Nutrition

Question 1

Name vitamin B1

Answer 1

Thiamine: TPP (precursor organic cofactor)

Question 2

Name vitamin B2

Answer 2

Riboflavin: FAD, FMN (precursor organic cofactor)

Question 3

Name vitamin B3

Answer 3

Niacin: NAD+ (precursor organic cofactor)

Question 4

Name vitamin B5

Answer 4

Pantothenic acid : CoA (precursor organic cofactor)

Question 5

Name vitamin B6

Answer 5

Pyridoxine: PLP (precursor organic cofactor)

Question 6

Name vitamin B7

Answer 6

Biotin

Question 7

Name vitamin B9

Answer 7

Folic acid

Storage 3-4 months (liver)

Question 8

Name vitamin B12

Answer 8

Cobalamin

Storage 3-4 years (liver)

Question 9

Name vitamine C

Answer 9

Ascorbic acid (coenzyme)

Question 10

Fat soluble vitamins

Answer 10

ADEK

Deficit in malabsorption diseases : cystic fibrosis, celiac disease; mineral oil intake

Question 11

Vitamin A function

Answer 11

Antioxydant
Constituent of visual pigments
Essential normal differenciation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells)
Prevents squamous metaplasia
Treat measles (rougeole)
Treat acute promyelocytic leukemia (trans-retinoic acid)
Treat acne (isotretinoin)

Found in liver, leafy vegetables

Question 12

Vitamin A deficiency

Answer 12

Night blindness (nyctalopia)
Dry, scaly skin (xerosis cutis)
Corneal degeneration (keratomalacia) and dryness
Bitot spots (keratin -> white) on conjunctiva
Immunosuppression

Question 13

Vitamin A excess

Answer 13

Acute toxicity : N, V, vertigo, blurred vision
Chronic toxicity : alopecia, dry skin, hepatic toxicity and enlargement, arthralgia, pseudotumor cerebri
Teratogenic : cleft palate, cardiac abnormalities (b-hCG negative + 2 forms of contraception if isotretinoin)

Question 14

Vitamin B1 function

Answer 14

Thiamine pyrophosphate (TPP) = cofactor dehydrogenase enzyme reactions:

• pyruvate dehydrogenase (links glycolysis to Krebs)
• alpha-ketoglutarate dehydrogenase (Krebs)
• transketolase (HMP shunt)
• branched-chained ketoacid dehydrogenase

Question 15

Vitamine B1 deficiency

Answer 15

Impaired glucose breakdown -> ATP depletion worsened by glucose infusion. High aerobic tissues (brain, heart) affected first

Dx: raised RBC transketolase after B1 given

In alcoholic or malnourished patients, give thiamine before dextrose to reduce risk of Wernicke-Korsakoff -> damage in medial dorsal nucleus of thalamus and mammillary bodies:

• Confusion + Ophtalmoplegia + Ataxia )classic triad)
• Confabulation
• Personality change, permanent memory loss

Dry beriberi: polyneuritis, symmetrical muscle wasting

Wet beriberi: high-output cardiac failure (dilated cardiomyopathy), edema

Question 16

Vitamin B2 function

Answer 16

Component of flavins FAD + FMN, cofactors in redox reactions (ex: succinate dehydrogenase in Krebs)

Question 17

Vitamin B2 deficiency

Answer 17

Cheilosis (inflammation lips, scaling and fissures corners mouth)
Corneal vascularization

Question 18

Vitamin B3 function

Answer 18

Constituent of NAD+, NADP+ used in redox reactions.
B3 synthesis using B2 and B6 derives from tryptophan (AA).
Treat DLPD : reduce VLDL, raises HDL

Question 19

Vitamin B3 deficiency

Answer 19

Glossitis

Severe -> pellagra:
Diarrhea, Dementia (hallucination), Dermatitis, hyperpigmentation of sunexposed limbs, C3/C4 circumferential broad collar rash (casal necklace)

DDx pellagra:

• B3 deficiency
• Hartnup disease
• Malignant carcinoid syndrome (raises tryptophan metabolism)
• Isoniazid (reduces B6)

Question 20

Hartnup disease

Answer 20

Autosomal recessive

Deficiency in neutral AA (tryptophan) transporters in TCP and enterocytes -> neutral aminoaciduria and reduced absorption from gut -> reduced conversion of tryptophan to niacin -> pellagra-like symptoms

Tx: high-protein diet and nicotinic acid

Question 21

Vitamin B3 excess

Answer 21

Facial flushing (induced by Pg, not histamine; avoidable by taking ASA with niacin)
Hyperglycemia
Hyperuricemia

Question 22

Vitamin B5 function

Answer 22

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

Question 23

Vitamin B5 deficiency

Answer 23

Dermatitis, enteritis, alopecia, adrenal insufficiency

Question 24

Vitamin B6 function

Answer 24

Converted to pyridoxal phosphate (PLP) -> cofactor in transamination (ALT, AST), decarboxylation reactions, glycogen phosphorylase

Synthesis of cystathionine, heme, niacin, histamine, NT (5-HTP, epinephrine, NE, dopamine, GABA)

Question 25

Vitamin B6 deficiency

Answer 25

Convulsions, hyperirritability, peripheral neuropathy, sideroblastic anemias (impaired Hb synthesis) and iron excess) Inducible by isoniazid and COC

Question 26

Vitamin B7 function

Answer 26

Cofactor for carboxylation enzymes (add 1 carbon group): | pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase

Question 27

Vitamin B7 deficiency

Answer 27

Rare. Caused by ATB use or excessive ingestion of raw egg whites Dermatitis, alopecia, enteritis.

Question 28

Vitamin B9 function

Answer 28

Converted to tetrahydrofolic acid (THF), coenzyme for 1-carbon transfer/methylation reactions Important for synthesis of nitrogenous bases in DNA and RNA (nucleosides) Found in leafy green vegetables. Absorption in jejunum.

Question 29

Vitamin B9 deficiency

Answer 29

Most common in USA. Seen in ROH, pregnancy, elderly Macrocytic, megaloblastic anemia Hypersegmented PMN Glossitis No neurologic symptoms Dx : raised homocysteine, normal methylmalonic acid

Question 30

Vitamin B12 function

Answer 30

Cofactor for methionine synthase and methymalonyl-CoA -> important for DNA synthesis Found in animal products. Synthesized by microorganisms.

Question 31

Vitamin B12 deficiency

Answer 31

Etiology: malabsorption (sprue, enteritis, dephyllobothium labum), lack of intrinsic factor (pernicious anemia, gastric bypass surgery), absence of terminal ileum (surgical resection), insufficient intake (vegan). Sx: macrocytic, megaloblastic anemia hypersegmented PMN Paresthesia Subacute combined degeneration due to abnormal myelin (dorsal columns, lateral corticospinal tracts and spinocerebellar tracts) If prolonged -> irreversible nerve damage Dx : anti-intrinsic factor Ac for pernicious anemia Raisez homocysteine and methylmalonic acid levels

Question 32

Vitamin C function

Answer 32

Antioxydant Facilitates iron absorption by reducing Fe2+ state Necessary for hydroxylation of proline and lysine in collagen synthesis Necessary for dopamine b-hydroxylase that converts dopamine to NE Found in fruits and vegetables Ancillary treatment for methemoglobinemia by reducing Fe3+ to Fe2+

Question 33

Vitamin C deficiency

Answer 33

Scurvy : swollen gums, bruising, petechiae, hemarthrosis, anemia, poor wound healing, perifollicular and subperiostal hemorrhages, corkscrew (tire bouchon) hair

Question 34

Vitamin C excess

Answer 34

N, V, D, fatigue, calcium oxalate nephrolithiasis Raises risk of iron toxicity in predisposed individuals (hemochromatosis, transfusions)

Question 35

Vitamin D function

Answer 35

GI absorption of calcium and phosphate Raises bone mineralization at low levels Raises bone resorption at high levels

Question 36

Vitamin D deficiency

Answer 36

Ricketts in children : deformity genu varum Osteomalacia in adults : bone pain and muscle weakness Hypocalcemic tetany FR: prematurity, pigmented skin, low sun exposure

Question 37

Vitamin D excess

Answer 37

Hypercalcemia, hypercalciuria, loss of appetite, stupor

Question 38

Vitamin E function

Answer 38

Antioxydant (protects RBC and membranes from free radical damade) High dose might affect vit K metabolism (enhanced ACO effect of warfarin)

Question 39

Vitamin E deficiency

Answer 39

Hemolytic anemia, acanthocytosis, muscle waekness, posterior column and spinocerebellar tract demyelination Similar to B12 but without megaloblastic anemia/hypersegmented PMN, and raised methylmalonic acid

Question 40

Vitamin K function

Answer 40

Cofactor on various proteins required for blood clothing (X, IX, VII, II, protein C and S) Synthetized by intestinal flora Inhibited by warfarin

Question 41

Vitamine K deficiency

Answer 41

Neonatal hemorrhage with raised PT, aPTT but normal bleeding time (sterile intestines) Can also occur after prolonged broad spectrum ATB use

Question 42

Zinc function

Answer 42

Essential for activity of > 100 enzymes and formation of zinc fingers

Question 43

Zinc deficiency

Answer 43

``` Delayed wound healing Hypogonadism Reduced adult hair (axillary, facial, pubic) Dysgeusia Anosmia Acrodermatitis enteropathica May predispose to alcoholic cirrhosis ```

Question 44

Kwashiorkor

Answer 44

Protein malnutrition: - skin lesions - edema (reduced oncotic pressure) - liver malfunction (fatty change because reduced apolipoprotein synthesis) - swollen abdomen ``` M alnutrition E dema A nemia L iver (fatty) S kin lesions (hyperkeratosis, hyperpigmentation) ```

Question 45

Marasmus

Answer 45

Malnutrition not causing edema. Diet deficient in calories but no nutrient is entirely missing Muscle wasting (like dry beriberi)