Nutriton Flashcards
Which vitamins are fat soluble?
A, D, E, K
Which vitamins are more likely to cause toxicity and why?
Fat soluble because they distribute into tissue
Who is at risk for fat soluble vitamin deficiencies?
Patients with CF, celiac sprue, or who take mineral oil
What is vitamin A?
An antioxidant used for normal differentiation of epithelial cells to specialized tissue cells
Prevents squamous metaplasia
What is vitamin A used to treat?
AML M3
Measles
What are the signs of deficiency of vitamin A?
Night blindness
Dry skin
What are the signs of vitamin A toxicity?
Arthalgia Fatigue Headache Skin changes Sore throat
What is required before prescribing isoretinoin for acne and why?
A negative pregnancy test and a reliable contraception because vitamin a is teratogenic
What foods contain vitamin A?
Liver and leafy vegetables
What is vitamin B1?
Thiamine pyrophosphate = TPP
What is the function of vitamin B1?
Participates in de carboxylation reactions
Alpha-ketoglutarate dehydrogenase
Transketolase
Pyruvate dehydrogenase
All of the above enzymes are required for ATP synthesis
What happens in the deficiency of vit B1?
There is impaired glucose breakdown –> can’t make ATP –> depletion
Which organs are affected first by B1 deficiency?
Brain and heart ( highly aerobic)
What makes the B1 deficiency worse?
Infusion of glucose
What is wernicke’s syndrome?
Ataxia + ophthalmoplegia + confusion
What is Korsakoff’s syndrome?
Wernicke’s + confabulation, personality change, memory loss
Where is the lesion in wernicke’s-Korsakoff’s?
In the medial dorsal nucleus of the thalamus and the mammillary bodies
What is dry beriberi?
Polyneuritis
Symmetrical muscle wasting
What is wet beriberi?
High output cardiac failure
Edema
Who is at risk for thiamine deficiency?
Alcoholics
People who. Are malnourished
What is the function of vitamin B2?
It is a cofactors in oxidation and reduction reactions
What is vitamin B2?
Riboflavin = FAD and FMN
What are the signs of vitamin B2 deficiency?
Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth)
Corneal vascularization
What is vitamin B3?
Niacin = NAD
What does the synthesis of vit B3 require?
Vit B6
What is the function of vit B3?
Used in redox reactions
Which amino acid is vit B3 derived from?
Tryptophan
What are the signs of vit B3 deficiency?
Glossitis
Pellagra
What is pellagra?
Vit B3 deficiency : diarrhea, dementia, dermatitis, death
What can cause pellagra?
carcinoid syndrome = increased tryptophan metabolism
Hartnup disease = decreased tryptophan absorption
INH = vit B6 deficiency
What are the signs of excess niacin?
Facial flushing
What can niacin be used to treat?
Hyperlipidemia
What is vit B5?
Pantothenate
What is the function of vit B5?
It is a cofactors for acyl transfer (essential component of CoA)
Cofactors for fatty acid synthase
What are the signs of vit B5 deficiency?
Dermatitis
Enteritis
Alopecia
Adrenal insufficiency
What is vitamin B6?
Pyridoxine
What is the function of vit B6?
It is a cofactors for transamination decarboxylation reactions and glycogen phosphorylase.
Needed for the synthesis of cystathionine, heme, niacin, histamine, NTs (serotonin, epi, norepinephrine, GABA)
What are the signs of vit B6 deficiency?
Convulsions
Irritability
Peripheral neuropathy
Sideroblastic anemia
What can vit B6 deficiency be induced by?
INH
Oral contraceptives
What is vit B7?
Biotin
What is the function of biotin?
Cofactor for carboxylation enzymes:
Pyruvate carboxylase
Acetyl-CoA carboxylase
Propionyl-CoA carboxylase
What are the signs of biotin defiency?
Dermatitis
Alopecia
Enteritis
What is biotin deficiency caused by?
Antibiotics
Ingestion of raw eggs
Which vitamin deficiencies cause alopecia?
Vit A, B5, B7
What is vit B9?
Folic acid
What is the function of vit B9?
Converted to THF then coenzyme for 1 carbon transfer/methylation reactions
Important for synthesis of nitrogenous bases in DNA and RNA
What food is vit B9 found in?
Leafy green vegetables
How long do folate reserves last?
Couple of months
What are the signs of float deficiency?
Macrocytic, megaloblastic anemia
What are the causes of folate deficiency?
Alcoholism Pregnancy (increased need) Phenytoin Sulfonamides MTX
What is the most common vitamin deficiency in the US?
Folate
What is B12?
Cobalamin
What is the function of vit B12?
Cofactors for homocysteine methyltransferase and methylmalonyl-CoA mutase
What are the signs of B12 deficiency?
Macrocytic, megaloblastic anemia Peripheral neuropathy Ataxia/falls Spasticity Dementia Hyper segmented PMNs
What are the levels of homocysteine and methylmalonic acid in B12 deficiency?
Both are high
What foods have B12 in them?
Animal products
What can cause B12 deficiency?
Strict vegan diet Sickle cell anemia (increased need) Malabsorption (sprue, enteritis, Diphyllobothrium latum) Pernicious anemia Gastric bypass surgery Chron's disease Resection of the terminal ileum
Where is folic acid absorbed in the gut?
Jejunum
Where is B12 absorbed in the gut?
Ileum
What is SAM?
s-adenosyl methionine = ATP + methionine
What is the function of SAM?
Transfers methyl units
What is SAM required for?
The conversion of NE to epi
What is the regeneration of methionine/SAM dependent on?
Folate and B12
What is vit C?
Antioxidant that facilitates iron absorption by keeping in iron reduced state.
Necessary for hydroxylation of proline and lysine in collagen synthesis. And dopamine b-hydroxylase (converting dopamine to NE)
Ascorbic acid
What does deficiency of vitamin C cause?
Scurvy - swollen gums, bruising, hemarthrosis, anemia, poor wound healing
Weakened immune response
What are the signs of excess vitamin C?
N/v, diarrhea, fatigue, sleep problems
Predisposes to iron toxicity in people with hemochromatosis or transfusions
What is vit D2 and D3?
D2- Ergocalciferol consumed from plants
D3 - cholecalciferol - from milk and sun
What is the storage form of vit D?
25-OH D3
What is the active form of vitamin D?
1,25-(OH)2 = calcitriol
What is the function of vit D?
Increases intestinal absorption of calcium and phosphate
Increases bone mineralization
What does vit D deficiency cause?
Rickets - children, bone pain and deformity
Osteomalacia - adults, bone pain and muscle weakness
Hypocalcemic tetany
What are the signs of excess vit D?
Hypercalcemia
Hypercalciuria
Loss of appetite
Stupor
In what condition is excess vit D seen?
Sarcoidosis from increased activation of vit D by the macrophages
What is vit E?
An antioxidant that protects RBCs from free radical damage
What are the signs of vit E deficiency?
Increased fragility of erythrocytes (hemolytic anemia)
Muscle weakness
Posterior column and spinocerebellar tract demyelination (ataxia, falls, paresthesia)
Who makes B12?
Microorganisms
Where does vit K come from?
Synthesized by intestinal flora
What is the function of vitamin K?
Catalyzes gamma carboxylation of glutamic acid residues on factor II, VII, IX, X, C, S
What enzyme is necessary for the reduction of vitamin K?
Epoxied reductase
What drug antagonizes vit K?
Warfarin blocks epoxied reductase
What are the sx of vit K deficiency?
Neonatal hemorrhage with increased PT and PTT time, but normal bleeding time
What are the causes of vit K deficiency?
New born
Malabsorption (CF, sprue)
Antibiotics
What is the function of Zinc?
Important for function of enzymes and zinc fingers of the transcription factor motif for altering DNA expression
What are the signs of zinc deficiency?
Delayed wound healing Hypogonadism Decreased adult hair Dysgeusia(distortion of taste) Anosmia Increased risk for alcoholic cirrhosis
What are the two enzymes involved in alcohol metabolism?
Alcohol dehydrogenase in the cytosol
Acetaldehyde dehydrogenase in the mitochondria
What is the limiting agent in alcohol metabolism?
NAD - needed to convert ethanol to acetaldehyde and acetaldehyde to acetate
What are the pharmacokinetics by which alcohol dehydrogenase works?
Operates via zero order kinetics
Why do you get hypoglycemia and fatty acid synthesis after alcohol ingestion?
Because NAD is converted to NADH during the metabolism of alcohol. You have so much NADH that the liver starts using it to convert pyruvate to lactate and oxaloacetate to malate. This inhibits gluconeogenesis and stimulates fatty acid synthesis
Why do you get acidosis after alcohol ingestion?
From overproduction of lactate
Ketone body production from depletion of oxaloacetate
Why do you get increased FA synthesis after alcohol ingestion?
From increased NADPH from the breakdown of excess malate