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NTRN 364 > Final Study Guide > Flashcards

Final Study Guide Flashcards

1
Q

What are the primary flavoenzymes riblofalvin makes? What is the predominate form?

A

-FAD: Flavin Adenine Dinucleotide; predominate form, complex with flavoproteins
-FMN: Flavin Mononucleotide

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2
Q

What are the roles of flavoenzymes?

A

-Energy production, metabolism of macronutrients, activation of vitamins

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3
Q

What are the properties of Riboflavin?

A

-upon exposure to light-very sensitive to destruction
-very heat stable, very bitter taste for supplements, produces green urine

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4
Q

Where are the best sources of riboflavin? Is there better absorption from animal or plant sources?

A

-Meat(pork), milk, eggs, broccoli, enriched grains/whole grains
-animal sources =better absorption

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5
Q

What is the Adult RDA for Riboflavin?

A

1.1 mg/d for females, 1.3 mg/d for males
Needs are related to protein status; catabolism of body protein causes loss of riboflavin
No UL

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6
Q

Describe the digestion of riboflavin

A

-Deitary fiboflavin is mainly tightly bound to protein as FAD or FMN
-Step 1: FAD and FMN released from food protein by stomach acid
-Step 2: FAD, FMN readily converted to free vitamin and vice versa
- Step 3: Once in free form, it absorbed across enterocyte and into intestinal mucosa as free vitamin. Once there, flavokinases rephosphorylate, then transported to the blood by riboflavin transporters (RFTS); by passive diffusion when dietary intake is high

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7
Q

Describe Riboflavin absorption

A

-Taken to liver: fate determined here
-Riboflavin is converted into FMN and FAD in cell cytoplasm
-conversion can occur in liver, small intestines, heart, kidney

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8
Q

Describe Ribolfavin excretion

A

-riboflavin in excess of need is primarily excreted in the urine
-very little is stored in body tissue
-most excreted as free ribofalvin
-rate of excretion varies with age, metabolic events and dietary intake

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9
Q

What are the different approaches to urinary riboflavin excretion assessment?

A

-Total riboflavin excreted (nmol or ug) and total creatinine excreted(g)

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10
Q

What is the preferred assessment method for riboflavin

A

-Erythrocyte glutathione reductase activity coefficient (EGRAC)-functional assessment

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11
Q

What is used for recent dietary intake of riboflavin

A

-plasma riboflavin is reflective of recent dietary intake

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12
Q

Why measure erthrocyte glutathione reductase activity coefficient

A

-Riboflavin also plays role in fighting oxidative stress, FAD co-factor for glutathione reductase

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13
Q

What is the presentation in riboflavin deficiency

A

-Anorexia, sore throat
-affects conversion of B6 to coenzymes
-angular stomatitis(sore mouth)
-seborrheic dermatitis
-peripheral neuropathy
-cheilosis (inflammation, small cracks)
-glossitis (magenta tongue)

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14
Q

What are the causes of riboflavin deficiency

A

-poor intake, lactose intolerance, malabsorption, inborn error of metabolism, destruction during phototherapy, phenobarbital use-longterm increased excretion, catabolic patients with nitrogen losses-increases excretion, increased requirement (infection, malnutrition)

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15
Q

What are the individuals at risk for primary deficiency of riboflavin

A

-alcoholics are at increased risk for riboflavin deficiency
-individuals with achlorohydria
-anorexic individuals may not consume enough riboflavin
-lactose intolerant individuals may not consume milk

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16
Q

What are the things that can cause a secondary deficiency of riboflavin

A

-malabsorption (celiac disease and alcoholism)
-individuals has acholohydria or absence of stomach acid( need acidity to release vitamin from protein bound foods)
-G-6-Phosphate dehydrogenase deficiency is a rare genetic disease that accelerated use of riboflavin

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17
Q

What are drugs that interfere with riboflavin

A

-anti-malarial medication, cancer chemotherapy agents, anti-psychotic and antidepressant medications
-long term use of anticonvulsants may increase destruction of riboflavin by liver enzymes

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18
Q

What is niacin?

A

-generic term for nicotinic acid and any derivative having biologic activity of nicotinic acid and nicotin-amide
-nicotinic acid and nicotin-amide are both stable compounds
-all tissues synthesize either acid or amide form

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19
Q

What are niacin rich foods and what form is with what foods

A

-Plant-based food (nuts, legumes, and grains)-form is mostly nicotinic acid
-animals foods (poultry, beef, and fish)-form is as nicotinamide
-fortified flours and cereals
-animal protein foods provide tryptophan

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20
Q

What are the factors that affect the Bioavailibility of Niacin

A

-even though widely distributed in food, niacin has low BA due to being so tightly bound

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21
Q

What is used for status assessment of Niacin?

A

-Urine

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22
Q

What is the deficiency of Niacin called? Describe it, how can it be prevented

A

-Pellagra; 4 Ds (diarrhea, dementia, dermatitis, death (50-60 days)
-decreased appetite and weight
-see inflammation of intestinal muscosa, vomiting, dysphagia, confusion, disorientation, hallucination, memory loss, pychoses
-prevented with an adequate protein diet

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23
Q

What are the risk factors for Pellagra?

A

-diets high in (untreated) corn and poor in animal protein sources (protein of low biological quality)
-hartnup disease
-alcholics
-malabsorption diseases like Crohn’s disease

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24
Q

What are the toxicity symptoms at pharmacological doses of Niacin

A

-vomiting and nausea, liver toxicity, vasodilatory effects(burning, flushing, tingling, itching)

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25
Q

Pathenoic Acid is needed for synthesis of

A

-Coezyme A (CoA) and Acyl Carrier Protein (both involved in fatty acid metabolism)

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26
Q

What are some rich sources of Pathenoic Acid?
What can affect the sources?

A

-Beef, Bran (100%), Broccoli(raw), Cashew notes, liver, eggs(hard-boiled), Chicken, Rice
- can be destroyed with heating and freezing; refining grains

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27
Q

Most dietary sources (85%) of Pathenoic acid are in the form of

A

-CoA and phosphopantetheine

28
Q

How is Pathenoic acid absorbed?

A

-PA is absorbed via sodium-dependent multivitamin transporter (SMVT) into enterocyte and into bloodstream via saturable, sodium-dependent active transport mechanism
-passive diffusion may occur at high concentrations

29
Q

What is used to assess Pathenoic acid levels?

A

-Urinary PA reflects best association with body status
-Whole Blood PA also correlates well with dietary intake but more challenging to assay.

30
Q

Symptoms of Pathenoic acid deficiency is difficult to identify because

A

-PA deficiency is often accompanied with deficiencies in other vitamins

31
Q

What is the main symptom of Pathenoic acid deficiency?

A

-Parathesia(burning/prickling sensation) thought to be main symptom referred to as “burning feet syndrome”

32
Q

What rare genetic disorder results in Pathenoic acid deficiency?

A

-PKAN is a rare, genetic movement disorder due to mutation of PANK2 gene, which results in deficiency of pantothenate kinase(PanK)
-PKAN is characterized by dystonia (movement disorder), parkinsonism(tremor and postrural instability) and iron accumulation in the brain

33
Q

What are the main functions of Pantothenic Acid?

A

-Helps convert food into useable energy, helps make and break down fats, helps make cholesterol, steroid hormones, neurotransmitters and hemoglobin
-helps the liver break down certain drugs and toxins

34
Q

What is another name for Pantothenic Acid?

A

-Vitamin B5

35
Q

What is another name for Riboflavin?

A

-Vitamin B2

36
Q

What is another name for Niacin?

A

-Vitamin B3

37
Q

What are some foods that are high in Biotin?

A

-organ meets, eggs, fish, meat, seeds, nuts and certain vegetables

38
Q

Describe the digestion of Biotin

A

-Biotin is highly bioavailable, once released from being bound in food
-most biotin in meats and cereals are protein bound
-GI proteases an dpeptidases break down protein-bound biotin into biocytin and biotin-ogliopeptides
-These are then broken down by biotidinase to form free biotin

39
Q

Biotin can be synthesized

A

-intestinally and absorbed from food

40
Q

How is Biotin transported?

A

-free biotin via sodium dependent multivitamin transported (SMVT) which is upregulated in deficiencies

41
Q

How is biotin absorbed?

A

-In Jejunum, both free biotin and biocytin absorbed via passive diffusion at high concentrations

42
Q

What are the functions of Biotin?

A

-Biotin is an essential cofactor for 4 carboxylases: Acetyl CoA carboxylase (ACC). Pyruvate Carboxylase(PC), Methylcrotonyl CoA Carboxylase (MCC), Propionyl CoA Carboxylase (PCC)

43
Q

How can you assess Biotin status?

A

-Plasma and urinary excretion of 3-hydroxyl-isovaleryl caritine and its derivative 3-hydroxyisovaleric acid in urine

44
Q

What are some Secondary deficiency risk factors of biotin deficiency?

A

-Biotinidase deficiency(genetic), certain medications(anti-convulsants) and longterm antibiotics, chronic alcohol exposure, preganant and breastfeeding women, consumption of raw egg whites consistently
-Total parenteral nutrition (TPN) solutions lacking biotin

45
Q

What are the biotin deficiency issues in infants

A

-Clinical biotin deficiency: baby breastfed deficient or biotin malabsorption
-function biotin deficiency: due to inborn errors of metabolism

46
Q

What are the signs of Biotin deficiency

A

-Periorificial dermatitis (aorund mouth), conjunctivitis (pink eye), alopecia (hair loss), ataxia, developmental delay

47
Q

What is another name for Biotin?

A

-Vitamin B7

48
Q

What are the main functions of Biotin?

A

-helps convert food into usable energy
-helps make glucose

49
Q

What is the family of vitamers B6 refers to

A

-pyridoxal/PL; Pyridoxine/PN; Pyridoxamine/PM

50
Q

What are the active coenzyme forms of pyridoxal and pyridoxamine

A

-PLP/pyridoxal phosphate and PMP/pyridoxamine phosphate

51
Q

What are the major forms found in animal tissues and plant derived foods for vitamin B6

A

-animal; PLP and PMP
-plant; PN and PNP

52
Q

What is the bioavailability of B6

A

-75 percent in mixed diet, absorption similar with or without food

53
Q

Give examples of B6 food sources

A

fortified breakfast cereals, salmon, potato baked with skin, banana, hazelnuts, chicken
-non-citrus fruits
-starchy vegetables

54
Q

What are the functions of B6 and what is the main coenzyme?

A

-Functions: metabolism of amino acids, one-carbon units, and lipids, gluconeogenesis, heme bio synthesis, neurotransmitter synthesis
-PLP is the main coenzyme

55
Q

How do you assess vitamin B6 status?

A

-Use more than 1 assessment due to so many factors impacting status biomarkers
-test urine and plasma PLP

56
Q

What can effect plasma PLP?

A

-protein intake, smoking, pregnancy, renal disease, sickle cell anemia, intense aerobic exercise

57
Q

Who are at most risk of deficiency of B6?

A

-alcoholics due to low dietary intake and impaired metabolism of the vitamin

58
Q

What are symptoms of B6 deficiency?

A

-Signs similar to pellagra, seborrheic dermatitis, microcytuc anemia due to decreased red blood cell (rbc) synthesis
-convulsions related to its role as a coezyme for neurotransmitter synthesis(not found in free living population)
-depression, confusion, impaired platelet funcion and clotting

59
Q

Is there an UL for B6?

A

-yes, UL 100mg
-painful and disfiguring dermatologic lesions and sensory neuropathy

60
Q

What is the UL of Folate and why?

A

-The UL is about 1000 mcg/day, based on masking vitamin B12 deficiency

61
Q

What are the main functions of Folate?

A

-Required for DNA synthesis, supports cell growth and repair, helps prevent neural tube defects

62
Q

What are good sources of folate?

A

-Legumes(lentils, peas, beans cooked), Green leafy vegetables (spinach cooked), Fortified food and supplements (enriched sliced bread)

63
Q

What B vitamin is folate?

A

-B9

64
Q

What are the main functions of B12?

A

-Helps make red blood cells, required for proper nerve function, helps maintain normal levels of homocysteine in the blood

65
Q

What are good sources of Vitamin B12?

A

-Seafood(shellfish, fish, clams(steamed), turkey (roasted), Red meat(lean beef plate)

66
Q

What is another name for B12?

A

-Cobalamin

NTRN 364 (7 decks)

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