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My DEMS 3 > Water soluble vitamins --review with handout > Flashcards

Water soluble vitamins --review with handout Flashcards

1
Q

Water soluble vitamins

A

Generally not “stored” in body (B12 = exception)
Chronic intakes DO alter tissues levels
Toxicity usually low (B6 = exception)
Absorption usually high
Excretion typically via urine (once tissue levels saturated)
Breast milk reflects maternal intake/status (folate = exception)

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2
Q

6 mo old breastfed infant, vomiting, ophthalmoplegia, congestive heart failure

A

thiamine def (beri-beri)(ophtalmoplegia and CHF)

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3
Q

5 yr old child only eats burgers (w/ bun) & milk, now limping & refusing to walk, ~ rash

A

Vit C def (scurvy)

-often presents w/ not walking

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4
Q

Alcoholic, “found down”, altered mental status, anemic

A

?B12, thiamine, folate

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5
Q

15 mo old breastfed infant, growth faltering, no longer walking; mom with dietary “limitations”

A

-B12 (mom w/ dietary limitations)

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6
Q

Obese adolescent, s/p bariatric surgery, can’t walk; falls down

A

B12

thiamine

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7
Q

Adult, low SES, chronic diarrhea/malabsorption, rash on arms, hands, neck

A

Pellagra

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8
Q

Thiamin (B1), Riboflavin (B2), Niacin (B3) (energy releasing B complex vit)

A

Functions:

  • All involved in glycolysis/Krebs cycle
  • TPP, FAD, NAD; decarboxylation, oxidation-reduction

Food sources: whole & enriched grains
Thiamin: pork, legumes; (decreased in polished rice)
Riboflavin: dairy, eggs, meats
Niacin: meat/poultry; tryptophan = precursor

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9
Q

Thiamin (B1) Deficiency

A

Beriberi - nervous & cardiovascular systems
-“Dry:” peripheral neuropathy; muscle tenderness (esp legs), weakness & atrophy; foot drop; eventual inability to walk w/o falling

-“Wet:” edema, circulatory collapse, congestive heart failure

Wernicke-Korsakoff (cerebral): confusion, ophthalmoplegia, ataxia, memory loss (complete correction 25%; partial 50%)

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10
Q

Risk for Thiamin Deficiency

A

Alcoholics
s/p bariatric surgery (esp 1st 6 mo post-op; associated w/ vomiting)
TPN (total parenteral nutrition), w/o thiamin(deficiency occurs w/in 2-3 wk)
Anorexia nervosa
Re-feeding
Endemic in So Asia (maternal & BF infant) – polished rice diet

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11
Q

Infantile beriberi

A 
Infant formula w/o thiamin
infants  (2-12 mo) present w/:
Infection
Vomiting
Lethargy/restlessness
Ophthalmoplegia
Low thiamine pyrophosphate, acidosis
Prompt response to high dose (50 mg/d x 2 wk)
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12
Q

Riboflavin (B2) deficiency

A
  • low dairy, animal products
  • cheilosis (lips cracked, looks like sores)
  • angular stomatitis (around mouth)
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13
Q

Niacin (B3) deficiency

A

-Pellagra
Predisposing factors:
Nutritional/dietary restriction
Cornmeal (w/o germ) based diet (esp historically)
Food faddism / restriction (eg, rice diet)
Breastfed infant of deficient mother
Malabsorption syndromes
Alcoholism
Metabolic “shunting” (carcinoid tumor –> ↑ serotonin –> decreased tryptophan)

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14
Q

Pellagra 4Ds

A

Diarrhea
Dermatitis:
symmetric, scaling w/ areas depigmentation & hyperpigmentation
aggravated by sun exposure (“Casal’s necklace”)
Dementia:
confusion, dizziness, hallucination
Death

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15
Q

B complex Vitamins: Hematopoietic

A

folate

B12

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16
Q

Folic Acid

A

Functions: single C transfers
nucleic acid synthesis
amino acid metabolism
DNA Methylation - epigenetics

Food sources:	“foliage,” deep green veg
orange juice
whole grains
(Grains enriched in US since 1998)
(Easily destroyed in prolonged cooking)
17
Q

Situations with Risk of folate deficiency

A

Inadequate intake or increased destruction in food
Alcoholics
Pregnancy – globally, high rates deficiency; WHO: routine supplementation, women of reproductive age

Hematopoietic conditions
Drug/nutrient interactions

18
Q

Signs/sx of folate deficiency

A

*Macrocytic anemia
*Hypersegmented neutrophils
*Glossitis, irritability
*Homocysteinemia
Neural tube defects (occurrence/recurrence)

  • Reversible with correction of deficiency
19
Q

Folate intake for women

A

Women of child bearing age advised to have intake of 400-800 microgr/day* to prevent neural tube defects (spina bifida, anencephaly)
-Recurrence
-Occurrence
Neural tube closes by 4-6 wk gestation - before most women realize they are pregnant
(Currently ~30-50% of women in US consume enough from diet or take supplements)

NTD risk also increased with MTHFR gene variants

20
Q

Vit B12 (cobalamin) function

A

Functions:
Reform tetrahydrafolate from methylfolate (synthesis of methionine)
Catabolism of odd chain length fatty acids
Catalyze isomerization of methylmalonyl Co-A to succinyl Co-A (lipid & CHO metabolism)

Metabolism intimately related to folate
One carbon transfers (methylation)
Interactions essential for homocysteine –> methionine, protein synthesis, nucleic acid syn

21
Q

Vit B12 Absorption

A

Cleave vitamin from dietary protein in stomach
Requires Intrinsic Factor from stomach
Cobalamin-IF absorbed in distal ileum
Transport in circulation: Transcobalamin II

22
Q

Vit B12: absorption, storage, excretion

A

Enterohepatic circulation
Large liver stores
Excretion: primarily via bile

23
Q

Dietary sources and requirements of Vit B12

A 
Food Sources:
Synthesized by soil bacteria
Found only in animal products
Requirements:
Long term storage & supply
Increased requirements if  decreased absorption/reabsorption
Vegans should take a supplement
24
Q

Vit B12 Deficiency

A

Risk factors/situations:
Inadequate IF secretion or antibodies to IF
Gastric atrophy/gastrectomy
Ileal resection
Breastfed infant of B12 deficient vegan mother

Effects:
Macrocytic anemia & hypersegmented neutrophils (just like with folate deficiency)
***Neurologic disturbances: depression, paresthesias, gait disturbances, burning tongue, dizziness

Hematological effects are reversible w/ B12 or folate Neurological effects eventually irreversible

Megaloblastic anemia should not be treated w/ folate unless have ruled out Vitamin B-12 deficiency

25
Q

Vitamin C (ascorbic acid): func/role

A

Reversible antioxidant, Vitamin E sparing
Provides reducing equivalents to enzymes:
Reduction of iron –> increased absorption
Leukocyte function (increased [AA] wbc)

Co-substrate in hydroxylation:
Collagen synthesis: hydroxylation of proline & lysine; cross-links for tropocollagen
Hydroxylation of tryptophan –> serotonin

Conversion dopamine –> norepinephrine

26
Q

Food Sources for Vit C

A 
Fruits and vegetables
 Contributions by food group in U.S.:
39% fruits
15% potatoes
38% other vegetables

Not in: grains, meat, dairy

27
Q

Absorption of Ascorbic acid

A 
Active (saturable) process
Low intake:  ~ 100%
Typical intakes (30-180 mg/d): 70-90%
Megadoses: 
1 - 1.5 g/d: ~ 50%
> 10  g/d:	15%

If taking large doses, better absorption if take in divided doses (80 mg/d leads to increased urine excretion
Intakes of 400-500 mg leads to no increased plasma [AA]

28
Q

Vit C Deficiency: Scurvy

A

Hemorrhagic signs:
Bleeding gums, ecchymoses, petechiae
Hyperkeratosis of hair follicles + perifollicular hemorrhages
Hypochondriasis: depression, weakness
Hematologic abnormalities
Anemia: iron &/or folate deficiencies, bleeding
Progression: weakness, aching joints/bones/muscles, hemorrhagic signs

29
Q

When do you often see scurvy in kids?

A

-autistic kids on restricted diets (rash, gingival hypertrophy, bruises)

30
Q

Benefits of “megadoses” of Vit C

A

Prevention/treatment of common cold?
antihistamine effects
neutrophil chemotaxis;  duration symptoms
Prevention of CVD, Ca?
RCT do not support
Fruits & vegetables
Wound healing: inflammation, proliferation, maturation

My DEMS 3 (19 decks)

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