Nutrition Flashcards
What are the different Vitamin B’s?
B1 - thiamine (TPP) B2 - riboflavin (FAD, FMN) B3 - niacin (NAD+) B5 - pantothenic acid (CoA) B6 - pyridoxine (PLP) B7 - biotin B9 - folate B12 - cobalamin
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Vitamin A
Important sources? What important biological processes is it part of? Deficiency symptoms? Excess symptoms? What can Vitamin A be used to treat?
Vitamin A can be found in dark green and yellow vegetables. Beta-cartonene is a pro-Vitamin A molecule that is converted into Vitamin A. It is stored in liver and takes many years to develop deficiency.
Vitamin A is component of rhodopsin, a light-sensing photoreceptor that converts light to neural impulses. It is also important for differentiation of epithelial cells in specialized tissue, so that it plays an role in regulation of keratin and mucous production. Antioxidant properties.
Deficiency can lead to night blindness, corneal degeneration/keratinization, APL (subtype of AML).
Excess can lead to dry skin, alopecia, hepatic toxicity/enlargement.
ATRA/tetrinoin can be used to treat AML by inducing differentiation in malignant cells. Other uses for vitamin A include measles, psoriasis, and acne. Isotretinoin (Accutane) is a derivative that can be used to treat acne but is HIGHLY TERATOGENIC.
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Vitamin C
Important sources? What important biological processes is it part of? Deficiency symptoms? Excess symptoms? What can Vitamin C be used to treat?
Important sources include fruits and vegetables.
Important in conversion of iron from non-heme to heme form (3+ –> 2+), which is important in non-meat consumers/vegans. Also important co-factor in post-translational hydroxylation of proline/lysine residues in collagen synthesis, as well as for conversion of dopamine to NE with dopamine beta-hydroxylase. Antioxidant properties.
Deficiency = scurvy –> swollen gums, easy bruising from weak vessels, petechiae, anemia, poor wound healing
Excess = increased risk for iron overload in predisposed patients and calcium oxalate stone formation (vitamin C can be metabolized to oxalate).
Used for treatment of methemoglobinemia by reducing Fe3+ –> Fe2+.
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Vitamin E
Main biological function?
Deficiency?
AKA tocopherol/tocotrienol
Main biological function is antioxidant by protecting RBCs and membranes from free radical damage.
Deficiency can lead to RBC membranes unprotected from oxidative damage –> hemolytic anemia, acanthocytosis (spiked RBC membranes from damage).
Muscle weakness, posterior column and spinocerebellar tract demyelination leading to ataxia and loss of proprioception/vibration
Least toxic of fat soluble vitamins but high dose supplementation can inhibit Vitamin K, may see increased warfarin effect and therefore enhanced anticoagulant effects –> may see increased INR
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Vitamin K
Sources?
Biological function?
Main clinical scenarios for deficiency?
Lab findings for deficiency?
Two forms of vitamin K:
K1 form from leafy green vegetables
K2 form from GI bacteria–rare for dietary deficiency.
Main biological function is to activate clotting factor precursors from liver. Precursors need to be gamma-carboxylated at the glutamate residues for activation.
Reduced form of vitamin K is cofactor for gamma-carboxylase, and this form can be regenerated from oxidized form with epoxide reductase.
One of the main clinical scenarios for vitamin K deficiency is from warfarin, which is an epoxide reductase inhibitor. Another is in neonates, who have sterile GI at birth and do not have bacteria to synthesize vitamin K.
On labs, would see increased PT/INR, might see increased PTT but less sensitive. Will see NORMAL BLEEDING TIME since platelet function is not affected.
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Zinc
Main sources? Risk factors for deficiency?
Biological function?
Symptoms of deficiency?
Found in meat/chicken and absorbed mostly in duodenum (like iron). Risk factors for deficiency include alcoholism/cirrhosis, chronic renal disease, malabsorption.
Zinc is important cofactor for activity of 100s of enzymes and is also important for formation of zinc fingers (transcription factor motif).
In children, would see poor growth and impaired sexual development (hypogonadism, decreased hair).
In children and adults, would also see the following symptoms:
1) Poor wound healing
2) Altered taste (ageusia, dysgeusia)
3) Immune dysfunction - zinc required for cytokine production
4) Dermatitis (esp. in patients on TPN without supplemental zinc): red skin, pustules
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Acrodermatitis enteropathica
AR mutation in membrane protein that binds zinc for transport and absorption.
Symptoms include immune dysfunction, hair loss, diarrhea, and dermatitis (classically presents periorally and perianally).
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