Biochem - Nutrition (Part 1: Vitamins A and B1-7) Flashcards
Pg. 91-93 in First Aid 2014 Sections include: -Vitamins: fat soluble -Vitamins: water soluble -Vitamin A (retinol) -Vitamin B1 (thiamine) -Vitamin B2 (riboflavin) -Vitamin B3 (niacin) -Vitamin B5 (pantothenate) -Vitamin B6 (pyridoxine) -Vitamin B7 (biotin)
Name the fat soluble vitamins.
A, D, E, K
What do vitamins A, D, E, and K have in common in terms of their classification and absorption?
Fat soluble vitamins; Absorption dependent on gut and pancreas
Is toxicity more common water-soluble or fat-solube vitamins, and why?
Fat-soluble vitamins; Toxicity more common than for water-soluble vitamins because fat-soluble vitamins accumulate in fat
Give at least 3 examples of conditions/contexts that may cause fat-soluble vitamin deficiencies.
Malabsorption syndromes (steatorrhea), such as (1) cystic fibrosis and (2) sprue, or (3) mineral oil intake can cause fat-soluble vitamin deficiencies
Name 9 water soluble vitamins. Give their letter names and full names. Also, where applicable, include important molecules in which they are found.
(1) B1 (thiamine: TPP) (2) B2 (riboflavin: FAD, FMN) (3) B3 (niacin: NAD+) (4) B5 (pathothenic acid: CoA) (5) B6 (pyridoxine: PLP) (6) B7 (biotin) (7) B9 (folate) (8) B12 (cobalamin) (9) C (absorbic acid)
Which water soluble vitamins do not not wash out easily from the body, and why?
All wash out easily from body except B12 and folate (stored in liver)
What are 3 symptoms that often result from B-complex deficiencies?
B-complex deficiencies often result in (1) dermatitis, (2) glossitis, and (3) diarrhea.
What is another name for Vitamin A? Besides being a fat-soluble vitamin, what other kind of property/classification does it have?
Vitamin A (Retinol); Antioxidant
What is a good way to remember the other name for Vitamin A and one of its clinical uses?
Think: “RETINol is vitamin A, so think retin-A (used topically for wrinkles and acne)”
What are 2 sources of Vitamin A (retinol)?
Found in liver and leafy vegetables
What are 3 natural functions of Vitamin A (retinol)?
(1) Constituent of visual pigments (retinal); (2) Essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells); (3) Prevents squamous metaplasia.
What are 2 potentially serious conditions that Vitamin A (retinol) is used to treat?
Used to treat (1) measles and (2) AML, subtype M3.
What are 5 symptoms associated with Vitamin A (retinol) deficiency?
(1) Night blindness (nyctalopia); (2) Dry, scaly skin (xerosis cutis); (3) Alopecia; (4) Corneal degeneration (keratomalacia); (5) Immune suppression.
What are 7 symptoms associated with Vitamin A excess?
(1) Athralgias, (2) Skin changes (e.g., scaliness), (3) Alopecia, (4) Cerebral edema, (5) Pseudotumor cerebri, (6) Osteoporosis, (7) Hepatic abnormalities.
Which fat soluble vitamin is associated with teratogenic effects? What teratogenic effects may it have? What is an important clinical consideration related to this?
Teratogenic (cleft palate, cardiac abnormalities), so a negative pregnancy test and reliable contraception are needed before isotretinoin is prescribed for severe acne.
What is another name for Vitamin B1? In general, what is its function?
Vitamin B1 (thiamine); In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions
What are 4 reactions for which Vitamin B1 (thiamine) functions as a cofactor?
In thiamine pyrophosphate (TPP), a cofactor for several dehydrogenase enzyme reactions: (1) Pyruvate dehydrogenase (links glycolysis to TCA cycle) (2) alpha-ketoglutarate dehydrogenase (TCA cycle) (3) Transketolase (HMP shunt) (4) Branched-chain ketoacid dehydrogenase; Think: “ATP: alpha-ketoglutarate dehydrogenase, Transketolase, and Pyruvate dehydrogenase”
What mechanism occurs in response to Vitamin B1 (thiamine) deficiency? Which tissues are affected first? Give 2 examples of such tissues.
Impaired glucose breakdown => ATP depletion worsened by glucose infusion; Highly aerobic tissues (e.g., brain, heart) are affected first.
What 2 conditions result from Vitamin B1 (thiamine) deficiency? In what other 2 conditions can this deficiency be secondary?
Wernicke-Korsakoff syndrome and beriberi. Seen in malnutrition and alcoholism (secondary to malnutrition and malabsorption). Think: “Spell beriberi as Ber1Ber1 to remember vitamin B1”
How is Vitamin B1 (thiamine) deficiency diagnosed?
Diagnosis made by increase in RBC transketolase activity following vitamin B1 administration.
What 6 symptoms characterize Wernicke-Korsakoff syndrome? What causes it?
Wernicke-Korsakoff syndrome - (1) confusion, (2) ophthalmoplegia, (3) ataxia (classic triad) + (4) confabulation, (5) personality change, (6) memory loss (permanent); Vitamin B1 (thiamine) deficiency; Damage to medial dorsal nucleus of thalamus, mammillary bodies.
What deficiency causes beriberi? What symptoms characterize dry versus wet beriberi?
Vitamin B1 (thiamine) deficiency; DRY BERIBERI - polyneuritis, symmetrical muscle wasting, WET BERIBERI - high-output cardiac failure (dilated cardiomyopathy), edema
What is another name for Vitamin B2?
Vitamin B2 (riboflavin)
What is (are) the major function(s) of Vitamin B2 (riboflavin)? Give a specific example.
Component of flavins FAD and FMN, used as cofactors in redox reactions, e.g., the succinate dehydrogenase reaction in the TCA cycle; Think: “Fad and Fmn are derived from riboFlavin (b2 = 2 atp)”
What are 2 symptoms that result from Vitamin B2 (riboflavin) deficiency?
(1) Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), (2) Corneal vascularization; Think: “the 2 C’s of b2”
What is another name for Vitamin B3?
Vitamin B3 (niacin)
Of what molecules is Vitamin B3 (niacin) a constituent, and in what reactions are such molecules used?
Constituent of NAD+, NADP+ (used in redox reactions); Think: “Nad derived from Niacin (b3 = 3 ATP)”
From what substance is Vitamin B3 (niacin) derived? What does synthesis of Vitamin B3 (niacin) require?
Derived from tryptophan. Synthesis requires vitamins B2 and B6.
What condition is Vitamin B3 (niacin) used to treat, and what effect(s) does it have in this context?
Used to treat dyslipidemia; lowers levels of VLDL and raises levels of HDL
What is a classic symptom of Vitamin B3 (niacin) deficiency? What can be caused by severe B3 deficiency?
Glossitis. Severe deficiency leads to Pellagra (Symptoms of Pellagra: Diarrhea, Dementia [also hallucinations], Dermatitis [e.g., Casal necklace or hyperpigmentation of sun-exposed limbs]); Think: “the 3 D’s of b3”
What are 3 conditions that may cause Pellagra, and what is the mechanism behind each?
Severe deficiency leads to pellagra, which can be caused by (1) Hartnup disease (decrease tryptophan absorption, (2) Malignant carcinoid syndrome (increase tryptophan metabolism), and (3) Isoniazid (decrease vitamin B6)
What are the symptoms of Pellagra?
Symptoms of Pellagra: Diarrhea, Dementia [also hallucinations], Dermatitis [e.g., Casal necklace or hyperpigmentation of sun-exposed limbs]; Think: “the 3 D’s of b3”
What are 2 presentations/examples of the dermatitis associated with Pellagra?
Dermatitis (e.g., Casal necklace or hyperpigmentation of sun-exposed limbs)
What are 3 symptoms of Vitamin B3 (niacin) excess?
(1) Facial flushing (induced by prostaglandin, not histamine) (2) Hyperglycemia (3) Hyperuricemia
What causes the facial flushing associated with Vitamin B3 (niacin) excess?
Facial flushing (induced by prostaglandin, not histamine)
What is another name for Vitamin B5?
Vitamin B5 (pantothenate); Think: “b5 is ‘PENTO’ thenate”
What is the function of Vitamin B5 (pantothenate)?
Essential component of coenzyme A (CoA, a cofactor for acyl transfers) and fatty acid synthase
What are 4 symptoms of Vitamin B5 (pantothenate) deficiency?
(1) Dermatitis (2) Enteritis (3) Alopecia (4) Adrenal insufficiency
What is another name for Vitamin B6?
Vitamin B6 (pyridoxine)
To what is Vitamin B6 (pyridoxine) converted, and in what 3 processes is this a cofactor?
Converted to pyridoxal phosphate, a cofactor used in transamination (e.g., ALT and AST), decarboxylation reactions, glycogen phosphorylase.
What are 9 substances synthesized using Vitamin B6 (pyridoxine)?
Synthesis of (1) cystathionine, (2) heme, (3) niacin, (4) histamine, and neurotransmitters including (5) serotonin, (6) epinephrine, (7) norepinephrine, (8) dopamine, and (9) GABA
What are 4 symptoms of Vitamin B6 (pyridoxine) deficiency?
(1) Convulsions, (2) Hyperirritability, (3) Peripheral neuropathy (deficiency inducible by isoniazid and oral contraceptives), (4) Sideroblastic anemias due to impaired hemoglobin synthesis and iron excess
What are 2 medications that may induce Vitamin B6 (pyridoxine) deficiency?
Convulsions, Hyperirritability, Peripheral neuropathy (deficiency inducible by [1] isoniazid and [2] oral contraceptives), Sideroblastic anemias due to impaired hemoglobin synthesis and iron excess
What is another name for Vitamin B7?
Vitamin B7 (biotin)
What are the 3 major enzymes and their reactions for which Vitamin B7 (biotin) serves as a cofactor? In general, what do all of these reactions accomplish?
Cofactor for carboxylation enzymes (which add a 1-carbon group): (1) Pyruvate carboxylase: pyruvate (3C) => Oxaloacetate (4C) (2) Acetyl-CoA carboxylase: Acetyl-CoA (2C) => Malonyl-CoA (3C) (3) Propionyl-CoA carboxylase: Propionyl-CoA (3C) => Methylmalonyl-CoA (4C)
How common is Vitamin B7 (biotin) deficiency?
Relatively rare
What are 3 symptoms associated with Vitamin B7 (biotin) deficiency?
(1) Dermatitis (2) Alopecia (3) Enteritis
What are 2 causes of Vitamin B7 (biotin) deficiency?
Caused by (1) antibiotic use or (2) excessive ingestion of raw egg whites; Think: “AVIDin in egg whites AVIDly binds biotin”
