase

what results from pantothenate deficiency

dermatitis, enteritis, alopecia, adrenal insufficiency

what is the function of vitamin B6 (pyridoxine)

converted to pyridoxal phosphate, a cofactor used in transamination (e.g. AST, ALT), decarboxylation rxns and glycogen phosphorylase

what important molecules depend on pyridoxine for their synthesis

cystathionene, heme, niacin, histamine, neurotransmitters (5-HT, Epi, NE, dopamine, GABA)

what results from pyridoxine deficiency

convulsions, hyperirritability, peripheral neuropathy, sideroblastic anemias due to impaired hemoglobin synthesis and iron excess

what drugs must pyridoxine be coadministered with to prevent side effect of B6 deficiency

isoniazid and oral contraceptives

what is the function of vitamin B7 (biotin)

cofactor for carboxylation enzymes (pyruvate carboxylase, acetyl-CoA carboxylase, propionyl CoA carboxylase)

how common is biotin deficiency

very rare

what results from biotin deficiency

dermatitis, alopecia, enteritis

what are two causes of biotin deficiency

antibiotic use, excessive ingestion of raw egg whites (avidin in egg whites binds biotin)

what is the function of vitamin B9 (folic acid)

converted to tetrahydrofolate, a coenzyme for methylation reactions and 1-carbon transfer reactions; important for synthesis of nitrogenous bases for DNA and RNA

what are sources of folate and where is folate absorbed in the GI tract

"foliage" (green, leafy veggies); absorbed in jejunum

what results from folate deficiency

macrocytic megaloblastic anemia, hypersegmented PMNs, glossitis, no neurologic symptoms (as opposed to B12)

levels of what molecules are altered with folate deficiency

increased homocysteine, normal methylmalonic acid

when is folate deficiency commonly seen

alcoholism and pregnancy

what drugs can cause folate deficiency

phenytoin, sulfonamides, methotrexate

what function does cobalamin serve

cofactor for homocysteine methyltransferase and methylmalonyl CoA mutase

what are the clinical manifestations of cobalamin deficiency

macrocytic megaloblastic anemia, hypersegmented PMNs; parasthesias, subacute combined degeneration increased serum homocysteine and methylmalonyl CoA

how do humans get cobalamin and how is it synthesized

found in animal products, symthesized only by microorganisms

list the causes of cobalamin deficiency

``` decreased intake (veganism) decreased absorption (sprue, enteritis, diphyllobothrium latum) lack of intrinsic factor (pernicious anemia, gastric bypass surgery) absence of terminal ileum (Crohn's) ```

how do you diagnose pernicious anemia

presence of anti-intrinsic factor antibodies

what are the four functions of ascorbic acid (vitamin C)

1. antioxidant 2. reduces iron to Fe2+ so it can be absorbed 3. hydroxylation of proline and lysine for collagen 4. necessary for dopamine beta-hydroxylase, which converts dopamine to NE